Method for preparing biomass-based hard carbon material under assistance of oil gas and application of biomass-based hard carbon material

Abstract

The invention relates to the technical field of energy storage materials and batteries, in particular to a method for preparing a biomass-based hard carbon material under the assistance of oil gas and application of the biomass-based hard carbon material. According to the invention, grease micromolecules are used as a deposition carbon source, and a high-temperature carbonization product is obtained by calcining in an inert atmosphere through CVD-like deposition, so that the hard carbon negative electrode material is prepared. Under the heating condition, grease small molecules can be quickly gasified and converted to form gaseous carbon source species such as carbon-containing free radicals, small molecule alkane or olefin, and under the driving of inert carrier gas, the gaseous grease carbon source can be efficiently diffused and deeply permeated into internal micropores of the biomass substrate, so that the carbon source is formed. The firm adsorption of the carbon source species on the surfaces of the pore walls is realized by virtue of Van der Waals force and pi-pi conjugate interaction between functional groups such as hydroxyl and carboxyl on the surfaces of the pore walls of the biomass and the carbon source species.

Description

Technical Field

[0001] This invention relates to the fields of energy storage materials and battery technology, specifically to a method and application of oil and gas-assisted preparation of biomass-based hard carbon materials. Background Technology

[0002] Hard carbon possesses advantages such as low operating potential and abundant raw material reserves, making it the most promising anode material for high-energy-density sodium-ion batteries. Composed of randomly dispersed graphene layers, hard carbon provides numerous sodium storage sites, thus exhibiting a very high theoretical sodium storage capacity. Currently, chemical vapor deposition (CVD), as a mature material synthesis technology, has become a key means of controlling the microstructure of carbon materials due to its core advantages of "gas-phase precursor-directional deposition-controllable structure". However, existing CVD-based hard carbon preparation technologies still have key bottlenecks that severely restrict their large-scale green applications: the selection of carbon sources is limited to organic compounds such as benzene, acetylene, and toluene. These carbon sources have the characteristics of being highly toxic, volatile, flammable, and explosive (Reference: Filling carbon: a microstructure-engineered hard carbon for efficient alkalimetal ion storage. Energy Environ. Sci. 2023,16, 4041-4053). In industrial production, complex sealing and exhaust gas treatment equipment are required, increasing production costs and safety risks, which contradicts the current "dual carbon" goals and green manufacturing trends, and exacerbates the environmental burden of the process. Patent CN120157111A constructs a mixed system by physically stirring waste oil and biomass, and achieves quantitative synergistic pyrolysis and co-carbonization of the two by relying on the chemical bonding mediated by ester bonds. However, this process has specific adaptability limitations on the structural characteristics and composition of biomass precursors, which significantly restricts its compatibility with different types of biomass raw materials.

[0003] At the same time, the traditional process of directly using biomass as a precursor for hard carbon, although it has the natural advantage of being green and environmentally friendly, generally has inherent defects such as high disorder of graphite-like domains, disordered pore structure, and large ion transport resistance after biomass is carbonized alone. It is difficult to achieve precise control of microstructure through simple carbonization, which greatly limits its application in hard carbon anode materials.

[0004] Therefore, based on inheriting the core advantages of CVD technology in precisely controlling the microstructure of hard carbon, it is crucial to overcome the technical bottlenecks of existing carbon sources being toxic and harmful, and substrate preparation being complex and costly. Developing a CVD-like process using green and non-toxic small oil molecules as carbon sources is essential to achieve green, low-cost, high-performance, and controllable preparation of hard carbon materials. This is of vital strategic significance and practical value for promoting the large-scale green application of hard carbon anodes in sodium-ion batteries. Summary of the Invention

[0005] The purpose of this invention is to provide a method and application for the preparation of biomass-based hard carbon materials using oil and gas assisted deposition. This invention uses small oil molecules as the carbon source for deposition, and through CVD-like deposition, calcination is carried out in an inert atmosphere to obtain high-temperature carbonization products, thus preparing hard carbon anode materials. Under heating conditions, small oil molecules can rapidly undergo gasification transformation to form gaseous carbon source species (such as carbon-containing free radicals, small molecule alkanes / olefins). Driven by an inert carrier gas, the gaseous oil carbon source can efficiently diffuse and deeply penetrate into the internal micropores of the biomass substrate. Through van der Waals forces and π-π conjugation interactions between the hydroxyl and carboxyl functional groups on the biomass pore wall surface and the carbon source species, the carbon source species are firmly adsorbed on the pore wall surface.

[0006] To achieve the above-mentioned technical objectives, the technical solution of the present invention is as follows: This invention provides a method for preparing biomass-based hard carbon materials with the assistance of oil and gas, comprising the following steps: (1) Take a certain amount of oil in a container and heat the oil; (2) Inert gas that has been heated by heat is introduced into the oil as a carrier gas to transport the oil molecules to the biomass material. (3) Heat the biomass material and keep it warm for a certain time to stop the transport of oil and gas molecules; (4) Introduce a pure inert atmosphere into the biomass material, heat it up, and keep it at that temperature for a certain time to obtain high-temperature carbonization of long-domain, low-defect, and high-closed-pore biomass-based hard carbon.

[0007] Under heating conditions, small oil molecules can rapidly undergo gasification to form gaseous carbon source species. Driven by an inert carrier gas, the gaseous oil carbon source can efficiently diffuse and deeply penetrate into the internal micropores of the biomass substrate. Through heating, it forms carbon-containing free radicals and small molecule alkanes / olefins, achieving strong adsorption on the pore wall surface. In addition, the long-chain alkyl or unsaturated bonds contained in the small oil molecules can gradually break down into regular carbon structure fragments on the pore wall surface after adsorption. These carbon fragments, as the basic structural units of graphite-like domains, can be directionally stacked and grown along the pore wall, laying a solid foundation for the subsequent formation of graphite-like domains with controllable size and regular structure.

[0008] In step (3), as the temperature rises from room temperature to a low-temperature zone of 200 ℃, more molecular chemical bonding and condensation reactions occur between oil and gas molecules and biomass molecules, generating more water vapor. Above 200 ℃ until the oil and gas stop entering, the oil and gas pyrolysis forms more carbon-containing free radicals, small molecule hydrocarbons, etc. These substances interfere with and couple with the biomass pyrolysis, undergoing dehydrogenation, carbon-carbon coupling, and rearrangement to form carbon. The small molecule substances of oil and gas pyrolysis interfere with the carbonization process of biomass at the molecular level, and the small molecule hydrogen-containing substances of oil and gas pyrolysis are conducive to the generation and growth of carbon domains, similar to the carbonization process of chemical vapor deposition. This staged control method of "synergistic carbonization-vapor deposition" in CVD-like deposition avoids the defect of random growth of carbon source in solid-phase mixing. The oil and gas formed by the gasification of oil and grease are continuously introduced into the reaction system in a non-quantitative form, making the carbon structure control more precise. The order and structural uniformity of the graphite-like domains are significantly better than those of traditional processes.

[0009] Preferably, the oil in step (1) is selected from one or more of soybean oil, peanut oil, pine oil, rapeseed oil, waste oil, linoleic acid, and linolenic acid fatty acids.

[0010] Preferably, the heating temperature of the grease in step (1) is 110-190℃.

[0011] Preferably, the gas flow rate in step (2) is 100-300 Sccm, and the gas is argon or nitrogen.

[0012] Preferably, in step (2), the temperature of the heat tracing is 120-180℃.

[0013] Preferably, the biomass in step (2) is one or more of banana peels, bamboo, soybean residue, peanut shells, and corn stalks.

[0014] Preferably, in step (3), the heating temperature is 500-900℃, the heating rate is 0.5-5℃ / min, and the holding time is 30-120min.

[0015] Preferably, in step (4), the high-temperature carbonization temperature is 1200-1500 ℃, the heating rate is 5-10℃ / min, the holding time is 60-180min, and the inert gas flow rate is 50-300 Sccm.

[0016] The present invention also provides a hard carbon material, which is obtained by the above preparation method.

[0017] This invention also provides an application of hard carbon material as a negative electrode material for sodium-ion batteries.

[0018] Beneficial effects 1. The preparation method of hard carbon anode material provided by the present invention utilizes small molecules of oil as a gas-phase carbon source to interfere with the biomass pyrolysis process. It is a CVD-like method, but the method is simpler and safer. 2. It has strong oil and gas permeability, effectively avoiding the technical defects of uneven permeation of traditional liquid carbon sources and low mass transfer efficiency of solid carbon sources. At the same time, it undergoes gasification transformation under oil and gas to form gaseous carbon source species, such as carbon free radicals and small molecule alkanes / olefins, which assist in the growth of hard carbon domains.

[0019] 3. The preparation method of the hard carbon anode material provided by this invention is green, non-toxic, and pollution-free. The small oil molecules are derived from renewable biomass resources (such as vegetable oils, waste catering oils, etc.), and their gasification and carbonization processes only produce non-toxic and harmless gases such as H2O and CO2, without the emission of toxic and harmful substances such as benzene and formaldehyde, thus overcoming the toxicity and pollution problem of traditional CVD carbon sources.

[0020] 4. The method for preparing hard carbon anode materials provided by this invention innovatively uses small oil molecules as a gas-phase carbon source to directionally regulate the evolution of biomass pyrolysis, constructing a CVD-like composite process system. This process integrates the advantages of chemical bond-mediated synergistic carbonization in traditional solid-phase mixing processes, and precisely incorporates the core characteristics of CVD vapor deposition in the later stages of carbonization, forming a staged regulation mode of "synergistic carbonization-vapor deposition". This method not only significantly shortens the reaction cycle, but also has a wider range of raw material compatibility and excellent process universality, giving the technology greater potential for large-scale application in multiple scenarios.

[0021] 5. The hard carbon prepared by this invention has long domains, low defects, and high closed-pore characteristics, and has excellent sodium storage effect.

[0022] 6. The preparation method of hard carbon anode material provided by the present invention has a wide range of raw material sources, which makes it very suitable for large-scale industrial manufacturing environments. Attached Figure Description

[0023] Figure 1 This is an HRTEM image of the hard carbon material obtained in Example 1 of the present invention.

[0024] Figure 2 The images show the Raman diagrams of the hard carbon materials obtained in Example 1 and Comparative Example 1 of this invention.

[0025] Figure 3 The diagram shows the rate performance of the hard carbon anode material prepared in Example 1 of this invention in a sodium-ion battery.

[0026] Figure 4 This is an HRTEM image of the hard carbon material of Comparative Example 1 of the present invention.

[0027] Figure 5The images show the cyclic test results of the hard carbon materials in Example 1 and Comparative Example 1 of this invention. Detailed Implementation

[0028] The present invention will be further described below with reference to specific embodiments, and the advantages and features of the present invention will become clearer with the description. However, the embodiments are merely exemplary and do not constitute any limitation on the scope of the present invention. Those skilled in the art should understand that modifications or substitutions can be made to the details and form of the technical solutions of the present invention without departing from the spirit and scope of the present invention, but all such modifications and substitutions fall within the protection scope of the present invention.

[0029] This invention provides a method for preparing biomass-based hard carbon materials with the assistance of oil and gas, comprising the following steps: (1) Take a certain amount of oil in a container and heat the oil; (2) Inert gas that has been heated by heat tracing is introduced into the oil as a carrier gas to carry the oil molecules into the biomass material area through the heat tracing pipe. (3) Start the heating furnace to temperature 1, keep it at that temperature for a certain period of time, and stop the oil and gas molecules from entering; (4) Switch to a pure inert atmosphere, heat to temperature II, hold for a certain time, and high-temperature carbonization to obtain long-domain, low-defect, high-closed-pore biomass-based hard carbon.

[0030] Example 1 A method for preparing biomass-based hard carbon materials with oil and gas assistance includes the following steps: Step 1: Place 200g of soybean oil in a heat-resistant container and heat the oil to 150℃; Step 2: Introduce heated nitrogen gas as a carrier gas into the heated oil liquid. The heating pipe is 150°C. The oil and gas molecules are carried into the biomass material area through the heating pipe. The gas flow rate is 200 Sccm and the corn straw material is 20 g. Step 3: Start the heating furnace to 600℃, hold for 1 hour, with a heating rate of 1℃ / min, and stop the entry of oil and gas molecules; Step 4: Switch to a pure inert atmosphere with a gas flow rate of 100 Sccm, continue heating to 1400℃, hold for 3 hours, heating rate of 5℃ / min, and then cool down to obtain long-domain, low-defect, high-closed-pore biomass-based hard carbon.

[0031] Weigh 80 mg of hard carbon material, 10 mg of acetylene black, and 10 mg of PVDF according to a mass ratio of 80%:10%:10%. Add an appropriate amount of NMP and stir for 20 min until a uniform slurry is formed. Use a 100 μm scraper to evenly coat the slurry onto a copper (Cu) foil. Place the slurry in a forced-air drying oven and dry for 12 h. Cut the Cu foil with active material into circular electrode sheets for later use.

[0032] The coin cell assembly was carried out in a glove box filled with Ar atmosphere. The prepared electrode sheet was used as the negative electrode, the commercial electrolyte 1.0 M NaPF6in DME=100 Vol% was used as the electrolyte, and the Na metal sheet was used as the counter electrode to assemble a 2032 coin cell.

[0033] Figure 1 This is a TEM image of the hard carbon anode material prepared in Example 1 of the present invention; it can be clearly observed from the image that, relative to Figure 4 The material surface has a large number of uniformly distributed long-range bent pseudo-graphite microcrystalline structures, which endow the material with high conductivity; at the same time, the bent pseudo-graphite domains cross-link to form a large number of closed-pore structures, which is beneficial for storing sodium in the low potential plateau region and obtaining high capacity.

[0034] Figure 2 Raman diagrams of the hard carbon materials obtained in Example 1 and Comparative Example 1 of this invention; the D peak (1350 cm⁻¹) representing the disordered graphite lattice vibrations in Example 1. - ¹) The peak intensity is weaker than that of Comparative Example 1, while the G peak (1580 cm⁻¹), which represents the vibration of an ideal graphite lattice, is weaker. - ¹) The peak intensity is higher, which is consistent with the pseudo-graphite structure observed by TEM, further confirming the pseudo-graphite domains formed by the pyrolysis of small oil molecules.

[0035] Figure 3 The figure shows the rate performance test results of the hard carbon material in Example 1 of this invention. As shown, at a current density of 20 mA / g, the reversible specific capacity is 356.94 mAh / g; at a current density of 1000 mA / g, the reversible specific capacity is 248.9 mAh / g. The excellent rate performance can be attributed to the uniformly distributed long-range bent pseudographite microcrystalline structure, which is beneficial for electron conduction.

[0036] Figure 4 This is the HRTEM image of the hard carbon material in Comparative Example 1 of this invention, and... Figure 2 The comparison shows that the graphite domains are shorter and the closed pores are fewer.

[0037] Figure 5 The figures show the cycle test results of the hard carbon materials in Example 1 and Comparative Example 1 of this invention. It can be seen that the rate performance of the hard carbon materials prepared by this CVD-like method is significantly better than that of Comparative Example 1.

[0038] Example 2 A method for preparing biomass-based hard carbon materials with oil and gas assistance includes the following steps: Step 1: Place 200g of soybean oil in a heat-resistant container and heat the oil to 180℃; Step 2: Introduce heated nitrogen gas as a carrier gas into the heated oil liquid. The heating pipe is 150°C. The oil and gas molecules are carried into the biomass material area through the heating pipe. The gas flow rate is 200 Sccm and the corn straw material is 20 g. Step 3: Start the heating furnace to 600℃, hold for 1 hour, with a heating rate of 1℃ / min, and stop the entry of oil and gas molecules; Step 4: Switch to a pure inert atmosphere with a gas flow rate of 100 Sccm, continue heating to 1400℃, hold for 3 hours, heating rate of 5℃ / min, and then cool down to obtain long-domain, low-defect, high-closed-pore biomass-based hard carbon.

[0039] The hard carbon anode material prepared above was used as the active material for the anode material in the preparation of sodium-ion batteries, and the specific method was the same as in Example 1. The reversible specific capacity reached 346.80 mAh / g at a current density of 20 mA / g.

[0040] Example 3 A method for preparing biomass-based hard carbon materials with oil and gas assistance includes the following steps: Step 1: Place 200g of soybean oil in a heat-resistant container and heat the oil to 120℃; Step 2: Introduce heated nitrogen gas as a carrier gas into the heated oil liquid. The heating pipe is 150°C. The oil and gas molecules are carried into the biomass material area through the heating pipe. The gas flow rate is 200 Sccm and the corn straw material is 20 g. Step 3: Start the heating furnace to 600℃, hold for 1 hour, with a heating rate of 1℃ / min, and stop the entry of oil and gas molecules; Step 4: Switch to a pure inert atmosphere with a gas flow rate of 100 Sccm, continue heating to 1400℃, hold for 3 hours at a heating rate of 5℃ / min, and then cool down to obtain long-domain, low-defect, high-closed-pore biomass-based hard carbon. The hard carbon material prepared above was used as the active material for the negative electrode of a sodium-ion battery, following the same method as in Example 1. The reversible specific capacity reached 348.55 mAh / g at a current density of 20 mA / g.

[0041] Example 4 A method for preparing biomass-based hard carbon materials with oil and gas assistance includes the following steps: Step 1: Place 200 g of linoleic acid in a heat-resistant container and heat the oil to 150°C; Step 2: Introduce heated nitrogen gas as a carrier gas into the heated oil liquid. The heating pipe is 150°C. The oil and gas molecules are carried into the biomass material area through the heating pipe. The gas flow rate is 200 Sccm and the corn straw material is 20 g. Step 3: Start the heating furnace to 600℃, hold for 1 hour, with a heating rate of 1℃ / min, and stop the entry of oil and gas molecules; Step 4: Switch to a pure inert atmosphere with a gas flow rate of 100 Sccm, continue heating to 1400℃, hold for 3 hours, heating rate of 5℃ / min, and then cool down to obtain long-domain, low-defect, high-closed-pore biomass-based hard carbon.

[0042] The hard carbon anode material prepared above was used as the active material for the anode material in the preparation of sodium-ion batteries, and the specific method was the same as in Example 1. The reversible specific capacity reached 339.12 mAh / g at a current density of 20 mA / g.

[0043] Example 5 A method for preparing biomass-based hard carbon materials with oil and gas assistance includes the following steps: Step 1: Place 200g of soybean oil in a heat-resistant container and heat the oil to 180℃; Step 2: Introduce heated nitrogen gas as a carrier gas into the heated oil liquid. The heating pipe is 150°C. The oil and gas molecules are carried into the biomass material area through the heating pipe. The gas flow rate is 200 Sccm and the corn straw material is 20 g. Step 3: Start the heating furnace to 600℃, hold for 2 hours, with a heating rate of 1℃ / min, and stop the entry of oil and gas molecules; Step 4: Switch to a pure inert atmosphere with a gas flow rate of 100 Sccm, continue heating to 1400℃, hold for 3 hours, heating rate of 5℃ / min, and then cool down to obtain long-domain, low-defect, high-closed-pore biomass-based hard carbon.

[0044] The hard carbon anode material prepared above was used as the active material for the anode material in the preparation of sodium-ion batteries, and the specific method was the same as in Example 1. The reversible specific capacity reached 342.34 mAh / g at a current density of 20 mA / g.

[0045] Example 6 A method for preparing biomass-based hard carbon materials with oil and gas assistance includes the following steps: Step 1: Place 200g of soybean oil in a heat-resistant container and heat the oil to 180℃; Step 2: Introduce heated nitrogen gas as a carrier gas into the heated oil liquid. The heating pipe is 150°C. The oil and gas molecules are carried into the biomass material area through the heating pipe. The gas flow rate is 200 Sccm and the corn straw material is 20 g. Step 3: Start the heating furnace to 500℃, keep it at that temperature for 1 hour, with a heating rate of 1℃ / min, and stop the entry of oil and gas molecules; Step 4: Switch to a pure inert atmosphere with a gas flow rate of 100 Sccm, continue heating to 1400℃, hold for 3 hours, heating rate of 5℃ / min, and then cool down to obtain long-domain, low-defect, high-closed-pore biomass-based hard carbon.

[0046] The hard carbon anode material prepared above was used as the active material for the anode material in the preparation of sodium-ion batteries, and the specific method was the same as in Example 1. The reversible specific capacity reached 341.50 mAh / g at a current density of 20 mA / g.

[0047] Example 7 A method for preparing biomass-based hard carbon materials with oil and gas assistance includes the following steps: Step 1: Place 200g of soybean oil in a heat-resistant container and heat the oil to 180℃; Step 2: Introduce heated nitrogen gas as a carrier gas into the heated oil liquid. The heating pipe is 150°C. The oil and gas molecules are carried into the biomass material area through the heating pipe. The gas flow rate is 200 Sccm and the corn straw material is 20 g. Step 3: Start the heating furnace to 900℃, hold for 1 hour, with a heating rate of 1℃ / min, and stop the entry of oil and gas molecules; Step 4: Switch to a pure inert atmosphere with a gas flow rate of 100 Sccm, continue heating to 1400℃, hold for 3 hours, heating rate of 5℃ / min, and then cool down to obtain long-domain, low-defect, high-closed-pore biomass-based hard carbon.

[0048] The hard carbon anode material prepared above was used as the active material for the anode material in the preparation of sodium-ion batteries, and the specific method was the same as in Example 1. The reversible specific capacity reached 338.95 mAh / g at a current density of 20 mA / g.

[0049] Example 8 A method for preparing biomass-based hard carbon materials with oil and gas assistance includes the following steps: Step 1: Place 200g of soybean oil in a heat-resistant container and heat the oil to 150℃; Step 2: Introduce heated nitrogen gas as a carrier gas into the heated oil liquid. The heating pipe is 150°C. The oil and gas molecules are carried into the biomass material area through the heating pipe. The gas flow rate is 200 Sccm and the peanut shell material is 20 g. Step 3: Start the heating furnace to 600℃, hold for 1 hour, with a heating rate of 1℃ / min, and stop the entry of oil and gas molecules; Step 4: Switch to a pure inert atmosphere with a gas flow rate of 100 Sccm, continue heating to 1400℃, hold for 3 hours, heating rate of 5℃ / min, and then cool down to obtain long-domain, low-defect, high-closed-pore biomass-based hard carbon.

[0050] The hard carbon anode material prepared above was used as the active material for the anode material in the preparation of sodium-ion batteries, and the specific method was the same as in Example 1. The reversible specific capacity reached 343.52 mAh / g at a current density of 20 mA / g.

[0051] Example 9 A method for preparing biomass-based hard carbon materials with oil and gas assistance includes the following steps: Step 1: Place 200g of soybean oil in a heat-resistant container and heat the oil to 150℃; Step 2: Introduce heated nitrogen gas as a carrier gas into the heated oil liquid. The heating pipe is 150°C. The oil and gas molecules are carried into the biomass material area through the heating pipe. The gas flow rate is 200 Sccm and the soybean residue material is 20 g. Step 3: Start the heating furnace to 600℃, hold for 1 hour, with a heating rate of 1℃ / min, and stop the entry of oil and gas molecules; Step 4: Switch to a pure inert atmosphere with a gas flow rate of 100 Sccm, continue heating to 1400℃, hold for 3 hours, heating rate of 5℃ / min, and then cool down to obtain long-domain, low-defect, high-closed-pore biomass-based hard carbon.

[0052] The hard carbon anode material prepared above was used as the active material for the anode material in the preparation of sodium-ion batteries, and the specific method was the same as in Example 1. The reversible specific capacity reached 348.76 mAh / g at a current density of 20 mA / g.

[0053] Comparative Example 1 This invention provides a comparative example of a method for preparing a biomass-based hard carbon anode material for sodium-ion batteries, the steps of which include: Step 1: Introduce heated inert gas into the biomass material zone at a flow rate of 200 Sccm, with 20g of corn stalk material. Step 2: Start the heating furnace to 600℃, hold for 1 hour, and increase the temperature at a rate of 1℃ / min. Step 3: Switch the gas to 100 Sccm, continue heating to 1400℃, hold for 3 hours, heating rate 5℃ / min, and then cool down to obtain long-domain, low-defect, high-closed-pore biomass-based hard carbon.

[0054] The hard carbon material prepared above was used as the active material for the negative electrode of a sodium-ion battery, and the specific method was the same as in Example 1. The assembled half-cell had a first-cycle specific capacity of 260.62 mAh / g at a current density of 20 mA / g.

[0055] Comparative Example 2 This invention provides a comparative example of a method for preparing a biomass-based hard carbon anode material for sodium-ion batteries, the steps of which include: Step 1: Weigh 8 g of soybean residue, wash it with an appropriate amount of distilled water, and place it in a forced-air drying oven. The drying temperature is 80 ℃ and the drying time is 12 h to remove impurities and moisture, and obtain dried material. Step 2: Mix the dried material with 1 g of soybean oil for 2 hours, let it stand for 2 hours to obtain the mixture; Step 3: Place the mixture obtained in step (2) in a tube furnace and heat it to 1400 ℃ at a heating rate of 5 ℃ / min under argon conditions. Hold it at the temperature for 2 h and then cool it to room temperature to obtain carbonized material. Step 4: The carbonized material obtained in step (3) is washed in 1 mol / L hydrochloric acid solution and distilled water for 6 h. It is then dried in a forced-air drying oven at 60 ℃ for 12 h to obtain hard carbon material.

[0056] Step 5: The waste oil obtained above is used to prepare a low-defect, pseudo-graphite domain-rich hard carbon material as the active material for the battery anode material in the preparation of sodium-ion batteries. The specific method is the same as in Example 1. The assembled half-cell has a first-cycle charge specific capacity of 330.41 mAh / g at a current density of 20 mA / g.

Claims

1. A method for preparing biomass-based hard carbon materials with oil and gas assistance, characterized in that, Includes the following steps: (1) Take a certain amount of oil in a container and heat the oil; (2) Inert gas that has been heated by heat is introduced into the oil as a carrier gas to transport the oil molecules to the biomass material. (3) Heat the biomass material and keep it warm for a certain time to stop the transport of oil and gas molecules; (4) Introduce a pure inert atmosphere into the biomass material, heat it up, and keep it at that temperature for a certain time to obtain high-temperature carbonization of long-domain, low-defect, and high-closed-pore biomass-based hard carbon.

2. The method for preparing biomass-based hard carbon materials with oil and gas assistance according to claim 1, characterized in that, The oil in step (1) is selected from one or more of soybean oil, peanut oil, pine oil, rapeseed oil, waste oil, linoleic acid, and linolenic acid fatty acids.

3. The method for preparing biomass-based hard carbon materials with oil and gas assistance according to claim 1, characterized in that, The heating temperature of the grease in step (1) is 110-190℃.

4. The method for preparing biomass-based hard carbon materials with oil and gas assistance according to claim 1, characterized in that, The gas flow rate in step (2) is 100-300 Sccm, and the gas is argon or nitrogen.

5. The method for preparing biomass-based hard carbon materials with oil and gas assistance according to claim 1, characterized in that, In step (2), the temperature of the heat tracing is 120-180℃.

6. The method for preparing biomass-based hard carbon materials with oil and gas assistance according to claim 1, characterized in that, The biomass used in step (2) is one or more of the following: banana peel, bamboo, soybean residue, peanut shells, and corn stalks.

7. The method for preparing biomass-based hard carbon materials with oil and gas assistance according to claim 1, characterized in that, In step (3), the heating temperature is 500-900℃, the heating rate is 0.5-5℃ / min, and the holding time is 30-120min.

8. The method for preparing biomass-based hard carbon materials with oil and gas assistance according to claim 1, characterized in that, In step (4), the high-temperature carbonization temperature is 1200-1500 ℃, the heating rate is 5-10℃ / min, the holding time is 60-180min, and the inert gas flow rate is 50-300 Sccm.

9. The biomass-based hard carbon material obtained by oil and gas assistance according to any one of claims 1-8.

10. The application of the biomass-based hard carbon material prepared by oil and gas assistance according to claim 9 in the anode material of sodium-ion batteries.

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