Hierarchical-pore-structure silicon-carbon negative electrode material based on pore forming of pore-forming agent, preparation method of hierarchical-pore-structure silicon-carbon negative electrode material and application of hierarchical-pore-structure silicon-carbon negative electrode material in lithium ion battery
By using a pore-forming agent to create pores, a multi-level porous silicon-carbon anode material was prepared, which solved the problems of equipment corrosion, high cost, and difficulty in controlling the pore structure in the existing technology. This improved the stability and conductivity of the material, alleviated the volume expansion of silicon, and enabled a highly efficient production process.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-26
- Publication Date
- 2026-03-13
AI Technical Summary
Existing methods for preparing porous carbon suffer from problems such as equipment corrosion, high cost, difficulty in accurately controlling pore structure, and environmental pollution, which affect the performance and production efficiency of silicon-carbon anode materials.
A pore-forming agent is used to create a multi-level porous structure by mixing a liquid carbon source with the pore-forming agent and a curing agent. This is combined with silane deposition and carbon coating to prepare a multi-level porous silicon-carbon anode material, thus avoiding the high-temperature alkaline activation process and controlling the formation of the pore structure.
This approach improves the stability and conductivity of the hierarchical porous structure, alleviates silicon volume expansion, enhances cycle stability, and reduces production costs and environmental pollution risks.
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Figure CN121662765A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of silicon-carbon anode material technology, and in particular to a multi-level porous silicon-carbon anode material based on pore-forming agents, its preparation method, and its application in lithium-ion batteries. Background Technology
[0002] In recent years, with the rapid growth of the new energy vehicle market and the continuous advancement of energy storage technology, the market demand for silicon-carbon anode materials has been steadily increasing. The popularization of new energy vehicles and consumers' increasing demands for driving range have driven the development of high-energy-density battery materials. Silicon-carbon anode materials, with their high energy density and excellent cycle performance, have become one of the key materials for improving battery energy density, leading to expanded market demand. Simultaneously, the demand for battery materials in energy storage systems is also constantly increasing, and silicon-carbon anode materials, due to their superior performance, have become an important choice in energy storage systems.
[0003] Silicon is an ideal anode material for lithium-ion batteries, with a theoretical lithium storage capacity of up to 4200 mAh / g and abundant reserves in the Earth's crust. Silicon exhibits a relatively low voltage plateau during lithiation (intercalation) and delithiation (typically 0.1-0.4 V vs. Li / Li+), which is higher than the lithium deposition potential (0 V vs. Li / Li+), helping to reduce the risk of lithium dendrite precipitation and improve battery safety. Simultaneously, this lower voltage plateau means the battery can provide a higher output voltage during discharge, which is beneficial for increasing energy density. However, silicon materials also have some significant drawbacks: (1) During lithium-ion intercalation and deintercalation, silicon volume expands by up to 300%, easily leading to silicon particle pulverization, which in turn causes a significant decrease in the reversible capacity of the electrode; (2) Silicon itself has relatively low conductivity (6.7 × 10⁻⁶). -4 (S / cm), which is not conducive to electron transport; (3) There is a high reactivity between silicon and organic electrolytes. This characteristic often leads to the formation of lithium dendrites during charging and discharging, which may cause short circuits or even more serious safety hazards.
[0004] In comparison, carbon materials possess advantages such as high stability, good conductivity, low cost, and wide availability, leading to their widespread application in battery anode materials. However, the theoretical lithium storage capacity of carbon materials is relatively low, which limits further performance improvements. To fully leverage the respective advantages of silicon and carbon and fundamentally address the problems inherent in silicon materials, combining silicon and carbon to form a silicon-carbon electrode material holds promise for rapidly advancing silicon-carbon electrode technology in lithium-ion batteries and contributing new impetus to battery technology progress.
[0005] However, the preparation of porous carbon typically employs alkali activation. At high temperatures (usually exceeding 600°C), strong alkalis (such as KOH) can corrode production equipment, increasing maintenance costs and potentially impacting production efficiency and product quality. Furthermore, KOH as an activator is relatively expensive, the reaction between the alkali and the material is difficult to control precisely, and the secondary processing is complex. After pyrolysis activation, a large amount of acid is required to neutralize residual potassium-containing compounds, further increasing production steps and costs, and potentially causing negative environmental impacts. Therefore, optimizing the preparation method of porous carbon is crucial for the development of silicon-carbon anodes. Summary of the Invention
[0006] The purpose of this invention is to provide a hierarchical porous silicon-carbon anode material based on pore-forming agents, its preparation method, and its application in lithium-ion batteries, thereby solving the aforementioned problems existing in current porous carbon preparation methods.
[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution:
[0008] This invention provides a method for preparing a hierarchical porous silicon-carbon anode material based on a pore-forming agent, comprising the following steps:
[0009] Liquid carbon source, pore-forming agent, and curing agent are mixed and cured to obtain cured material;
[0010] The cured material is carbonized under a protective atmosphere to obtain porous carbon;
[0011] Porous carbon is deposited with silane gas under a protective atmosphere, and then coated with carbon source gas to obtain a hierarchical porous silicon-carbon anode material with pores formed by a pore-forming agent.
[0012] Preferably, the liquid carbon source is one or more of phenolic resin, epoxy resin, polyimide resin, and furan resin; and the curing agent is one or more of hexamethylenetetramine, diethylenetriamine, and triethylenetetramine.
[0013] Preferably, the pore-forming agent is an inorganic pore-forming agent and / or an organic pore-forming agent; the inorganic pore-forming agent includes one or more of sodium carbonate, sodium bicarbonate, copper chloride, potassium bicarbonate, potassium carbonate, and zinc chloride; the organic pore-forming agent includes one or more of polyethylene glycol with a molecular weight of 1,000 to 20,000, polyvinylpyrrolidone with a molecular weight of 5,000 to 10,000, and block copolymers with a molecular weight of 5,000 to 10,000.
[0014] Preferably, the mass ratio of the liquid carbon source to the inorganic pore-forming agent is 1:1 to 8; the mass of the organic pore-forming agent is 10 to 30% of the mass of the liquid carbon source; and the mass of the curing agent is 5 to 10% of the mass of the liquid carbon source.
[0015] Preferably, the curing temperature is 50–150°C; and the curing time is 0.5–10 h.
[0016] Preferably, the carbonization temperature is 500–1000°C; and the carbonization time is 0.5–4 hours.
[0017] Preferably, the silane gas is one or more selected from methylene silane, ethyl silane, propane, monochlorosilane, dichlorosilane, trichlorosilane, tetrafluorosilane, hexamethyldisilane, dichlorodimethylsilane, and trimethylsilane; the flow rate of the silane gas is 0.5–8 L / min; the temperature of the silane deposition is 400–1000 °C; and the deposition time is 60–550 min.
[0018] Preferably, the carbon source gas is one or more of methane, ethane, butane, propane, ethylene, propylene, butene, and acetylene; the flow rate of the carbon source gas is 0.5–8 L / min; the carbon coating temperature is 500–700 °C; and the carbon coating time is 60–480 min.
[0019] This invention also provides a method for preparing a hierarchical porous silicon-carbon anode material based on a pore-forming agent. The method yields a hierarchical porous silicon-carbon anode material based on a pore-forming agent, wherein the mass fraction of silicon in the hierarchical porous silicon-carbon anode material is 10–90%, and the mass fraction of carbon in the silicon-carbon anode material is 10–90%.
[0020] This invention also provides an application of a hierarchical porous silicon-carbon anode material based on pore-forming agents in lithium-ion batteries.
[0021] As can be seen from the above technical solution, compared with the prior art, the present invention has the following beneficial effects:
[0022] (1) This invention adds an appropriate amount of pore-forming agent to a liquid carbon source, allowing it to penetrate into the interior of the liquid carbon source and form a denser pore network structure. The inorganic pore-forming agent particles can be uniformly dispersed in the matrix material. These particles are removed through physical dissolution (water washing, acid washing), thermal decomposition (such as carbonate decomposition to produce CO2), or chemical reactions, leaving behind their original shape and size pore structure. Low molecular weight pore-forming agents help obtain microporous structures, forming interconnected pore networks, promoting ion diffusion, and improving the conductivity and stability of the material. Higher molecular weight pore-forming agents help obtain mesoporous structures, effectively mitigating the volume expansion of silicon. This invention, by controlling the type and molecular weight of the pore-forming agent, achieves differentiated decomposition rates and gasification behaviors during sintering, thereby constructing a multi-level pore structure (micropore-mesopore synergistic distribution). This multi-level pore structure effectively buffers the volume expansion of the silicon anode during charging and discharging, improving cycle stability.
[0023] (2) Compared with the preparation of porous carbon by alkaline activation, the present invention uses a pore-forming agent to effectively avoid the problems of excessive alkaliization and difficulty in accurately controlling the pore structure during alkaline activation. The pore-forming process of the pore-forming agent is relatively mild and will not cause violent reactions to the material matrix, which is conducive to maintaining the original properties and structural stability of the material. In addition, it can also eliminate the problem of waste liquid pollution generated by water washing after alkali treatment. Attached Figure Description
[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below.
[0025] Figure 1 This is a flowchart illustrating the preparation process of the hierarchical porous silicon-carbon anode material based on pore-forming agents according to the present invention. Detailed Implementation
[0026] This invention provides a method for preparing a hierarchical porous silicon-carbon anode material based on a pore-forming agent, the preparation process of which is as follows: Figure 1 As shown, it includes the following steps:
[0027] Liquid carbon source, pore-forming agent, and curing agent are mixed and cured to obtain cured material;
[0028] The cured material is carbonized under a protective atmosphere to obtain porous carbon;
[0029] Porous carbon is deposited with silane gas under a protective atmosphere, and then coated with carbon source gas to obtain a hierarchical porous silicon-carbon anode material with pores formed by a pore-forming agent.
[0030] In this invention, the liquid carbon source is preferably one or more of phenolic resin, epoxy resin, polyimide resin, and furan resin, more preferably phenolic resin or epoxy resin, and even more preferably phenolic resin.
[0031] In this invention, the pore-forming agent is preferably an inorganic pore-forming agent and / or an organic pore-forming agent; the inorganic pore-forming agent preferably includes one or more of sodium carbonate, sodium bicarbonate, copper chloride, potassium bicarbonate, potassium carbonate, and zinc chloride, more preferably sodium bicarbonate or zinc chloride, and even more preferably sodium bicarbonate; the organic pore-forming agent preferably includes one or more of polyethylene glycol with a molecular weight of 1000-20000, polyvinylpyrrolidone with a molecular weight of 5000-10000, and block copolymers with a molecular weight of 5000-10000, more preferably polyethylene glycol with a molecular weight of 1000-4000, polyvinylpyrrolidone with a molecular weight of 5000-8000, and Pluronic F127 with a molecular weight of 5000-8000, and even more preferably polyethylene glycol with a molecular weight of 1000.
[0032] In this invention, the curing agent is preferably one or more of hexamethylenetetramine, diethylenetriamine, and triethylenetetramine, more preferably hexamethylenetetramine or diethylenetriamine, and even more preferably hexamethylenetetramine.
[0033] In this invention, the mass ratio of the liquid carbon source to the inorganic pore-forming agent is preferably 1:1 to 8, more preferably 1:2 to 6, and even more preferably 1:4; the mass of the organic pore-forming agent is preferably 10 to 30% of the mass of the liquid carbon source, more preferably 10 to 20%, and even more preferably 10%.
[0034] In this invention, the mass of the curing agent is preferably 5-10% of the mass of the liquid carbon source, more preferably 5-8%, and even more preferably 5%.
[0035] In this invention, the curing temperature is preferably 50-150°C, more preferably 80-130°C, and even more preferably 120°C; the curing time is preferably 0.5-10h, more preferably 2-8h, and even more preferably 4h.
[0036] In this invention, the carbonization temperature is preferably 500–1000°C, more preferably 700–950°C, and even more preferably 900°C; the carbonization time is preferably 0.5–4 h, more preferably 1–3 h, and even more preferably 2 h; the carbonization heating rate is preferably 1–10°C / min, more preferably 3–7°C / min, and even more preferably 5°C / min; the protective atmosphere is preferably one or more of argon, helium, and nitrogen, more preferably argon or nitrogen, and even more preferably argon.
[0037] In this invention, the silane gas is preferably one or more of methylsilane, ethylsilane, propane, monochlorosilane, dichlorosilane, trichlorosilane, tetrafluorosilane, hexamethyldisilane, dichlorodimethylsilane, and trimethylsilane, more preferably one or more of methylsilane, ethylsilane, and propane, and even more preferably methylsilane; the protective atmosphere is preferably one or more of argon, helium, and nitrogen, more preferably helium or nitrogen, and even more preferably nitrogen; the flow rate of the silane gas is preferably 0.5–8 L / min, more preferably 1–4 L / min, and even more preferably 3 L / min. The flow rate ratio of the silane gas to the protective atmosphere is preferably 1:1 to 15, more preferably 1:1 to 5, and even more preferably 1:2; the silane deposition temperature is preferably 400 to 1000°C, more preferably 450 to 700°C, and even more preferably 550°C; the silane deposition heating rate is preferably 1 to 10°C / min, more preferably 2 to 5°C / min, and even more preferably 3°C / min; the silane deposition time is preferably 60 to 550 min, more preferably 200 to 520 min, and even more preferably 500 min.
[0038] In this invention, the carbon source gas is preferably one or more of methane, ethane, butane, propane, ethylene, propylene, butene, and acetylene, more preferably one or more of methane, ethane, and acetylene, and even more preferably acetylene; the protective atmosphere is preferably one or more of argon, helium, and nitrogen, more preferably helium or nitrogen, and even more preferably nitrogen; the flow rate of the carbon source gas is preferably 0.5–8 L / min, more preferably 1–4 L / min, and even more preferably 2 L / min; the ratio of the flow rate of the carbon source gas to the flow rate of the protective atmosphere is preferably 1:1–15, more preferably 1:1–3, and even more preferably 1:2; the carbon coating temperature is preferably 500–700°C, more preferably 500–600°C, and even more preferably 500°C; the heating rate of the carbon coating is preferably 1–10°C / min, more preferably 2–8°C / min, and even more preferably 5°C / min; the carbon coating time is preferably 60–480 min, more preferably 160–400 min, and even more preferably 240 min.
[0039] This invention also provides a method for preparing a hierarchical porous silicon-carbon anode material based on a pore-forming agent. The method yields a hierarchical porous silicon-carbon anode material based on a pore-forming agent, wherein the mass fraction of silicon in the hierarchical porous silicon-carbon anode material is preferably 10-90%, more preferably 20-60%, and even more preferably 50%; the mass fraction of carbon in the silicon-carbon anode material is preferably 10-90%, more preferably 30-70%, and even more preferably 50%.
[0040] This invention also provides an application of a hierarchical porous silicon-carbon anode material based on pore-forming agents in lithium-ion batteries.
[0041] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0042] Example 1
[0043] This embodiment provides a method for preparing a hierarchical porous silicon-carbon anode material based on a pore-forming agent, including the following steps:
[0044] (1) Mix waterborne phenolic resin, 10% polyethylene glycol (molecular weight 1000) relative to the resin mass, and 5% hexamethylenetetramine relative to the resin mass until uniform, and cure at 120°C for 4 hours to obtain cured material.
[0045] (2) The curing material is heated to 900°C at a heating rate of 5°C / min under an argon atmosphere, carbonized at this temperature for 2 hours, and then cooled to room temperature to obtain porous carbon.
[0046] (3) The temperature was increased to 550°C at a heating rate of 3°C / min under a nitrogen atmosphere. The flow rate of silane gas was 3L / min (silane gas flow rate: nitrogen gas flow rate = 1:2) to perform silane deposition for 500min. Then, acetylene gas was introduced at a flow rate of 2L / min (acetylene gas flow rate: nitrogen gas flow rate = 1:2) and carbon coating was performed at 550°C for 240min to obtain a hierarchical porous silicon-carbon anode material based on pore-forming agent. The silicon content of the material was 50% and the carbon content was 50%.
[0047] Example 2
[0048] This embodiment provides a method for preparing a hierarchical porous silicon-carbon anode material based on a pore-forming agent, specifically referring to Example 1, except that in step (1), polyethylene glycol with a molecular weight of 1000 is replaced with polyethylene glycol with a molecular weight of 4000. The prepared material has a silicon content of 50% and a carbon content of 50%.
[0049] Example 3
[0050] This embodiment provides a method for preparing a hierarchical porous silicon-carbon anode material based on a pore-forming agent. See Example 1 for details, except that in step (1), polyethylene glycol with a molecular weight of 1000 is replaced with polyvinylpyrrolidone with a molecular weight of 5000. The amount of polyvinylpyrrolidone added is 15% relative to the resin mass, and the amount of hexamethylenetetramine added is 8% relative to the resin mass. The curing time is 2 hours. The prepared material has a silicon content of 50% and a carbon content of 50%.
[0051] Example 4
[0052] This embodiment provides a method for preparing a hierarchical porous silicon-carbon anode material based on a pore-forming agent. See Example 1 for details, except that in step (1), polyethylene glycol with a molecular weight of 1000 is replaced with sodium bicarbonate, the mass ratio of sodium bicarbonate to resin is 4:1, the amount of hexamethylenetetramine added is 10% relative to the resin mass, and the silane deposition time in step (3) is 550 min. The prepared material has a silicon content of 52% and a carbon content of 48%.
[0053] Comparative Example 1
[0054] This comparative example provides a method for preparing a silicon-carbon anode material, specifically referring to Example 1, except that the porous carbon obtained in step (2) of Example 1 is replaced with alkali-activated porous carbon. The method for preparing alkali-activated porous carbon is as follows: water-based phenolic resin is carbonized at 800°C for 2 hours; the carbonized material is mixed with potassium hydroxide at a mass ratio of 1:3, and then alkali-treated at 800°C for 2 hours to obtain an activated material. After acid washing and water washing, porous carbon is obtained. The silicon-carbon anode material prepared has a silicon content of 50% and a carbon content of 50%.
[0055] The silicon-carbon anode materials prepared in Examples 1-4 and Comparative Example 1 were subjected to performance testing. The specific method was as follows: the anode materials were fabricated into CR2032 coin cells. The test conditions were as follows: electrolyte: LiPF6 electrolyte, concentration 1.2 mol / L; solvent: a mixture of EC and DEC with a volume ratio of 1:1; ratio: active material: SP: SWCNT: LA132 = 94:1:1:4; counter electrode: pure lithium sheet. Charge-discharge regime: 1) resting for 10 min; 2) constant current discharge (0.1C, 0.005V); 3) resting for 10 min; 4) rate discharge (0.05C, 0.005V); 5) resting for 10 min; 6) rate discharge (0.02C, 0.005V); 7) resting for 10 min; 8) rate charge (0.1C, 1.5V). The results are shown in Table 1.
[0056] Table 1 Performance test results of silicon-carbon anode materials
[0057]
[0058] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A method for preparing a hierarchical porous silicon-carbon anode material based on a pore-forming agent, characterized in that, Includes the following steps: Liquid carbon source, pore-forming agent, and curing agent are mixed and cured to obtain cured material; The cured material is carbonized under a protective atmosphere to obtain porous carbon; Porous carbon is deposited with silane gas under a protective atmosphere, and then coated with carbon source gas to obtain a hierarchical porous silicon-carbon anode material with pores formed by a pore-forming agent.
2. The method for preparing a hierarchical porous silicon-carbon anode material based on a pore-forming agent according to claim 1, characterized in that, The liquid carbon source is one or more of phenolic resin, epoxy resin, polyimide resin, and furan resin; the curing agent is one or more of hexamethylenetetramine, diethylenetriamine, and triethylenetetramine.
3. The method for preparing a hierarchical porous silicon-carbon anode material based on a pore-forming agent according to claim 2, characterized in that, The pore-forming agent is an inorganic pore-forming agent and / or an organic pore-forming agent; the inorganic pore-forming agent includes one or more of sodium carbonate, sodium bicarbonate, copper chloride, potassium bicarbonate, potassium carbonate, and zinc chloride; the organic pore-forming agent includes one or more of polyethylene glycol with a molecular weight of 1,000 to 20,000, polyvinylpyrrolidone with a molecular weight of 5,000 to 10,000, and block copolymers with a molecular weight of 5,000 to 10,000.
4. The method for preparing a hierarchical porous silicon-carbon anode material based on a pore-forming agent according to claim 3, characterized in that, The mass ratio of the liquid carbon source to the inorganic pore-forming agent is 1:1 to 8; the mass of the organic pore-forming agent is 10 to 30% of the mass of the liquid carbon source; and the mass of the curing agent is 5 to 10% of the mass of the liquid carbon source.
5. A method for preparing a hierarchical porous silicon-carbon anode material based on a pore-forming agent according to claim 1 or 3, characterized in that, The curing temperature is 50–150°C; the curing time is 0.5–10 h.
6. The method for preparing a hierarchical porous silicon-carbon anode material based on a pore-forming agent according to claim 5, characterized in that, The carbonization temperature is 500–1000℃; the carbonization time is 0.5–4 hours.
7. The method for preparing a hierarchical porous silicon-carbon anode material based on a pore-forming agent according to claim 6, characterized in that, The silane gas is one or more of the following: methanesilane, ethylsilane, propanesilane, monochlorosilane, dichlorosilane, trichlorosilane, tetrafluorosilane, hexamethyldisilane, dichlorodimethylsilane, and trimethylsilane; the flow rate of the silane gas is 0.5–8 L / min; the temperature of the silane deposition is 400–1000 °C; and the deposition time is 60–550 min.
8. The method for preparing a hierarchical porous silicon-carbon anode material based on a pore-forming agent according to claim 7, characterized in that, The carbon source gas is one or more of methane, ethane, butane, propane, ethylene, propylene, butene, and acetylene; the flow rate of the carbon source gas is 0.5–8 L / min; the carbon coating temperature is 500–700 °C; and the carbon coating time is 60–480 min.
9. The method for preparing a hierarchical porous silicon-carbon anode material based on a pore-forming agent according to any one of claims 1 to 8, characterized in that, The silicon-carbon anode material with a hierarchical porous structure based on pore-forming agent has a silicon mass fraction of 10-90% and a carbon mass fraction of 10-90%.
10. The application of the hierarchical porous silicon-carbon anode material based on pore-forming agent as described in claim 9 in lithium-ion batteries.