Method for constructing hard carbon from oily biomass and applications thereof

Abstract

The application belongs to the technical field of energy storage materials and batteries, and particularly relates to a method for constructing hard carbon from oil-containing biomass and application of the method. The method comprises the following steps: crushing oil-containing biomass, performing steam puffing treatment, and then drying to obtain puffed oil-containing biomass material; performing oil extraction treatment on the puffed oil-containing biomass material to obtain oil-removed biomass; performing high-temperature carbonization under inert gas conditions to obtain carbonized material; performing acid washing on the carbonized material with a dilute acid solution, and then performing washing with deionized water until the solution is neutral, and drying to obtain biomass-based hard carbon. In the application, the oil-containing biomass is subjected to extraction treatment to remove a certain amount of oil small molecules, and molecular-level vacancies are left after removal of fatty acids. In the high-temperature carbonization process, the space steric hindrance effect inhibits excessive orientation stacking of carbon layers along the 002 crystal plane, directional induction is formed around edge defects, a multi-defect system with edge defects as the core is formed, additional active sodium storage sites are introduced, and preparation of hard carbon negative electrode material with high sodium storage active sites is realized.

Description

Technical Field

[0001] This invention belongs to the field of energy storage materials and battery technology, specifically relating to a method and application for constructing hard carbon from oily biomass. Background Technology

[0002] With the global energy structure transformation and the rapid development of sustainable energy systems, sodium-ion batteries have become an important supplement and alternative to lithium-ion batteries due to their abundant resources and low cost. Hard carbon materials, especially biomass-derived hard carbon, are widely considered to be one of the most promising anode materials for sodium-ion batteries due to their wide availability, tunable structure, and good sodium-ion intercalation capability.

[0003] Currently, research on biomass precursors largely focuses on their three main components—cellulose, lignin, and hemicellulose—which play a dominant role in the construction of the carbon skeleton during pyrolysis. Researchers attempt to optimize their pore structure, interlayer spacing, and surface chemical state by controlling the pyrolysis pathway, introducing dopants, or performing surface modifications to improve their sodium storage capacity and rate performance. However, such research generally overlooks the structure-directing potential of small molecule components in biomass (especially natural oils). Although a related patent (CN116344804A) attempts to use waste oils as an exogenous carbon source for pore structure modification in hard carbon materials, its mechanism of action remains limited to simple physical effects. It fails to reveal the intrinsic regulatory mechanism of small oil molecules on carbon layer growth kinetics and microstructure evolution within the biomass matrix at the molecular level, resulting in the core value of oil components in the preparation of biomass-based hard carbon not being fully explored. Conversely, patent CN117613268A argues that the oily impurities remaining on the surface of wood shavings are long-chain organic compounds, which are prone to incomplete decomposition during high-temperature carbonization, leaving behind heteroatoms or impurities that affect the electrochemical performance of the material. In fact, most natural oily biomass (such as soybean, pine, camphor, camellia seed meal, peanut shells, sunflower seed meal, etc.) contains 5%-20% by mass of small-molecule oils. These components mainly exist in the form of triglycerides (≥80%) and unsaturated fatty acids (such as oleic acid and linoleic acid, with 1-3 double bonds). Although their content is lower than that of macromolecules such as cellulose and lignin, they exhibit pyrolysis behavior and reaction pathways that are drastically different from the three main components during high-temperature carbonization. Currently, there is a lack of systematic research exploring how to precisely control the microcrystal evolution and pore formation during the carbonization process by degreasing oily biomass before carbonization. The presence of oil molecules not only affects pyrolysis kinetics but may also interfere with the directional arrangement of carbon layers and the graphitization process through their decomposition products.

[0004] Therefore, there is a need for a method that can regulate the preparation of hard carbon pseudographite domains and low-defect-density hard carbon materials by controlling the lipids of biomass itself, so as to achieve efficient sodium storage performance. Summary of the Invention

[0005] The purpose of this invention is to provide a method and application for constructing hard carbon from oily biomass. This invention uses biomass containing natural oils as raw material, and removes a certain amount of small oil molecules through extraction. The molecular-level vacancies remaining after fatty acid removal are used to suppress excessive orientation stacking of carbon layers along the 002 crystal plane during high-temperature carbonization through steric hindrance. This directionally induces the formation of a multi-element defect system with edge defects as the core, introducing additional active sodium storage sites, thus achieving the preparation of hard carbon anode materials with high sodium storage activity sites.

[0006] To achieve the above-mentioned objectives, the technical solution of the present invention is as follows: This invention provides a method for constructing hard carbon from oily biomass, comprising the following steps: (1) The oily biomass material is crushed, steam-expanded, and then dried to obtain the expanded oily biomass material; (2) Use an oil extractant to extract oil from the puffed oily biomass material, and then dry it to obtain de-oiled biomass; (3) The deoiled biomass obtained in step (2) is placed in a heating device and carbonized at high temperature under inert gas conditions to obtain carbonized material; (4) The carbonized material obtained in step (3) is first acid-washed with dilute acid solution, then washed with deionized water until the solution is neutral, and then dried to obtain biomass-based hard carbon anode material based on oil removal control.

[0007] Among them, the molecular-level vacancies left after fatty acid removal, during high-temperature carbonization, suppress the excessive orientation stacking of carbon layers along the 002 crystal plane through steric hindrance, directionally inducing the formation of a multi-dimensional defect system with edge defects as the core. These edge defects not only expose a large number of highly active unsaturated sp3+ particles, but also... 2 Hybridized carbon sites also simultaneously mediate the directional construction of mesopores (pore size 2-50 nm); at the same time, the removal of lipid components leads to a more singular pyrolysis reaction pathway for biomass macromolecules (cellulose, lignin), and the defect sites synergistically generated during the directional coupling of carbon free radicals significantly enhance Na+ by regulating the electronic state density distribution and Fermi level position of carbon materials. + The charge storage dynamics, and the directionally constructed mesoporous structure acts as both a Na+ and a Na+. + The efficient physical insertion sites, along with the construction of continuous ion transport channels spanning the carbon framework, significantly reduce Na+. + The diffusion barrier within the carbon framework was overcome through a synergistic mechanism of "vacancy induction - defect evolution - active sodium storage sites," successfully constructing a hard carbon anode material enriched with high sodium storage active sites. Compared to the control group, the hard carbon material prepared in the experimental group exhibited superior high-rate and cycling performance in terms of sodium storage.

[0008] Preferably, the oil-containing biomass in step (1) is one or more of the oil-containing biomass of pine trees, olive shells, soybeans, and camphor trees.

[0009] Preferably, in step (1), the particle size of the oily biomass pulverized material is no greater than 2 mm, the drying temperature is 50-100 degrees Celsius, and the drying time is 1-6 h.

[0010] Preferably, the puffing device used in step (1) is a steam puffing machine, the medium is high-temperature and high-pressure saturated steam, the pressure is 0.8-2.0 MPa, and the temperature is 180-240℃.

[0011] Preferably, the oil extractant in step (2) is selected from one or more of n-pentane, isohexane or n-hexane, n-pentane or cyclopentane, bio-based dimethyl ether, limonene, ethanol or isopropanol.

[0012] Preferably, in step (2), a Soxhlet extractor is used as the oil extraction device.

[0013] Preferably, the extraction time in step (2) is 1-14 h.

[0014] Preferably, the high-temperature carbonization temperature in step (3) is between 1200-1700 ℃.

[0015] Preferably, in step (3), the high-temperature carbonization heating rate is 0.2-10 ℃ / min, and the high-temperature carbonization time is 1-6 h.

[0016] Preferably, the apparatus used for high-temperature carbonization in step (3) is a tubular furnace, a Joule furnace, or a microwave heating furnace.

[0017] Preferably, the dilute acid solution in step (4) is hydrochloric acid with a concentration of 1-2 mol / L and an acid washing time of 6-12 h, to ensure the full removal of impurities from the high-temperature carbonized material.

[0018] Preferably, the water washing process in step (4) involves repeated filtration and washing with deionized water, with the number of washes being 3 to 10 times, to ensure the removal of hydrochloric acid.

[0019] Preferably, the high-temperature carbonization protective gas in step (3) is one of hydrogen, argon, nitrogen, hydrogen-argon, or hydrogen-nitrogen.

[0020] The present invention also provides a hard carbon with high sodium storage active sites, which is obtained by the above preparation process.

[0021] This invention also provides the application of the aforementioned high sodium storage active site hard carbon as a negative electrode material for sodium-ion batteries.

[0022] Beneficial effects: 1. The method for preparing hard carbon anode material provided by this invention utilizes the molecular-level vacancies left after fatty acid removal. During high-temperature carbonization, the steric hindrance effect suppresses the excessive orientation stacking of carbon layers along the 002 crystal plane, directionally inducing the formation of a multi-element defect system with edge defects as the core, serving as the Na... + The physical embedding sites enhance Na + The charge storage capacity was utilized to construct a continuous ion transport channel, effectively reducing Na+. + Diffusion resistance within the carbon framework induces defects to construct hard carbon anode materials with high sodium storage active sites.

[0023] 2. The hard carbon anode material provided by this invention, due to its rich defect-induced mesopores, facilitates the rapid migration of sodium ions, thereby improving rate performance. The continuous mesoporous structure constructs a connected electronic conduction network, improving the electronic conductivity of hard carbon and significantly reducing charge transfer resistance. Simultaneously, it better resists the volume changes caused by repeated sodium ion insertion / extraction, contributing to extended cycle life.

[0024] 3. The preparation method of hard carbon anode material provided by the present invention has the advantages of wide availability of raw materials and simple process, which makes it very suitable for large-scale industrial manufacturing environment. Attached Figure Description

[0025] Figure 1 This is an HRTEM image of the hard carbon anode material of Example 1 of the present invention.

[0026] Figure 2 The images show the XRD patterns of the deoiled soybean powder from Example 1 and the undeoiled soybean flour from Comparative Example 1.

[0027] Figure 3 The images show the FTIR images of the de-oiled soybeans in Example 1 of the present invention and the un-de-oiled soybean flour in Comparative Example 1.

[0028] Figure 4 The images show the Raman diagrams of the hard carbon materials obtained in Example 1 and Comparative Example 1 of this invention.

[0029] Figure 5 The diagram shows the rate performance of the hard carbon anode materials prepared in Example 1 and Comparative Example 1 of this invention in sodium-ion batteries.

[0030] Figure 6 This is an HRTEM image of the hard carbon material of Comparative Example 1 of the present invention. Detailed Implementation

[0031] 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.

[0032] This invention provides a method for preparing a hard carbon anode material with high sodium storage active sites based on defects induced by the removal of small molecule oils, comprising the following steps: (1) The oily biomass raw material is crushed, steam-expanded, and preliminarily dried to remove surface free moisture; (2) Place the dried soybean sample into the filter paper sleeve of the Soxhlet extractor, then install the Soxhlet extractor on the flask, add an appropriate amount of n-pentane extractant to the flask for oil extraction, and dry after extraction; (3) The mixture obtained in step (2) is placed in a tube furnace and carbonized at a certain heating rate under inert gas conditions to obtain carbonized material; (4) The carbonized material obtained in step (3) is washed with dilute hydrochloric acid solution and deionized water until the solution is neutral, and then dried to obtain a hard carbon anode material with high sodium storage active sites constructed by inducing defects.

[0033] Among these processes, the molecular-level vacancies left after fatty acid removal inhibit the excessive orientation stacking of carbon layers along the 002 crystal plane during high-temperature carbonization through steric hindrance, directionally inducing the formation of a multi-dimensional defect system centered on edge defects. These edge defects not only expose a large number of highly active unsaturated sp² hybrid carbon sites but also simultaneously mediate the directional construction of mesopores (pore size 2-50 nm). Meanwhile, the removal of lipid components leads to a more singular pyrolysis reaction pathway for biomass macromolecules (cellulose, lignin). The defect sites synergistically generated during the directional coupling of carbon free radicals significantly enhance Na+ by regulating the electronic state density distribution and Fermi level position of the carbon material. + The charge storage dynamics, and the directionally constructed mesoporous structure acts as both a Na+ and a Na+. + The efficient physical insertion sites, along with the construction of continuous ion transport channels spanning the carbon framework, significantly reduce Na+. + The diffusion barrier within the carbon framework was ultimately overcome through a synergistic mechanism of "vacancy induction - defect evolution - active sodium storage sites," successfully constructing a hard carbon anode material enriched with high sodium storage active sites.

[0034] Example 1 A method for constructing hard carbon based on oily biomass includes the following steps: Step 1: Weigh 1 kg of soybeans and crush them. Then, steam puff the sieved crushed material at a pressure of 1.0 MPa and a temperature of 190 ℃. Finally, dry the puffed material at 80 ℃ for 2 h.

[0035] Step 2: Take the expanded and dried material and extract it with n-pentane using a Soxhlet extractor for 7 hours, then air dry it for 12 hours to obtain the de-oiled material; Step 3: Place the deoiled material obtained in Step 2 into a tube furnace and heat it to 1400 ℃ at a heating rate of 5 ℃ / min under argon atmosphere. Hold it at this temperature for 2 h and then cool it to room temperature to obtain carbonized material. Step 4: Wash the carbonized material obtained in Step 3 with 1 mol / L hydrochloric acid solution for 6 h, wash with distilled water until neutral, and dry in a forced-air drying oven at 60 ℃ for 12 h to obtain a hard carbon anode material enriched with high sodium storage active sites.

[0036] Step 5: The hard carbon anode material with high sodium storage active sites, constructed based on defects induced by the removal of small molecule grease, prepared above is used as the battery anode. The steps are as follows: Weigh out 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.

[0037] 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.

[0038] 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: Weigh 1 kg of soybeans and crush them. The sieved crushed material is then subjected to steam puffing treatment at a pressure of 1.0 MPa and a temperature of 190 ℃. The puffed material is then dried in a forced-air dryer at 80 ℃ for 2 h. Step 2: Place the material obtained in Step 1 in a tube furnace and heat it to 1400 ℃ at a heating rate of 5 ℃ / min under argon atmosphere. Hold it at this temperature for 2 h. After cooling to room temperature, remove the material to obtain carbonized material. Step 3: The carbonized material obtained in Step 2 is washed in 1 mol / L hydrochloric acid solution and distilled water for 6 h, and then dried in a forced-air drying oven at 60 ℃ for 12 h to obtain a hard carbon anode material enriched with high sodium storage active sites.

[0039] Step 4: Use the purified carbonized material obtained above as the active material of the battery negative electrode material for the preparation of sodium-ion batteries. The specific method is the same as in Example 1.

[0040] 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 6 The material surface has a large number of uniformly distributed edge defects and pore structures, which provide the material with continuous ion transport channels; at the same time, the bent pseudographite domains cross-link to form a closed-pore structure, which is beneficial for sodium storage in the low potential plateau region.

[0041] Figure 2 The images show the XRD patterns of the de-oiled soybeans in Example 1 and the un-de-oiled soybean powder in Comparative Example 1. The (002) peak of the precursor in Example 1 is broader than that in Comparative Example 1, which indicates that the removal of oil disrupts the ordered structure of the raw materials, making the materials more disordered and providing favorable conditions for the formation of subsequent defects.

[0042] Figure 3 The images show the FTIR spectra of the de-oiled soybeans in Example 1 of this invention and the un-de-oiled soybean flour in Comparative Example 1; 3438 cm⁻¹ - ¹ -OH stretching vibration and 1700 cm - The weakening of the C=O stretching vibration at point ¹ indicates the release of small fat molecules.

[0043] Figure 4 Raman spectroscopy plots of hard carbon 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 significantly stronger than that of Comparative Example 1. This result is consistent with the edge defect structure and pore structure observed by TEM, further confirming the inhibitory effect of the desorption of small oleic molecule materials on the degree of graphitization of the material.

[0044] Figure 5The figures show the rate performance test results of the hard carbon materials in Example 1 and Comparative Example 1 of this invention. As shown, at a current density of 20 mA / g, the reversible specific capacity is 262.74 mAh / g; at a current density of 1000 mA / g, the reversible specific capacity is 200.07 mAh / g. The excellent rate performance can be attributed to defect-induced active sodium storage sites. The half-cell assembled from the material obtained in Comparative Example 1 has a first-cycle charge specific capacity of 225.49 mAh / g at a current density of 20 mA / g.

[0045] Figure 6 The image shows the HRTEM image of the hard carbon material obtained in Comparative Example 1.

[0046] Example 2 A method for constructing hard carbon based on oily biomass includes the following steps: Step 1: Weigh 1 kg of soybeans and crush them. Then, steam puff the sieved crushed material at a pressure of 1.0 MPa and a temperature of 190 ℃. Finally, dry the puffed material at 80 ℃ for 2 h.

[0047] Step 2: Take the expanded and dried material and extract it with n-pentane using a Soxhlet extractor for 1 hour, then air dry it for 12 hours to obtain the de-oiled material; Step 3: Place the deoiled material obtained in Step 2 into a tube furnace and heat it to 1400 ℃ at a heating rate of 5 ℃ / min under argon atmosphere. Hold it at this 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, and then dried in a forced-air drying oven at 60 ℃ for 12 h to obtain a hard carbon anode material enriched with high sodium storage active sites.

[0048] Step 5: Using the hard carbon anode material with high sodium storage active sites prepared above and based on the defects induced by the removal of small molecule oils, a sodium-ion battery was constructed using the same method as in Example 1. The reversible specific capacity reached 257.19 mAh / g at a current density of 20 mA / g.

[0049] Example 3 A method for constructing hard carbon based on oily biomass includes the following steps: Step 1: Weigh 1 kg of soybeans and crush them. Then, steam puff the sieved crushed material at a pressure of 1.0 MPa and a temperature of 190 ℃. Finally, dry the puffed material at 80 ℃ for 2 h.

[0050] Step 2: Take the expanded and dried material and extract it with n-pentane using a Soxhlet extractor for 14 h, then air dry it for 12 h to obtain the de-oiled material; Step 3: Place the deoiled material obtained in Step 2 into a tube furnace and heat it to 1400 ℃ at a heating rate of 5 ℃ / min under argon atmosphere. Hold it at this 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, and then dried in a forced-air drying oven at 60 ℃ for 12 h to obtain a hard carbon anode material enriched with high sodium storage active sites.

[0051] Step 5: Using the hard carbon anode material with high sodium storage active sites prepared above and constructed based on defects induced by the removal of small molecule oils, a sodium-ion battery was constructed using the same method as in Example 1. The reversible specific capacity reached 260.33 mAh / g at a current density of 20 mA / g.

[0052] Example 4 A method for constructing hard carbon based on oily biomass includes the following steps: Step 1: Weigh 1 kg of soybeans and crush them. Then, steam puff the sieved crushed material at a pressure of 1.2 MPa and a temperature of 210 ℃. Finally, dry the puffed material at 80 ℃ for 2 h.

[0053] Step 2: Take the expanded and dried material and extract it with n-pentane using a Soxhlet extractor for 7 hours, then air dry it for 12 hours to obtain the de-oiled material; Step 3: Place the deoiled material obtained in Step 2 into a tube furnace and heat it to 1400 ℃ at a heating rate of 5 ℃ / min under argon atmosphere. Hold it at this 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, and then dried in a forced-air drying oven at 60 ℃ for 12 h to obtain a hard carbon anode material enriched with high sodium storage active sites.

[0054] Step 5: Using the hard carbon anode material with high sodium storage active sites prepared above and based on the defects induced by the removal of small molecule oils, a sodium-ion battery was constructed using the same method as in Example 1. The reversible specific capacity reached 248.99 mAh / g at a current density of 20 mA / g.

[0055] Example 5 A method for constructing hard carbon based on oily biomass includes the following steps: Step 1: Weigh 1 kg of soybeans and crush them. Then, steam puff the sieved powder at a pressure of 0.8 MPa and a temperature of 190 ℃. Finally, dry the puffed material at 80 ℃ for 2 h.

[0056] Step 2: Take the expanded and dried material and extract it with n-pentane using a Soxhlet extractor for 7 hours, then air dry it for 12 hours to obtain the de-oiled material; Step 3: Place the deoiled material obtained in Step 2 into a tube furnace and heat it to 1400 ℃ at a heating rate of 5 ℃ / min under argon atmosphere. Hold it at this 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, and then dried in a forced-air drying oven at 60 ℃ for 12 h to obtain a hard carbon anode material enriched with high sodium storage active sites.

[0057] Step 5: Using the hard carbon anode material with high sodium storage active sites prepared above and constructed based on defects induced by the removal of small molecule oils, a sodium-ion battery was constructed using the same method as in Example 1. The reversible specific capacity reached 255.78 mAh / g at a current density of 20 mA / g.

[0058] Example 6 A method for constructing hard carbon based on oily biomass includes the following steps: Step 1: Weigh 1 kg of soybeans and crush them. Then, steam puff the sieved crushed material at a pressure of 1.0 MPa and a temperature of 190 ℃. Finally, dry the puffed material at 80 ℃ for 2 h.

[0059] Step 2: Take the expanded and dried material and extract it with n-pentane using a Soxhlet extractor for 7 hours, then air dry it for 12 hours to obtain the de-oiled material; Step 3: Place the deoiled material obtained in Step 2 into a tube furnace and heat it to 1300 ℃ at a heating rate of 5 ℃ / min under argon atmosphere. Hold it at this temperature for 2 h. After cooling to room temperature, remove the material 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, and then dried in a forced-air drying oven at 60 ℃ for 12 h to obtain a hard carbon anode material enriched with high sodium storage active sites.

[0060] Step 5: Using the hard carbon anode material with high sodium storage active sites prepared above and constructed based on defects induced by the removal of small molecule oils, a sodium-ion battery was constructed using the same method as in Example 1. The reversible specific capacity reached 251.26 mAh / g at a current density of 20 mA / g.

[0061] Example 7 A method for constructing hard carbon based on oily biomass includes the following steps: Step 1: Weigh 1 kg of soybeans and crush them. Then, steam puff the sieved crushed material at a pressure of 1.0 MPa and a temperature of 190 ℃. Finally, dry the puffed material at 80 ℃ for 2 h.

[0062] Step 2: Take the expanded and dried material and extract it with n-pentane using a Soxhlet extractor for 5 h, then air dry it for 12 h to obtain the de-oiled material; Step 3: Place the deoiled material obtained in Step 2 into a tube furnace and heat it to 1400 ℃ at a heating rate of 2 ℃ / min under argon atmosphere. Hold it at this temperature for 2 h. After cooling to room temperature, remove the material 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, and then dried in a forced-air drying oven at 60 ℃ for 12 h to obtain a hard carbon anode material enriched with high sodium storage active sites.

[0063] Step 5: Using the hard carbon anode material with high sodium storage active sites prepared above and constructed based on defects induced by the removal of small molecule oils, a sodium-ion battery was constructed using the same method as in Example 1. The reversible specific capacity reached 246.14 mAh / g at a current density of 20 mA / g.

[0064] Example 8 A method for constructing hard carbon based on oily biomass includes the following steps: Step 1: Weigh 1 kg of soybeans and crush them. Then, steam puff the sieved crushed material at a pressure of 1.0 MPa and a temperature of 190 ℃. Finally, dry the puffed material at 80 ℃ for 2 h.

[0065] Step 2: Take the expanded and dried material and extract it with isohexane using a Soxhlet extractor for 7 hours, then air dry it for 12 hours to obtain the de-oiled material; Step 3: Place the deoiled material obtained in Step 2 into a tube furnace and heat it to 1400 ℃ at a heating rate of 5 ℃ / min under argon atmosphere. Hold it at this 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, and then dried in a forced-air drying oven at 60 ℃ for 12 h to obtain a hard carbon anode material enriched with high sodium storage active sites.

[0066] Step 5: Using the hard carbon anode material with high sodium storage active sites prepared above and based on the defects induced by the removal of small molecule oils, a sodium-ion battery was constructed using the same method as in Example 1. The reversible specific capacity reached 256.46 mAh / g at a current density of 20 mA / g.

[0067] Comparative Example 2 A method for constructing hard carbon based on oily biomass includes the following steps: Step 1: Weigh 1 kg of soybeans and crush them. Then, steam puff the sieved crushed material at a pressure of 1.0 MPa and a temperature of 190 ℃. Finally, dry the puffed material at 80 ℃ for 2 h.

[0068] Step 2: Take the puffed and dried material and extract it with isohexane for 18 hours using a Soxhlet extractor to completely remove the oil. Then air dry it for 12 hours to obtain the de-oiled material. Step 3: Place the deoiled material obtained in Step 2 into a tube furnace and heat it to 1400 ℃ at a heating rate of 5 ℃ / min under argon atmosphere. Hold it at this 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, and then dried in a forced-air drying oven at 60 ℃ for 12 h to obtain hard carbon anode material.

[0069] Step 5: The hard carbon anode material prepared above is used to construct a sodium-ion battery, and the reversible specific capacity reaches 197.52 mAh / g at a current density of 20 mA / g.

Claims

1. A method for constructing hard carbon from oily biomass, characterized in that, Includes the following steps: (1) The oily biomass material is crushed, steam-expanded, and then dried to obtain the expanded oily biomass material; (2) Use an oil extractant to extract oil from the puffed oily biomass material, and then dry it to obtain de-oiled biomass; (3) The deoiled biomass obtained in step (2) is placed in a heating device and carbonized at high temperature under inert gas conditions to obtain carbonized material; (4) The carbonized material obtained in step (3) is first acid-washed with dilute acid solution, then washed with deionized water until the solution is neutral, and then dried to obtain biomass-based hard carbon anode material based on oil removal control. The oily biomass in step (1) is one or more of the oily biomass from pine trees, olive shells, soybeans, and camphor trees; The oil extraction agent in step (2) is selected from one or more of n-pentane, isohexane or n-hexane, n-pentane or cyclopentane, bio-based dimethyl ether, limonene, ethanol or isopropanol.

2. The method for constructing hard carbon from oily biomass according to claim 1, characterized in that, In step (1), the particle size of the oily biomass pulverized material is no greater than 2 mm, the drying temperature is 50-100℃, and the drying time is 1-6 h.

3. The method for constructing hard carbon from oily biomass according to claim 1, characterized in that, The puffing device used in step (1) is a steam puffing machine, the medium is high-temperature and high-pressure saturated steam, the pressure is 0.8-2.0 MPa, and the temperature is 180-240℃.

4. The method for constructing hard carbon from oily biomass according to claim 1, characterized in that, In step (2), a Soxhlet extractor is used as the oil extraction device.

5. The method for constructing hard carbon from oily biomass according to claim 1, characterized in that, The extraction time in step (2) is 1-14 h.

6. The method for constructing hard carbon from oily biomass according to claim 1, characterized in that, The high-temperature carbonization temperature in step (3) is 1200-1700 ℃.

7. The method for constructing hard carbon from oily biomass according to claim 1, characterized in that, In step (3), the high-temperature carbonization heating rate is 0.2-10 ℃ / min, and the high-temperature carbonization time is 1-6 h.

8. The method for constructing hard carbon from oily biomass according to claim 1, characterized in that, The high-temperature carbonization in step (3) uses a tubular furnace, a Joule furnace, or a microwave heating furnace.

9. The method for constructing hard carbon from oily biomass according to claim 1, characterized in that, The dilute acid solution in step (4) is hydrochloric acid with a concentration of 1-2 mol / L and an acid washing time of 6-12 h.

10. The method for constructing hard carbon from oily biomass according to claim 1, characterized in that, The washing process in step (4) involves repeatedly filtering and washing with deionized water, with the number of washes being 3 to 10.

11. The method for constructing hard carbon from oily biomass according to claim 1, characterized in that, In step (3), the high-temperature carbonization protective gas is one of hydrogen, argon, nitrogen, hydrogen-argon, or hydrogen-nitrogen.

12. Hard carbon material prepared by the method according to any one of claims 1-11.

13. The application of the hard carbon material according to claim 12 in the anode material of sodium-ion batteries.

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