A method for preparing high-purity phenolic resin carbon microspheres

Abstract

This invention discloses a method for preparing high-purity phenolic resin carbon microspheres, belonging to the field of battery material technology. The method mainly includes the purification, polymerization, separation, drying and carbonization of raw materials. The resin carbon microspheres obtained by the method of this invention have high density, high purity, good strength, ash content of less than 0.01%, and total content of trace elements (iron, cobalt, chromium, nickel, zinc) of less than 100 ppb. They can be used as precursors for silicon-carbon, phosphorus-carbon and hard carbon anode materials.

Description

Technical Field

[0001] This invention belongs to the field of battery materials technology, specifically a method for preparing high-purity phenolic resin carbon microspheres. Background Technology

[0002] Carbon materials are widely used as anode materials in batteries, such as graphite and hard carbon. Phenolic resin carbon, due to its high carbon content, thermal stability, and low cost, and especially its good microstructure adjustment function and subsequent activation and pore-forming function, is increasingly being used in high-end carbon materials.

[0003] In recent years, silicon-carbon, phosphorus-carbon, and hard carbon anode materials have been increasingly used in high-end and novel batteries. These anode materials require resin carbon with good conductivity, strength, resistance to charge-discharge volume expansion stress, and low impurities, particularly low levels of magnetic impurities (iron, cobalt, chromium, nickel, and zinc). Patent CN116395665A proposes a manufacturing process for carbon materials with a homogeneous spherical structure, which significantly improves the resistance to internal expansion stress during charge-discharge. Patent CN104387239B mentions using cation exchange resins to purify phenol to prepare nonylphenol; however, phenol is weakly acidic, and high concentrations can affect ion exchange balance, making it difficult or resulting in very low exchange rates for metal cation impurities in phenol. With the increasing demand for high-end batteries, impurities in carbon materials, especially magnetic impurities (iron, cobalt, chromium, nickel, and zinc), can lead to electrochemical side reactions in the battery, affecting its cycle life, safety, and stability. Summary of the Invention

[0004] To address the above problems, the purpose of this invention is to provide a method for preparing high-purity phenolic resin carbon microspheres.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] A method for preparing high-purity phenolic resin carbon microspheres includes purification, polymerization, separation, drying and carbonization of raw materials;

[0007] The raw materials are purified using aminocarboxylic acid chelating resins or aminophosphate chelating resins.

[0008] The preparation method of the high-purity phenolic resin carbon microspheres specifically includes the following steps:

[0009] 1) Purification of raw materials: Phenol is melted into a liquid state and flows through ion exchange column A; the aldehyde compound solution flows through ion exchange column B to obtain purified phenol and aldehyde compounds;

[0010] 2) Polymerization: The purified phenol and aldehyde compounds, non-metallic ion catalyst and solvent obtained in step 1) are added to the reaction vessel in sequence. Under stirring, the prepolymerization reaction is carried out at 50-80℃ for 0.1-5h. Then, a dispersant is added to form spherical droplets. The temperature is then raised to 80-150℃ and the curing reaction is carried out for 0.5-10h. After cooling, a phenolic resin suspension is obtained.

[0011] 3) Separation: The phenolic resin suspension obtained in step 2) is filtered through a filter to obtain solid phenolic resin and mother liquor;

[0012] 4) Drying: Dry the solid phenolic resin obtained in step 3) to obtain thermosetting phenolic resin;

[0013] 5) Carbonization: The thermosetting phenolic resin obtained in step 4) is placed in a high-temperature furnace and carbonized at 500-900℃ for 0.5-10 hours. After cooling, the material is discharged and broken up to obtain high-purity phenolic resin carbon microspheres.

[0014] In step 1), the ion exchange column A is filled with one or both of aminocarboxylic acid chelating resin and aminophosphate chelating resin, and has an insulation jacket; the ion exchange column B is filled with one or both of aminocarboxylic acid chelating resin and aminophosphate chelating resin, and does not require an insulation jacket.

[0015] The aldehyde compound mentioned in step 1) is one or two of formaldehyde, acetaldehyde, and paraformaldehyde.

[0016] The non-metallic ion catalyst mentioned in step 2) is one or two of aniline, hexamethylenetetramine, ammonia, triethylamine, trimethylamine, diethanolamine, triethanolamine and diamine hydrogen phosphate.

[0017] The solvent mentioned in step 2) is one or two of the following: deionized water, propylene glycol, ethylene glycol, glycerin, turbine oil, vegetable oil, and dioctyl phthalate.

[0018] The dispersant mentioned in step 2) is one or two of gelatin, gum arabic, polyvinyl alcohol, polyvinylpyrrolidone, hydroxymethyl cellulose, carboxyethyl cellulose, methyl hydroxyethyl cellulose, lignin, polydiallyl ammonium chloride, and sodium oleate.

[0019] The mass ratio of phenol, aldehyde compound, non-metallic ion catalyst, solvent and dispersant in step 2) is 94:30-200:1-30:50-300:1-10.

[0020] The filter mentioned in step 3) is one or two of the following: a high-speed centrifuge, a plate and frame filter press, and a sedimentation tank.

[0021] The high-temperature furnace mentioned in step 5) is one or two of the following: roller kiln, tunnel kiln, box furnace, or cladding furnace.

[0022] The high-purity phenolic resin carbon microspheres mentioned in step 5) have a particle size of 2 to 1000 μm.

[0023] The present invention also includes the application of high-purity phenolic resin carbon microspheres as precursors for silicon-carbon, phosphorus-carbon and hard carbon anode materials.

[0024] In this invention, the parts of the equipment used in the preparation process that come into contact with the materials need to be treated with non-metallic materials, including but not limited to the following treatment methods: the ion exchange column is made of fiberglass, PP column, carbon steel or stainless steel and lined with polytetrafluoroethylene; the reaction vessel and pipeline are lined with polytetrafluoroethylene; the carbonization crucible is made of silicon carbide or graphite crucible and the dispersant is lined with ceramic.

[0025] The present invention has the following advantages over the prior art:

[0026] This invention is the first to develop an industrially producible high-purity phenolic resin carbon microsphere, which is prepared by purifying, polymerizing, separating, drying and carbonizing the raw materials. First, controlling the purity of raw materials is crucial. Industrial-grade phenol and formaldehyde, upstream raw materials for phenolic resin carbon, are typically acidic and corrosive to commonly used stainless steel or galvanized production equipment, pipes, or storage tanks, introducing magnetic impurities such as iron, cobalt, chromium, nickel, and zinc. This invention is the first to propose using chelating resins to purify the raw phenol or aldehyde compounds. The functional groups in the chelating resin can complex with impurity ions in a weakly acidic system, selectively adsorbing impurity metal ions, thus reducing a significant source of impurities in the carbon microspheres. Second, non-metallic catalysts are used. Phenolic polycondensation commonly uses inorganic acid or base catalysts. Conventional catalysts can leave inorganic ions in the resin, which cannot volatilize during subsequent carbonization, thus affecting the purity of the carbon material. Third, non-metallic treatment of production equipment is essential. For equipment parts in contact with production materials, low-temperature sections are lined with rubber or polytetrafluoroethylene, while high-temperature equipment is lined with ceramic or made of silicon carbide or graphite.

[0027] This invention achieves high purity control of carbon microsphere products through the purification of raw materials, the use of pure organic raw and auxiliary materials, and the non-metallization treatment of manufacturing equipment. The high-purity phenolic resin carbon microspheres prepared by this invention have a particle size between 2 and 1000 μm. Particles smaller than 2 μm have poor subsequent processing performance, and excessively small particle size results in low compaction density and large specific surface area, affecting battery capacity and first-time efficiency. Larger particle size leads to poorer internal heat transfer during preparation, affecting the uniformity of microstructure. The volume resistivity is less than 1 Ω·cm, the ash content is less than 0.01%, the carbon content is greater than 99.99%, and the total content of trace elements (iron, cobalt, chromium, nickel, and zinc) is less than 100 ppb. Attached Figure Description

[0028] Figure 1 This is a particle size distribution diagram of the high-purity phenolic resin carbon microspheres prepared in Example 1 of the present invention. Detailed Implementation

[0029] To better understand the technical solution of the present invention, the following detailed embodiments are provided to further illustrate the above-mentioned content of the present invention. However, this should not be construed as limiting the scope of the subject matter of the present invention to the following examples. All technologies implemented based on the above-mentioned content of the present invention fall within the scope of the present invention.

[0030] Example 1: Phenol was melted into a liquid state and flowed through a polytetrafluoroethylene-lined stainless steel ion exchange column packed with aminocarboxylic acid type chelating resin; a 37% (w / w) formaldehyde aqueous solution was flowed through a PP ion exchange column packed with aminophosphoric acid type chelating resin; purified phenol and formaldehyde aqueous solution were obtained; 94g of purified phenol, 85g of purified formaldehyde aqueous solution, 10g of 25% (w / w) ammonia water, and 100g of ethylene glycol were sequentially added to a reaction flask, and prepolymerized at 75°C under stirring. After reacting for 0.5 hours, 5g of sodium oleate was added, forming spherical droplets. The temperature was then raised to 120℃, and the solidification reaction was continued for 7 hours. After cooling, a phenolic resin suspension was obtained. The obtained phenolic resin suspension was filtered through a high-speed centrifuge to obtain solid phenolic resin and mother liquor. The obtained solid phenolic resin was dried to obtain thermosetting phenolic resin. The obtained thermosetting phenolic resin was placed in a roller kiln and carbonized at 600℃ for 5 hours. After cooling, the material was discharged and dispersed to obtain high-purity phenolic resin carbon microspheres. The particle size distribution is shown in the figure below. Figure 1 As shown.

[0031] Example 2: Phenol was melted into a liquid state and flowed through a polytetrafluoroethylene-lined stainless steel ion exchange column packed with aminocarboxylic acid chelating resin; a 40% (w / w) aqueous solution of acetaldehyde was also flowed through the same column; purified phenol and acetaldehyde aqueous solution were obtained. 94g of purified phenol, 75g of purified acetaldehyde aqueous solution, 5g of aniline, and 150g of glycerol were sequentially added to a reaction flask, and the mixture was subjected to a prepolymerization reaction at 65°C with stirring. After 5 hours, 6g of gelatin was added to form spherical droplets. The temperature was then raised to 110℃ and the curing reaction was carried out for 10 hours. After cooling, a phenolic resin suspension was obtained. The obtained phenolic resin suspension was filtered through a plate and frame filter press to obtain solid phenolic resin and mother liquor. The obtained solid phenolic resin was dried to obtain thermosetting phenolic resin. The obtained thermosetting phenolic resin was placed in a tunnel kiln and carbonized at 500℃ for 10 hours. After cooling, the material was discharged and dispersed to obtain high-purity phenolic resin carbon microspheres.

[0032] Example 3: Phenol was melted into a liquid state and flowed through a polytetrafluoroethylene-lined stainless steel ion exchange column packed with aminophosphate chelating resin; paraformaldehyde solution was also flowed through a polytetrafluoroethylene-lined stainless steel ion exchange column packed with aminophosphate chelating resin; purified phenol and paraformaldehyde solution were obtained; 94g of purified phenol, 100g of purified paraformaldehyde solution, 8g of hexamethylenetetramine, and 120g of water were sequentially added to a reaction flask, and the mixture was prepolymerized at 68°C for 4 hours with stirring. 4g of hydroxymethyl cellulose was added to form spherical droplets. The temperature was then raised to 95℃ and the curing reaction was carried out for 8 hours. After cooling, a phenolic resin suspension was obtained. The obtained phenolic resin suspension was settled in a sedimentation tank, and the upper mother liquor was discharged, leaving solid phenolic resin at the bottom. The obtained solid phenolic resin was dried to obtain thermosetting phenolic resin. The obtained thermosetting phenolic resin was placed in a coating furnace and carbonized at 600℃ for 7 hours. After cooling, the material was discharged and dispersed to obtain high-purity phenolic resin carbon microspheres.

[0033] Example 4: Phenol was melted into a liquid state and flowed through a PP ion exchange column packed with aminophosphate chelating resin; a 37% (w / w) formaldehyde aqueous solution was flowed through a polytetrafluoroethylene-lined stainless steel ion exchange column packed with aminocarboxylic acid chelating resin; purified phenol and formaldehyde aqueous solution were obtained; 94g of purified phenol, 150g of purified formaldehyde aqueous solution, 15g of triethanolamine, and 150g of turbine oil were sequentially added to a reaction flask, and the mixture was subjected to a prepolymerization reaction at 70°C with stirring for 3 days. After 5 hours, 5g of sodium oleate was added to form spherical droplets. The temperature was then raised to 110℃ and the solidification reaction was carried out for 7 hours. After cooling, a phenolic resin suspension was obtained. The phenolic resin suspension was filtered through a high-speed centrifuge to obtain solid phenolic resin and mother liquor. The solid phenolic resin was dried to obtain thermosetting phenolic resin. The thermosetting phenolic resin was placed in a box furnace and carbonized at 650℃ for 5 hours. After cooling, the material was discharged and dispersed to obtain high-purity phenolic resin carbon microspheres.

[0034] Example 5: Phenol was melted into a liquid state and flowed through a PP ion exchange column packed with aminophosphate chelating resin; a 40% (w / w) aqueous solution of acetaldehyde was flowed through a polytetrafluoroethylene-lined stainless steel ion exchange column packed with aminophosphate chelating resin; purified phenol and aqueous acetaldehyde solution were obtained; 94g of purified phenol, 120g of purified aqueous acetaldehyde solution, 20g of trimethylamine, and 180g of vegetable oil were sequentially added to a reaction flask, and the mixture was subjected to a prepolymerization reaction at 75°C with stirring for 2 hours. h, then add 6g of gum arabic to form spherical droplets, continue heating to 120℃, and cure for 6h. Cool to obtain a phenolic resin suspension. Filter the obtained phenolic resin suspension through a high-speed centrifuge to obtain solid phenolic resin and mother liquor. Dry the obtained solid phenolic resin to obtain thermosetting phenolic resin. Place the obtained thermosetting phenolic resin in a box furnace and carbonize at 700℃ for 4h. Cool down, discharge, and break up to obtain high-purity phenolic resin carbon microspheres.

[0035] Example 6: Phenol was melted into a liquid state and flowed through a PP ion exchange column packed with aminophosphate chelating resin; a 40% (w / w) aqueous solution of acetaldehyde was flowed through a polytetrafluoroethylene-lined stainless steel ion exchange column packed with aminocarboxylic acid chelating resin; purified phenol and aqueous acetaldehyde solution were obtained; 94g of purified phenol, 150g of purified aqueous acetaldehyde solution, 12g of aniline, and 150g of water were sequentially added to a reaction flask, and the mixture was subjected to a prepolymerization reaction at 72°C for 2.5 seconds with stirring. h, then add 5g of lignin to form spherical droplets, continue heating to 98℃, and solidify for 8h. Cool to obtain a phenolic resin suspension. Filter the obtained phenolic resin suspension through a plate and frame filter press to obtain solid phenolic resin and mother liquor. Dry the obtained solid phenolic resin to obtain thermosetting phenolic resin. Place the obtained thermosetting phenolic resin in a box furnace and carbonize at 750℃ for 3h. Cool down, discharge, and break up to obtain high-purity phenolic resin carbon microspheres.

[0036] Example 7: Phenol was melted into a liquid state and flowed through a PP ion exchange column packed with aminophosphate chelating resin; a 37% (w / w) formaldehyde aqueous solution was flowed through a polytetrafluoroethylene-lined stainless steel ion exchange column packed with aminocarboxylic acid chelating resin; purified phenol and formaldehyde aqueous solution were obtained; 94g of purified phenol, 115g of purified formaldehyde aqueous solution, 30g of hexamethylenetetramine, and 300g of propylene glycol were sequentially added to a reaction flask, and the mixture was subjected to a prepolymerization reaction at 80°C under stirring. After 5 hours, 7g of sodium oleate was added to form spherical droplets. The temperature was then raised to 140℃ and the solidification reaction was carried out for 3 hours. After cooling, a phenolic resin suspension was obtained. The obtained phenolic resin suspension was filtered through a plate and frame filter press to obtain solid phenolic resin and mother liquor. The obtained solid phenolic resin was dried to obtain thermosetting phenolic resin. The obtained thermosetting phenolic resin was placed in a box furnace and carbonized at 800℃ for 2 hours. After cooling, the material was discharged and dispersed to obtain high-purity phenolic resin carbon microspheres.

[0037] Example 8: Phenol was melted into a liquid state and flowed through a PP ion exchange column packed with aminocarboxylic acid chelating resin; paraformaldehyde solution was flowed through a polytetrafluoroethylene-lined stainless steel ion exchange column packed with aminocarboxylic acid chelating resin; purified phenol and paraformaldehyde solution were obtained; 94g of purified phenol, 120g of purified paraformaldehyde solution, 25g of 25% ammonia solution, and 150g of deionized water were sequentially added to a reaction flask, and the mixture was subjected to a prepolymerization reaction at 74°C under stirring. After 2 hours, 6g of sodium oleate was added to form spherical droplets. The temperature was then raised to 120℃ and the curing reaction was carried out for 7 hours. After cooling, a phenolic resin suspension was obtained. The obtained phenolic resin suspension was filtered through a plate and frame filter press to obtain solid phenolic resin and mother liquor. The obtained solid phenolic resin was dried to obtain thermosetting phenolic resin. The obtained thermosetting phenolic resin was placed in a box furnace and carbonized at 700℃ for 4 hours. After cooling, the material was discharged and dispersed to obtain high-purity phenolic resin carbon microspheres.

[0038] Comparative Example

[0039] The preparation method of phenolic resin carbon microspheres is the same as that in Example 1, except that the raw materials phenol and formaldehyde aqueous solution are not purified by ion exchange column, and the parts of the equipment used in the preparation process that come into contact with the materials are not treated with non-metallic materials.

[0040] The high-purity phenolic resin carbon microspheres prepared in Examples 1-8 and the phenolic resin carbon microspheres prepared in the comparative examples were analyzed according to the methods in the national standard GB / T24533-2019. The analytical spectral lines of Fe, Co, Gr, Ni, and Zn were 238.204 nm, 228.616 nm, 267.716 nm, 231.604 nm, and 213.857 nm, respectively. The detection results are shown in Table 1.

[0041] Table 1. Performance Test Results of Phenolic Resin Carbon Microspheres Prepared in Examples and Comparative Examples

[0042]

[0043] As can be seen from the results in Table 1, the high-purity phenolic resin carbon microspheres prepared by the method of the present invention have a particle size between 2 and 1000 μm compared with the comparative example; a volume resistivity of less than 1 Ω·cm, indicating good conductivity; a significantly reduced ash content of less than 0.01%; a higher carbon content of more than 99.99% compared with the comparative example; and a significantly lower total content of trace elements (iron, cobalt, chromium, nickel, and zinc) of less than 100 ppb compared with the comparative example, indicating high purity and low impurities.

[0044] While the specific embodiments of the present invention have been described above, they are not intended to limit the scope of protection of the present invention. Based on the technical solutions of the present invention, various modifications or variations that can be made by those skilled in the art without creative effort are still within the scope of protection of the present invention.

Claims

1. A method for preparing high-purity phenolic resin carbon microspheres, characterized in that: The preparation process comprises raw material purification, polymerization, separation, drying and carbonization. The raw material purification is melting phenol into liquid state and flowing through ion exchange column A; and flowing aldehyde compound solution through ion exchange column B to obtain purified phenol and aldehyde compound. The ion exchange column A is packed with one or both of amine carboxylic acid type chelating resin and amine phosphoric acid type chelating resin, and has a heat insulation interlayer; and the ion exchange column B is packed with one or both of amine carboxylic acid type chelating resin and amine phosphoric acid type chelating resin, and does not need a heat insulation interlayer.

2. The method for preparing high-purity phenolic resin carbon microspheres as described in claim 1, characterized in that: The preparation process comprises the following steps: 1) Raw material purification: melting phenol into liquid state and flowing through ion exchange column A; 2) Polymerization: adding purified phenol and aldehyde compound obtained in step 1), non-metallic ionic catalyst and solvent into a reaction kettle in sequence, and performing pre-polymerization reaction at 50-80℃ for 0.1-5h under stirring, then adding dispersant to form spherical droplets, and continuing to heat to 80-150℃ for solidification reaction for 0.5-10h, and cooling to obtain phenolic resin suspension; 3) Separation: filtering the phenolic resin suspension obtained in step 2) through a filter to obtain solid phenolic resin and mother liquor; 4) Drying: drying the solid phenolic resin obtained in step 3) to obtain thermosetting phenolic resin; 5) Carbonization: placing the thermosetting phenolic resin obtained in step 4) into a high-temperature furnace, and carbonizing at 500-900℃ for 0.5-10h, cooling, discharging, and dispersing to obtain high-purity phenolic resin carbon microspheres. The aldehyde compound in step 1) is one or both of formaldehyde, acetaldehyde and polyformaldehyde.

3. The method for preparing high-purity phenolic resin carbon microspheres as described in claim 2, characterized in that: The non-metallic ionic catalyst in step 2) is one or both of aniline, urotropine, ammonia, triethylamine, trimethylamine, diethanolamine, triethanolamine and phosphoric acid diamine; the solvent in step 2) is one or both of deionized water, propylene glycol, ethylene glycol, glycerol, turbine oil, vegetable oil and dioctyl phthalate; and the dispersant in step 2) is one or both of gelatin, gum arabic, polyvinyl alcohol, polyvinylpyrrolidone, hydroxymethyl cellulose, carboxyethyl cellulose, methylhydroxyethyl cellulose, lignin, polydimethyl diallyl ammonium chloride and sodium oleate.

4. The method for preparing high-purity phenolic resin carbon microspheres as described in claim 2, characterized in that: The mass ratio of phenol, aldehyde compound, non-metallic ionic catalyst, solvent and dispersant in step 2) is 94:30-200:1-30:50-300:1-10.

5. The method for preparing high-purity phenolic resin carbon microspheres as described in claim 2, characterized in that: The filter in step 3) is one or both of high-speed centrifuge, plate and frame filter press and sedimentation tank.

6. The method for preparing high-purity phenolic resin carbon microspheres as described in claim 2, characterized in that: The high-temperature furnace in step 5) is one or both of roller kiln, tunnel kiln, box furnace or cladding furnace; and the particle size of the high-purity phenolic resin carbon microspheres in step 5) is 2-1000µm.

7. The method for preparing high-purity phenolic resin carbon microspheres as described in claim 2, characterized in that: The equipment and material contact parts used in the preparation process need to be treated with non-metals, including but not limited to the following treatment methods: the ion exchange column is lined with polytetrafluoroethylene inside a glass steel, PP column, carbon steel or stainless steel column; the reaction kettle and pipeline are lined with polytetrafluoroethylene; the carbonization crucible is made of silicon carbide or graphite crucible, and the dispersing machine is lined with ceramic.

8. The method for preparing high-purity phenolic resin carbon microspheres as described in claim 2, characterized in that: ​ 9. Use of the high-purity phenolic resin carbon microspheres of claim 1 as a precursor of negative electrode materials for silicon-carbon, phosphorus-carbon and hard carbon.

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