A preparation method and application of biomass hard carbon material and its precursor

Abstract

The invention discloses a preparation method and application of a biomass hard carbon material and a precursor thereof, and belongs to the technical field of preparation of electrode materials for sodium ion batteries. The preparation method of the precursor of the biomass hard carbon material comprises the following steps: steam carbonization and steam explosion; for the steam carbonization, crushed biomass powder is put into a steam explosion kettle at room temperature, the kettle cover is closed, and steam is introduced to start steam carbonization; for the steam explosion, after the steam carbonization is completed, the temperature in the steam explosion kettle is kept unchanged, the pressure is released, and then the material in the steam explosion kettle is taken out and dried to obtain the precursor of the biomass hard carbon material; the preparation method of the biomass hard carbon material comprises the following steps: crushing, high-temperature carbonization, and coating carbonization; the preparation method of the invention can solve the technical problems that the yield of biomass hard carbon materials is difficult to improve, the pore structure is difficult to control, and the purity needs to be improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of sodium ion battery electrode material preparation, and in particular relates to a biomass hard carbon material and a preparation method and application of a precursor thereof. Background Art

[0002] With the rapid development of all sectors and industries in society, the demand for high-performance, low-cost electrochemical energy storage systems is growing. Sodium-ion batteries have the advantages of abundant raw materials and low cost, and have great potential in the field of energy storage. As an important component of sodium-ion batteries, the negative electrode plays a decisive role in its performance. Compared with other types of negative electrode materials, biomass hard carbon materials have an amorphous or partially crystalline structure with a certain degree of order in the short range. This structure provides more insertion sites for sodium ions and helps the diffusion of sodium ions inside the material. It has many advantages such as high sodium storage capacity, low sodium storage potential, good cycle stability and rate performance. It can meet the long cycle life and fast charging and discharging requirements of sodium-ion batteries, and is the most promising negative electrode material for sodium-ion batteries.

[0003] Biomass hard carbon materials have the advantages of wide sources, low cost, and environmental friendliness, and can be prepared in a variety of ways. Chinese patent CN118270767A discloses a biomass hard carbon material, a preparation method thereof, and its application in sodium ion batteries, comprising the following steps: pre-carbonization of biomass raw materials by hydrothermal treatment; stirring and reacting the pre-carbonized material in an alcohol solvent to modify the pre-carbonized material; high-temperature carbonization of the modified pre-carbonized material to obtain a biomass hard carbon material. This method effectively solves the problems of low specific capacity and low first coulomb efficiency when hard carbon materials are used as negative electrodes of sodium ion batteries in the prior art. Chinese patent CN118125419B discloses a preparation method of a hard carbon negative electrode material for sodium ion batteries and a sodium ion battery, comprising the following steps: washing, dehydrating, drying, and crushing of biomass materials; steam explosion of biomass fine powder; vacuum freeze drying; heat treatment and carbonization; washing and crushing and then heat treating it to obtain a hard carbon negative electrode material for sodium ion batteries. This method successfully improves the first coulomb efficiency and achieves the purpose of improving capacity and efficiency.

[0004] However, with the practical application of the above methods, some difficult-to-solve technical problems have also emerged: the yield of biomass hard carbon materials is difficult to improve; during the preparation of biomass hard carbon materials, the pore structure formed is disordered and difficult to control, resulting in unstable electrochemical performance; the main purpose of the pickling process during the preparation process is to remove the ash of the material itself. The less ash the final product has, the higher the purity and the better the electrochemical performance. However, due to the limitations of the current pickling process, the purity of biomass hard carbon materials needs to be improved.

[0005] Therefore, there is an urgent need to provide a method for preparing biomass hard carbon materials to solve the above problems. Summary of the invention

[0006] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a preparation method and application of a biomass hard carbon material and its precursor, so as to solve the current technical problems that the yield of biomass hard carbon materials is difficult to increase, the pore structure is difficult to control, and the purity needs to be improved.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for preparing a precursor of a biomass hard carbon material comprises the following steps: steam carbonization, steam explosion;

[0009] The steam carbonization comprises placing the crushed biomass powder into a steam explosion kettle at room temperature, closing the kettle cover and introducing steam to start steam carbonization;

[0010] Preferably, the biomass powder is one of bamboo powder or nut shell powder;

[0011] Preferably, after closing the kettle cover and before introducing steam, CO is introduced into the steam explosion kettle. 2 Until the pressure in the steam explosion kettle is 1.8-2MPa;

[0012] Preferably, the steam carbonization temperature is 220-280°C and the time is 15-120min;

[0013] The steam explosion, after the steam carbonization is completed, keeps the temperature in the steam explosion kettle unchanged, releases the pressure, then takes out the material in the steam explosion kettle and dries it to obtain the precursor of the biomass hard carbon material;

[0014] Preferably, the pressure relief time is 0.5-1s.

[0015] A method for preparing a biomass hard carbon material comprises the following steps: crushing, high temperature carbonization, and coating carbonization;

[0016] The pulverizing comprises pulverizing the precursor of the biomass hard carbon material to obtain a pulverized material;

[0017] Preferably, the crushed material has D10=3μm, D50=10μm, and D90=24μm;

[0018] The high temperature carbonization is to calcine the crushed material to obtain a high temperature carbonized material;

[0019] Preferably, the calcination is carried out under a nitrogen atmosphere;

[0020] Preferably, the calcination temperature is 1300-1400°C and the time is 1-1.5h;

[0021] The coating carbonization comprises adding asphalt to the high temperature carbonized material, stirring, spin drying, and calcining to obtain a biomass hard carbon material;

[0022] Preferably, the stirring time is 6-7h;

[0023] Preferably, the pitch accounts for 4-6% of the high temperature carbonized material.

[0024] Preferably, the calcination is carried out under a nitrogen atmosphere;

[0025] Preferably, the calcination temperature is 1000-1100°C and the time is 1-1.5h;

[0026] Preferably, a method for preparing a biomass hard carbon material further comprises pickling, wherein the pickling is performed after pulverization and before high-temperature carbonization;

[0027] Further preferably, the acid washing comprises completely immersing the crushed material in a hydrochloric acid solution with a concentration of 0.8-1.2 mol / L, immersing at 75-85° C. for 1.5-2.5 h, filtering and washing multiple times until the filtrate is neutral, and collecting the filter cake for drying.

[0028] An application of the biomass hard carbon material obtained by the aforementioned preparation method.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) The preparation method of the biomass hard carbon material and its precursor of the present invention comprises steam carbonization, steam explosion, crushing, high temperature carbonization and coating carbonization. Among them, steam carbonization is carried out in a steam explosion kettle. Compared with the traditional hydrothermal carbonization method, steam carbonization avoids the loss of water-soluble small molecular substances caused by hydrolysis during the carbonization process, and improves the yield of the carbonization process. After the steam carbonization is completed, the pressure relief device on the steam explosion kettle is opened to realize the rapid expansion and release of steam in the steam explosion kettle to complete the steam explosion process. Steam explosion destroys the crystalline structure of the carbon material through the flash evaporation of superheated water and the volume expansion of water vapor, thereby increasing the amorphous carbon structure and increasing the number of mesopores and macropores in the carbon material, reducing the specific surface area of ​​the carbon material. The yield of the precursor of the hard carbon material obtained in the end is high, and the hard carbon material made from the precursor of the hard carbon material has a high discharge capacity and first coulomb efficiency. During the steam carbonization process, CO introduced 2 It can form an acidic atmosphere, and under high temperature and high pressure conditions, it can fully react with the ash in the carbon material, thereby improving the ash removal effect, thereby reducing the ash content of the precursor of the biomass hard carbon material and improving the purity of the precursor of the biomass hard carbon material;

[0031] (2) The method for preparing the biomass hard carbon material and its precursor of the present invention solves the technical problems that the yield of the biomass hard carbon material is difficult to improve, the pore structure is difficult to control, and the purity needs to be improved. The ash content of the precursor of the prepared biomass hard carbon material is 0.076-1.687%, the yield of the precursor of the biomass hard carbon material is 45.06-67.21%, and the specific surface area of ​​the prepared biomass hard carbon material is 3.17-8.92m 2 / g, the yield of biomass hard carbon materials is 18.54-26.07%;

[0032] (3) The method for preparing the biomass hard carbon material and its precursor of the present invention, wherein the button-type battery assembled from the prepared biomass hard carbon material has a charging capacity of 277.5-401.5 mAh / g and a first-cycle coulombic efficiency of 87.99-92.61%;

[0033] (4) The method for preparing the biomass hard carbon material and its precursor of the present invention can increase the obtained biomass hard carbon material and increase the interlayer spacing of the biomass hard carbon material to 0.43 nm, thereby being more conducive to the storage of sodium ions;

[0034] (5) The method for preparing the biomass hard carbon material and its precursor of the present invention uses steam to carbonize the material. The steam directly contacts the material, heats evenly and has a high heat transfer rate, thus saving energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The charge and discharge curves of button batteries assembled from biomass hard carbon materials obtained in Example 2, Example 5, and Example 8;

[0036] Figure 2 The rate performance diagram of button cells assembled from biomass hard carbon materials obtained in Example 2, Example 5, and Example 8;

[0037] Figure 3 This is the SEM image of the biomass hard carbon material obtained in Example 1;

[0038] Figure 4 This is the SEM image of the biomass hard carbon material obtained in Comparative Example 2;

[0039] Figure 5 This is a TEM image of the biomass hard carbon material obtained in Example 1;

[0040] Figure 6 This is the TEM image of the biomass hard carbon material obtained in Comparative Example 2. DETAILED DESCRIPTION

[0041] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0042] Example 1

[0043] A method for preparing a precursor of a biomass hard carbon material comprises the following steps:

[0044] 1. Steam carbonization: At room temperature, put the crushed bamboo powder into a metal basket with dense small holes, and then put it into the steam explosion kettle. Close the kettle cover and let in steam to start steam carbonization. The temperature of steam carbonization is controlled at 220℃ and the time is 15min.

[0045] 2. Steam explosion: After the steam carbonization is completed, the steam carbonization temperature is kept unchanged, and the pressure relief valve on the steam explosion kettle is opened for steam explosion. The pressure relief time is 1 second, and then the material after steam explosion is taken out and added into the oven for drying to obtain the precursor of biomass hard carbon material.

[0046] A method for preparing a biomass hard carbon material comprises the following steps:

[0047] 1. Crushing: Using a jet mill, the precursor of the biomass hard carbon material prepared above is crushed to D10=3μm, D50=10μm, and D90=24μm to obtain a crushed material;

[0048] 2. Pickling: Soak the crushed material completely in a 1 mol / L HCL solution, heat it to 80°C and soak it for 2 hours, filter and wash it several times until the filtrate is neutral, collect the filter cake and dry it to obtain the acid-washed material;

[0049] 3. High temperature carbonization: Add the pickled material into a tubular furnace and calcine it at 1300°C for 1 hour in a nitrogen atmosphere to obtain a high temperature carbonized material;

[0050] 4. Coating carbonization: Add 5% asphalt to the high-temperature carbonized material and stir for 6 hours, then use a rotary evaporator to spin dry it, add the dried material to a tubular furnace, calcine it at 1000°C for 1 hour in a nitrogen atmosphere for high-temperature carbonization to obtain a biomass hard carbon material.

[0051] Example 2

[0052] The steam carbonization time in the first step of steam carbonization was changed to 60 min, and the steam carbonization temperature remained unchanged.

[0053] Example 3

[0054] The steam carbonization time in the first step of steam carbonization in Example 1 was changed to 120 min, and the steam carbonization temperature remained unchanged.

[0055] Example 4

[0056] The temperature of steam carbonization in the first step of steam carbonization in Example 1 was changed to 260° C., and the time was changed to 15 min.

[0057] Example 5

[0058] The temperature of steam carbonization in the first step of steam carbonization in Example 1 was changed to 260° C., and the time was changed to 60 min.

[0059] Example 6

[0060] The temperature of steam carbonization in the first step of steam carbonization in Example 1 was changed to 260° C., and the time was changed to 120 min.

[0061] Example 7

[0062] The temperature of steam carbonization in the first step of steam carbonization in Example 1 was changed to 280° C., and the time was changed to 15 min.

[0063] Example 8

[0064] The temperature of steam carbonization in the first step of steam carbonization in Example 1 was changed to 280° C. and the time was changed to 60 min.

[0065] Example 9

[0066] The temperature of steam carbonization in the first step of steam carbonization in Example 1 was changed to 280° C., and the time was changed to 120 min.

[0067] Example 10

[0068] A method for preparing a precursor of a biomass hard carbon material comprises the following steps:

[0069] 1. Steam carbonization: Put the crushed bamboo powder into a metal basket with dense small holes at room temperature, then put it into the steam explosion kettle, close the kettle cover, and introduce CO into the steam explosion kettle. 2 , the pressure in the steam explosion kettle is 2MPa, and then steam is introduced to start steam carbonization, and the temperature of steam carbonization is controlled to be 260℃ and the time is 60min;

[0070] 2. Steam explosion: After the steam carbonization is completed, the steam carbonization temperature is kept unchanged, and the pressure relief valve on the steam explosion kettle is opened for steam explosion. The pressure relief time is 1 second, and then the material after steam explosion is taken out and added into the oven for drying to obtain the precursor of biomass hard carbon material.

[0071] A method for preparing a biomass hard carbon material comprises the following steps:

[0072] 1. Crushing: Using a jet mill, the precursor of the biomass hard carbon material prepared above is crushed to D10=3μm, D50=10μm, and D90=24μm to obtain a crushed material;

[0073] 2. Pickling: Soak the crushed material completely in a 1 mol / L HCL solution, heat it to 80°C and soak it for 2 hours, filter and wash it several times until the filtrate is neutral, collect the filter cake and dry it to obtain the acid-washed material;

[0074] 3. High temperature carbonization: Add the pickled material into a tubular furnace and calcine it at 1300°C for 1h in a nitrogen atmosphere to obtain a high temperature carbonized material;

[0075] 4. Coating carbonization: Add 5% asphalt to the high-temperature carbonized material and stir for 6 hours, then use a rotary evaporator to spin dry it, add the dried material to a tubular furnace, calcine it at 1000°C for 1 hour in a nitrogen atmosphere for high-temperature carbonization to obtain a biomass hard carbon material.

[0076] Embodiment 11

[0077] A method for preparing a biomass hard carbon material and a precursor thereof comprises the following steps:

[0078] 1. Steam carbonization: put the crushed nut shell powder into a metal basket with dense small holes at room temperature, and then put it into the steam explosion kettle. After closing the kettle cover, steam is introduced to start steam carbonization. The steam carbonization temperature is controlled at 260℃ and the time is 60min.

[0079] 2. Steam explosion: After the steam carbonization is completed, the steam carbonization temperature is kept unchanged, and the pressure relief valve on the steam explosion kettle is opened for steam explosion. The pressure relief time is 1 second, and then the material after steam explosion is taken out and added into the oven for drying to obtain the precursor of biomass hard carbon material.

[0080] A method for preparing a biomass hard carbon material comprises the following steps:

[0081] 1. Crushing: Using a jet mill, the precursor of the biomass hard carbon material prepared above is crushed to D10=3μm, D50=10μm, and D90=24μm to obtain a crushed material;

[0082] 2. High temperature carbonization: Add the crushed material into a tubular furnace and calcine it at 1300℃ for 1h in a nitrogen atmosphere to obtain high temperature carbonized material; (because the ash content in nut shell powder is small, it does not need to be acid washed after crushing, and high temperature carbonization can be carried out directly)

[0083] 3. Coating carbonization: Add 5% asphalt to the high-temperature carbonized material and stir for 6 hours, then use a rotary evaporator to spin dry it, add the dried material to a tubular furnace, calcine it at 1000°C for 1 hour in a nitrogen atmosphere for high-temperature carbonization to obtain a biomass hard carbon material.

[0084] Comparative Example 1

[0085] A method for preparing a precursor of a biomass hard carbon material comprises the following steps:

[0086] 1. Hydrothermal carbonization: Put the crushed bamboo powder and deionized water into the reactor at a solid-liquid ratio of 8:10, close the reactor cover and start hydrothermal carbonization, control the hydrothermal carbonization temperature to 260°C and the time to 60 minutes. After the hydrothermal carbonization is completed, take out the material and put it into an oven for drying to obtain the precursor of the biomass hard carbon material.

[0087] A method for preparing a biomass hard carbon material comprises the following steps:

[0088] 1. Crushing: Using a jet mill, the precursor of the biomass hard carbon material prepared above is crushed to D10=3μm, D50=10μm, and D90=24μm to obtain a crushed material;

[0089] 2. Pickling: Soak the crushed material completely in a 1 mol / L HCL solution, heat it to 80°C and soak it for 2 hours, filter and wash it several times until the filtrate is neutral, collect the filter cake and dry it to obtain the acid-washed material;

[0090] 3. High temperature carbonization: Add the pickled material into a tubular furnace and calcine it at 1300°C for 1 hour in a nitrogen atmosphere to obtain a high temperature carbonized material;

[0091] 4. Coating carbonization: Add 5% asphalt to the high-temperature carbonized material and stir for 6 hours, then use a rotary evaporator to spin dry it, add the dried material to a tubular furnace, calcine it at 1000°C for 1 hour in a nitrogen atmosphere for high-temperature carbonization to obtain a biomass hard carbon material.

[0092] Comparative Example 2

[0093] A method for preparing a precursor of a biomass hard carbon material comprises the following steps:

[0094] 1. Steam carbonization: put the crushed bamboo powder into a metal basket with dense small holes at room temperature, and then put it into the steam explosion kettle. Close the kettle cover and let in steam to start steam carbonization. The steam carbonization temperature is controlled at 260℃ and the time is 60min.

[0095] 2. Steam explosion: After the steam carbonization is completed, the pressure in the steam explosion kettle is naturally reduced to 0, and the pressure relief time is 1 minute. Then the steam carbonized material is taken out and added into an oven for drying to obtain the precursor of the biomass hard carbon material.

[0096] A method for preparing a biomass hard carbon material comprises the following steps:

[0097] 1. Crushing: Using a jet mill, the precursor of the biomass hard carbon material prepared above is crushed to D10=3μm, D50=10μm, and D90=24μm to obtain a crushed material;

[0098] 2. Pickling: Soak the crushed material completely in a 1 mol / L HCL solution, heat it to 80°C and soak it for 2 hours, filter and wash it several times until the filtrate is neutral, collect the filter cake and dry it to obtain the acid-washed material;

[0099] 3. High temperature carbonization: Add the pickled material into a tubular furnace and calcine it at 1300°C for 1 hour in a nitrogen atmosphere to obtain a high temperature carbonized material;

[0100] 4. Coating carbonization: Add 5% asphalt to the high-temperature carbonized material and stir for 6 hours, then use a rotary evaporator to spin dry it, add the dried material to a tubular furnace, calcine it at 1000°C for 1 hour in a nitrogen atmosphere for high-temperature carbonization to obtain a biomass hard carbon material.

[0101] Comparative Example 3

[0102] A method for preparing a precursor of a biomass hard carbon material comprises the following steps:

[0103] 1. Steam explosion: at room temperature, put the crushed bamboo powder into a metal basket with dense small holes, and then put it into a steam explosion kettle. Close the kettle cover and introduce steam to start heating. After the temperature reaches 260°C, keep it for 2 minutes. Open the pressure relief valve on the steam explosion kettle to perform steam explosion. The pressure relief time is 1 second. After the steam explosion is completed, open the kettle cover, take out the steam-exploded material and put it into an oven for drying to obtain the steam-exploded material;

[0104] 2. Steam carbonization: put the steam-exploded material at room temperature into a metal basket with dense small holes, and then put it into a steam explosion kettle. Close the kettle cover and let steam in to start steam carbonization. Control the steam carbonization temperature to 260°C and the time to 60 minutes. After the steam carbonization is completed, naturally reduce the pressure in the steam explosion kettle to 0, and the pressure relief time is 1 minute. Then take out the steam carbonized material and put it into an oven for drying to obtain the precursor of biomass hard carbon material.

[0105] A method for preparing a biomass hard carbon material comprises the following steps:

[0106] 1. Crushing: Using a jet mill, the precursor of the biomass hard carbon material prepared above is crushed to D10=3μm, D50=10μm, and D90=24μm to obtain a crushed material;

[0107] 2. Pickling: Soak the crushed material completely in a 1 mol / L HCL solution, heat it to 80°C and soak it for 2 hours, filter and wash it several times until the filtrate is neutral, collect the filter cake and dry it to obtain the acid-washed material;

[0108] 3. High temperature carbonization: Add the pickled material into a tubular furnace and calcine it at 1300°C for 1 hour in a nitrogen atmosphere to obtain a high temperature carbonized material;

[0109] 4. Coating carbonization: Add 5% asphalt to the high-temperature carbonized material and stir for 6 hours, then use a rotary evaporator to spin dry it, add the dried material to a tubular furnace, calcine it at 1000°C for 1 hour in a nitrogen atmosphere for high-temperature carbonization to obtain a biomass hard carbon material.

[0110] Product effect test 1

[0111] The ash content and yield of the precursors of the biomass hard carbon materials obtained in Examples 1-11 and Comparative Examples 1-3, and the specific surface area and yield of the obtained biomass hard carbon materials were tested. The test results are shown in Table 1:

[0112] Table 1

[0113]

[0114] Product effect test 2

[0115] The biomass hard carbon material obtained in Example 1-11 and Comparative Example 1-3 was mixed with acetylene black and sodium alginate in a mass ratio of 8:1:1, and then water was added as a solvent. After mixing evenly, it was coated on a copper foil, dried in a vacuum oven at 102°C, rolled and cut into circular electrode pieces with a diameter of 8 mm. The circular electrode piece was used as the positive electrode, the sodium sheet was used as the negative electrode, and the NaPF with a model of NP-001 was used as the negative electrode. 6The ester electrolyte was used as the electrolyte and the glass fiber diaphragm was used as the diaphragm. The button cells were assembled in a glove box filled with argon. The charge and discharge performance of the prepared sodium ion battery was tested. The battery test was carried out using a blue battery test system. The test results are shown in Table 2:

[0116] Table 2

[0117]

[0118] The charge and discharge curves of the button-type batteries assembled from the biomass hard carbon materials obtained in Example 2, Example 5, and Example 8 are shown in Figure 1 , see the rate performance diagram Figure 2 .

[0119] Product effect test three

[0120] 1. The biomass hard carbon materials obtained in Example 1 and Comparative Example 2 were analyzed by scanning electron microscope. The SEM image of the biomass hard carbon material in Example 1 is shown in Figure 3 The SEM image of the biomass hard carbon material of Comparative Example 2 is shown in Figure 4 ;

[0121] Depend on Figure 1 and Figure 2 It can be seen that the pore size of the biomass hard carbon material obtained in Example 1 becomes larger and the structure becomes looser, which indicates that the steam explosion method of Example 1 has the effect of expanding the pores.

[0122] 2. The biomass hard carbon materials obtained in Example 1 and Comparative Example 2 were analyzed by transmission electron microscopy. The TEM image of the biomass hard carbon material in Example 1 is shown in Figure 5 The TEM image of the biomass hard carbon material of Comparative Example 2 is shown in Figure 6 ;

[0123] Depend on Figure 5 and Figure 6 It can be seen that the interlayer spacing of the biomass hard carbon material obtained in Example 1 is 0.43 nm, and the interlayer spacing of the biomass hard carbon material obtained in Comparative Example 2 is 0.37 nm. The interlayer spacing of the biomass hard carbon material obtained in Example 1 is larger.

[0124] From the results of product effect test 1 and product effect test 2, it can be seen that steam carbonization can obtain higher yields of biomass hard carbon material precursors and biomass hard carbon material than hydrothermal carbonization; steam explosion can increase the number of mesopores and macropores of biomass hard carbon material, reduce the specific surface area of ​​biomass hard carbon material, and effectively improve the discharge capacity and first-cycle coulomb efficiency of biomass hard carbon material; CO is introduced into the steam carbonization stage. 2The ash content of the obtained biomass hard carbon material precursor is lower; the steam carbonization combined with steam explosion technology can be applied to both crushed bamboo powder and crushed nut shell powder in the preparation of biomass hard carbon material precursor, and has universal applicability.

[0125] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a precursor of a biomass hard carbon material, characterized in that: The following steps are involved: Steam carbonization, steam explosion; The steam carbonization comprises placing the crushed biomass powder into a steam explosion kettle at room temperature, closing the kettle cover and introducing steam to start steam carbonization; During the steam carbonization, after closing the kettle cover and before introducing steam, CO2 is introduced into the steam explosion kettle until the pressure inside the steam explosion kettle reaches 1.8-2MPa; In the steam carbonization, the temperature of the steam carbonization is 220-280° C. and the time is 15-120 min; In the steam explosion, after the steam carbonization is completed, the temperature in the steam explosion kettle is kept constant, the pressure is released, and then the material in the steam explosion kettle is taken out and dried to obtain the precursor of the biomass hard carbon material.

2. The method for preparing a precursor of a biomass hard carbon material according to claim 1, characterized in that: In the steam carbonization, the biomass powder is one of bamboo powder and nut shell powder.

3. The method for preparing a precursor of a biomass hard carbon material according to claim 1, characterized in that: In the steam explosion, the pressure relief time is 0.5-1s.

4. A method for preparing a biomass hard carbon material, characterized in that: The method comprises the following steps: crushing, high temperature carbonization, and coating carbonization; The pulverizing comprises pulverizing the precursor of the biomass hard carbon material prepared by the preparation method according to any one of claims 1 to 3 to obtain a pulverized material; The high temperature carbonization is to calcine the crushed material to obtain a high temperature carbonized material; In the coating carbonization, asphalt is added to the high-temperature carbonized material, and the mixture is stirred, spin-dried, and calcined to obtain the biomass hard carbon material.

5. The method for preparing biomass hard carbon material according to claim 4, characterized in that: During the pulverization, the pulverized material has D10=3μm, D50=10μm, and D90=24μm; During the high temperature carbonization, the calcination is performed under a nitrogen atmosphere; The calcination temperature is 1300-1400° C. and the calcination time is 1-1.5 h.

6. The method for preparing biomass hard carbon material according to claim 4, characterized in that: During the coating carbonization, the stirring time is 6-7h; Asphalt accounts for 4-6% of the high temperature carbonized material; The calcination is carried out under a nitrogen atmosphere; The calcination temperature is 1000-1100° C. and the calcination time is 1-1.5 h.

7. The method for preparing biomass hard carbon material according to claim 4, characterized in that: The method for preparing the biomass hard carbon material further comprises pickling, wherein the pickling is performed after crushing and before high-temperature carbonization; For the acid washing, the crushed material is completely immersed in a hydrochloric acid solution with a concentration of 0.8-1.2 mol / L, immersed at 75-85° C. for 1.5-2.5 hours, filtered and washed multiple times until the filtrate is neutral, and the filter cake is collected and dried.

8. Application of a biomass hard carbon material prepared by the preparation method according to any one of claims 4 to 7.

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