Process for the preparation of a highly conductive resin-based porous carbon material having a porous carbon skeleton

Abstract

The application discloses a preparation method of a high-conductivity resin-based porous carbon material with a porous carbon skeleton, which comprises the following steps: mixing a phenolic aldehyde compound, a catalyst and a modifier to prepare a precursor solution, cross-linking and solidifying the precursor solution through a low-temperature polymerization reaction, forming a three-dimensional high-conductivity carbon framework through high-temperature carbon activation, and obtaining the high-conductivity resin-based porous carbon material with a surface area of 2000-2250 m 2 / g, a pore volume of 0.8-1.0 mL / g, an ash content of less than or equal to 0.1%, and a microporosity of 80-100% through physical activation. The application significantly improves the intrinsic conductivity of the porous carbon material, realizes efficient regulation and stability of the porous structure, has simple preparation process, low cost, and is easy to scale production, and resin raw materials are widely available and have high purity. The application uses commercial phenolic aldehyde resin and common chemical reagents as raw materials, adopts a simple process of solution mixing and one-step heat treatment, avoids complex template removal and ultrahigh-temperature process, and greatly reduces production cost and energy consumption.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery anode material preparation technology, specifically relating to a method for preparing a highly conductive resin-based porous carbon material. The prepared highly conductive resin-based porous carbon material can be used as a carbon skeleton material for silicon-carbon anodes in lithium-ion batteries. Background Technology

[0002] Lithium-ion batteries possess advantages such as high energy density, long cycle life, and low self-discharge rate, leading to their widespread application in consumer electronics, electric vehicles, and energy storage systems. With the rapid development of the new energy industry, the requirements for technical indicators such as high safety, high energy density, high output voltage, and fast charging are becoming increasingly stringent. The anode material is one of the key factors affecting the performance of lithium-ion batteries. Currently, the mainstream anode material on the market is graphite, with a theoretical specific capacity of 372 mA·h / g. Commercial graphite anode materials have already achieved capacities close to their theoretical values. Silicon anodes have a theoretical specific capacity of 4200 mA·h / g, and an electrochemical lithium intercalation potential of approximately 0.4 V vs. Li / Li. + Silicon is an ideal anode material for high-capacity lithium-ion batteries. However, silicon anodes suffer from a volume effect of approximately 300%, extremely low intrinsic conductivity, and a lithium-ion diffusion coefficient of approximately 10⁻⁶. -12 cm 2 / s to 10 -13 cm 2 Its low electronic and ionic conductivity ( / s) hinders its commercialization.

[0003] To address the issue of low intrinsic conductivity in silicon, a common approach is to combine silicon particles with carbon materials to prepare Si–C composite anode materials. Research indicates that chemical vapor deposition (CVD) is a promising method for preparing silicon-carbon anodes. This involves the deposition of vapor-phase silanes within a porous carbon framework, where the internal voids of the porous carbon buffer volume expansion. However, this method places high demands on the carbon substrate material. On one hand, the carbon framework needs to possess sufficient voids to buffer the volume expansion of the silicon material; on the other hand, the carbon framework material must have high electronic conductivity to provide a rapid electron transport channel for the silicon material.

[0004] However, traditional carbon coatings have limited conductivity, and a single carbon shell is difficult to effectively suppress the volume effect of silicon during long-term cycling, making it prone to cracking and failure. Therefore, developing a novel carbon matrix that combines a highly conductive three-dimensional network with excellent buffer space is crucial for the preparation of high-performance silicon-carbon composite anodes. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a highly conductive resin-based porous carbon material with a porous carbon framework that is simple to process, low in cost, has a continuous three-dimensional conductive network and a uniformly distributed microporous structure, can effectively load silicon nanoparticles, and significantly improves the first coulombic efficiency, fast-charging performance and cycle performance of silicon-carbon anode materials. This method aims to solve the problem of low electronic and ionic conductivity of silicon materials in the application of silicon-carbon anodes.

[0006] To achieve the above-mentioned objectives of the present invention, the preparation method of the highly conductive resin-based porous carbon material with a porous carbon framework of the present invention is carried out by the following process steps:

[0007] S1, Preparation of precursor solution

[0008] A phenolic compound and an aldehyde compound are mixed, a first catalyst is added, and the mixture is placed in a water bath at a temperature range of 55-65°C to obtain mixture 1; the phenolic compound includes one, any two or three of phenol, o-methylphenol, and resorcinol; the first catalyst includes one, any two or three of ammonia, melamine, and aniline.

[0009] Weigh out the second catalyst according to the proportion and dissolve it in deionized water to prepare mixed solution 1; the second catalyst is any one, two or more of hexamethylenetetramine, sodium hydroxide, barium hydroxide, and sodium carbonate;

[0010] S2, cross-linking polymerization reaction

[0011] The mixed solution 1 is transferred to a reactor and stirred. Then, the mixture 1 is poured into the reactor containing the mixed solution 1, and a resin modifier is added and mixed. The mixture is heated at 80~120℃ for 6~12h to allow the reactants in the reactor to achieve cross-linking polymerization and solidification, thereby obtaining a solidified product. The resin modifier is any one, two or more of the following: petroleum coke, asphalt, needle coke, carbon black, carbon nanotubes, graphene, conductive particles, and conductive fibers.

[0012] S3, High-temperature carbonization and activation

[0013] The cured product obtained in step S2 is heated to 195-210℃ at a rate of 2-5℃ / min under an inert atmosphere and held for 1-3 hours; then the temperature is further increased to 800-1000℃ at a rate of 5-10℃ / min and held for 2-5 hours to obtain the first carbide; then the first carbide is activated by carbon dioxide gas at 800-1000℃ for 9-14 hours to obtain a highly conductive resin-based porous carbon material product.

[0014] Preferably, in step S2, the stirring speed of the reactor is controlled at 300~350 rpm; the molar ratio of the aldehyde mixture and the phenolic compound is (1.4~1.6):1.

[0015] Preferably, in step S1, the amount of the first catalyst added accounts for 0.5% to 1.5% of the total mass of the mixture of phenolic compounds and aldehyde compounds; and the amount of the second catalyst added accounts for 0.8% to 4.0% of the total mass of the mixture of phenolic compounds and aldehyde compounds.

[0016] Preferably, in step S2, the amount of resin modifier added accounts for 4.0% to 18.0% of the total mass of the mixture of phenolic and aldehyde compounds.

[0017] Preferably, in step S3, the inert gas used for the inert atmosphere is Ar or N2.

[0018] Furthermore, by synergistically adjusting the process parameters of each step, the surface area of ​​the highly conductive resin-based porous carbon material product is controlled to be 2000–2250 m². 2 / g, pore volume of 0.8–1.0 mL / g, ash content ≤0.1%, microporosity 80–100%. The prepared highly conductive resin-based porous carbon material product has a particle size D 50 Under conditions of 6–8 micrometers and 150 MPa pressure, the conductivity is 27–45 S / cm.

[0019] Experimental studies have shown that, compared with existing technologies, the preparation method of the highly conductive resin-based porous carbon material with a porous carbon framework of the present invention has the following advantages after adopting the above technical solution:

[0020] (1) Significantly improved intrinsic conductivity of porous carbon materials. Existing technologies for preparing porous carbon result in carbon skeletons with low graphitization and require optimization of conductivity. This invention introduces soft carbon to prepare soft-hard carbon composite porous carbon, which significantly improves the conductivity of the carbon skeleton at a relatively low carbonization temperature (800-1000℃), constructing a continuous three-dimensional high-speed electron transport channel. The conductivity can reach over 35 S / cm at 150 MPa, which greatly improves the rate performance and electron transport efficiency in electrode applications compared to traditional porous carbon materials (typically <15 S / cm).

[0021] (2) Efficient control and stability of porous structures are achieved. Traditional hard template methods are complex and costly. This invention successfully constructs a hierarchical pore structure with micropores as the main component and mesopores as the auxiliary component through physical activation of the resin precursor carbon dioxide. This structure not only provides a huge specific surface area (>2000 m² / g), but also effectively buffers the volume expansion effect during the charging and discharging of silicon anodes.

[0022] (3) The carbon skeleton made of resin has high mechanical strength and uses carbon dioxide physical activation to create pores with a microporosity of >80%, providing effective pores for high-content silane deposition. The pore structure has good stability during the cycle and is not easy to collapse. The highly conductive and high-strength carbon skeleton network ensures that silicon particles are in full contact with the carbon matrix, significantly improving the problem of poor intrinsic conductivity of silicon.

[0023] (4) The preparation process is simple, the cost is low, and it is easy to scale up production. The resin raw materials are widely available and have high purity. This invention uses commercial phenolic resin and common chemical reagents as raw materials and adopts a simple process of solution mixing and one-step heat treatment, which avoids complex template removal and ultra-high temperature process, and greatly reduces production costs and energy consumption. Attached Figure Description

[0024] Figure 1 The image shows a SEM image of the porous carbon precursor (i.e., the cross-linked polymerization curing product) prepared in Example 2.

[0025] Figure 2 The images show the pore volume and pore size test results of the highly conductive resin-based porous carbon specific surface area analyzer prepared in Example 2.

[0026] Figure 3 The image shows the Raman spectrum of the highly conductive resin-based porous carbon prepared in Example 2.

[0027] Figure 4 EDS diagram of the silicon-carbon composite material prepared in Example 2. Detailed Implementation

[0028] To describe the present invention, the preparation method of the highly conductive resin-based porous carbon material with a porous carbon framework of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments, but this is not intended to limit the present invention.

[0029] Example 1

[0030] The preparation method of highly conductive resin-based porous carbon materials with porous carbon framework includes the following steps:

[0031] Step 1: ① Weigh 139g of formaldehyde and 90.7g of phenol, stir at 60℃ for 10min, add 1.9g of ammonia water to obtain the first precursor solution; ② Weigh 300g of deionized water, add 2g of hexamethylenetetramine, stir to form a solution, and then mix with the first precursor solution to obtain the second precursor solution.

[0032] Step 2: In the second precursor solution reactor, start stirring at 320 rpm, add 10g of asphalt and mix. Heat at 80~120℃ for 6-12 hours to allow the resin to complete cross-linking and curing, and obtain the cured product.

[0033] Step 3: ① Under an inert atmosphere (Ar or N2), the cured product obtained in Step 2 is heated to 200℃ at a rate of 2~5℃ / min and held for 1-3 hours. Then, the temperature is increased to 800-1000℃ at a rate of 2~5℃ / min and held for 2~5 hours to obtain the first carbide. ② The first carbide is activated by carbon dioxide gas at an activation temperature of 800-100℃ for 9-14 hours to obtain a highly conductive resin-based porous carbon material.

[0034] Example 2

[0035] Step 1: ① Weigh 139g of formaldehyde and 90.7g of phenol, stir at 60℃ for 10 minutes, add 1.9g of ammonia water to obtain the first precursor solution; ② Weigh 300g of deionized water, add 6g of hexamethylenetetramine, stir to form a solution, and then mix with the first precursor solution to obtain the second precursor solution.

[0036] Step 2: In the second precursor solution reactor, start stirring at 320 rpm, add 20g of asphalt and mix. Heat the mixture at 80-120℃ for 6-12 hours to allow the resin to complete cross-linking and curing, and obtain the cured product—porous carbon precursor.

[0037] Step 3: ① Under an inert atmosphere (Ar or N2), the cured product obtained in Step 3 is heated to 400℃ at a rate of 2-5℃ / min and held for 1-3 hours. Then, the temperature is increased to 800-1000℃ at a rate of 2-5℃ / min and held for 2-5 hours to obtain the first carbide. ② The first carbide is activated by carbon dioxide gas at an activation temperature of 800-1000℃ for 9-14 hours to obtain a highly conductive resin-based porous carbon material.

[0038] Step 4: The highly conductive resin-based porous carbon material obtained in Step 3 is composited with silane gas via chemical vapor deposition. 1 kg of the highly conductive resin-based porous carbon material is added to a reactor and heated to 520°C under a nitrogen protective atmosphere. The temperature is maintained for 30 minutes, and then silane gas is introduced. This causes the silane gas to decompose and deposit within the pores of the highly conductive resin-based porous carbon material, forming silicon nanoparticles. The silicon deposition amount accounts for 50% of the mass of the silicon-carbon material, thus obtaining the silicon-carbon precursor material.

[0039] Step 5: After reaching the target amount of silicon deposition, shut off the silane gas, raise the reactor temperature from Step 4 to 580°C, and start introducing acetylene gas for carbon coating. The amount of carbon coating accounts for 3% of the mass of the silicon-carbon composite material. Under a nitrogen atmosphere, cool the reactor to room temperature and remove the material to obtain the silicon-carbon composite material.

[0040] Step Six: Weigh the silicon-carbon composite material, binder, and conductive agent in a mass ratio of 8:1:1 to prepare the silicon-carbon negative electrode sheet. Use a lithium metal sheet as the counter electrode and assemble coin cells in a glove box. Perform charge-discharge cycles on a battery programmable tester and calculate the average data of four coin cells. The test conditions for the first discharge specific capacity and first coulombic efficiency are as follows: charge-discharge rate of 0.1C, voltage range of 0.005V to 1.5V. 0.1C discharge specific capacity: 1970.56 mAh / g, first coulombic efficiency: 92.76%.

[0041] Figure 1 The image shown is a SEM image of the porous carbon precursor (i.e., the cross-linked polymerization and curing product) prepared in step two of Example 2. It has a spherical morphology with isotropic characteristics, which improves the uniformity of the material.

[0042] Figure 2 This is a test image showing the pore volume and pore size of the highly conductive resin-based porous carbon prepared in step three of Example 2. The porous carbon has a specific surface area of ​​2032 m². 2 / g, total pore volume 0.95856 mL / g, average pore size 1.8865nm, microporosity 89.3%. The high pore volume provides sufficient space to load silicon nanoparticles and buffer volume expansion, while the high microporosity (<2nm) helps to limit silicon particle agglomeration.

[0043] Figure 3 The Raman spectrum of the highly conductive resin-based porous carbon prepared in step three of Example 2 shows two peaks: the defect characteristic peak D and the graphite characteristic peak G. D / I G The value is 0.93.

[0044] Figure 4 Example 2 shows the EDS diagram of the silicon-carbon composite material prepared in step five. According to the distribution of Si and C elements, it can be seen that porous carbon uniformly supports silicon particles.

[0045] Example 3

[0046] Step 1: ① Weigh 139g of formaldehyde and 90.7g of phenol, stir at 60℃ for 10min, add 1.9g of ammonia water to obtain the first precursor solution; ② Weigh 300g of deionized water, add 8g of hexamethylenetetramine, stir to form a solution, and then mix with the first precursor solution to obtain the second precursor solution.

[0047] Step 2: In the second precursor solution reactor, start stirring at 320 rpm, add 30g of asphalt and mix. Heat the mixture at 80-120℃ for 6-12 hours to allow the resin to complete cross-linking and curing, and obtain the cured product.

[0048] Step 3: ① Under an inert atmosphere (Ar or N2), the cured product obtained in Step 2 is heated to 400℃ at a rate of 2-5℃ / min and held for 1-3 hours. Then, the temperature is increased to 800-1000℃ at a rate of 2-5℃ / min and held for 2-5 hours to obtain the first carbide. ② The first carbide is activated by carbon dioxide gas at a temperature of 800-1000℃ for 9-14 hours to obtain a highly conductive resin-based porous carbon material.

[0049] Comparative Example 1

[0050] The preparation method of the porous carbon material in Comparative Example 1 includes the following steps:

[0051] Step 1: ① Weigh 139g of formaldehyde and 90.7g of phenol, stir at 60℃ for 10min, add 1.9g of ammonia water to obtain the first precursor solution; ② Weigh 300g of deionized water, add 2g of hexamethylenetetramine, stir to form a solution, and then mix with the first precursor solution to obtain the second precursor solution.

[0052] Step 2: In the second precursor solution reactor, the stirring is turned on at 320 rpm, and the mixture is heated at 80~120℃ for 6-12 hours to allow the resin to complete cross-linking and curing, thus obtaining the cured product.

[0053] Step 3: ① Under an inert atmosphere (Ar or N2), the cured product obtained in Step 2 is heated to 200℃ at a rate of 2~5℃ / min and held for 1-3 hours. Then, the temperature is increased to 800~1000℃ at a rate of 2~5℃ / min and held for 2~5 hours to obtain the first carbide. ② The first carbide is activated by carbon dioxide gas at an activation temperature of 800-1000℃ for 9-14 hours to obtain a porous carbon material.

[0054] Comparative Example 2

[0055] Step 1: ① Weigh 139g of formaldehyde and 90.7g of phenol, stir at 60℃ for 10min, add 1.9g of ammonia water to obtain the first precursor solution; ② Weigh 300g of deionized water, add 2g of hexamethylenetetramine, stir to form a solution, and then mix with the first precursor solution to obtain the second precursor solution.

[0056] Step 2: In the second precursor solution reactor, start stirring at 320 rpm, add 20g of carbon black and mix. Heat at 80~120℃ for 6-12 hours to allow the resin to complete cross-linking and curing, and obtain the cured product.

[0057] Step 3: ① Under an inert atmosphere (Ar or N2), the cured product obtained in Step 2 is heated to 200℃ at a rate of 2~5℃ / min and held for 1-3 hours. Then, the temperature is increased to 800~1000℃ at a rate of 2~5℃ / min and held for 2~5 hours to obtain the first carbide. ② The first carbide is activated by carbon dioxide gas at an activation temperature of 800-1000℃ for 9-14 hours to obtain a porous carbon material.

[0058] The test data of the electrical conductivity performance parameters of the porous carbon prepared in Examples 1, 2, and 3 and Comparative Examples 1 and 2 are shown in Table 1.

[0059] Table 1 Test data of electrical conductivity performance parameters of porous carbon

[0060]

[0061] Table 1 shows the powder conductivity and compaction density test results. It can be seen that the porous carbon powder prepared in Example 2 has the highest conductivity, reaching 36.5485 S / cm at 150 MPa pressure. This is 1.5 times higher than the conductivity of the conventional resin porous carbon in Comparative Example 1, indicating a significant improvement in the conductivity of the carbon skeleton. Combined with... Figure 2 Example 2: Porous carbon with a specific surface area of ​​2032 m² was prepared. 2 / g, total pore volume 0.95856 mL / g, abundant pore structure with a certain amount of porosity to buffer the volume expansion of silicon material, silicon distribution after vapor deposition as follows Figure 4 As shown in Table 1, silicon is uniformly distributed. Furthermore, the excellent high electronic conductivity of silicon provides a rapid electron transport channel, making it a carbon framework material with great application potential in the field of silicon-carbon anodes.

[0062] Unless otherwise specified, the raw materials and equipment used in this invention are all commonly used in the field; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0063] The above description is merely an embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, alterations, and equivalent transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

[0064] The material selection, material ratio, upper and lower limits and ranges of process parameters involved in this invention can all achieve the desired results. The technical performance of the finally prepared highly conductive resin-based porous carbon material product is: surface area 2000-2250 m². 2 / g, pore volume 0.8~1.0 mL / g, ash content ≤0.1%, microporosity 80~100%. These will not be listed individually here.

Claims

1. A method for preparing a highly conductive resin-based porous carbon material with a porous carbon framework, characterized in that... The following steps are to be taken: S1, Preparation of precursor solution A phenolic compound and an aldehyde compound are mixed, a first catalyst is added, and the mixture is placed in a water bath at a temperature range of 55-65°C to obtain mixture 1; the phenolic compound includes one, any two or three of phenol, o-methylphenol, and resorcinol; the first catalyst includes one, any two or three of ammonia, melamine, and aniline. Weigh out the second catalyst according to the specified ratio and dissolve it in deionized water to prepare mixed solution 1; the second catalyst is hexamethylenetetramine. The molar ratio of the aldehyde mixture to the phenolic compound is (1.4~1.6):1; the amount of the first catalyst added is 0.5%~1.5% of the total mass of the phenolic compound and aldehyde compound mixture; the amount of the second catalyst added is 0.8%~4.0% of the total mass of the phenolic compound and aldehyde compound mixture. S2, cross-linking polymerization reaction The mixed solution 1 is transferred to a reactor and stirred. Then, the mixture 1 is poured into the reactor containing the mixed solution 1, and a resin modifier is added and mixed. The mixture is heated at 80~120℃ for 6~12h to allow the reactants in the reactor to achieve cross-linking polymerization and solidification, thereby obtaining a solidified product. The resin modifier is asphalt. The amount of resin modifier added is 4.0~18.0% of the total mass of the mixture of phenolic compounds and aldehyde compounds. S3, High-temperature carbonization and activation The cured product obtained in step S2 is heated to 195-210℃ at a rate of 2-5℃ / min under an inert atmosphere and held for 1-3 hours; then the temperature is further increased to 800-1000℃ at a rate of 5-10℃ / min and held for 2-5 hours to obtain the first carbide; then the first carbide is activated by carbon dioxide gas at 800-1000℃ for 9-14 hours to obtain a highly conductive resin-based porous carbon material product. The surface area of ​​the obtained highly conductive resin-based porous carbon material products is 2000–2250 m². 2 / g, pore volume is 0.8~1.0mL / g, ash content ≤0.1%, microporosity is 80~100%.

2. The method for preparing a highly conductive resin-based porous carbon material with a porous carbon framework as described in claim 1, characterized in that: In step S2, the stirring speed of the reactor is controlled at 300~350 rpm; in step S3, the inert gas used for the inert atmosphere is Ar or N2.

3. The method for preparing a highly conductive resin-based porous carbon material with a porous carbon framework as described in claim 1 or 2, characterized in that: The prepared highly conductive resin-based porous carbon material products have a particle size D 50 Under conditions of 6–8 micrometers and 150 MPa pressure, the conductivity is 27–45 S / cm.

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