A spherical resin pellet and a spherical porous carbon suitable for a silicon-carbon negative electrode and a preparation method thereof

Abstract

The application discloses a kind of spherical resin pellets suitable for silicon-carbon negative electrode and spherical porous carbon and preparation method thereof, belong to energy material and energy storage device field.The spherical resin pellets meet the following conditions simultaneously: (a) average particle size is 12-25 μm;(b) sphericity is greater than or equal to 0.95;(c) pore volume is 0.1-0.5 ml / g;(d) compressive strength is 500-1000 MPa;(e) particle size distribution T is less than 5, T=(D90-D10) / D50.The spherical porous carbon meets the following requirements: (1) average particle size is 3-10 μm;(2) sphericity is greater than or equal to 0.95;(3) specific surface area is greater than or equal to 1600 m² / g;(4) compressive strength is 200-600 MPa.The spherical resin pellets of the application have small particle size, high sphericity, high pore volume and high compressive strength, and the spherical porous carbon has small particle size and high sphericity.When the spherical resin pellets and the spherical porous carbon are used to prepare electrode materials, the high compressive strength can avoid roller pressing damage, and the pore structure is controllable, which is suitable for energy storage, electrocatalysis, adsorption separation and other fields.

Description

Technical Field

[0001] This application relates to a spherical resin microsphere suitable for silicon-carbon anodes and a spherical porous carbon and its preparation method, belonging to the field of energy materials and energy storage devices. Background Technology

[0002] Silicon-carbon anodes have become a research hotspot in lithium-ion batteries due to their high specific capacity and cycle stability. Porous carbon plays a crucial role in mitigating the silicon volume effect and improving conductivity and electrode stability. Among porous carbon materials, spherical structures are the preferred form for silicon-carbon anode composite systems due to their good fluidity, high packing density, and uniform current distribution. However, the existing preparation processes for spherical resin microspheres and spherical porous carbon materials still face significant technical bottlenecks, resulting in their performance not fully meeting the application requirements of silicon-carbon anodes. Specifically:

[0003] (1) Insufficient sphericity and uneven particle size distribution: Existing preparation technologies (such as spray drying) are limited by factors such as precursor flowability and reaction temperature gradient, making it difficult to accurately control the spherical shape of particles. This results in some products having surface depressions and edge defects, with sphericity generally below 0.8. At the same time, the particle size distribution is wide, and the gap between large and small particles is uneven, which can easily lead to fluctuations in the porosity inside the electrode.

[0004] (2) The pore structure is simple and the pore volume is too small, resulting in limited electrolyte wettability and ion diffusion performance: Existing spherical porous carbon materials have small pore volumes. Although they have high pressure resistance, they have small ion diffusion channels, resulting in poor electrolyte wettability and high ion diffusion resistance.

[0005] (3) Insufficient mechanical strength and easy pulverization during cycling: During the cycling process, the volume expansion of silicon in silicon-carbon anodes will exert continuous extrusion pressure on the porous carbon skeleton. If the mechanical strength of the porous carbon is insufficient, the skeleton is prone to fracture and particle pulverization. Existing spherical porous carbon materials generally have poor mechanical properties due to their loose pore structure and low degree of cross-linking of the carbon skeleton. During cycling, the carbon skeleton is prone to fracture due to stress concentration, resulting in silicon particle shedding. After 50 cycles, the capacity retention rate of the battery is generally less than 50%, which cannot meet the requirements of commercial battery cycle life (≥1000 cycles).

[0006] Therefore, there is an urgent need to develop a resin precursor with controllable particle size distribution, high sphericity, reasonable pore structure, and high mechanical strength, as well as its spherical porous carbon. Summary of the Invention

[0007] To address the aforementioned issues, a spherical resin microsphere and a spherical porous carbon are provided for silicon-carbon anodes, resolving problems such as insufficient sphericity, uncontrollable pore structure, excessively large or small pore volume, and poor cycle stability in existing resins and carbon spheres.

[0008] According to a first aspect of this application, a spherical resin microsphere suitable for silicon-carbon anodes is provided, the spherical resin microsphere simultaneously satisfying the following requirements:

[0009] (a) The average particle size is 12-25 μm;

[0010] (b) Sphericity ≥ 0.95;

[0011] (c) The pore volume is 0.1-0.5 ml / g;

[0012] (d) Compressive strength is 500-1000 MPa;

[0013] (e) Particle size distribution T < 5, T = (D90 - D10) / D50.

[0014] The spherical resin microspheres prepared in this application have small particle size, high sphericity, narrow particle size distribution, and smooth particle surfaces without depressions or sharp corner defects. This effectively avoids localized current concentration caused by particle agglomeration. Simultaneously, the optimized pore structure increases pore volume, improves pore shape ratio adaptability, and enhances mass transfer efficiency. Furthermore, the spherical resin microspheres exhibit increased cross-linking degree, forming a denser three-dimensional network structure, significantly improving compressive strength and structural stability.

[0015] Optionally, the average particle size of the spherical resin microspheres is 12.8-22.4 μm.

[0016] Optionally, the particle size distribution T of the spherical resin microspheres is <3.4.

[0017] Optionally, the pore volume of the spherical resin microspheres is 0.25-0.42 ml / g.

[0018] The spherical resin microspheres of this application have small particle size, narrow particle size distribution, and large pore volume, which can improve the consistency of silicon-carbon anodes and thus improve the cycle life of batteries.

[0019] Optionally, the spherical resin microspheres are selected from at least one of styrene-divinylbenzene ion exchange resin, phenolic resin, furfural resin, furan resin, urea-formaldehyde resin, or melamine resin.

[0020] The spherical resin microspheres of this application are diverse in type and have stable structure. The microsphere pore structure can be controlled, which lays the foundation for maintaining a highly spherical and porous carbon morphology after subsequent carbonization.

[0021] According to a second aspect of this application, a method for preparing spherical resin microspheres suitable for silicon-carbon anodes is provided. When the type of spherical resin microspheres is styrene-divinylbenzene ion exchange resin, the method includes the following steps:

[0022] 1) Styrene, divinylbenzene, initiator and soft template agent are premixed at room temperature to obtain a mixture, wherein the divinylbenzene accounts for more than 10 wt% of the total weight of styrene and divinylbenzene; the initiator accounts for 1-2% of the total weight of styrene and divinylbenzene; and the soft template agent accounts for 30-90% of the total weight of styrene and divinylbenzene.

[0023] 2) Add the mixture to the dispersant solution, heat to 50-80℃ for prepolymerization reaction for 1-2 hours, and then heat to 70-120℃ for polymerization reaction for 2-5 hours;

[0024] 3) After polymerization, filter, wash, and remove the soft template agent to obtain the final product;

[0025] When the spherical resin beads are made of phenolic resin, furfural resin, furan resin, urea-formaldehyde resin, or melamine resin, the process includes the following steps:

[0026] S1: The reactants and soft template agent are prepolymerized to obtain a solution containing the prepolymer. The reactants of phenolic resin are formaldehyde and phenol, and the molar ratio of formaldehyde to phenol is ≥1.5:1. The reactants of furfural resin are furfural and resorcinol, and the molar ratio of furfural to resorcinol is ≥2:1. The reactants of furan resin are formaldehyde and furfuryl alcohol, and the molar ratio of formaldehyde to furfuryl alcohol is ≥1.8:1. The reactants of melamine resin are melamine and formaldehyde, and the molar ratio of formaldehyde to melamine is ≥2:1. The reactants of urea-formaldehyde resin are formaldehyde and urea, and the molar ratio of formaldehyde to urea is ≥1.8:1.

[0027] S2: Add the solution containing the prepolymer to the dispersant solution, heat to 50-80℃ for prepolymerization reaction for 1-2 hours, and then heat to 70-120℃ for polymerization reaction for 2-5 hours;

[0028] S3: Filter, wash and remove the soft template agent from the product of step S2 to obtain the final product.

[0029] Specifically, the initiator mentioned in step 1) is AIBN.

[0030] Specifically, the mass ratio of the mixture to the dispersant solution in step 2) is 1:(2-10).

[0031] Specifically, the method for removing the soft template agent in step 3) is by solvent extraction, pyrolysis, vacuum evaporation or acid washing.

[0032] Specifically, in step S1, ethanol is added as a solvent, and the ethanol accounts for 50-200% of the total weight of the reactants.

[0033] Specifically, in step S2, the mass ratio of the solution containing the prepolymer to the dispersant solution is 1:(2-10).

[0034] In the above preparation method, when the spherical resin microspheres are styrene-divinylbenzene ion exchange resin, styrene and divinylbenzene are first prepolymerized by heating, and then the polymerization reaction is carried out by heating again, so as to achieve orderly growth of molecular weight and uniform molecular weight distribution, which makes the crosslinking degree and thermal stability of the resin microspheres more consistent. When the spherical resin microspheres are phenolic resin, furfural resin, furan resin, urea-formaldehyde resin or melamine resin, the reactants are first prepolymerized and then crosslinked to improve the crosslinking degree of the spherical resin, so as to improve the compressive strength of the spherical porous carbon.

[0035] Optionally, the soft template agent is selected from at least one of toluene, xylene, and surfactants.

[0036] Optionally, the surfactant is at least one of Pluronic P123, CTAB, PVP, and PEG.

[0037] The addition of the soft template agent in this application acts as a pore-opening agent to promote the opening of microspheres, constructing ordered, multi-level channels, while reducing carbon corrosion and increasing the yield of spherical resin microspheres.

[0038] Optionally, in step 1), when adding the soft template agent, a monomer containing a conductive element is also added. The conductive element in the monomer contains a conductive element accounting for 1-10 wt% of the total weight of styrene and divinylbenzene. The monomer containing the conductive element is selected from at least one of nitrogen source monomer, phosphorus source monomer, sulfur source monomer, and boron source monomer.

[0039] Optionally, in step S1, when adding the soft template agent, a monomer containing a conductive element is also added. The conductive element in the monomer containing the conductive element accounts for 1-10 wt% of the total weight of the reactant monomers. The monomer containing the conductive element is selected from at least one of nitrogen source monomers, phosphorus source monomers, sulfur source monomers, and boron source monomers.

[0040] Specifically, the nitrogen source monomer is at least one of acrylamide, acrylonitrile, 2-aminoethyl acrylate, melamine, and urea.

[0041] Specifically, the phosphorus source monomer is at least one of phosphoric acid, triphenyl phosphate, and dimethylpropenyl phosphate.

[0042] Specifically, the sulfur source monomer is at least one of 2-(phenylthio)ethyl acrylate and vinyl sulfonic acid.

[0043] Specifically, the boron source monomer is at least one of trimethyl borate and triethyl borate.

[0044] This application contains monomers containing conductive elements, which can impart conductive elements to spherical resin microspheres, thereby improving the conductivity of the spherical resin microspheres. The addition of conductive elements can enhance the conductivity of porous carbon, thus enabling rapid charge and discharge.

[0045] Specifically, in step S1, a catalyst is also added when adding the soft template agent.

[0046] Specifically, the catalyst is at least one of ammonia and phosphoric acid, accounting for 1-10% of the total weight of the reactants.

[0047] Specifically, the dispersant solution mentioned in steps S2 and S2 is selected from at least one of polyvinylpyrrolidone solution, Tween 80 solution, polyvinyl alcohol solution, Span 80 solution, carboxymethyl cellulose solution, and sodium polyacrylate solution; the concentration of the dispersant solution is 1-5 wt%.

[0048] The addition of dispersant solution can form an emulsion system, which can improve the uniformity of microdroplets in the synthesis, thereby improving the sphericity and particle size uniformity of spherical resin microspheres, and thus obtaining spherical resin microspheres with high sphericity and narrow particle size distribution.

[0049] Specifically, the emulsion system is selected from water-in-oil (O / W), oil-in-water (W / O), biemulsion, or Pickering emulsion.

[0050] According to a third aspect of this application, a spherical porous carbon is provided, which is prepared by pre-oxidation, carbonization, and activation of spherical resin microspheres prepared by the method described in the first aspect of this application or by the method described in the second aspect of this application. The spherical porous carbon meets the following requirements:

[0051] (1) The average particle size is 3-10 μm;

[0052] (2) Sphericity ≥ 0.95;

[0053] (3) Specific surface area ≥ 1600 m² 2 / g;

[0054] (4) Pressure resistance 200-600MPa.

[0055] The spherical porous carbon particles prepared in this application have small particle size, high sphericity, large specific surface area, and high compressive strength, which can prevent breakage during the preparation of silicon-carbon anode materials.

[0056] Specifically, the average particle size of the spherical porous carbon is 6-8 μm.

[0057] Specifically, when the soft template agent needs to be removed by thermal desorption in step 3) of the second aspect of this application, the soft template agent can be removed during the preparation of spherical porous carbon, and this step is no longer performed in step 3).

[0058] Specifically, the pre-oxidation conditions are: air or oxygen atmosphere, temperature 150-300℃, time 2-5h.

[0059] Specifically, the carbonization temperature is 600-1200℃, and the time is 1-5 hours.

[0060] Specifically, the carbonization temperature is 800-1000℃.

[0061] Specifically, the activation is physical or chemical activation, the activation temperature is 850℃-1000℃, and the activation time is 1-20h.

[0062] Specifically, the physical activation is selected from at least one of CO2 atmosphere, steam atmosphere, and air atmosphere.

[0063] Specifically, the chemical activation is selected from at least one of KOH activator, NaOH activator, ZnCl2 activator, and H3PO4 activator.

[0064] The pre-oxidation process enhances the cross-linking degree and skeletal stability of the resin microspheres, resulting in porous carbon with uniform structure and high sphericity after carbonization. It is not easily pulverized during cycling. Activation can optimize the density of the skeletal structure, resulting in spherical porous carbon with high mechanical strength.

[0065] Optionally, the spherical porous carbon also satisfies the following conditions: microporosity of 85-95% and mesoporosity of 5-15%.

[0066] Optionally, the spherical porous carbon also satisfies the following condition: pore volume 0.5-1.2 ml / g.

[0067] Specifically, the spherical porous carbon also satisfies the following condition: pore volume 0.75-1.15 ml / g.

[0068] The spherical porous carbon of this application has a microporous-mesoporous synergistic structure, which can provide specific surface area to improve lithium-ion storage capacity, reduce ion diffusion resistance through mesopores, and has low functional group content and good electrolyte wettability.

[0069] The beneficial effects of this application include, but are not limited to:

[0070] 1. The spherical resin microspheres of this application, suitable for silicon-carbon anodes, have small particle size and high sphericity, which effectively avoids local current concentration caused by particle agglomeration. Simultaneously, the optimized pore structure increases pore volume, improves pore shape ratio adaptability, and enhances mass transfer efficiency. Furthermore, the spherical resin microspheres have increased cross-linking degree, significantly improving their compressive strength and structural stability.

[0071] 2. According to the spherical resin microspheres suitable for silicon-carbon anodes of this application, the addition of conductive elements such as nitrogen, phosphorus, sulfur and boron improves the conductivity of the spherical resin microspheres and the spherical porous carbon.

[0072] 3. According to the preparation method of spherical resin microspheres suitable for silicon-carbon anodes in this application, by adding a soft template agent, an organic phase separation can be formed during the polymerization process of the resin microspheres, and a porous structure with adjustable pore volume in the range of 0.5-1.2 ml / g can be obtained, avoiding the problem of uncontrollable pore size caused by traditional preparation methods.

[0073] 4. The spherical porous carbon according to this application has a reasonable pore structure and a micropore-mesopore synergistic structure, which can not only provide specific surface area to improve lithium-ion storage capacity, but also reduce ion diffusion resistance through mesopores and has good electrolyte wettability.

[0074] 5. The spherical porous carbon according to this application has a compressive strength of 200-600 MPa, which is suitable for electrode rolling processes.

[0075] 6. According to the spherical porous carbon of this application, the pre-oxidation process enhances the cross-linking degree and skeleton stability of the resin microspheres, and after carbonization, a porous carbon with uniform structure and high sphericity is formed, which is not easy to pulverize during cycling. The skeleton density can be optimized by activation, resulting in spherical porous carbon with high mechanical strength. Detailed Implementation

[0076] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0077] Unless otherwise specified, the raw materials used in the embodiments and comparative examples of this application were all purchased commercially.

[0078] Unless otherwise specified, the methods used in the embodiments and comparative examples of this application are conventional methods in the prior art.

[0079] Example 1

[0080] This embodiment relates to the preparation of spherical resin microspheres suitable for silicon-carbon anodes and the preparation of spherical porous carbon, as detailed below:

[0081] Preparation of spherical resin microspheres suitable for silicon-carbon anodes:

[0082] 1) 90 g of styrene, 10 g of divinylbenzene, 1 g of initiator AIBN, 30 g of soft template agent toluene, and 3.8 g of acrylonitrile (nitrogen source monomer) were premixed at room temperature to obtain a mixture;

[0083] 2) Add the mixture to the polyvinylpyrrolidone solution (content is 2wt%), so that the mass ratio of the mixture to the polyvinylpyrrolidone solution is 1:2. Heat to 50℃ for prepolymerization reaction for 2h, and then heat to 70℃ again for polymerization reaction for 5h. Stir at 1000r / min.

[0084] 3) After polymerization, filter, wash three times with deionized water, and remove toluene by vacuum evaporation at 120°C to obtain spherical resin balls.

[0085] Preparation of spherical porous carbon:

[0086] The obtained spherical resin spheres were pre-oxidized in air at 230℃ for 2 h, carbonized at 700℃ in N2 atmosphere for 1 h, and activated at 850℃ in water vapor atmosphere for 3 h to obtain spherical porous carbon.

[0087] Example 2

[0088] This embodiment relates to the preparation of spherical resin microspheres suitable for silicon-carbon anodes and the preparation of spherical porous carbon, as detailed below:

[0089] Preparation of spherical resin microspheres suitable for silicon-carbon anodes:

[0090] S1: Weigh 10g of phenol and 15.6g of triphenyl phosphate (phosphorus source monomer), melt them into liquid at 50℃, add 13g of 37wt% formaldehyde solution, 4.45g of soft template agent xylene, and 1g of 10wt% ammonia water, prepolymerize for 30min to obtain a solution containing phenolic prepolymer.

[0091] S2: Prepare a polyvinyl alcohol solution with a concentration of 4wt%. Add the solution containing phenolic prepolymer to the polyvinyl alcohol solution. The mass ratio of the solution containing phenolic prepolymer to the polyvinyl alcohol solution is 1:2. Heat to 80℃ for polymerization reaction for 1 hour, and then heat to 120℃ again for 2 hours. Stir at 800 r / min.

[0092] S3: After polymerization, filter, wash three times with deionized water, and remove xylene by vacuum evaporation at 120℃ to obtain spherical resin balls.

[0093] Preparation of spherical porous carbon:

[0094] The obtained spherical resin spheres were pre-oxidized in air at 240℃ for 2 h, carbonized at 600℃ in N2 atmosphere for 2 h, and activated at 850℃ in water vapor atmosphere for 2.5 h to obtain spherical porous carbon.

[0095] Example 3

[0096] This embodiment relates to the preparation of spherical resin microspheres suitable for silicon-carbon anodes and the preparation of spherical porous carbon, as detailed below:

[0097] Preparation of spherical resin microspheres suitable for silicon-carbon anodes:

[0098] S1: Weigh 35g of furfural, 20g of resorcinol, 20g of ethanol, 3.6g of 2-(phenylthio)ethyl acrylate (sulfur source monomer), 49.5g of soft template agent toluene, and 5g of 10wt% ammonia water. Prepolymerize at 30℃ for 30min to obtain a solution containing furfural prepolymer.

[0099] S2: Using paraffin oil as a solvent, prepare a 1 wt% Span 80 solution. Add the solution containing furfural prepolymer to the Span 80 solution. The mass ratio of the solution containing furfural prepolymer to the Span 80 solution is 1:10. Heat to 50℃ for polymerization reaction for 2 hours, then heat to 70℃ again for 5 hours. Stir at 800 r / min.

[0100] S3: After polymerization, filter, wash three times with deionized water, and remove toluene by vacuum evaporation at 120°C to obtain spherical resin balls.

[0101] Preparation of spherical porous carbon:

[0102] The obtained spherical resin spheres were pre-oxidized in air at 230℃ for 2 h, carbonized at 750℃ in N2 atmosphere for 1 h, and activated at 850℃ in CO2 atmosphere for 8 h to obtain spherical porous carbon.

[0103] Example 4

[0104] The difference between this embodiment and embodiment 3 is that 6g of urea (nitrogen source monomer) is added in step S1 to replace 2-(phenylthio)ethyl acrylate, while the rest are the same.

[0105] Example 5

[0106] The difference between this embodiment and Embodiment 3 is that 50g of trimethyl borate (boron source monomer) is added in step S1 instead of 2-(phenylthio)ethyl acrylate, while the rest are the same.

[0107] Example 6

[0108] This embodiment relates to the preparation of spherical resin microspheres suitable for silicon-carbon anodes and the preparation of spherical porous carbon, as detailed below:

[0109] Preparation of spherical resin microspheres suitable for silicon-carbon anodes:

[0110] S1: Weigh 13g of 37wt% formaldehyde solution, 10g of melamine, 8g of soft template agent CTAB, and 2g of 10wt% ammonia water, put them into a reactor and polymerize at 60℃ for 1h with a stirring speed of 200r / min. After the reaction is completed, cool to room temperature to obtain a solution containing melamine prepolymer.

[0111] S2: Using paraffin oil as a solvent, prepare a 2wt% Span 80 solution. Add the solution containing melamine prepolymer to the Span 80 solution. The mass ratio of the solution containing melamine prepolymer to the Span 80 solution is 1:4. Heat to 70℃ for polymerization reaction for 1.5h, then heat to 100℃ again for 3h. The stirring speed is 1500r / min.

[0112] S3: After polymerization, filter and wash three times with deionized water to obtain spherical resin balls.

[0113] Preparation of spherical porous carbon:

[0114] The obtained spherical resin spheres were pre-oxidized in air at 250°C for 2 h, carbonized at 650°C in a N2 atmosphere for 1 h (at which CTAB could be removed), and activated at 850°C in a water vapor atmosphere for 3 h to obtain spherical porous carbon.

[0115] Example 7

[0116] This embodiment relates to the preparation of spherical resin microspheres suitable for silicon-carbon anodes and the preparation of spherical porous carbon, as detailed below:

[0117] Preparation of spherical resin microspheres suitable for silicon-carbon anodes:

[0118] S1: Weigh 10g of furfuryl alcohol, 14.9g of 37wt% formaldehyde solution, 5g of soft template agent PVP, and 10g of 85wt% phosphoric acid solution (which serves as both a phosphorus source monomer and a catalyst). Polymerize at room temperature for 1h to obtain a solution containing furan prepolymer.

[0119] S2: Using paraffin oil as a solvent, prepare a 2.5 wt% Span 80 solution. Add the solution containing furan prepolymer to the Span 80 solution. The mass ratio of the solution containing furan prepolymer to the Span 80 solution is 1:6. Heat to 80℃ for polymerization reaction for 1 h, then heat to 80℃ again for 4 h. The stirring speed is 2000 r / min.

[0120] S3: After polymerization, filter and wash three times with deionized water to obtain spherical resin balls.

[0121] Preparation of spherical porous carbon:

[0122] The obtained spherical resin spheres were pre-oxidized in air at 220℃ for 2 h, carbonized at 700℃ in N2 atmosphere for 1 h, at which time PVP could be removed, and activated at 950℃ in CO2 atmosphere for 5 h to obtain spherical porous carbon.

[0123] Example 8

[0124] This embodiment relates to the preparation of spherical resin microspheres suitable for silicon-carbon anodes and the preparation of spherical porous carbon, as detailed below:

[0125] Preparation of spherical resin microspheres suitable for silicon-carbon anodes:

[0126] S1: Weigh 20g of urea, 48.7g of 37wt% formaldehyde solution, and 2g of 10wt% ammonia water. React at 50℃ for 1h, then cool to room temperature and add 7.4g of 85wt% phosphoric acid solution (which serves as both a phosphorus source monomer and a catalyst) and 22.8g of soft template agent toluene. Stir for 30 minutes to form a solution containing urea-formaldehyde prepolymer.

[0127] S2: Prepare a 3.3 wt% Span 80 solution using paraffin oil as a solvent. Add the solution containing urea-formaldehyde prepolymer to the Span 80 solution. The mass ratio of the solution containing urea-formaldehyde prepolymer to the Span 80 solution is 1:8. Heat to 60℃ for polymerization reaction for 2 hours, then heat to 110℃ again for 2.5 hours. Stir at 1500 r / min.

[0128] S3: After polymerization, filter, wash three times with deionized water, and remove toluene by vacuum evaporation at 120℃ to obtain spherical resin balls.

[0129] Preparation of spherical porous carbon:

[0130] The obtained spherical resin spheres were pre-oxidized in air at 240℃ for 2 h, carbonized at 700℃ in N2 atmosphere for 1 h, and activated at 850℃ in CO2 atmosphere for 6 min to obtain spherical porous carbon.

[0131] Example 9

[0132] This embodiment relates to the preparation of spherical resin microspheres suitable for silicon-carbon anodes and the preparation of spherical porous carbon, as detailed below:

[0133] Preparation of spherical resin microspheres suitable for silicon-carbon anodes:

[0134] 1) 85 g of styrene, 15 g of divinylbenzene, 2 g of AIBN, 90 g of soft template agent toluene, and 50.8 g of acrylamide (nitrogen source monomer) were premixed at room temperature to obtain a mixture;

[0135] 2) Add the mixture to the polyvinylpyrrolidone solution (content is 5wt%), so that the mass ratio of the mixture to the polyvinylpyrrolidone solution is 1:10. Heat to 80℃ for prepolymerization reaction for 1h, then heat to 120℃ again for 2h. Stir at 1500r / min.

[0136] 3) After polymerization, filter, wash three times with deionized water, and remove toluene by vacuum evaporation at 120°C to obtain spherical resin balls.

[0137] Preparation of spherical porous carbon:

[0138] The obtained spherical resin spheres were pre-oxidized in air at 250℃ for 2 h, carbonized at 600℃ in N2 atmosphere for 1 h, and activated at 850℃ in CO2 atmosphere for 9 h to obtain spherical porous carbon.

[0139] Example 10

[0140] The difference between this embodiment and Embodiment 1 is that 75g of acrylonitrile is added in step 1), while the rest are the same.

[0141] Comparative Example 1

[0142] The difference between this comparative example and Example 1 is that in step 1), there are 95 g of styrene and 5 g of divinylbenzene, while the rest are the same.

[0143] Comparative Example 2

[0144] The difference between this embodiment and Embodiment 2 is that 8.6g of 37wt% formaldehyde solution is added in step S1, while the rest are the same.

[0145] Comparative Example 3

[0146] The difference between this comparative example and Example 1 is that toluene is not added in step 1), while the rest are the same.

[0147] Comparative Example 4

[0148] The difference between this comparative example and Example 1 is that 100g of toluene was added in step 1), while the rest are the same.

[0149] Comparative Example 5

[0150] The difference between this comparative example and Example 1 is that steps 2) and 3) are not performed. The mixture obtained in step 1) is directly spray-dried to obtain resin microspheres. All other steps are the same.

[0151] Test Example 1

[0152] The average particle size, particle size range, particle size distribution, pore volume, pore size, specific surface area, gel content, swelling degree, sphericity, and compressive strength of the spherical resin microspheres prepared above were tested. The test results are shown in Table 1. The average particle size, dopant element and content, pore volume, specific surface area, sphericity, and compressive strength of the prepared spherical porous carbon were tested. The test results are shown in Table 2. The specific test methods are as follows:

[0153] Sphericity: Dynamic image analysis method;

[0154] Compressive strength: Single-particle compressive strength test;

[0155] Particle size and particle size distribution: Malvern laser particle size analyzer; Particle size distribution T = (D100 - D00) / D50;

[0156] Specific surface area, pore size, pore volume: BET specific surface area tester;

[0157] Gel content: Solvent extraction method, take 1 gram of resin, extract with toluene for 6 hours, and record the mass of the remaining part as M. Then the gel content is 100M%.

[0158] Table 1 Spherical Resin Balls

[0159]

[0160] Table 1 shows that the spherical resin microspheres obtained in Examples 1-10 have small particle size, high sphericity, and large pore volume, especially the spherical resin microspheres obtained in Example 1, which have the highest compressive strength. However, the spherical resin microspheres in Comparative Example 1 have a lower gel content than other spherical resin microspheres due to the low mass ratio of divinylbenzene. This is because divinylbenzene is a bifunctional monomer, and its low content leads to a significant reduction in the number of crosslinking points, making the structure loose and resulting in low gel content. Comparative Example 2 has a low formaldehyde content, resulting in low gel content, low crosslinking degree, and low resin ball strength. The spherical resin microspheres in Comparative Example 3 have significantly reduced pore volume and specific surface area due to the lack of a soft template agent, because the organic phase was not separated, leading to uncontrollable pore volume. Comparative Example 4 has excessive toluene, affecting its compressive strength and sphericity. Comparative Example 5 uses spray drying to prepare spherical resin microspheres, resulting in a significant decrease in sphericity. This is because the complex airflow inside the drying tower directly interferes with the formation of the spherical resin microspheres.

[0161] Table 2 Spherical Porous Carbon

[0162]

[0163] As shown in Table 2, the spherical porous carbon particles obtained in Examples 1-10 have small particle size, large pore volume, large specific surface area, and high compressive strength, and are mainly microporous with no macropores. In contrast, the spherical porous carbon obtained in Comparative Example 1 has low sphericity and low compressive strength, the spherical porous carbon obtained in Comparative Example 2 has small pore volume and specific surface area, the spherical porous carbon obtained in Comparative Example 3 has a relatively small pore volume, the pore size in Comparative Example 4 is relatively large, and the sphericity in Comparative Example 5 is low. This is closely related to the spherical resin microspheres prepared.

[0164] Test Example 2

[0165] The conductivity of the spherical porous carbon prepared above was tested. The test method was as follows: 10g of dried porous carbon powder was placed in a mold with a diameter of 10 mm and held under a pressure of 10 MPa for 30 seconds to form a sheet with a thickness of 2 mm. The sheet was then tested using a four-probe conductivity meter at 10 MPa. -4 The voltage value was measured under current A, and then the thickness was measured with a micrometer. The result was calculated using the following formula:

[0166] σ=(π*d*I) / (4*V)

[0167] Where σ is the volumetric conductivity of porous carbon, in S / m; d is the thickness of the wafer, in m; I is the test current, in A; and V is the recording voltage, in V. The test results are shown in Table 3.

[0168] Table 3

[0169]

[0170] As shown in Table 3, the spherical porous carbon obtained in Examples 1-10 has high electrical conductivity, especially the spherical porous carbon obtained in Example 9 has the highest electrical conductivity, while the spherical porous carbon obtained in Comparative Examples 1-5 all have low electrical conductivity.

[0171] The above description is merely an embodiment of this application, and the scope of protection of this application is not limited to these specific embodiments, but is determined by the claims of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the technical concept and principles of this application should be included within the scope of protection of this application.

Claims

1. A spherical resin microsphere suitable for silicon-carbon anodes, characterized in that, The spherical resin microspheres simultaneously meet the following requirements: (a) The average particle size is 12-25 μm; (b) Sphericity ≥ 0.95; (c) The pore volume is 0.1-0.5 ml / g; (d) Compressive strength is 500-1000 MPa; (e) Particle size distribution T < 5, T = (D90 - D10) / D50; The spherical resin balls are selected from at least one of styrene-divinylbenzene ion exchange resin, furfural resin, furan resin, urea-formaldehyde resin, or melamine resin.

2. The spherical resin microspheres suitable for silicon-carbon anodes according to claim 1, characterized in that, The average particle size of the spherical resin microspheres is 12.8-22.4 μm; and / or The particle size distribution of the spherical resin microspheres is T < 3.4; The pore volume of the spherical resin microspheres is 0.25-0.42 ml / g.

3. The method for preparing spherical resin microspheres suitable for silicon-carbon anodes according to any one of claims 1-2, characterized in that, When the spherical resin beads are made of styrene-divinylbenzene ion exchange resin, the process includes the following steps: 1) Styrene, divinylbenzene, initiator, and soft template agent are premixed at room temperature to obtain a mixture, wherein the divinylbenzene accounts for 10 wt% or more of the total weight of styrene and divinylbenzene; the initiator accounts for 1-2% of the total weight of styrene and divinylbenzene; and the soft template agent accounts for 30-90% of the total weight of styrene and divinylbenzene. 2) Add the mixture to the dispersant solution, heat to 50-80℃ for prepolymerization reaction for 1-2 hours, and then heat to 70-120℃ for polymerization reaction for 2-5 hours; 3) After polymerization, filter, wash, and remove the soft template agent to obtain the final product; When the spherical resin beads are made of furfural resin, furan resin, urea-formaldehyde resin, or melamine resin, the process includes the following steps: S1: The reactants and soft template agent are prepolymerized to obtain a solution containing the prepolymer. The reactants of furfural resin are furfural and resorcinol, and the molar ratio of furfural to resorcinol is ≥2:

1. The reactants of furan resin are formaldehyde and furfuryl alcohol, and the molar ratio of formaldehyde to furfuryl alcohol is ≥1.8:

1. The reactants of melamine resin are melamine and formaldehyde, and the molar ratio of formaldehyde to melamine is ≥2:

1. The reactants of urea-formaldehyde resin are formaldehyde and urea, and the molar ratio of formaldehyde to urea is ≥1.8:

1. The soft template agent accounts for 30-90% of the total weight of the reactants. S2: Add the solution containing the prepolymer to the dispersant solution, heat to 50-80℃ for 1-2 hours, and then heat to 70-120℃ for 2-5 hours. S3: Filter, wash and remove the soft template agent from the product of step S2 to obtain the final product.

4. The preparation method according to claim 3, characterized in that, The soft template agent is selected from toluene, xylene, and surfactants; The surfactant is at least one of Pluronic P123, CTAB, PVP, and PEG.

5. The preparation method according to claim 3, characterized in that, In step 1), when adding the soft template agent, a monomer containing a conductive element is also added. The conductive element in the monomer contains 1-10 wt% of the total weight of styrene and divinylbenzene. The monomer containing the conductive element is selected from at least one of nitrogen source monomer, phosphorus source monomer, sulfur source monomer, and boron source monomer.

6. The preparation method according to claim 3, characterized in that, In step S1, when adding the soft template agent, a monomer containing a conductive element is also added. The conductive element in the monomer contains a conductive element accounts for 1-10 wt% of the total weight of the reactant monomers. The monomer containing the conductive element is selected from at least one of nitrogen source monomers, phosphorus source monomers, sulfur source monomers, and boron source monomers.

7. A spherical porous carbon, characterized in that, The spherical porous carbon is prepared by pre-oxidation, carbonization, and activation of spherical resin microspheres prepared by the method described in any one of claims 1-2 or claims 3-6, and the spherical porous carbon meets the following requirements: (1) The average particle size is 3-10 μm; (2) Sphericity ≥ 0.95; (3) Specific surface area ≥ 1600 m² 2 / g; (4) Pressure resistance 200–600 MPa.

8. The spherical porous carbon according to claim 7, characterized in that, The spherical porous carbon also meets the following requirements: microporosity 85-95%, mesoporosity 5-15%.

9. The spherical porous carbon according to claim 7, characterized in that, The spherical porous carbon also satisfies the following condition: pore volume 0.5-1.2 ml / g.

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