Mesoporous silicon carbon negative electrode material and preparation method and application thereof

Abstract

The invention provides a mesoporous silicon carbon negative electrode material and a preparation method and application thereof, and relates to the technical field of battery negative electrode materials, the mesoporous silicon carbon negative electrode material comprises a mesoporous carbon matrix and silicon; the mesoporous carbon matrix can be a spherical, spheroidic or irregular block, the mesoporous carbon matrix has mesoporous structures, and preferably, the mesoporous structures are in ordered distribution; according to the invention, the preparation of the uniform mesoporous structure is realized, the volume expansion of the silicon is effectively relieved, the close combination of the silicon and the carbon is realized by vapor deposition of the silicon on the mesoporous sphere carbon matrix material, and the cycling stability of the material is improved. According to the meso-porous silicon carbon negative electrode material provided by the invention, by optimizing the structural design of the material, the problems of silicon volume expansion, infirm interface bonding, complex preparation process and the like in the prior art are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of battery negative electrode materials, and in particular to a mesoporous silicon-carbon negative electrode material and a preparation method and application thereof. Background Art

[0002] Lithium-ion batteries (Li-ion batteries) are widely used in consumer electronics, electric vehicles, and energy storage systems due to their high energy density, long cycle life, and environmentally friendly properties. Anode materials, as key components of Li-ion batteries, directly impact battery performance. While traditional graphite anode materials offer good cycle stability and low cost, their low theoretical specific capacity (approximately 372 mAh / g) makes them inadequate for meeting the growing demand for higher energy density. Silicon (Si), with its extremely high theoretical specific capacity (approximately 4200 mAh / g) and abundant natural resources, is considered an ideal anode material for next-generation, high-energy-density Li-ion batteries. However, Si undergoes significant volume expansion (approximately 300%) during charge and discharge, leading to material pulverization, electrode structural damage, and electrical contact failure, severely impacting the battery's cycle life and rate performance. To mitigate Si's volume expansion, researchers have proposed various solutions, with Si-carbon composites being one of the most promising approaches. Carbon materials, with their excellent electrical conductivity and mechanical stability, can effectively buffer Si's volume changes and improve electrode conductivity.

[0003] However, existing silicon-carbon composite materials still have the following problems: the interface bonding between silicon and carbon is not strong, which leads to the shedding of silicon particles during the cycle; the material structure design is unreasonable, which cannot fully utilize the high capacity characteristics of silicon; the preparation process is complicated, and it is difficult to achieve large-scale production. Mesoporous materials have high specific surface area, adjustable pore size distribution and good structural stability, which can effectively alleviate the volume expansion of silicon and provide more lithium ion transmission channels. Introducing mesoporous structures into silicon-carbon composite materials can not only improve the cycle stability of the material, but also enhance its rate performance. Although some studies have attempted to apply mesoporous structures to silicon-carbon composite materials, for example, the existing technology mostly uses hard template method, soft template method and other methods to prepare mesoporous carbon. Hard template method: Using hard templates such as silica and alumina, mesoporous carbon is prepared through steps such as impregnation, carbonization, and template removal. Soft template method: Using soft templates such as surfactants, mesoporous carbon is prepared through steps such as self-assembly, carbonization, and template removal. However, these materials still have the following shortcomings: First, the mesoporous structure is uneven, resulting in unstable performance; second, the distribution of silicon and carbon is uneven, affecting the overall performance of the material; third, the preparation process is complex and the cost is high, making it difficult to achieve industrial production.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] One of the objectives of the present invention is to provide a mesoporous silicon-carbon anode material that addresses at least one of the technical problems existing in the prior art. By optimizing the material's structural design, the mesoporous silicon-carbon anode material provided by the present invention addresses the problems of silicon volume expansion, weak interfacial bonding, and complex preparation processes in the prior art.

[0006] A second object of the present invention is to provide a method for preparing a mesoporous silicon-carbon negative electrode material.

[0007] The third object of the present invention is to provide a mesoporous silicon-carbon negative electrode material or the use of the mesoporous silicon-carbon negative electrode material prepared by the preparation method of the mesoporous silicon-carbon negative electrode material in the preparation of a battery negative electrode.

[0008] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are adopted:

[0009] In a first aspect, the present invention provides a mesoporous silicon-carbon negative electrode material, comprising a mesoporous carbon matrix and silicon; the mesoporous carbon matrix is ​​spherical, quasi-spherical or irregular block, and the mesoporous carbon matrix has a mesoporous structure;

[0010] The silicon is uniformly distributed in the mesoporous structure.

[0011] Furthermore, the average pore size of the mesopores is 2.0-6.0 nm, wherein the isothermal adsorption curve of the carbonized mesoporous carbon shows that the pore volume with p / p0>0.75 (corresponding to pores larger than 10 nm) accounts for less than 10%, wherein the mesopore proportion (BJH pore volume / total pore volume) is greater than 80%; preferably, the mesopore proportion is greater than 83.0%;

[0012] Preferably, the mesoporous structure is orderly distributed;

[0013] Furthermore, the pore volume of the mesoporous carbon matrix is ​​0.01 to 2 cm 3 / g, preferably 0.6 to 1.1 cm 3 / g;

[0014] and / or, the median particle size of the mesoporous carbon matrix is ​​5 to 20 μm, preferably 6 to 12 μm;

[0015] and / or, the diameter pitch of the mesoporous carbon matrix is ​​0.8 to 2.0, preferably 0.8 to 1.2;

[0016] and / or, the sphericity of the mesoporous carbon matrix is ​​greater than 0.7;

[0017] Furthermore, the silicon content of the mesoporous silicon-carbon negative electrode material is 5% to 90%, preferably 30% to 60%;

[0018] And / or, the specific surface area of ​​the mesoporous silicon carbon negative electrode material is 0.1 to 50 m 2 / g, preferably 0.5 to 5m 2 / g;

[0019] And / or, the true density of the mesoporous silicon carbon anode material measured by helium pycnometry is 1.3 to 2.0 g / cm 3 , the closed pore volume is 0.01~0.25cm 3 / g;

[0020] And / or, the median particle size of the mesoporous silicon-carbon negative electrode material is 5 to 20 μm, preferably 6 to 12 μm;

[0021] And / or, the diameter pitch of the mesoporous silicon-carbon negative electrode material is 0.8 to 2.0, preferably 0.8 to 1.2.

[0022] In a second aspect, the present invention provides a method for preparing a mesoporous silicon-carbon negative electrode material, comprising the following steps:

[0023] The carbon source and the template agent are mixed to obtain a precursor solution, which is then subjected to spherical formation, solidification, calcination, dicalcination and activation treatments in sequence to obtain a mesoporous carbon matrix, which is then subjected to vapor deposition silicon treatment to obtain a mesoporous silicon-carbon negative electrode material.

[0024] Further, the carbon source includes phenolic resin;

[0025] And / or, the carbon source preparation process comprises: mixing an aldehyde raw material, a phenol raw material, a catalyst and water to obtain a phenolic resin mixed solution;

[0026] and / or, the preparation temperature of the carbon source is 40-100° C.;

[0027] and / or, the aldehyde raw material comprises at least one of formaldehyde, acetaldehyde and furfural;

[0028] and / or, the phenolic raw material comprises at least one of phenol and resorcinol;

[0029] And / or, the mass of the aldehyde raw material accounts for 60%-130% of the mass of the phenol raw material;

[0030] and / or, the catalyst comprises at least one of an acidic catalyst and a basic catalyst;

[0031] and / or, the mass of the catalyst accounts for 1%-5% of the mass of the phenols;

[0032] and / or, the acidic catalyst comprises at least one of hydrochloric acid, sulfuric acid and oxalic acid;

[0033] And / or, the alkaline catalyst includes at least one of sodium hydroxide, calcium hydroxide and ammonia water.

[0034] Furthermore, the preparation process of the precursor solution includes: mixing a template agent, a carbon source and a solvent to obtain a precursor solution;

[0035] And / or, the mass ratio of the carbon source, the template agent and the solvent is 0.7-1.5:0.5-2:0.1-4.0;

[0036] and / or, the precursor solution is prepared at a temperature of 30-70° C. and stirred for 0.5-24 hours;

[0037] And / or, the template agent is obtained by polycondensation reaction of polyoxyethylene, polyoxypropylene and polystyrene;

[0038] And / or, the template agent includes at least one of PEO-PPO-PEO, PPO-PEO-PPO and PEO-PS-PEO;

[0039] and / or, the molecular weight of the template agent is 1500-40000;

[0040] and / or, the PEO-PPO-PEO group includes at least one of F127, F188 and P123;

[0041] And / or, the solvent includes at least one of methanol, ethanol, tetrahydrofuran and dimethyl sulfoxide.

[0042] Furthermore, the spheroidization is carried out by adopting an oil phase emulsion polymerization method;

[0043] And / or, the spheroidization process includes: mixing a precursor solution, silicone oil and heat transfer oil, performing primary solidification, and then separating to obtain solid particles;

[0044] And / or, the mass ratio of the precursor solution, silicone oil and thermal oil is 1:1-5:1-10;

[0045] And / or, the silicone oil includes at least one of dimethyl silicone oil and phenyl silicone oil;

[0046] and / or, the viscosity of the silicone oil is 10-1000 cst, preferably 100-600 cst;

[0047] And / or, the heat transfer oil comprises at least one of aromatic heat transfer oil and silicone heat transfer oil;

[0048] and / or, the viscosity of the heat transfer oil is 20-100 cst, preferably 20-60 cst;

[0049] and / or, the primary curing temperature is 80-150° C.;

[0050] And / or, the primary curing time is 1-24h;

[0051] Furthermore, the curing temperature is 110-200° C., and the curing time is 3-24 hours.

[0052] Furthermore, the calcination temperature is 300-500° C., and the calcination time is 0.5-100 h in air or sufficient oxygen;

[0053] Furthermore, the second calcination temperature is 500-1000° C., under a nitrogen atmosphere, and the time is 0.5-100 h;

[0054] And / or, the activation temperature is 750-1100° C., and the activation time is 0.5-50 h;

[0055] And / or, the activation method includes at least one of CO2 activation, water activation and O2 activation.

[0056] Furthermore, a pore-enlarging agent is added during the preparation of the precursor solution;

[0057] And / or, the pore-enlarging agent includes at least one of a compound having a hydrophobic group of C5 or greater and a compound having a hydrophilic group;

[0058] and / or, the hydrophobic group compound having C5 or more comprises at least one of mesitylene, n-pentane, n-heptane, hexadecyltrimethylammonium bromide and hexadecyltrimethylammonium chloride;

[0059] And / or, the compound having a hydrophilic group includes at least one of tetraethyl titanate, triisopropyl aluminate, tetra-n-propyl zirconate, methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate and butyl orthosilicate;

[0060] And / or, the amount of the pore-enlarging agent added is 0%-50% of the template agent.

[0061] In a third aspect, the present invention provides a mesoporous silicon-carbon negative electrode material or a mesoporous silicon-carbon negative electrode material prepared by a method for preparing a mesoporous silicon-carbon negative electrode material, and its use in preparing a battery negative electrode.

[0062] Compared with the prior art, the present invention has the following beneficial effects:

[0063] The mesoporous silicon-carbon negative electrode material provided by the present invention, the mesoporous carbon matrix can be spherical, quasi-spherical or irregular blocks. When the mesoporous carbon matrix is ​​spherical, it is a mesoporous spherical carbon matrix. The surface of the mesoporous spherical carbon matrix is ​​smooth and has no edges and corners. The mesoporous spheres with high sphericity and smooth surface solve the problems of capacity attenuation and short life of traditional negative electrode materials (such as silicon and metal oxides) by synergistically optimizing ion diffusion, mechanical stability and interface characteristics. It is an effective strategy to improve energy density, rate performance and cycle stability; the silicon material is uniformly deposited in the orderly distributed mesopores of the mesoporous carbon matrix. Compared with microporous carbon, ordered mesoporous carbon provides more active sites and fast ion transport channels. At the same time, its high conductivity and structural stability improve electronic conduction and cycle stability. Good interfacial compatibility also helps to form a stable SEI film, reduce side reactions, and thus improve the overall performance of the battery. The mesoporous silicon-carbon negative electrode material can effectively alleviate volume changes during charging and discharging, reduce the pulverization and shedding of electrode materials, and extend battery life.

[0064] The preparation method of the mesoporous silicon-carbon negative electrode material provided by the present invention, by adding a template agent, using a template with regular pores (F127, etc.) to guide the directional filling or assembly of the carbon precursor, and then removing the template to obtain an ordered pore structure, realizes the preparation of a uniform mesoporous structure, and effectively alleviates the volume expansion of silicon; by vapor-depositing silicon on the mesoporous carbon matrix material, a close combination of silicon and carbon is achieved, thereby improving the cyclic stability of the material; the preparation method of the mesoporous silicon-carbon negative electrode material provided by the present invention solves the problems of silicon volume expansion, weak interface bonding and complex preparation process in the prior art by optimizing the preparation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0066] Figure 1 TEM image of the carbonized mesoporous fullerene carbon material (ordered mesoporous fullerene carbon matrix) in Example 1;

[0067] Figure 2 Graph showing the adsorption and desorption curves of the carbonized mesoporous fullerene material (ordered mesoporous fullerene matrix) in Example 1;

[0068] Figure 3 TEM image of the carbonized mesoporous fullerene material (disordered mesoporous fullerene matrix) in Example 7;

[0069] Figure 4: This is an SEM image of the carbonized mesoporous fullerene carbon material (mesoporous fullerene carbon matrix, spherical mesoporous carbon) in Example 1;

[0070] Figure 5 : This is an SEM image of the carbonized mesoporous fullerene material (mesoporous fullerene matrix) in Example 13;

[0071] Figure 6 This is the SEM image of the carbonized mesoporous spherical carbon material (irregular bulk mesoporous carbon matrix) in Example 14. DETAILED DESCRIPTION

[0072] Unless otherwise defined herein, scientific and technical terms used in conjunction with the present invention shall have the meanings commonly understood by those of ordinary skill in the art. The meaning and scope of the terms should be clear; however, in the event of any potential ambiguity, the definitions provided herein take precedence over any dictionary or external definitions. In this application, the use of "or" means "and / or" unless otherwise stated. In addition, the use of the term "including" and other forms is non-limiting.

[0073] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0074] The first aspect of the present invention provides a mesoporous silicon-carbon negative electrode material, comprising a mesoporous carbon matrix and silicon; the mesoporous carbon matrix is ​​spherical, quasi-spherical or irregular block, and the mesoporous carbon matrix has a mesoporous structure. Preferably, the mesoporous structure is orderly distributed; the silicon is evenly distributed in the mesoporous structure.

[0075] Preferably, when the mesoporous carbon matrix is ​​spherical, it is a mesoporous spherical carbon matrix, the surface of the mesoporous spherical carbon matrix is ​​smooth and has no edges and corners, the sphericity is greater than 0.7 (the sphericity of the particle is defined as the ratio of the equivalent diameter of the circumference of the particle to the equivalent diameter of the area of ​​the particle), and silicon is uniformly deposited on the inner wall of the orderly distributed mesopores.

[0076] In the present invention, the sphericity of the mesoporous spherical carbon matrix is ​​greater than 0.7, which can improve ion diffusion, mechanical stability and interface properties, solve the problems of capacity attenuation and short life of traditional negative electrode materials (such as silicon and metal oxides), and is an effective strategy to improve energy density, rate performance and cycle stability.

[0077] In some preferred embodiments, the average pore size of the mesoporous carbon matrix is ​​2.0-6.0 nm, wherein the isothermal adsorption curve of the carbonized mesoporous carbon has a pore volume ratio of less than 10% with p / p0>0.75 (corresponding to pores larger than 10 nm), wherein the mesopore ratio (BJH pore volume / total pore volume) is greater than 80%; preferably, the mesopore ratio is greater than 83.0%;

[0078] Preferably, the mesoporous structure is distributed in an orderly manner.

[0079] In the present invention, Figure 1 As shown in Figure 2, the mesoporous carbon matrix has obvious pores and pore wall stripes in TEM, indicating that it has orderly distributed mesopores, such as Figure 2 As shown, the adsorption isotherm curve has a significant rise at p / p0=0.5-0.7, and the proportion of P / P0>0.75 is less than 10%. The purpose of P / P0>0.75 is to limit the proportion of 10nm pores. Macropores store electrolyte but are not suitable for Li + Low transport contribution leads to localized electrolyte enrichment, resulting in concentration polarization. Furthermore, a high proportion of macropores increases stress concentration points during material cycling, leading to structural collapse caused by volume changes. A mesoporous carbon with a macropore content of less than 10% significantly improves rate performance by shortening ion paths, enhancing structural stability, and optimizing electronic conduction.

[0080] BJH is the abbreviation of the Brunaure-Joyner-Halenda method, a theoretical model for calculating pore size distribution from nitrogen adsorption-desorption isotherms. BJH pore volume refers to the mesopore volume calculated by the BJH method. Total pore volume refers to the total volume of all pores in the sample (including micropores, mesopores, and macropores). Mesopore fraction (BJH pore volume / total pore volume) represents the proportion of mesopores in the entire pore structure. The data showing a mesopore fraction (BJH pore volume / total pore volume) greater than 83.0% indicates that the pores of the mesoporous fullerene matrix are primarily mesopores, with very little contribution from micropores and macropores.

[0081] Therefore, the mesoporous fullerene matrix of the present invention has a highly uniform mesoporous structure. The adsorption isotherm and BJH pore volume show that its pore structure is primarily mesoporous, with a relatively small contribution from micropores and macropores. This mesoporous structure is particularly important for lithium-ion battery anode materials, as it provides sufficient active sites and mitigates the volume expansion of silicon during charge and discharge.

[0082] In some preferred embodiments, the pore volume of the mesoporous carbon matrix is ​​between 0.01 and 2 cm 3 / g, for example, it can be 0.01cm 3 / g, 0.1cm 3 / g, 0.5cm 3 / g, 1cm3 / g, 1.5cm 3 / g, 2cm 3 / g, etc.; preferably 0.6 to 1.1 cm 3 / g, for example, it can be 0.6cm 3 / g, 0.7cm 3 / g, 0.8cm 3 / g, 0.9cm 3 / g, 1cm 3 / g, 1.1cm 3 / g, etc.

[0083] And / or, the median particle size d of the mesoporous carbon matrix V,50 It is 5 to 20 μm, for example, it can be 5 μm, 10 μm, 15 μm, 20 μm, etc.; it is preferably 6 to 12 μm, for example, it can be 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, etc.

[0084] And / or, the diameter distance (d V,90 -d V,10 ) / d V,50 It is 0.8 to 2.0, for example, it can be 0.8, 1.4, 2.0, etc.; preferably it is 0.8 to 1.2, for example, it can be 0.8, 0.9, 1.0, 1.1, 1.2, etc.

[0085] In some preferred embodiments, the silicon content of the mesoporous silicon-carbon negative electrode material is 5% to 90%, for example, it can be 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, etc.; preferably, it can be 30% to 60%, for example, it can be 30%, 35%, 40%, 45%, 50%, 55%, 60%, etc.

[0086] And / or, the specific surface area of ​​the mesoporous silicon carbon negative electrode material is 0.1 to 50 m 2 / g, for example, it can be 0.1m 2 / g、1m 2 / g、5m 2 / g、10m 2 / g, 20m 2 / g、30m 2 / g, 40m 2 / g, 50m 2 / g, etc.; preferably 0.5 to 5m 2 / g, for example, it can be 0.5m 2 / g、1m 2 / g, 1.5m 2 / g、5m 2 / g, etc.

[0087] And / or, the true density of the mesoporous silicon carbon anode material measured by helium pycnometry is 1.3 to 2.0 g / cm 3 , for example, it can be 1.3g / cm 3 , 0.8g / cm 3 , 2.0g / cm 3 etc.; closed pore volume is 0.01~0.25cm 3 / g, for example, it can be 0.01cm 3 / g, 0.05cm 3 / g, 0.1cm 3 / g, 0.25cm 3 / g, etc.

[0088] And / or, the median particle size d of the mesoporous silicon-carbon negative electrode material V,50 It is 5 to 20 μm, for example, it can be 5 μm, 10 μm, 15 μm, 20 μm, etc.; it is preferably 6 to 12 μm, for example, it can be 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, etc.

[0089] And / or, the diameter distance (d V,90 -d V,10 ) / d V,50 It is 0.8 to 2.0, for example, it can be 0.8, 1.4, 2.0, etc.; preferably it is 0.8 to 1.2, for example, it can be 0.8, 0.9, 1.0, 1.1, 1.2, etc.

[0090] A second aspect of the present invention provides a method for preparing a mesoporous silicon-carbon negative electrode material, comprising the following steps:

[0091] The carbon source and the template agent are mixed to obtain a precursor solution, which is then subjected to oil phase spheroidization, solidification, calcination, dicalcination and activation treatments in sequence to obtain a mesoporous carbon matrix, which is then subjected to vapor phase silicon deposition treatment to obtain a mesoporous silicon-carbon negative electrode material.

[0092] Preferably, in the present invention, the ordered mesoporous spherical carbon material is prepared by a soft template method.

[0093] In some preferred embodiments, the carbon source comprises phenolic resin;

[0094] And / or, the carbon source preparation process comprises: mixing an aldehyde raw material, a phenol raw material, a catalyst and water to obtain a phenolic resin mixed solution;

[0095] And / or, the preparation temperature of the carbon source is 40-100°C, for example, 40°C, 70°C, 100°C, etc.

[0096] and / or, the aldehyde raw material comprises at least one of formaldehyde, acetaldehyde and furfural;

[0097] and / or, the phenolic raw material comprises at least one of phenol and resorcinol;

[0098] And / or, the mass of the aldehyde raw material accounts for 60%-130% of the mass of the phenol raw material, for example, 60%, 80%, 100%, 130%, etc.;

[0099] and / or, the catalyst comprises at least one of an acidic catalyst and a basic catalyst;

[0100] And / or, the mass of the catalyst accounts for 1%-5% of the mass of the phenols, for example, it can be 1%, 2%, 3%, 4%, 5%, etc.

[0101] and / or, the acidic catalyst comprises at least one of hydrochloric acid, sulfuric acid and oxalic acid;

[0102] And / or, the alkaline catalyst includes at least one of sodium hydroxide, calcium hydroxide and ammonia water.

[0103] In some preferred embodiments, the preparation process of the precursor solution includes: mixing a template agent, a carbon source and a solvent, and optionally adding a certain amount of a pore-enlarging agent to obtain a precursor solution;

[0104] And / or, the mass ratio of the carbon source, the template agent and the solvent is 0.7-1.5:0.5-2:0.1-4.0;

[0105] Here, "0.7-1.5" can be, for example, 0.7, 1, 1.5, etc.

[0106] Wherein "0.5-2" can be, for example, 0.5, 1, 1.5, 2, etc.;

[0107] Here, “0.1-4.0” can be, for example, 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, etc.

[0108] The amount of the pore-enlarging agent added is 0-50% of the template agent, for example, 0%, 10%, 20%, 30%, 40%, 50%, etc.

[0109] And / or, the preparation temperature of the precursor solution is 30-70° C., for example, 30° C., 40° C., 50° C., 60° C., 70° C., etc.; the stirring time is 0.5-24 hours, for example, 0.5 hours, 1 hour, 2 hours, 5 hours, 8 hours, 12 hours, 24 hours, etc.;

[0110] And / or, the template agent is obtained by polycondensation reaction of hydrophilic polyethylene oxide (PEO), hydrophobic polypropylene oxide (PPO) and polystyrene (PS);

[0111] And / or, the template agent includes at least one of PEO-PPO-PEO, PPO-PEO-PPO and PEO-PS-PEO;

[0112] and / or, the molecular weight of the template agent is 1500-40000;

[0113] and / or, the PEO-PPO-PEO group includes at least one of F127, F188 and P123;

[0114] And / or, the solvent includes at least one of methanol, ethanol, tetrahydrofuran and dimethyl sulfoxide.

[0115] And / or, the pore expanding agent can be a hydrophobic group compound with C5 or above, such as mesitylene, n-pentane, n-heptane, hexadecyltrimethylammonium bromide and hexadecyltrimethylammonium chloride, etc., or it can be a compound with a hydrophilic group, such as tetraethyl titanate, triisopropyl aluminate, tetra-n-propyl zirconate, methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate, butyl orthosilicate, etc.

[0116] In the present invention, the pore size in the mesoporous carbon can be adjusted by adjusting the proportion of the triblock copolymer.

[0117] In some preferred embodiments, the spheroidization process is carried out by oil phase emulsion polymerization;

[0118] And / or, the spheroidization process includes: mixing the precursor solution, silicone oil and heat transfer oil, performing primary curing (slowly forming spheroids at a certain temperature), and then separating to obtain solid particles;

[0119] And / or, the mass ratio of the precursor solution, silicone oil and thermal oil is 1:1-5:1-10;

[0120] Here, “1-5” can be, for example, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, etc.;

[0121] Here, "1-10" can be, for example, 1, 2, 5, 8, 10, etc.

[0122] And / or, the silicone oil includes at least one of dimethyl silicone oil and phenyl silicone oil;

[0123] And / or, the viscosity of the silicone oil is 10-1000 cst, for example, it can be 10 cst, 50 cst, 100 cst, 500 cst, 1000 cst, etc., preferably 100-600 cst, for example, it can be 100 cst, 200 cst, 300 cst, 400 cst, 500 cst, 600 cst, etc.

[0124] And / or, the heat transfer oil comprises at least one of aromatic heat transfer oil and silicone heat transfer oil;

[0125] And / or, the viscosity of the heat transfer oil is 20-100 cst, for example, it can be 20 cst, 40 cst, 60 cst, 80 cst, 100 cst, etc., preferably 20-60 cst, for example, it can be 20 cst, 30 cst, 40 cst, 50 cst, 60 cst, etc.

[0126] In some preferred embodiments, the temperature of the primary curing (i.e., oil phase spheroidization) is 80-150° C., for example, 80° C., 100° C., 120° C., 150° C., etc.; the time of the primary curing is 1-24 h, for example, 1 h, 3 h, 5 h, 10 h, 12 h, 16 h, 24 h, etc.;

[0127] In some preferred embodiments, the curing temperature (i.e., deep curing after balling) is 110-200°C, for example, 110°C, 130°C, 150°C, 180°C, 200°C, etc., preferably 130-200°C; the deep curing time is 3-24h, for example, 3h, 5h, 10h, 12h, 16h, 24h, etc.

[0128] In some preferred embodiments, the calcination is carried out in air or oxygen atmosphere at a temperature of 300-500° C., for example, 300° C., 350° C., 400° C., 500° C., etc.; the calcination (i.e., primary carbonization) time is 0.5-100 h, for example, 0.5 h, 1 h, 5 h, 10 h, 50 h, 100 h, etc.;

[0129] In some preferred embodiments, the temperature of the secondary calcination (i.e., secondary carbonization) is 500-1000° C., and the atmosphere is nitrogen, for example, 500° C., 750° C., 1000° C., etc.; the time of the secondary calcination (i.e., secondary carbonization) is 0.5-100 h, for example, 0.5 h, 1 h, 5 h, 10 h, 50 h, 100 h, etc.;

[0130] And / or, the activation temperature is 750-1100°C, for example, 750°C, 850°C, 1000°C, 1100°C, etc.; the activation time is 0.5-50h, for example, 0.5h, 1h, 5h, 10h, 50h, etc.

[0131] And / or, the activation method includes at least one of CO2 activation, water activation and O2 activation.

[0132] The ordered mesoporous spherical silicon-carbon material provided by the present invention has a simple process and can be mass-produced, the pore size and particle size can be adjusted, the rate performance and cycle performance are excellent, and the volume expansion is effectively reduced.

[0133] This invention proposes a novel mesoporous spherical silicon-carbon anode material. By optimizing the material's structural design and preparation process, it addresses existing issues such as silicon volume expansion, weak interfacial bonding, and complex preparation processes. The mesoporous spherical silicon-carbon anode material of the invention has the following advantages: a uniform mesoporous pore structure effectively mitigates silicon volume expansion; a close bond between silicon and carbon improves the material's cyclic stability; a simplified preparation process reduces production costs and facilitates industrialization; and, more importantly, the ability to produce mesoporous spherical silicon-carbon materials of a specific particle size, effectively reducing yield losses caused by crushing and grading.

[0134] The third aspect of the present invention provides a mesoporous silicon-carbon negative electrode material or a mesoporous silicon-carbon negative electrode material prepared by a method for preparing a mesoporous silicon-carbon negative electrode material, and its use in preparing a battery negative electrode, preferably a battery negative electrode of a lithium battery.

[0135] In the optional solution of the present invention, preferably, the preparation method of the mesoporous silicon-carbon negative electrode material specifically comprises the following steps:

[0136] Step 1. Prepare a carbon source (synthetic phenolic resin): disperse a certain proportion of aldehyde raw material, phenol raw material and catalyst in water, prepare a uniform phenolic resin mixture at 40-100°C, stir in a container, and then perform vacuum distillation after stirring to remove excess water to obtain phenolic resin;

[0137] Step 2. Prepare a precursor solution: Stir the template agent, carbon source, and solvent at 30-70° C. for 0.5-24 hours to obtain a uniform mixed solution; optionally, add a certain amount of pore-enlarging agent;

[0138] Step 3. Using an oil phase emulsion polymerization method to form pellets: After mixing a certain mass of precursor solution, silicone oil and thermal oil, primary curing is performed. The primary curing (i.e., oil phase pelletization) temperature is 80-150°C and the time is 1-24 hours. After that, solid-liquid separation is performed. After washing the solid particles, they are placed in an oven at a high temperature for deep curing again. The curing temperature is 130-200°C and the time is 3-24 hours.

[0139] Step 4: placing the solidified particles into a tube furnace, and sequentially performing primary calcination, secondary calcination, and activation to obtain a mesoporous fullerene matrix;

[0140] Step 5. Use chemical vapor deposition to deposit silicon on the mesoporous spherical carbon matrix to obtain a mesoporous silicon-carbon negative electrode material.

[0141] The present invention is further described below by way of examples. Unless otherwise specified, the materials in the examples were prepared according to existing methods or directly purchased from the market.

[0142] Example 1

[0143] This embodiment provides a mesoporous silicon-carbon negative electrode material, the preparation process of which is as follows:

[0144] Step 1. Prepare a carbon source (synthesize phenolic resin): disperse 40 grams of an aldehyde raw material (specifically formaldehyde), 34.45 grams of a phenol raw material (specifically phenol), and 0.34 grams of a catalyst (specifically hydrochloric acid) in water, and prepare a uniform phenolic resin mixture at 70° C. The mixture is stirred in a container for 2 hours. After stirring, the mixture is distilled under reduced pressure to remove excess water to obtain a phenolic resin;

[0145] Step 2. Prepare a precursor solution: Stir the template agent, carbon source, and solvent at 50°C for 4 hours to obtain a uniform mixed solution, wherein the template agent is F127, and the mass ratio of phenolic resin, F127, and ethanol is 1:0.5:0.5;

[0146] Step 3. Using an oil phase emulsion polymerization method to form pellets: a precursor solution, silicone oil (specifically dimethyl silicone oil) and heat transfer oil (specifically aromatic heat transfer oil) are mixed, wherein the mass ratio of the precursor solution, silicone oil and heat transfer oil is 1:1:4, and stirred in a reactor. The primary curing temperature is 110°C (i.e., the temperature at which the oil phase forms pellets). After the primary curing is carried out for 6 hours under heat preservation and stirring conditions, solid-liquid separation is performed, the solid particles are washed, and then placed in an oven heated to 150°C for deep curing for 10 hours;

[0147] Step 4. Firing: Place the solidified particles in a tube furnace, heat at 350°C for 3 hours in air or oxygen atmosphere, and remove the template;

[0148] Step 5. Second calcination: Place the pellets after the first calcination in a tube furnace, heat to 600°C under a nitrogen atmosphere and carbonize for 3 hours;

[0149] Step 6. The above-mentioned calcined particles were heated at 800°C for 3 hours with water vapor to obtain a mesoporous carbon matrix (such as Figure 4 shown), with a pore volume of 0.87 cm 3 / g, specific surface area is 1279m 2 / g, average pore size is 3.3nm;

[0150] Step 7. Depositing silicon on the mesoporous fullerene matrix using chemical vapor deposition:

[0151] The powder was placed in a tube furnace, heated from room temperature to 550°C at 5°C / min in a N2 atmosphere, then changed to a 25% SiH4-N2 mixed gas, and maintained at 550°C for 15 hours for Si deposition; then changed to a 25% C2H4-N2 mixed atmosphere and maintained at 550°C for 8 hours, and then changed to a N2 atmosphere and cooled naturally, crushed and graded to obtain a mesoporous silicon-carbon negative electrode material; the true density of the silicon-carbon negative electrode material measured by helium pycnometry was 1.35 g / cm 3 , the closed pore volume is 0.08cm 3 / g; the silicon content in the obtained mesoporous silicon-carbon negative electrode material is 50.50wt.%, and the specific surface area is 2.40m 2 / g, median particle size d V,50 is 12.2 μm, and the diameter distance ((d V,90 -d V,10 ) / d V,50 is 1.2.

[0152] The obtained silicon-carbon negative electrode material was prepared and charged to characterize the electrochemical performance.

[0153] Example 2

[0154] This embodiment provides a mesoporous silicon-carbon negative electrode material, and the difference between its preparation process and that of embodiment 1 is that in step 3, the mass ratio of the precursor solution, silicone oil, and thermal oil is 1:2:4;

[0155] The remaining steps are consistent with those in Example 1;

[0156] After carbonization activation, the pore volume was 0.82 cm 3 / g, specific surface area is 1105m 2 / g, a uniform mesoporous carbon material (mesoporous spherical carbon matrix) with an average pore size of 3.1nm; the true density of the silicon-carbon negative electrode material measured by helium specific gravity method is 1.54g / cm 3 , the closed pore volume is 0.03cm 3 / g; the silicon content in the mesoporous silicon-carbon negative electrode material obtained after silicon deposition is 49.84wt.%, and the specific surface area is 1.78m 2 / g, median particle size d V,50 is 11.4μm, and the diameter distance (d V,90 -d V,10 ) / d V,50 is 1.1.

[0157] Example 3

[0158] This embodiment provides a mesoporous silicon-carbon negative electrode material, and the difference between its preparation process and that of embodiment 1 is that in step 3, the mass ratio of the precursor solution, silicone oil, and thermal oil is 1:3:4;

[0159] The remaining steps are consistent with those in Example 1;

[0160] After carbonization activation, the pore volume was 0.85 cm 3 / g, the specific gravity is 1078m 2 / g, a uniform mesoporous carbon material (mesoporous spherical carbon matrix) with an average pore size of 2.9nm; the true density of the silicon-carbon negative electrode material measured by helium specific gravity method is 1.6g / cm 3 , the closed pore volume is 0.10cm 3 / g; the silicon content in the mesoporous silicon-carbon negative electrode material obtained after silicon deposition is 49.90wt.%, and the specific surface area is 1.28m 2 / g, median particle size d V,50 is 10.3 μm, and the diameter distance (d V,90 -d V,10 ) / d V,50 is 1.07.

[0161] Example 4

[0162] This embodiment provides a mesoporous silicon-carbon negative electrode material. The difference between its preparation process and that of Example 1 is that in step 2, the mass ratio of phenolic resin, F127, and ethanol is 1:0.75:0.75, and in step 3, the mass ratio of precursor solution, silicone oil, and thermal oil is 1:3:4;

[0163] The remaining steps are consistent with those in Example 1;

[0164] After carbonization activation, the pore volume was 0.87 cm 3 / g, the specific gravity is 1208m 2 / g, a uniform mesoporous carbon material (mesoporous spherical carbon matrix) with an average pore size of 3.5nm; the true density of the silicon-carbon negative electrode material measured by helium pycnometer is 1.46g / cm 3 , the closed pore volume is 0.17 cm 3 / g; the silicon content in the silicon-carbon negative electrode material obtained after silicon deposition is 50.24wt.%, and the specific surface area is 2.10m 2 / g, median particle size d V,50 is 9.1μm, and the diameter distance (d V,90 -d V,10 ) / d V,50 is 1.03.

[0165] Example 5

[0166] This embodiment provides a mesoporous silicon-carbon negative electrode material, and the difference between its preparation process and that of embodiment 1 is that in step 2, the mass ratio of phenolic resin, F127, and ethanol is 1:0.5:4;

[0167] In step 3, the mass ratio of the precursor solution, silicone oil, and thermal oil is 1:5:10;

[0168] The remaining steps are consistent with those in Example 1;

[0169] After carbonization activation, the pore volume was 0.91 cm 3 / g, the specific gravity is 1228m 2 / g, a uniform mesoporous carbon material (mesoporous spherical carbon matrix) with an average pore size of 3.3nm; the true density of the silicon-carbon negative electrode material measured by helium specific gravity method is 1.7g / cm 3 , the closed pore volume is 0.021cm 3 / g; the silicon content in the silicon-carbon negative electrode material obtained after silicon deposition is 50.24wt.%, and the specific surface area is 2.10m 2 / g, median particle size d V,50 is 9.1μm, and the diameter distance (d V,90 -d V,10 ) / d V,50 is 1.03.

[0170] Example 6

[0171] This embodiment provides a mesoporous silicon-carbon negative electrode material, and the difference between its preparation process and that of embodiment 1 is that in step 2, the mass ratio of phenolic resin, F127, and ethanol is 1:2:0.1;

[0172] In step 3, the mass ratio of the precursor solution, silicone oil, and thermal oil is 1:5:10;

[0173] The remaining steps are consistent with those in Example 1;

[0174] After carbonization activation, the pore volume was 0.87 cm 3 / g, the specific gravity is 1046m 2 / g, a uniform mesoporous carbon material (mesoporous spherical carbon matrix) with an average pore size of 3.2nm; the true density of the silicon-carbon negative electrode material measured by helium specific gravity method is 1.72g / cm 3 , the closed pore volume is 0.13cm 3 / g; the silicon content in the silicon-carbon negative electrode material obtained after silicon deposition is 50.60wt.%, and the specific surface area is 1.90m 2 / g, median particle size d V,50 is 7.8μm, and the diameter distance (d V,90 -d V,10 ) / d V,50 is 0.98.

[0175] Example 7

[0176] This embodiment provides a mesoporous silicon-carbon negative electrode material, and the difference between its preparation process and that of embodiment 1 is that in step 2, the mass ratio of phenolic resin, F127, and ethanol is 1:0.4:4.5;

[0177] The remaining steps are consistent with those in Example 1;

[0178] After carbonization activation, the pore volume was 0.92 cm 3 / g, the specific gravity is 1150.7m 2 / g, mesoporous carbon material with an average pore size of 3.2nm (disordered mesoporous carbon matrix, such as Figure 3 The true density of the silicon-carbon negative electrode material measured by helium specific gravity method is 1.82g / cm 3 , the closed pore volume is 0.21cm 3 / g; the silicon content in the silicon-carbon negative electrode material obtained after silicon deposition is 16.20wt.%, and the specific surface area is 1.05m 2 / g, median particle size d V,50 is 8.29 μm, and the diameter distance (d V,90 -d V,10 ) / d V,50 is 1.06.

[0179] Example 8

[0180] This embodiment provides a mesoporous silicon-carbon negative electrode material, and the difference between its preparation process and that of embodiment 1 is that in step 2, the mass ratio of phenolic resin, F127, and ethanol is 1:2.5:0.05;

[0181] The remaining steps are consistent with those in Example 1;

[0182] After carbonization activation, the pore volume was 0.83 cm 3 / g, the specific gravity is 1290m 2 / g, a uniform mesoporous carbon material (mesoporous spherical carbon matrix) with an average pore size of 3.5nm; the true density of the silicon-carbon negative electrode material measured by helium specific gravity method is 1.57g / cm 3 , the closed pore volume is 0.15cm 3 / g; the silicon content in the silicon-carbon negative electrode material obtained after silicon deposition is 50.35wt.%, and the specific surface area is 1.36m 2 / g, median particle size d V,50 is 8.57 μm, and the diameter distance (d V,90 -d V,10 ) / d V,50 is 1.07.

[0183] Example 9

[0184] This embodiment provides a mesoporous silicon-carbon negative electrode material, and the difference between its preparation process and that of embodiment 1 is that in step 3, the mass ratio of the precursor solution, silicone oil, and thermal oil is 1:6:0.05;

[0185] The remaining steps are consistent with those in Example 1;

[0186] After carbonization activation, the pore volume was 0.86 cm 3 / g, the specific gravity is 1160m 2 / g, a uniform mesoporous carbon material (mesoporous spherical carbon matrix) with an average pore size of 2.8nm; the true density of the silicon-carbon negative electrode material measured by helium pycnometer is 1.38g / cm 3 , the closed pore volume is 0.13cm 3 / g; the silicon content of the silicon-carbon negative electrode material obtained after silicon deposition is 50.35wt.%, and the specific surface area is 2.09m 2 / g, median particle size d V,50 is 8.90 μm, and the diameter distance (d V,90 -d V,10 ) / d V,50 is 1.05.

[0187] Example 10

[0188] This embodiment provides a mesoporous silicon-carbon negative electrode material, and the difference between its preparation process and that of embodiment 1 is that in step 3, the mass ratio of the precursor solution, silicone oil, and thermal oil is 1:0.5:11;

[0189] The remaining steps are consistent with those in Example 1;

[0190] After carbonization activation, the pore volume was 0.86 cm 3 / g, the specific gravity is 1205m 2 / g, a uniform mesoporous carbon material (mesoporous spherical carbon matrix) with an average pore size of 3.4nm; the true density of the silicon-carbon negative electrode material measured by helium pycnometer is 1.46g / cm 3 , the closed pore volume is 0.20cm 3 / g; the silicon content in the silicon-carbon negative electrode material obtained after silicon deposition is 50.20wt.%, and the specific surface area is 1.37m 2 / g, median particle size d V,50 is 8.48 μm, and the diameter distance (d V,90 -d V,10 ) / d V,50 is 1.14.

[0191] Example 11

[0192] This embodiment provides a mesoporous silicon-carbon negative electrode material, and the difference between its preparation process and that of embodiment 1 is that in step 2, a pore-enlarging agent, mesitylene, is additionally added at a mass ratio of 20% of the template agent;

[0193] The remaining steps are consistent with those in Example 1;

[0194] After carbonization activation, the pore volume was 0.83 cm 3 / g, the specific gravity is 1175m 2 / g, a uniform mesoporous carbon material (mesoporous spherical carbon matrix) with an average pore size of 3.5 nm; the true density of the silicon-carbon negative electrode material measured by helium pycnometer is 1.46 g / cm 3 , the closed pore volume is 0.20cm 3 / g; the silicon content in the silicon-carbon negative electrode material obtained after silicon deposition is 50.20wt.%, and the specific surface area is 1.37m 2 / g, median particle size d V,50 is 8.48 μm, and the diameter distance (d V,90 -d V,10 ) / d V,50 is 1.14.

[0195] Example 12

[0196] This embodiment provides a mesoporous silicon-carbon negative electrode material, and the difference between its preparation process and that of embodiment 1 is that in step 2, a pore-enlarging agent, mesitylene, is additionally added at a mass ratio of 50% of the template agent;

[0197] The remaining steps are consistent with those in Example 1;

[0198] After carbonization activation, the pore volume was 0.82 cm 3 / g, the specific gravity is 1225m 2 / g, a uniform mesoporous carbon material (mesoporous spherical carbon matrix) with an average pore size of 3.7nm; the true density of the silicon-carbon negative electrode material measured by helium specific gravity method is 1.46g / cm 3 , the closed pore volume is 0.20cm 3 / g; the silicon content in the silicon-carbon negative electrode material obtained after silicon deposition is 50.20wt.%, and the specific surface area is 1.37m 2 / g, median particle size d V,50 is 8.48 μm, and the diameter distance (d V,90 -d V,10 ) / d V,50 is 1.14.

[0199] Example 13

[0200] This embodiment provides a mesoporous silicon-carbon negative electrode material. The difference between its preparation process and that of embodiment 1 is that in step 3, during the primary curing, stirring is performed at 110°C for 3 hours, then stirring is stopped and kept warm for 3 hours. After solid-liquid separation, the material is placed in an oven at 150°C for 10 hours for curing, and then crushed by jet mill to obtain D v50 =10, mesoporous carbon sphere solidified material with a diameter distance of 1.01;

[0201] After carbonization and activation, the pore volume is 0.88cm 3 / g, the specific gravity is 1275m 2 / g, mesoporous carbon material with an average pore size of 3.71nm (mesoporous spherical carbon matrix) (see Figure 5 The true density of the silicon-carbon negative electrode material measured by helium pycnometer is 1.43 g / cm 3 , the closed pore volume is 0.18cm 3 / g; the silicon content in the silicon-carbon negative electrode material obtained after silicon deposition is 50.10wt.%, and the specific surface area is 1.37m 2 / g, median particle size d V,50 is 8.48 μm, and the diameter distance (d V,90 -d V,10 ) / d V,50 is 1.04;

[0202] The remaining steps are consistent with those in Example 1.

[0203] Example 14

[0204] This embodiment provides a mesoporous silicon-carbon negative electrode material. The difference between its preparation process and that of embodiment 1 is that in step 3, stirring is performed at 110°C for 1 hour, then stirring is stopped and kept warm for 5 hours. After solid-liquid separation, the material is placed in an oven at 150°C for 10 hours for solidification, and then crushed by jet mill to obtain D v50 =10, irregular block solidified material of mesoporous carbon with a diameter distance of 1.02;

[0205] After carbonization activation, the pore volume was 0.88 cm 3 / g, the specific gravity is 1265m 2 / g, mesoporous carbon material with an average pore size of 3.73nm (irregular bulk mesoporous carbon matrix) (see Figure 6 ); The true density of the silicon-carbon negative electrode material measured by helium specific gravity method is 1.36g / cm 3 , the closed pore volume is 0.19 cm 3 / g; the silicon content in the silicon-carbon negative electrode material obtained after silicon deposition is 50.11wt.%, and the specific surface area is 1.35m 2 / g, median particle size d V,50 is 8.48 μm, and the diameter distance (d V,90 -d V,10 ) / dV,50 is 1.05;

[0206] The remaining steps are consistent with those in Example 1.

[0207] Comparative Example 1

[0208] This comparative example provides a silicon-carbon negative electrode material, and its preparation process is as follows:

[0209] Step 1: Curing the phenolic resin at 150℃ for 10h, crushing the solid, carbonizing it at 400℃ for 2h under an inert gas atmosphere, and then changing to water vapor and continuing to treat it at 800℃ for 3h to obtain a specific surface area of ​​1900m 2 / g, pore volume is 0.90cm 3 / g, porous carbon framework material with an average pore size of 1.87nm;

[0210] Step 2: The above materials were heated from room temperature to 550°C at 5°C / min in N2 atmosphere, and then changed to 25% SiH4-N2 mixed gas, and kept at 550°C for 15 hours in the mixed atmosphere for Si deposition; then changed to 25% C2H4-N2 mixed atmosphere and kept at 550°C for 8 hours, and then changed to N2 atmosphere and cooled naturally, crushed and graded to obtain silicon-carbon negative electrode material; the silicon content in the obtained silicon-carbon negative electrode material was 50.15wt.%, and the specific surface area was 1.68m 2 / g, median particle size d V,50 is 8.0μm, the diameter distance (d V,90 -d V,10 ) / d V,50 The obtained silicon-carbon negative electrode material was used to prepare a buckle to characterize the electrochemical performance.

[0211] Comparative Example 2

[0212] This comparative example provides a silicon-carbon negative electrode material, which differs from Example 1 in that: no primary calcination treatment is performed, and only a secondary calcination treatment is performed in the carbonization stage. The remaining steps are the same as those in Example 1.

[0213] After carbonization activation, the pore volume was 0.92 cm 3 / g, the specific gravity is 1808m 2 / g, a carbon material with an average pore size of 1.87nm (at this time there is no ordered mesoporous structure); the true density of the silicon-carbon negative electrode material measured by helium pycnometer is 1.35g / cm 3 , the closed pore volume is 0.03cm 3 / g; the silicon content in the silicon-carbon negative electrode material obtained after silicon deposition is 49.80wt.%, and the specific surface area is 1.90m 2 / g, median particle size d V,50 is 8.29 μm, and the diameter distance (d V,90 -d V,10) / d V,50 is 1.04.

[0214] Power-off test:

[0215] The silicon-based composite materials prepared in Examples 1-14 and Comparative Examples 1 and 2 were used as negative electrode active materials to prepare negative electrode sheets. The negative electrode sheets were used to prepare CR2032 button batteries using conventional methods, and the batteries were tested for electrical performance. The specific testing methods are as follows:

[0216] (1) Half-cell assembly: CR2032 button cells were assembled in a glove box, with a lithium metal sheet as the counter electrode, a polypropylene microporous membrane as the separator, and the electrolyte being a mixture of LiPF6 dissolved in ethyl carbonate (EC) and diethyl carbonate (DEC) (volume ratio EC:DEC = 1:1), where the LiPF6 concentration was 1 mol / L.

[0217] The battery was tested for charge and discharge using the LAND battery testing system.

[0218] (2) Cyclic gram capacity and first efficiency test: After the CR2032 battery is uncharged and left to stand for 6 hours, it is discharged at 0.1C to 0.005V, and the capacity is recorded as Q1; then it is discharged at a constant voltage of 0.005V until the current reaches 0.01C and then cut off; after standing for 5 minutes, it is charged at a constant current of 0.1C to 1.5V; the first delithiation gram capacity is the gram capacity (or mass specific capacity) of the electrode material, and the ratio of the first delithiation capacity to the first lithium insertion capacity is the first coulombic efficiency of the battery.

[0219] (3) Capacity retention rate test: After standing for 5 minutes, repeat the above charge and discharge steps twice; select 3 button batteries and discharge them to 0.05V at 0.1C. After standing for 2 hours, disassemble and measure the thickness of the negative electrode in turn, and record the average value as h1. Then discharge the remaining 3 button batteries to 0.005V at 0.25C; after standing for 5 minutes, charge them to 1.5V at 0.25C constant current, and cycle 50 times. The gram capacity retention rate is calculated by the charge capacity of the 50th cycle / the charge capacity of the 1st cycle × 100%, and the average value of the expanded thickness after 50 cycles is h2. The full charge expansion ratio = (h2-h1) / h1×100%;

[0220] Sphericity Testing: The ratio of the major axis to the minor axis (Aspect Ratio, AR) of a spheroid (or near-spherical particle) is a key parameter for measuring its proximity to perfect sphericity. A perfect sphere has an AR of 1, and the closer the AR of an actual particle is to 1, the higher the sphericity. Using SEM to measure the AR of a sphere's major axis to minor axis, we can determine the degree of its proximity to perfect sphericity.

[0221] The test results are shown in Table 2. Table 1 shows the average pore size, pore volume, BJH mesopore ratio and P / P0>0.75 ratio of the mesoporous carbon matrix.

[0222] Table 1

[0223]

[0224] Table 2

[0225]

[0226]

[0227] As can be seen from Table 1, the pore size in each embodiment is controlled between 2-6 nm, so that the mesopore size in the porous carbon matrix is ​​small mesopores rather than large mesopores larger than 10 nm, which can ensure that the deposition of silicon is more uniform, which is beneficial to reducing the expansion of silicon. The pore volume with p / p0>0.75 accounts for a smaller proportion, which can ensure that the finished silicon-carbon electrolyte is less adsorbed in pores larger than 10 nm, which is beneficial to the performance of the material in the cycle and improves the cycle performance of the battery cell.

[0228] In the present invention, the pore volume proportion of p / p0>0.75 is controlled to less than 10% (except for Example 7, in which the mesoporous spherical carbon matrix is ​​a disordered mesoporous spherical carbon matrix), thereby reducing the unfavorable factors such as uneven silicon deposition caused by large-diameter pores and the penetration of electrolyte in large pores, thereby having beneficial improvements on the cycle life of the battery cell, improving expansion, and inhibiting high-temperature gas production.

[0229] As can be seen from Table 2, in Examples 1-3, when the ratio of carbon source: template agent: ethanol is the same and different silicone oil heat transfer oils are used to prepare spherical particles, the rates of Examples 1-3 are not much different from the first effect, and the product of Example 3 has better overall performance. This is due to the smaller average pore size and better first effect.

[0230] By comparing the result data of Example 4 and Example 3, it can be seen that when the ratio of carbon source: template agent: ethanol is adjusted to 1:0.5:0.5, the product performance of Example 3 is slightly reduced. This may be because the order degree is reduced to a certain extent due to the reduction in the amount of template agent added.

[0231] Compared with Example 1, in Examples 7 and 8, when the amount of template agent added is too low (less than 0.5 times) or exceeds two parts by mass, a disordered mesoporous carbon material is prepared, and the overall performance is attenuated after silicon deposition.

[0232] Compared with Example 1, in Example 9 and Example 10, the excessive amount of silicone oil in Example 9 will cause the liquid phase curing time to be prolonged or even fail, resulting in poor overall product performance; the proportion of heat transfer oil in Example 10 is too high, which makes it more difficult to form liquid phase balls, reduces the sphericity, and affects the overall performance of the product.

[0233] Compared with Example 1, in Examples 11 and 12, although a certain amount of pore expander was added to increase the average pore diameter, there was no substantial improvement in the specific capacity, but there was a certain improvement in the rate performance. This may be because the larger pore diameter leads to larger silicon particle deposition, which is beneficial to ion conduction.

[0234] Mesoporous carbons with other morphologies were prepared in Example 13 and Example 14. For mesoporous carbons with different morphologies (mesoporous spherical carbon matrix was prepared in Example 13, and irregular bulk mesoporous carbon matrix was prepared in Example 14), there was no obvious difference in electrochemical performance when the pore size and pore volume of the mesoporous spherical carbon matrix and the irregular bulk mesoporous carbon matrix were similar.

[0235] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A mesoporous silicon-carbon negative electrode material, characterized in that: The invention comprises a mesoporous carbon matrix and silicon; the mesoporous carbon matrix is ​​spherical, quasi-spherical or irregular block, and has a mesoporous structure; the silicon is uniformly distributed in the mesoporous structure.

2. The mesoporous silicon-carbon negative electrode material according to claim 1, characterized in that: The average pore size of the mesoporous carbon matrix is ​​2.0-6.0 nm, wherein in the isothermal adsorption curve of the carbonized mesoporous carbon matrix, the pore volume with p / p0>0.75 accounts for less than 10%, wherein the mesopore proportion is>80%; preferably, the mesopore proportion is>83.0%; Preferably, the mesoporous structure is orderly distributed; And / or, the pore volume of the mesoporous carbon matrix is ​​0.01 to 2 cm 3 / g, preferably 0.6 to 1.1 cm 3 / g; and / or, the median particle size of the mesoporous carbon matrix is ​​5 to 20 μm, preferably 6 to 12 μm; and / or, the diameter pitch of the mesoporous carbon matrix is ​​0.8 to 2.0, preferably 0.8 to 1.2; And / or, the sphericity of the mesoporous carbon matrix is ​​greater than 0.

7.

3. The mesoporous silicon-carbon negative electrode material according to claim 1, characterized in that The silicon content of the mesoporous silicon-carbon negative electrode material is 5% to 90%, preferably 30% to 60%; And / or, the specific surface area of ​​the mesoporous silicon carbon negative electrode material is 0.1 to 50 m 2 / g, preferably 0.5 to 5m 2 / g; And / or, the true density of the mesoporous silicon carbon anode material measured by helium pycnometry is 1.3 to 2.0 g / cm 3 , the closed pore volume is 0.01~0.25cm 3 / g; And / or, the median particle size of the mesoporous silicon-carbon negative electrode material is 5 to 20 μm, preferably 6 to 12 μm; And / or, the diameter pitch of the mesoporous silicon-carbon negative electrode material is 0.8 to 2.0, preferably 0.8 to 1.

2.

4. The method for preparing the mesoporous silicon-carbon negative electrode material according to any one of claims 1 to 3, wherein: The following steps are involved: The carbon source and the template agent are mixed to obtain a precursor solution, which is then subjected to spherical formation, solidification, calcination, dicalcination and activation treatments in sequence to obtain a mesoporous carbon matrix, which is then subjected to vapor deposition silicon treatment to obtain a mesoporous silicon-carbon negative electrode material.

5. The method for preparing the mesoporous silicon-carbon negative electrode material according to claim 4, characterized in that: The carbon source is phenolic resin; And / or, the carbon source preparation process comprises: mixing an aldehyde raw material, a phenol raw material, a catalyst and water to obtain a phenolic resin mixed solution; and / or, the preparation temperature of the carbon source is 40-100° C.; and / or, the aldehyde raw material comprises at least one of formaldehyde, acetaldehyde and furfural; and / or, the phenolic raw material comprises at least one of phenol and resorcinol; And / or, the mass of the aldehyde raw material accounts for 60%-130% of the mass of the phenol raw material; and / or, the catalyst comprises at least one of an acidic catalyst and a basic catalyst; and / or, the mass of the catalyst accounts for 1%-5% of the mass of the phenols; and / or, the acidic catalyst comprises at least one of hydrochloric acid, sulfuric acid and oxalic acid; And / or, the alkaline catalyst includes at least one of sodium hydroxide, calcium hydroxide and ammonia water.

6. The method for preparing the mesoporous silicon-carbon negative electrode material according to claim 4, characterized in that: The preparation process of the precursor solution includes: mixing a template agent, a carbon source and a solvent to obtain a precursor solution; And / or, the mass ratio of the carbon source, the template agent and the solvent is 0.7-1.5:0.5-2:0.1-4.0; and / or, the precursor solution is prepared at a temperature of 30-70° C. and stirred for 0.5-24 hours; And / or, the template agent is obtained by polycondensation reaction of polyoxyethylene, polyoxypropylene and polystyrene; And / or, the template agent includes at least one of PEO-PPO-PEO, PPO-PEO-PPO and PEO-PS-PEO; and / or, the molecular weight of the template agent is 1500-40000; and / or, the PEO-PPO-PEO group includes at least one of F127, F188 and P123; And / or, the solvent includes at least one of methanol, ethanol, tetrahydrofuran and dimethyl sulfoxide.

7. The method for preparing the mesoporous silicon-carbon negative electrode material according to claim 4, characterized in that: The spheroidization is carried out by adopting oil phase emulsion polymerization method; And / or, the spheroidization process includes: mixing a precursor solution, silicone oil and heat transfer oil, performing primary solidification, and then separating to obtain solid particles; And / or, the mass ratio of the precursor solution, silicone oil and thermal oil is 1:1-5:1-10; And / or, the silicone oil includes at least one of dimethyl silicone oil and phenyl silicone oil; and / or, the viscosity of the silicone oil is 10-1000 cst, preferably 100-600 cst; And / or, the heat transfer oil comprises at least one of aromatic heat transfer oil and silicone heat transfer oil; and / or, the viscosity of the heat transfer oil is 20-100 cst, preferably 20-60 cst; and / or, the primary curing temperature is 80-150° C.; And / or, the primary curing time is 1-24 hours.

8. The method for preparing the mesoporous silicon-carbon negative electrode material according to claim 4, characterized in that: The curing temperature is 110-200°C and the curing time is 3-24h; And / or, the calcination temperature is 300-500°C and the calcination time is 0.5-100h; And / or, the temperature of the secondary calcination is 500-1100° C., and the time of the secondary calcination is 0.5-100 h; And / or, the activation temperature is 750-1100° C., and the activation time is 0.5-50 h; And / or, the activation method includes at least one of CO2 activation, water activation and O2 activation.

9. The method for preparing the mesoporous silicon-carbon negative electrode material according to claim 7, characterized in that: When preparing the precursor solution, add a pore-enlarging agent; And / or, the pore-enlarging agent includes at least one of a compound having a hydrophobic group of C5 or greater and a compound having a hydrophilic group; and / or, the hydrophobic group compound having C5 or more comprises at least one of mesitylene, n-pentane, n-heptane, hexadecyltrimethylammonium bromide and hexadecyltrimethylammonium chloride; And / or, the compound having a hydrophilic group includes at least one of tetraethyl titanate, triisopropyl aluminate, tetra-n-propyl zirconate, methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate and butyl orthosilicate; And / or, the amount of the pore-enlarging agent added is 0%-50% of the template agent.

10. Use of the mesoporous silicon-carbon negative electrode material according to any one of claims 1 to 3 or the mesoporous silicon-carbon negative electrode material prepared by the preparation method of the mesoporous silicon-carbon negative electrode material according to any one of claims 4 to 9 in preparing a battery negative electrode.

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