A method for preparing a coal-based silicon-carbon composite material
By modifying anthracite to prepare porous carbon materials, and combining nano-silicon deposition and carbon coating, the shortcomings of anthracite-based silicon-carbon composite materials in terms of power performance and initial efficiency are solved, achieving high-efficiency battery performance and low expansion.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CENT SOUTH UNIV
- Filing Date
- 2026-06-17
- Publication Date
- 2026-07-31
AI Technical Summary
Existing anthracite-based silicon-carbon composite materials perform poorly in terms of power performance and initial efficiency, making it difficult to balance cost and consistency. Furthermore, the difficulty in creating pores in porous carbon affects the amount of active material deposited.
Using anthracite as raw material, porous carbon materials are prepared by modifying the material with organic acids, sulfur sources, and organic carbon sources, combined with composite activators and photocatalytic reactions. Furthermore, the electronic conductivity and surface microporous structure of the material are improved through nano-silicon deposition and carbon coating.
It significantly improves the power performance and first-pass efficiency of silicon-carbon materials, reduces expansion, increases the electronic conductivity and surface oxidation activation of materials, and enhances the pore structure consistency of materials.
Smart Images
Figure CN122482467A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of silicon-carbon anode materials, specifically relating to a method for preparing a coal-based silicon-carbon composite material. Background Technology
[0002] Currently, the widely used silicon-carbon composite materials on the market are mainly: porous carbon prepared by activating bio-based or resin-based raw materials, and then carbon-coated after silane pyrolysis deposition of the porous carbon. The carbon matrix raw materials used in the porous carbon play an important role in the capacity, power, expansion and cycling of silicon-carbon materials.
[0003] However, bio-based silicon-carbon composites suffer from low compaction density and poor consistency; while resin-based silicon-carbon composites are characterized by high cost and high impedance, making it impossible for any silicon-carbon material to achieve a balance between power, specific capacity, and cost. Anthracite, as a bulk material with high residual carbon content, wide availability, high consistency, and low cost, and with its high anisotropy in carbon-based materials, can reduce impedance, faces challenges in pore formation. This affects the consistency of porous carbon and the number of pores, reducing the deposition of active materials. Consequently, existing coal-based silicon-carbon composites perform worse than expected in terms of power performance and initial efficiency, making them difficult to accept and apply in the market.
[0004] Therefore, the applicant hopes to find a technical solution to address the above-mentioned technical problems of anthracite carbon-based materials. Summary of the Invention
[0005] In view of this, the purpose of the present invention is to provide a method for preparing a coal-based silicon-carbon composite material, the obtained coal-based silicon-carbon composite material can significantly improve the power performance and initial efficiency of its applied battery.
[0006] The technical solution adopted in this invention is as follows: A method for preparing a coal-based silicon-carbon composite material includes at least the following steps: S1. Anthracite, organic acid, sulfur source, and organic carbon source are added to diethyl ether solvent and mixed evenly. The mixture is then transferred to a high-pressure reactor and reacted at 100-200℃ for 1-3 hours. After filtration and drying, the resulting material is transferred to a pre-oxidation furnace and heated to 300-600℃. An oxidizing mixed gas is introduced at a flow rate of 100-300 ml / min for pre-oxidation treatment for 30-300 min to obtain the precursor material. S2. Mix the precursor material obtained in step S1 with the composite activator evenly, activate it at a temperature of 900-1100℃ for 1-6 hours, and then cool it down to obtain porous carbon material. S3. Mix the porous carbon material obtained in step S2 with the photosensitizer evenly, carry out a photocatalytic reaction, and then heat it to 900-1100℃ for a secondary carbonization treatment for 1-6 hours to obtain a coal-based porous carbon composite material. S4. Transfer the coal-based porous carbon composite material obtained in step S3 to a fluidized bed, introduce inert gas to purge the air from the fluidized bed, raise the temperature to 450-600℃, and introduce a silane mixed gas at a flow rate of 100-500 ml / min for 60-600 min. Then raise the temperature to 700-900℃, and introduce a carbon source gas and a fluorinated gas at a flow rate of 10-100 ml / min for 30-300 min. Finally, cool down in an inert gas atmosphere to obtain the coal-based silicon-carbon composite material.
[0007] Preferably, in step S1, the organic acid is selected from any one or a mixture of several of citric acid, malic acid, tartaric acid, succinic acid, benzoic acid, oxalic acid, and lactic acid; the sulfur source is selected from any one or a mixture of several of benzyl mercaptan, thioether, hydrazine sulfate, phenylthiourea, n-propanethiol, dithiodiazole, and diethyl disulfide; the organic carbon source is any one or a mixture of several of glucose, fructose, galactose, starch, cellulose, and hemicellulose; and the oxidizing mixed gas is a mixture of at least one oxidizing gas selected from oxygen, bromine, and nitrogen dioxide with nitrogen, wherein the volume ratio of the oxidizing gas to nitrogen is in the range of 10:1-5.
[0008] Preferably, in step S1, the mass ratio of anthracite: organic acid: sulfur source: organic sugar source is in the range of 100:5-20:1-5:100-300.
[0009] Preferably, in step S2, the composite activator is composed of an inorganic activator and an organic activator, wherein the mass ratio of the inorganic activator to the organic activator is in the range of 10:1-5.
[0010] Preferably, the inorganic activator is selected from any one or a mixture of potassium hydroxide, potassium carbonate, and sodium hydroxide; the organic activator is selected from any one or a mixture of ethanolamine, diethanolamine, and triethanolamine.
[0011] Preferably, in step S2, the mass ratio of precursor material to composite activator is in the range of 100:100-500.
[0012] Preferably, in step S3, the photosensitizer is any one of ruthenium dipyridyl, tri[2-(4-tert-butylphenyl)pyridine]iridium, 1,5-cyclooctadiene bis(methylbiphenylphosphine)iridium hexafluorophosphate, and 1,5-cyclooctadiene (pyridine) (tricyclohexylphosphine)iridium hexafluorophosphate.
[0013] Preferably, in step S3, the conditions for the photocatalytic reaction are: a wavelength of 200-800 nm and a light intensity of 50-200 mW / cm². 2 The light source is irradiated for 1-3 hours at a temperature of 20-50℃.
[0014] Preferably, in step S3, the mass ratio of porous carbon material to photosensitizer is in the range of 100:10-30.
[0015] Preferably, in step S4, the silane mixed gas is a mixture of silane gas and carrier gas; wherein the volume ratio of silane gas to carrier gas is in the range of 1:1-5; the silane gas is any one of methanesilane, ethylsilane, monochlorosilane, and dichlorosilane; and the carrier gas is any one of nitrogen and argon. The carbon source gas is any one of methane, ethane, ethylene, and acetylene; the fluorinated gas is any one of nitrogen tetrafluoride, nitrogen trifluoride, hydrogen fluoride, and ammonium fluoride; wherein the volume ratio of carbon source gas to fluorinated gas is in the range of 10:1-5.
[0016] It should be noted that the coal-based silicon-carbon composite material prepared in this application is suitable as a negative electrode material for lithium-ion batteries.
[0017] The working mechanism and technical effects of this application are as follows: In order to improve the power performance of silicon-carbon materials while taking into account the initial efficiency and cost, this application uses anthracite as raw material and modifies the anthracite material with organic acid, sulfur source and organic carbon source to facilitate the activation and pore formation of the composite activator, so as to prepare anthracite porous carbon (i.e. porous carbon material) with suitable pore volume. Then, the surface of the material is modified by photosensitizer to reduce defects and obtain coal-based porous carbon composite material. Then, the coal-based porous carbon composite material is used as the matrix for nano-silicon deposition and carbon coating, which significantly improves the power performance and initial efficiency of the battery applied by the coal-based porous carbon composite material. The beneficial effects achieved by this application mainly include the following: 1. Using anthracite as raw material, the material is modified by organic acid, sulfur source, and organic carbon source. Sulfur doping with sulfur source improves the electronic conductivity of the material, organic acid oxidizes and activates the surface of the material to create micropores, and the introduction of organic carbon source can form spherical small particles to improve power performance. It also has the characteristics of high anisotropy with block coal and plays a synergistic role between the two, which can significantly improve the power performance of the material in battery applications.
[0018] 2. The precursor material is activated by a composite activator. The inorganic activator in the composite activator activates the macroporous structure, while the organic activator activates the microporous structure, so that the material forms a material with a reasonable macroporous and microporous structure, thereby reducing the expansion of silicon-carbon materials.
[0019] 3. By modifying the surface of porous carbon materials through photocatalytic reaction to reduce defects, the silicon-carbon anode material used in lithium-ion batteries can be applied to significantly improve the initial efficiency of the battery. Attached Figure Description
[0020] Figure 1 This is a SEM image of the coal-based silicon-carbon composite material obtained in Example 1 of this application. Detailed Implementation
[0021] This embodiment proposes a method for preparing coal-based silicon-carbon composite materials, which includes at least the following steps: S1. Anthracite, organic acid, sulfur source, and organic carbon source are added to diethyl ether solvent and mixed evenly. The mixture is then transferred to a high-pressure reactor and reacted at 100-200℃ for 1-3 hours. After filtration and drying, the resulting material is transferred to a pre-oxidation furnace and heated to 300-600℃. An oxidizing mixed gas is introduced at a flow rate of 100-300 ml / min for pre-oxidation treatment for 30-300 min to obtain the precursor material. Preferably, in step S1, the organic acid is selected from any one or a mixture of several of citric acid, malic acid, tartaric acid, succinic acid, benzoic acid, oxalic acid, and lactic acid. The sulfur source is selected from any one or a mixture of several of benzyl mercaptan, thioether, hydrazine sulfate, phenylthiourea, n-propanethiol, dithiodiazole, and diethyl disulfide; the organic carbon source is any one or a mixture of several of glucose, fructose, galactose, starch, cellulose, and hemicellulose; the oxidizing mixed gas is a mixture of at least one oxidizing gas selected from oxygen, bromine, and nitrogen dioxide with nitrogen, wherein the volume ratio of the oxidizing gas to nitrogen ranges from 10:1 to 5; preferably, in step S1, the mass ratio of anthracite: organic acid: sulfur source: organic sugar source ranges from 100:5 to 20:1 to 5:100 to 300.
[0022] S2. The precursor material obtained in step S1 is mixed evenly with the composite activator, and activated at a temperature of 900-1100℃ for 1-6 hours, followed by cooling to obtain porous carbon material; preferably, in step S2, the composite activator is composed of an inorganic activator and an organic activator, wherein the mass ratio of the inorganic activator to the organic activator is in the range of 10:1-5; the inorganic activator is selected from any one or a mixture of potassium hydroxide, potassium carbonate, and sodium hydroxide; the organic activator is selected from any one or a mixture of ethanolamine, diethanolamine, and triethanolamine; in step S2, the mass ratio of the precursor material to the composite activator is in the range of 100:100-500.
[0023] S3. The porous carbon material obtained in step S2 is mixed evenly with a photosensitizer, and after photocatalytic reaction, the mixture is heated to 900-1100℃ for secondary carbonization treatment for 1-6 hours to obtain a coal-based porous carbon composite material. Preferably, in step S3, the photosensitizer is any one of ruthenium dipyridylene, tris[2-(4-tert-butylphenyl)pyridine]iridium, 1,5-cyclooctadiene bis(methylbiphenylphosphine)iridium hexafluorophosphate, or 1,5-cyclooctadiene (pyridine)(tricyclohexylphosphine)iridium hexafluorophosphate. The photocatalytic reaction conditions are: wavelength 200-800nm, light intensity 50-200mW / cm². 2 The light source is irradiated for 1-3 hours at a temperature of 20-50℃; the mass ratio of porous carbon material to photosensitizer is 100:10-30.
[0024] S4. Transfer the coal-based porous carbon composite material obtained in step S3 to a fluidized bed. After introducing inert gas to purge the air from the fluidized bed, raise the temperature to 450-600℃ and introduce a silane mixed gas at a flow rate of 100-500 ml / min for 60-600 min. Then raise the temperature to 700-900℃ and introduce a carbon source gas and a fluorinated gas at a flow rate of 10-100 ml / min for 30-300 min. Finally, cool down in an inert gas atmosphere to obtain the coal-based silicon-carbon composite material; preferably... In step S4, the silane mixed gas is a mixture of silane gas and carrier gas; wherein the volume ratio of silane gas to carrier gas is in the range of 1:1-5; the silane gas is any one of methanesilane, ethylsilane, monochlorosilane, and dichlorosilane; the carrier gas is any one of nitrogen and argon; the carbon source gas is any one of methane, ethane, ethylene, and acetylene; and the fluorinated gas is any one of nitrogen tetrafluoride, nitrogen trifluoride, hydrogen fluoride, and ammonium fluoride; wherein the volume ratio of carbon source gas to fluorinated gas is in the range of 10:1-5.
[0025] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions in the embodiments of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.
[0026] Based on the above-described implementation schemes, this application further proposes the following specific embodiments: It should be noted that, unless otherwise specified, the raw materials used in the following specific embodiments of the present invention are all commercially available products. Example 1: A method for preparing a coal-based silicon-carbon composite material, comprising the following steps: Step S1: Add 100g anthracite, 10g citric acid, 3g benzyl mercaptan, and 200g glucose to 1000g diethyl ether solvent and mix well. Then transfer the mixture to a high-pressure reactor and react at 150℃ for 2 hours. After filtration, dry under vacuum at 80℃ for 24 hours. Then transfer the obtained material to a tube furnace (as a pre-oxidation furnace), heat to 450℃, and pre-oxidize for 150 minutes by introducing an oxygen mixture (oxygen:nitrogen volume ratio of 10:3) at a flow rate of 200ml / min to obtain the precursor material. Step S2: Mix 100g of the precursor material obtained in step S1 with 100g of potassium hydroxide and 25g of ethanolamine, heat to 1000℃ for activation for 3 hours, and then cool naturally to room temperature to obtain porous carbon material. Step S3: Mix 100g of the porous carbon material obtained in step S2 with 20g of ruthenium dipyridylene, and set the following parameters: wavelength 500nm, light intensity 100mW / cm². 2 The light source was irradiated at 30℃ for 2 hours to carry out photocatalytic reaction. Then the resulting material was heated to 1000℃ for secondary carbonization treatment for 3 hours to obtain coal-based porous carbon composite material. Step S4: Transfer the coal-based porous carbon composite material obtained in step S3 to a fluidized bed. First, nitrogen gas is introduced to purge the air from the fluidized bed. Then, the temperature is raised to 520°C, and a mixture of silane and nitrogen gas (silane:nitrogen volume ratio of 1:3) is introduced at a flow rate of 300 ml / min for 300 min. Then, the temperature is raised to 800°C, and ethylene and nitrogen trifluoride gas (ethylene:nitrogen trifluoride volume ratio of 10:3) is introduced at a flow rate of 50 ml / min for 150 min. Finally, the temperature is lowered to room temperature under a nitrogen atmosphere to obtain the coal-based silicon-carbon composite material.
[0027] Please see Figure 1 As shown, the coal-based silicon-carbon composite material prepared in Example 1 has a particle size between 5 and 10 μm, exhibits a granular structure, and has a microporous structure on its surface.
[0028] Example 2: A method for preparing a coal-based silicon-carbon composite material, comprising the following steps: Step S1: Add 100g anthracite, 5g malic acid, 1g sulfide, and 100g sucrose to 1000g diethyl ether solvent and mix well. Then transfer the mixture to a high-pressure reactor and react at 100℃ for 3 hours. After filtration, dry under vacuum at 80℃ for 24 hours. Then transfer the obtained material to a tube furnace, heat to 300℃, and pre-oxidize for 300 minutes by introducing a bromine-oxygen mixed gas (bromine-oxygen:nitrogen volume ratio of 10:1) at a flow rate of 100ml / min to obtain the precursor material. Step S2: Mix 100g of the precursor material obtained in step S1 with 89g of potassium carbonate and 11g of diethanolamine, heat to 900℃ for activation for 6 hours, and then cool naturally to room temperature to obtain porous carbon material. Step S3: Mix 100g of the porous carbon obtained in step S2 above with 10g of tris[2-(4-tert-butylphenyl)pyridine]iridium evenly, and set the parameters as follows: wavelength 200nm, light intensity 50mW / cm. 2 The light source was used to perform a photocatalytic reaction by irradiating the material at 20°C for 3 hours. Then, the resulting material was heated to 900°C for a second carbonization treatment for 6 hours to obtain a coal-based porous carbon composite material. Step S4: Transfer the coal-based porous carbon composite material obtained in step S3 to a fluidized bed. First, nitrogen gas is introduced to purge the air from the fluidized bed. Then, the temperature is raised to 450°C, and a mixture of silane gas (silane gas: argon gas volume ratio of 1:1) is introduced at a flow rate of 100 ml / min for 600 min. Then, the temperature is raised to 700°C, and acetylene gas and nitrogen trifluoride gas (acetylene gas: nitrogen trifluoride gas volume ratio of 10:1) are introduced at a flow rate of 10 ml / min for 300 min. Finally, the temperature is lowered to room temperature under a nitrogen atmosphere to obtain the coal-based silicon-carbon composite material.
[0029] Example 3: A method for preparing a coal-based silicon-carbon composite material, comprising the following steps: Step S1: Add 100g anthracite, 20g tartaric acid, 5g hydrazine sulfate, and 300g galactose to 1000g diethyl ether solvent and mix thoroughly. Then transfer the mixture to a high-pressure reactor and react at 1200℃ for 1 hour. After filtration, dry under vacuum at 80℃ for 24 hours. Then transfer the obtained material to a tube furnace, heat to 600℃, and pre-oxidize for 30 minutes by introducing a nitric oxide mixed gas (nitric oxide:nitrogen volume ratio of 10:5) at a flow rate of 300ml / min to obtain the precursor material. Step S2: Mix 100g of the precursor material obtained in step S1 with 333g of sodium hydroxide and 177g of triethanolamine, heat to 1100℃ for activation for 1 hour, and then cool naturally to room temperature to obtain porous carbon material. Step S3: Mix 100g of the porous carbon obtained in step S2 above with 30g of 1,5-cyclooctadiene bis(methylbiphenylphosphine)iridium hexafluorophosphate evenly, and set the following parameters: use a light source with a wavelength of 800nm and a light intensity of 200mW / cm2 to irradiate at 50℃ for 1 hour for photocatalytic reaction, and then heat the obtained material to 1100℃ for secondary carbonization treatment for 1 hour to obtain coal-based porous carbon composite material; Step S4: Transfer the coal-based porous carbon composite material obtained in step S3 to a fluidized bed. First, nitrogen gas is introduced to purge the air from the fluidized bed. Then, the temperature is raised to 600℃, and a mixture of monochlorosilane gas (monochlorosilane:nitrogen volume ratio of 1:5) is introduced at a flow rate of 500 ml / min for 60 min. Then, the temperature is raised to 900℃, and methane gas and hydrogen fluoride gas (methane gas:hydrogen fluoride gas volume ratio of 10:5) are introduced at a flow rate of 100 ml / min for 30 min. Finally, the temperature is lowered to room temperature under a nitrogen atmosphere to obtain the coal-based silicon-carbon composite material.
[0030] Comparative Example 1: The remaining technical solutions of Comparative Example 1 are the same as those of Example 1, except that glucose is not added in step S1 of Comparative Example 1.
[0031] Comparative Example 2: The remaining technical solutions of Comparative Example 2 are the same as those of Example 1, except that benzyl mercaptan is not added in step S1 of Comparative Example 2.
[0032] Comparative Example 3: The remaining technical solutions of Comparative Example 3 are the same as those of Example 1, except that: in Comparative Example 3, step S4 is omitted and the coal-based porous carbon composite material obtained in step S3 is used directly.
[0033] Comparative Example 4: The remaining technical solutions of Comparative Example 4 are the same as those of Example 1, except that ethanolamine is not added in step S2 of Comparative Example 4.
[0034] Comparative Example 5: The rest of the technical solutions of Comparative Example 5 are the same as those of Example 1, except that: Comparative Example 5 uses commercially available biomass silicon carbon material as the comparative example. Manufacturer: Liyang Tianmu Pioneer Co., Ltd., material model: SC2A.
[0035] To verify the technical effects achieved by the embodiments of this application, the following physical and chemical tests and button cell tests were conducted: I. The physicochemical properties of the silicon-carbon composite materials provided in Examples 1-3 and Comparative Examples 1-5 were tested respectively:
[0036] According to the methods in the national standard GB / T 38823-2020 "Silicon-Carbon", the tap density, specific surface area, silicon grain size, and specific capacity of the silicon-carbon composite materials prepared in Examples 1-3 and Comparative Examples 1-5 were tested respectively. Powder resistivity, coating integrity, and gas generation tests were also conducted respectively. Among them, the powder resistivity was tested using a four-probe test; the coating integrity of the powder material was tested using XPS; the test conditions for gas generation of the material were set as follows: (45℃, 48h); the test results are shown in Table 1 below. II. Button Cell Battery Testing:
[0037] The coin cell was prepared according to the following method: Coin cells were prepared using the silicon-carbon composite materials obtained in Examples 1-3 and Comparative Examples 1-5 as the active materials for the negative electrode sheet of the battery.
[0038] The specific preparation process of each coin cell is as follows: Preparation of the negative electrode sheet: Add binder, conductive agent and solvent to each silicon-carbon composite material (as the active material of the negative electrode sheet) corresponding to Examples 1-3 and Comparative Examples 1-5 respectively, stir and slurry, coat on copper foil, and obtain each negative electrode sheet after drying and rolling; wherein, the binder is LA136D binder, the conductive agent is carbon nanotubes, the solvent is double-distilled water, and the ratio of each substance is: silicon-carbon composite material: CNT: LA136D: double-distilled water = 95g: 1g: 4g: 220mL.
[0039] Coin cell fabrication: The electrolyte was a LiPF6 solution with a concentration of 1.1 mol / L, and the solvent was a 1:1 weight ratio mixture of ethylene carbonate (EC) and diethyl carbonate (DMC). A lithium metal sheet was used as the counter electrode, and polyethylene (PE) was used as the separator. The simulated battery was assembled in an argon-filled glove box. Electrochemical performance was tested using a Wuhan Landian CT2001A battery tester under the following conditions: charge / discharge voltage range of 0.005V to 1.5V, and charge / discharge rate of 0.1C. The initial discharge specific capacity and initial efficiency of the coin cells corresponding to Examples 1-3 and Comparative Examples 1-5 were tested. Simultaneously, the charging DCR (0.1C, 50% SOC) and room temperature cycling performance of the coin cells were tested (test conditions: 0.2C / 0.2C, 100 cycles). The full-charge expansion of the negative electrode of the coin cells was also tested (full-charge expansion test: the electrode thickness D1 after rolling was tested, and the electrode thickness D2 was tested after charging to 100% SOC; full-charge expansion = (D2-D1) / D1). The test results are shown in Table 1 below.
[0040]
[0041] As shown in Table 1 above, the silicon-carbon composite materials provided in Examples 1-3 of this application have high specific surface area, and the resulting coin cells exhibit excellent initial discharge specific capacity, initial efficiency, low powder resistance, and cycle performance, as well as low full-charge expansion and high tap density. Therefore, it can be confirmed that the silicon-carbon composite materials provided in Examples 1-3 of this application possess the characteristics of low expansion and high power. Experimental results show that relying on the high anisotropy of coal-based materials to improve the tap density and reduce impedance, and performing photocatalysis on their surface to reduce defects, improves the initial efficiency. Simultaneously, doping with organic acids to create pores increases the specific surface area, and sulfur source doping improves the electronic conductivity and rate performance of the material. III. Soft-pack battery testing:
[0042] The silicon-carbon composite materials prepared in Examples 1-3 and Comparative Examples 1-5 were each doped with 90% artificial graphite as negative electrode materials (i.e., negative electrode sheets), and ternary materials LiNi were used. 1 / 3 Co 1 / 3 Mn 1 / 3 O2 was used as the positive electrode material, electrolyte, and separator to assemble a 5Ah pouch battery. The separator was Celegard 2400, and the electrolyte was a LiPF6 solution. The LiPF6 solution was a 1:1 volume ratio mixture of EC and DEC, with a LiPF6 concentration of 1.3 mol / L. Negative electrode sheets were prepared from the silicon-carbon composite materials corresponding to Examples 1-3 and Comparative Examples 1-5. The liquid absorption capacity (characterized by liquid absorption rate) and maximum compaction density of each negative electrode sheet were tested. The test results are shown in Table 2 below.
[0043] The liquid absorption capacity test process is as follows: a 1mL burette is used to draw VmL of electrolyte. The electrolyte is dropped onto the surface of the negative electrode sheet and timed until the electrolyte is completely absorbed. The time t is recorded. The electrode sheet's maximum compaction density is determined by pressing the electrode sheet with a roller press until the electrode sheet has no shiny edges and no powder falling off. The compaction density of the electrode sheet is taken as the maximum compaction density of the electrode sheet.
[0044]
[0045] As shown in Table 2 above, the negative electrode sheets made using the silicon-carbon composite materials provided in Examples 1-3 of this application have significantly better liquid absorption capacity and electrode compaction density than those in Comparative Examples 1-5. The main reason may be that the silicon-carbon composite materials provided in this embodiment have a better specific surface area, which can significantly improve the liquid absorption and retention capacity of the electrode sheet, and the materials provided in this embodiment have a high tap density, thereby improving the ultimate compaction density of the material.
[0046] This application also tested the rate performance of each pouch cell as described above, and the test results are shown in Table 3 below.
[0047] The conditions for rate performance testing were as follows: the charge / discharge voltage range was 2.5-4.2V, the temperature was 25±3.0℃, and each coin cell was charged at 1.0C, 3.0C, and 5.0C respectively, and discharged at 1.0C. The results of the rate performance test are shown in Table 3 below.
[0048]
[0049] As shown in Table 3 above, the rate charging performance of the soft-pack battery made using the silicon-carbon composite material provided in Examples 1-3 of this application is significantly better than that of Comparative Examples 1-5. In other words, the soft-pack battery made in the examples of this application has a shorter and faster charging time. The main reason is that the material provided in the examples of this application has low powder resistivity and high specific surface area, which can improve the rate performance of the material.
[0050] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.
[0051] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.
Claims
1. A method for preparing a coal-based silicon-carbon composite material, characterized in that, It should include at least the following steps: S1. Anthracite, organic acid, sulfur source, and organic carbon source are added to diethyl ether solvent and mixed evenly. The mixture is then transferred to a high-pressure reactor and reacted at 100-200℃ for 1-3 hours. After filtration and drying, the resulting material is transferred to a pre-oxidation furnace and heated to 300-600℃. An oxidizing mixed gas is introduced at a flow rate of 100-300 ml / min for pre-oxidation treatment for 30-300 min to obtain the precursor material. S2. Mix the precursor material obtained in step S1 with the composite activator evenly, activate it at a temperature of 900-1100℃ for 1-6 hours, and then cool it down to obtain porous carbon material. S3. Mix the porous carbon material obtained in step S2 with the photosensitizer evenly, carry out a photocatalytic reaction, and then heat it to 900-1100℃ for a secondary carbonization treatment for 1-6 hours to obtain a coal-based porous carbon composite material. S4. Transfer the coal-based porous carbon composite material obtained in step S3 to a fluidized bed, introduce inert gas to purge the air from the fluidized bed, raise the temperature to 450-600℃, and introduce a silane mixed gas at a flow rate of 100-500 ml / min for 60-600 min. Then raise the temperature to 700-900℃, and introduce a carbon source gas and a fluorinated gas at a flow rate of 10-100 ml / min for 30-300 min. Finally, cool down in an inert gas atmosphere to obtain the coal-based silicon-carbon composite material.
2. The method for preparing the coal-based silicon-carbon composite material according to claim 1, characterized in that, In step S1, the organic acid is selected from any one or a mixture of several of citric acid, malic acid, tartaric acid, succinic acid, benzoic acid, oxalic acid, and lactic acid; the sulfur source is selected from any one or a mixture of several of benzyl mercaptan, thioether, hydrazine sulfate, phenylthiourea, n-propanethiol, dithiodiazole, and diethyl disulfide; the organic carbon source is any one or a mixture of several of glucose, fructose, galactose, starch, cellulose, and hemicellulose; the oxidizing mixed gas is a mixture of at least one oxidizing gas selected from oxygen, bromine, and nitrogen dioxide with nitrogen, wherein the volume ratio of the oxidizing gas to nitrogen ranges from 10:1 to 5.
3. The method for preparing the coal-based silicon-carbon composite material according to claim 1, characterized in that, In step S1, the mass ratio of anthracite: organic acid: sulfur source: organic sugar source ranges from 100:5-20:1-5:100-300.
4. The method for preparing the coal-based silicon-carbon composite material according to claim 1, characterized in that, In step S2, the composite activator is composed of an inorganic activator and an organic activator, wherein the mass ratio of the inorganic activator to the organic activator is in the range of 10:1-5.
5. The method for preparing the coal-based silicon-carbon composite material according to claim 4, characterized in that, The inorganic activator is selected from any one or a mixture of potassium hydroxide, potassium carbonate, and sodium hydroxide; the organic activator is selected from any one or a mixture of ethanolamine, diethanolamine, and triethanolamine.
6. The method for preparing the coal-based silicon-carbon composite material according to claim 1, characterized in that, In step S2, the mass ratio of precursor material to composite activator ranges from 100:100 to 500.
7. The method for preparing the coal-based silicon-carbon composite material according to claim 1, characterized in that, In step S3, the photosensitizer is any one of ruthenium dipyridyl, tri[2-(4-tert-butylphenyl)pyridine]iridium, 1,5-cyclooctadiene bis(methylbiphenylphosphine)iridium hexafluorophosphate, and 1,5-cyclooctadiene (pyridine) (tricyclohexylphosphine)iridium hexafluorophosphate.
8. A method for preparing a coal-based silicon-carbon composite material according to claim 1 or 7, characterized in that, In step S3, the conditions for the photocatalytic reaction are: a wavelength of 200-800 nm and a light intensity of 50-200 mW / cm². 2 The light source is irradiated for 1-3 hours at a temperature of 20-50℃.
9. The method for preparing a coal-based silicon-carbon composite material according to claim 1, characterized in that, In step S3, the mass ratio of porous carbon material to photosensitizer is in the range of 100:10-30.
10. The method for preparing a coal-based silicon-carbon composite material according to claim 1, characterized in that, In step S4, the silane mixed gas is a mixture of silane gas and carrier gas; wherein the volume ratio of silane gas to carrier gas is in the range of 1:1-5; the silane gas is any one of methanesilane, dichlorosilane, monochlorosilane, and dichlorosilane; the carrier gas is any one of nitrogen and argon; the carbon source gas is any one of methane, ethane, ethylene, and acetylene; the fluorinated gas is any one of nitrogen tetrafluoride, nitrogen trifluoride, hydrogen fluoride, and ammonium fluoride; wherein the volume ratio of carbon source gas to fluorinated gas is in the range of 10:1-5.