Spherical porous carbon, method for preparing the same, and use thereof

Abstract

The application relates to the technical field of batteries, in particular to a spherical porous carbon and a preparation method and application thereof, the spherical porous carbon satisfying: a spheroidization degree of 0.9-1.0; and an R value of 0.7-0.9; wherein the spheroidization degree = V p is the particle volume of the spherical porous carbon, S p is the particle surface area of the spherical porous carbon; and the R value is the ratio of the diffraction peak intensity of a (002) crystal face to the diffraction peak intensity of an alpha-aluminum oxide (104) crystal face in an X-ray diffraction pattern of the spherical porous carbon. The spherical porous carbon satisfies the above conditions, has high strength, can bear high pressure, has good compression resistance when used as a negative electrode material, is not prone to powdering, electrode cracking and negative electrode peeling, and has high specific capacity and good cycle stability.

Description

Technical Field

[0001] This application relates to the specific field of batteries, specifically to spherical porous carbon and its preparation methods and applications, and more specifically to spherical porous carbon and its preparation methods, spherical silicon-carbon composite materials and their preparation methods, negative electrode sheets, batteries and electrical devices. Background Technology

[0002] Silicon-carbon anode materials prepared by vapor deposition have shown significant improvements in discharge specific capacity and initial coulombic efficiency, typically exceeding 2000 mAh / g and reaching around 90%. They also effectively reduce material volume expansion, making them considered the most promising anode material for solid-state batteries. However, due to the solid-solid interface contact problem, solid-state batteries often require extremely high pressure to shape the solid electrolyte during assembly. Vapor-phase silicon-carbon materials in related technologies cannot withstand this high pressure, rapidly leading to material pulverization, electrode cracking, and anode peeling. Currently, they cannot achieve good compatibility and application in solid-state battery systems. Therefore, silicon-carbon anode material technology still needs improvement. Summary of the Invention

[0003] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, this invention proposes a spherical porous carbon with high strength and good electrochemical performance, its preparation method, and its applications.

[0004] In a first aspect, this application provides a spherical porous carbon. According to embodiments of this application, the spherical porous carbon satisfies the following: a sphericity of 0.9 to 1.0; and an R value of 0.7 to 0.9, wherein the sphericity = V p S represents the particle volume of the spherical porous carbon. p R is the particle surface area of ​​the spherical porous carbon; R is the ratio of the diffraction peak intensity of the (002) crystal plane to the diffraction peak intensity of the α-alumina (104) crystal plane in the X-ray diffraction pattern of the spherical porous carbon.

[0005] The spherical porous carbon of this application has a high degree of sphericity, which gives it high mechanical strength and dispersibility. It can withstand high pressure without breaking or pulverizing. The R value is 0.7~0.9, which not only helps to improve the mechanical strength, thermal stability and chemical stability of the spherical porous carbon, but also gives it suitable electrical conductivity, thus giving it good ion transport performance.

[0006] According to embodiments of this application, spherical porous carbon satisfies: The sphericity is 0.92~1.0; The R value is 0.72~0.80.

[0007] According to the embodiments of this application, the total pore volume of the spherical porous carbon is 0.3 mL / g to 1.2 mL / g, specifically 0.7 mL / g to 1.0 mL / g.

[0008] According to an embodiment of this application, the specific surface area of ​​the spherical porous carbon is 300 m². 2 / g~2800 m 2 / g, specifically 1500m 2 / g~2200 m 2 / g.

[0009] According to embodiments of this application, the micropore content of the spherical porous carbon is 60% to 95%, specifically 85% to 90%.

[0010] According to embodiments of this application, the average particle size of the spherical porous carbon is 3 μm to 10 μm, specifically 4 μm to 6 μm.

[0011] According to embodiments of this application, the spherical porous carbon includes at least one of chemical-based carbon, biomass carbon, and sugar-based carbon. In some embodiments, the chemical-based carbon includes at least one of resin carbon and pitch carbon, the biomass carbon includes at least one of coconut shell carbon, bamboo block carbon, and straw carbon, and the sugar-based carbon includes at least one of sucrose carbon, glucose carbon, and starch carbon.

[0012] In a second aspect, this application provides a spherical silicon-carbon composite material. According to an embodiment of this application, the spherical silicon-carbon composite material comprises: a core, the core comprising the aforementioned spherical porous carbon and silicon material, with at least a portion of the silicon material located within the pores of the spherical porous carbon; and a carbon coating layer, the carbon coating layer covering at least a portion of the outer surface of the core. This spherical silicon-carbon composite material exhibits good crush resistance, high specific capacity, and good cycle stability. Specifically, by employing the aforementioned spherical porous carbon, the spherical silicon-carbon composite material also possesses high mechanical strength, capable of withstanding high pressure without breakage or pulverization, effectively improving the problem of negative electrode material particle breakage during electrode preparation, thereby effectively improving phenomena such as powder shedding and electrode cracking. Simultaneously, the spherical silicon-carbon composite material also exhibits superior conductivity and ion transport performance, possessing high initial coulombic efficiency and long cycle life, and the spherical porous carbon can accommodate a large amount of silicon material, resulting in a high specific capacity. In addition, the carbon coating can effectively block the desilication phenomenon caused by the expansion of silicon materials, reduce the problem of excessive SEI film side reaction caused by desilication, and at the same time have better conductivity, lower negative electrode impedance, and reduced polarization phenomenon, thereby improving the cycle coulombic efficiency and cycle capacity of silicon-carbon composite materials.

[0013] According to an embodiment of this application, the sphericity of the spherical silicon-carbon composite material is 0.9~1.0, specifically 0.92~1.0.

[0014] According to the embodiments of this application, the crush resistance of the spherical silicon-carbon composite material is 30 mN~60 mN, specifically 40 mN~50 mN.

[0015] According to embodiments of this application, the spherical silicon-carbon composite material has a pressure resistance of 600 MPa to 1200 MPa, specifically 800 MPa to 1000 MPa.

[0016] According to an embodiment of this application, the thickness of the carbon coating layer is 5 nm to 50 nm, specifically 5 nm to 20 nm.

[0017] According to embodiments of this application, the specific surface area of ​​the spherical silicon-carbon composite material can be reduced to 1 m². 2 / g~20 m 2 / g, specifically 1 m 2 / g~5 m 2 / g.

[0018] According to embodiments of this application, the mass percentage of silicon in the spherical silicon-carbon composite material is 20% to 60%, specifically 45% to 55%.

[0019] According to embodiments of this application, the mass percentage of carbon in the spherical silicon-carbon composite material is 40% to 80%, specifically 45% to 55%.

[0020] A third aspect of this application provides a method for preparing the aforementioned spherical porous carbon. According to an embodiment of this application, the method includes: subjecting a carbon source to a first sintering and a first pulverization to obtain a carbon precursor; and activating the carbon precursor to obtain the spherical porous carbon, wherein the sphericity of the carbon source is 0.85~1.0.

[0021] According to an embodiment of this application, the carbon source satisfies: K ≤ 1.2, K = (D 90 -D 10 ) / D 50 .

[0022] According to an embodiment of this application, the first sintering includes a first-stage sintering and a second-stage sintering performed sequentially. The temperature of the first-stage sintering is 300~600℃, and the holding time of the first-stage sintering is 1~3h. The temperature of the second-stage sintering is 800~1600℃, and the holding time of the second-stage sintering is 5~20h.

[0023] According to an embodiment of this application, the first pulverization includes sequential mechanical grinding and spheroidization followed by a first airflow pulverization, and satisfies at least one of the following conditions: The average primary particle size of the product obtained by the first mechanical grinding and spheroidizing process is 10 μm to 100 μm; The average primary particle size of the carbon precursor obtained by the first airflow pulverization is 4 μm to 15 μm.

[0024] According to an embodiment of this application, the activation treatment includes: preheating the carbon precursor under a protective atmosphere, and then performing a second sintering on the carbon precursor in the presence of an activator; The activation treatment satisfies at least one of the following conditions: The activator includes at least one of CO2, H2O, NH3, KOH, K2CO3, KHCO3, Na2CO3, NaOH, NaHCO3, NH4OH, NH4HCO3, (NH4)2CO3, LiOH, Li2CO3, LiHCO3, Ca(OH)2, Ba(OH)2, and Al(OH)3; The preheating temperature is 300℃~500℃; The preheating time is 1 hour to 4 hours; The flow rate of the activator is 10 scc to 100 scc; The second sintering temperature is 600℃~1500℃; The second sintering time is 3h~18h.

[0025] A fourth aspect of this application provides a method for preparing the aforementioned spherical silicon-carbon composite material. According to an embodiment of this application, the method includes: depositing silicon material in the pores of the aforementioned spherical porous carbon to obtain a core; and depositing a carbon coating layer on at least a portion of the surface of the core to obtain the spherical silicon-carbon composite material. This method is convenient to operate, and the prepared silicon-carbon composite material can inherit the high sphericity and R-value of the spherical porous carbon, significantly improving the discharge specific capacity and initial coulombic efficiency. It also effectively reduces the volume expansion of the silicon-carbon composite material. Furthermore, the deposition forms a uniform and stable carbon coating layer, effectively preventing desilication caused by silicon material expansion, mitigating the excessive SEI film side reaction problem caused by desilication, and improving the cycle coulombic efficiency and cycle capacity of the silicon-carbon composite material. Moreover, the carbon coating layer formed by this method is uniform and thin, mitigating the conductivity reduction problem caused by conventional coating methods, reducing negative electrode impedance and polarization, and simultaneously improving the rate performance and discharge specific capacity of the silicon-carbon composite material.

[0026] According to embodiments of this application, the silicon material and the carbon coating layer are each obtained independently by chemical vapor deposition.

[0027] A fifth aspect of this application provides a negative electrode sheet. According to an embodiment of this application, the negative electrode sheet includes a negative electrode current collector and a negative electrode material layer disposed on at least one surface of the negative electrode current collector, the negative electrode material layer comprising the spherical silicon-carbon composite material described above. This negative electrode sheet has high specific capacity, is not prone to powder shedding or cracking, has high structural stability, and thus has a long cycle life.

[0028] In a sixth aspect, this application provides a battery. According to embodiments of this application, the battery comprises the spherical silicon-carbon composite material described above or the negative electrode sheet described above. This battery exhibits high initial coulombic efficiency and specific capacity, and a long cycle life.

[0029] According to embodiments of this application, a single-cell battery is provided, comprising the aforementioned spherical silicon-carbon composite material or the aforementioned negative electrode sheet. This single-cell battery exhibits high initial coulombic efficiency and specific capacity, and long cycle life.

[0030] According to an embodiment of this application, a battery module is provided. According to an embodiment of this application, the battery module includes the aforementioned spherical silicon-carbon composite material, the aforementioned negative electrode sheet, the aforementioned battery, or the aforementioned single cell. This battery module has high initial coulombic efficiency and specific capacity, and long cycle life.

[0031] According to an embodiment of this application, a battery pack is provided. According to an embodiment of this application, the battery pack includes the aforementioned spherical silicon-carbon composite material, the aforementioned negative electrode sheet, the aforementioned battery, the aforementioned single cell, or the aforementioned battery module. This battery pack exhibits high initial coulombic efficiency and specific capacity, and a long cycle life.

[0032] In a seventh aspect, this application provides an electrical device. According to an embodiment of this application, the electrical device includes the aforementioned spherical silicon-carbon composite material, the aforementioned negative electrode sheet, the aforementioned battery, the aforementioned single cell, the aforementioned battery module, or the aforementioned battery pack. This electrical device possesses all the features and advantages of the aforementioned spherical silicon-carbon composite material, negative electrode sheet, battery, single cell, battery module, and battery pack, which will not be elaborated upon here. Attached Figure Description

[0033] Figure 1 This is a SEM image of the spherical silicon-carbon composite material of Example 1 of this application.

[0034] Figure 2 This is a SEM image of the spherical silicon-carbon composite material of Comparative Example 1 of this application.

[0035] Figure 3 This is a diagram showing the particle size distribution of spherical porous carbon particles in Example 1 of this application.

[0036] Figure 4This is the cycling test curve of the half-cell of Embodiment 3 of this application at a 1C rate.

[0037] Figure 5 This is the XRD pattern of the spherical silicon-carbon composite material of Example 1 of this application. Detailed Implementation

[0038] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0039] In a first aspect, this application provides a spherical porous carbon. According to embodiments of this application, the spherical porous carbon satisfies the following: a sphericity of 0.9 to 1.0; and an R value of 0.7 to 0.9. As an example, the sphericity can specifically be 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 1.0, or any two of these values; the R value can specifically be 0.7, 0.75, 0.8, 0.85, 0.9, or any two of these values.

[0040] The spherical porous carbon of this application has a high degree of sphericity, which gives it high mechanical strength and dispersion, allowing it to withstand high pressure without breaking or pulverizing. A higher R value indicates a more obvious and ordered graphite microcrystalline structure and higher crystallinity in the spherical porous carbon, but this is more difficult to achieve. A lower R value indicates a higher proportion of amorphous carbon, lower graphitization, and more disordered structure. This application controls the R value to be between 0.7 and 0.9, which is beneficial for improving the mechanical strength, thermal stability, and chemical stability of the spherical porous carbon, and also allows it to have suitable electrical conductivity, thus exhibiting good ion transport performance, while being easy to achieve.

[0041] Applying this spherical porous carbon to anode materials, the synergistic effect of sphericity and R-value can effectively improve the problem of particle breakage in anode material during electrode preparation, thereby effectively improving phenomena such as powder shedding and electrode cracking, and significantly improving the yield. At the same time, the higher sphericity can also reduce the specific surface area of ​​the anode material, and the R-value brings better conductivity, ion transport performance, mechanical strength, thermal stability and chemical stability, which can effectively improve the initial coulombic efficiency, specific capacity and cycle life.

[0042] When spherical porous carbon is applied to silicon-carbon anode materials, the expansion degree of silicon-carbon anode materials can be significantly reduced, alleviating the problems of silicon-carbon particle pulverization and cracking caused by the expansion of anode materials during charge-discharge cycles, which is conducive to improving the specific capacity and cycle life of anode materials.

[0043] In this article, sphericity = V p S represents the particle volume of the spherical porous carbon. p Let be the surface area of ​​the spherical porous carbon particles. Sphericity is a geometric parameter that quantitatively characterizes how close the particle morphology is to an ideal sphere. Its value ranges from 0 to 1. The closer the value is to 1, the more regular the particle shape is, and the closer it is to an ideal sphere.

[0044] As an example, the method for testing sphericity is as follows: By combining SEM images of spherical porous carbon with image processing techniques, the SEM images of spherical porous carbon are processed and analyzed using the particle image analysis software Cellpose to obtain the particle size and shape information of each particle. That is, the particle volume and particle surface area of ​​spherical porous carbon can be directly output. Then, the particle volume and particle surface area of ​​10 to 500 particles of spherical porous carbon in the SEM image are statistically analyzed, and the average value is calculated to obtain the sphericity.

[0045] In this paper, R value is the ratio of the diffraction peak intensity of the (002) crystal plane to the diffraction peak intensity of the α-alumina (104) crystal plane in the X-ray diffraction pattern of the spherical porous carbon. It can be obtained by XRD testing of the spherical porous carbon.

[0046] In this paper, the diffraction peak intensity of the α-alumina (104) crystal plane in the X-ray diffraction pattern refers to a continuous and slowly changing counting curve formed by the superposition of various incoherent scattering, instrument noise, and amorphous scattering of the sample itself at the position where there is no Bragg diffraction signal. In other words, the diffraction peak intensity of the α-alumina (104) crystal plane refers to the intensity of the part of the X-ray diffraction pattern that has "no peak".

[0047] According to embodiments of this application, the spherical porous carbon satisfies the following conditions: a sphericity of 0.92 to 1.0; and an R value of 0.72 to 0.8. As an example, the sphericity can specifically be 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 1.0, or any two of these values; the R value can specifically be 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.79, 0.8, or any two of these values. Therefore, the mechanical strength and electrochemical performance of the spherical porous carbon can be further improved, and when applied to anode materials, its overall electrochemical performance can be further enhanced.

[0048] According to embodiments of this application, the total pore volume of the spherical porous carbon is 0.3 mL / g to 1.2 mL / g, specifically 0.7 mL / g to 1.0 mL / g. As an example, the total pore volume of the spherical porous carbon can be 0.3 mL / g, 0.4 mL / g, 0.5 mL / g, 0.6 mL / g, 0.7 mL / g, 0.8 mL / g, 0.9 mL / g, 1.0 mL / g, 1.1 mL / g, 1.2 mL / g, or any range thereof. Therefore, when applied to silicon-carbon anode materials, a higher silicon content can be accommodated, resulting in higher specific capacity, higher initial coulombic efficiency, lower volume expansion, and longer cycle life.

[0049] According to an embodiment of this application, the specific surface area of ​​the spherical porous carbon is 300 m². 2 / g~2800 m 2 / g, specifically 1500 m 2 / g~2200 m 2 / g. As an example, the specific surface area of ​​spherical porous carbon can be 300m. 2 / g、500m 2 / g、800m 2 / g, 1000m 2 / g、1200m 2 / g, 1500m 2 / g、1800m 2 / g、2000m 2 / g、2200m 2 / g、2500m 2 / g、2800m 2 / g or any range between / g and either of these. Therefore, there are many sites for storing active ions, resulting in a high theoretical capacity, while also allowing for the storage of active ions (such as Li). + It consumes less, has relatively fewer side reactions, and has lower resistance to diffusion of active ions, which is conducive to achieving high capacity, high initial coulombic efficiency, and long cycle length at the same time.

[0050] According to embodiments of this application, the micropore content of the spherical porous carbon is 60% to 95%, specifically 85% to 90%. As an example, the micropore content of the spherical porous carbon can be 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or any range between two of these. Therefore, it exhibits superior active ion transport performance, which is beneficial for improving rate performance. Furthermore, when used in silicon-carbon anode materials, it facilitates the inclusion of more silicon material, thereby increasing the specific capacity of the anode material.

[0051] According to embodiments of this application, the average particle size of the spherical porous carbon is 3 μm to 10 μm, specifically 4 μm to 6 μm. As an example, the average particle size of the spherical porous carbon can be 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, or any combination thereof. Therefore, when used as an anode material, the active ion diffusion path is shorter, which is beneficial for improving rate performance without excessively increasing slurry viscosity, making it easier to process. It also provides buffer space for the expansion of the anode material, thereby improving cycle life. When used for vapor-deposited silicon-carbon anode materials, the above particle size range facilitates uniform fluidization in a fluidized bed, thereby improving the uniformity of the deposited silicon material.

[0052] In this paper, the average particle size of spherical porous carbon can be detected by a Malvern laser particle size analyzer to obtain the average particle size result.

[0053] According to embodiments of this application, the porous carbon can be at least one of chemical-based carbon, biomass carbon, and sugar-based carbon. For example, the chemical-based carbon includes at least one of resin carbon and pitch carbon; the biomass carbon includes at least one of coconut shell carbon, bamboo block carbon, and straw carbon; and the sugar-based carbon includes at least one of sucrose carbon, glucose carbon, and starch carbon. Therefore, the raw materials are widely available and the cost is low. In some embodiments, the porous carbon includes resin carbon. Resin carbon has a high char residue value and mechanical strength, which is beneficial for improving the strength and electrochemical performance of the negative electrode material.

[0054] In a second aspect, this application provides a spherical silicon-carbon composite material. According to an embodiment of this application, the spherical silicon-carbon composite material comprises: a core, the core comprising the aforementioned spherical porous carbon and silicon material, with at least a portion of the silicon material located within the pores of the spherical porous carbon; and a carbon coating layer, the carbon coating layer covering at least a portion of the outer surface of the core. This spherical silicon-carbon composite material exhibits good crush resistance, high specific capacity, and good cycle stability. Specifically, by employing the aforementioned spherical porous carbon, the spherical silicon-carbon composite material also possesses high mechanical strength, capable of withstanding high pressure without breakage or pulverization, effectively improving the problem of negative electrode material particle breakage during electrode preparation, thereby effectively improving phenomena such as powder shedding and electrode cracking. Simultaneously, the spherical silicon-carbon composite material also exhibits superior conductivity and ion transport performance, possessing high initial coulombic efficiency and long cycle life, and the spherical porous carbon can accommodate a large amount of silicon material, resulting in a high specific capacity. In addition, the carbon coating can effectively block the desilication phenomenon caused by the expansion of silicon materials, reduce the problem of excessive SEI film side reaction caused by desilication, and at the same time have better conductivity, lower negative electrode impedance, and reduced polarization, thereby improving the cycle coulombic efficiency and cycle capacity of silicon-carbon composite materials.

[0055] According to embodiments of this application, the thickness of the carbon coating layer is 5 nm to 50 nm, specifically 5 nm to 20 nm. As an example, the thickness of the carbon coating layer can be 5 nm, 10 nm, 5 nm, 0 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, or any range between two of these. Therefore, a thinner coating layer results in better electrical conductivity, reducing negative electrode impedance and polarization, while simultaneously improving the material's rate performance and discharge specific capacity.

[0056] According to embodiments of this application, the sphericity of the spherical silicon-carbon composite material is 0.9 to 1.0, specifically 0.92 to 1.0. As an example, the sphericity of the spherical silicon-carbon composite material can specifically be 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 1.0, or any range between two of these. With the above-mentioned sphericity, the spherical silicon-carbon composite material can withstand higher pressure during electrode preparation without breaking or pulverizing, thereby improving problems such as powder shedding and electrode cracking, and effectively improving cycle performance. Simultaneously, a higher sphericity results in a smaller contact area with the electrolyte, which is beneficial for improving the initial coulombic efficiency.

[0057] According to embodiments of this application, the crush resistance of the spherical silicon-carbon composite material is 30 mN to 60 mN, specifically 40 mN to 50 mN. As an example, the crush resistance of the spherical silicon-carbon composite material can specifically be 30 mN, 32 mN, 35 mN, 38 mN, 40 mN, 42 mN, 45 mN, 48 mN, 50 mN, 52 mN, 55 mN, 58 mN, 60 mN, or any range between two of these. Meeting the above crush resistance requirements, the spherical silicon-carbon composite material will not fracture even under significant pressure during electrode fabrication, thus improving the initial coulombic efficiency and cycle life.

[0058] In this article, "compressive strength" refers to a material's ability to resist breakage under external pressure, which is usually tested by applying gradually increasing pressure until the material breaks. In this article, the compressive strength tester can be used for this test. The specific testing method is as follows: randomly select 20-50 intact, uniformly sized particles as samples, align the probe with the particles, continuously apply pressure, and record the maximum pressure value when the particles break.

[0059] According to embodiments of this application, the spherical silicon-carbon composite material has a pressure resistance of 600 MPa to 1200 MPa, specifically 800 MPa to 1000 MPa. As an example, the pressure resistance of the spherical silicon-carbon composite material can specifically be 600 MPa, 700 MPa, 800 MPa, 900 MPa, 1000 MPa, 1100 MPa, 1200 MPa, or any range between two of these. With the aforementioned pressure resistance, the spherical silicon-carbon composite material will not fracture even under significant pressure during electrode fabrication, thus improving the initial coulombic efficiency and cycle life.

[0060] In this article, "pressure resistance" refers to the pressure a material can withstand when subjected to external pressure and reaching its compressive strength limit. Its value is calculated from the compressive strength and particle size and morphology using the formula: Pressure resistance = Compressive strength / Area under stress. The area under stress can be automatically calculated by software, and then imported into the compressive strength calculation to obtain the pressure resistance. For example, the formula for calculating the compressive strength of spherical particles is 4F / πD. 2 F is the crushing force, and D is the diameter of the spherical particle.

[0061] According to an embodiment of this application, the specific surface area of ​​the spherical silicon-carbon composite material is 1 m². 2 / g~20 m 2 / g, specifically 1 m 2 / g~5 m 2 / g. As an example, the specific surface area of ​​spherical silicon-carbon composites can be 1 m². 2 / g、2m 2 / g、5m 2 / g、8m 2 / g, 10m 2 / g、12m 2 / g, 15m 2 / g、18m 2 / g、20m 2 / g or any range between / g and either of these. Therefore, there are many sites for storing active ions, resulting in a high theoretical capacity, while also allowing for the storage of active ions (such as Li). + It consumes less, has relatively fewer side reactions, and has lower resistance to active ion diffusion, which is conducive to achieving high capacity, high initial coulombic efficiency, and long cycle length at the same time.

[0062] According to embodiments of this application, the mass percentage of silicon in the spherical silicon-carbon composite material is 20% to 60%, specifically 45% to 55%. As an example, the mass percentage of silicon in the spherical silicon-carbon composite material can be 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, or any combination thereof. Therefore, the spherical silicon-carbon composite material has a high specific capacity.

[0063] According to embodiments of this application, the mass percentage of carbon in the spherical silicon-carbon composite material is 40% to 80%, specifically 45% to 55%. As an example, the mass percentage of carbon in the spherical silicon-carbon composite material can be 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, or any combination thereof. Therefore, the spherical silicon-carbon composite material possesses both high strength and high specific capacity.

[0064] In some embodiments, the above-mentioned spherical silicon-carbon composite material is applied to batteries, and its physicochemical properties can reach the following levels: 0.05C delithiation specific capacity of 1500 mAh / g to 2500 mAh / g, initial coulombic efficiency of 85% to 90%, capacity retention rate of 80% to 90% after 300 cycles at 1C room temperature, and capacity retention rate of 70% to 90% at 1C / 0.05C.

[0065] A third aspect of this application provides a method for preparing the aforementioned spherical porous carbon. According to embodiments of this application, the method includes: S10: The carbon source is first sintered and first crushed to obtain a carbon precursor.

[0066] In this step, the sphericity of the carbon source is 0.85~1.0 (specifically, 0.85, 0.86, 0.87, 0.88, 0.89, 0.90, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 1.0, or any two of these ranges). A carbon source satisfying the above sphericity can transfer its high sphericity to spherical porous carbon, thereby obtaining spherical porous carbon with extremely high sphericity.

[0067] According to an embodiment of this application, the carbon source satisfies: K ≤ 1.2, K = (D 90 -D 10 ) / D 50 Therefore, the carbon source has a narrower particle size and higher concentration, which is conducive to obtaining spherical porous carbon with high sphericity and good particle uniformity.

[0068] In this article, D 50 This refers to the particle size at which the cumulative volume percentage reaches 50% on the cumulative particle size distribution curve, indicating that 50% of the volume of particles is smaller than D. 50 50% of the volume is greater than or equal to D 50 ;D 10 This refers to the particle size at which the cumulative volume percentage reaches 10% on the cumulative particle size distribution curve, indicating that 10% of the particles by volume are smaller than D. 10 90% of the volume is greater than or equal to D10 ;D 90 This refers to the particle size at which the cumulative volume percentage reaches 90% on the cumulative particle size distribution curve, indicating that 90% of the volume of particles is smaller than D. 90 10% of the volume is greater than or equal to D 90 Specifically, this can be tested using a laser particle size analyzer.

[0069] According to an embodiment of this application, the first sintering includes a first-stage sintering and a second-stage sintering performed sequentially. Through segmented sintering, volatiles, pyrolysis gases, and other components can be removed during the first-stage sintering process. Then, during the second-stage sintering process, a hard carbon framework is generated and its structure rearranged, and defects are healed. This ensures the safe pyrolysis of the carbon source and facilitates the adjustment of the microstructure of the target product (such as pore size distribution, specific surface area, and crystallite size, which can be precisely designed). Simultaneously, it can inherit the sphericity of the carbon source, thereby facilitating the acquisition of spherical porous carbon with high sphericity and a suitable R-value.

[0070] According to an embodiment of this application, the sintering temperature of the first stage is 300℃~600℃, specifically 300℃, 350℃, 400℃, 450℃, 500℃, 550℃, 600℃, or any two of these ranges. Within the above temperature range, volatiles and pyrolysis gases can be sufficiently removed, and the volatiles are released in stages, ensuring safety and controllability.

[0071] According to an embodiment of this application, the holding time for the sintering stage is 1 hour to 3 hours, specifically 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, or any combination thereof. Within this time range, it is generally possible to ensure that volatiles and pyrolysis gases are fully discharged without wasting time.

[0072] According to embodiments of this application, the two-stage sintering temperature is 800℃~1600℃, specifically 800℃, 850℃, 900℃, 950℃, 1000℃, 1050℃, 1100℃, 1150℃, 1200℃, 1250℃, 1300℃, 1350℃, 1400℃, 1500℃, 1600℃, or any range between two of these. Within the above temperature range, a carbon framework can be rapidly grown and its structure rearranged, defects healed, resulting in spherical porous carbon with high sphericity and an R-value that meets requirements.

[0073] According to the embodiments of this application, the holding time for the two-stage sintering is 5h to 20h, specifically 5h, 8h, 10h, 12h, 15h, 18h, 20h, or any two of these ranges. Within the above time range, spherical porous carbon with high sphericity and satisfactory R-value, pore size distribution, specific surface area, and crystallite size can be obtained without wasting time.

[0074] According to an embodiment of this application, the first pulverization includes sequentially performing a first mechanical grinding and spheroidization followed by a first airflow milling. Thus, the first mechanical grinding and spheroidization coarsely breaks down the sintered product, and then the first airflow milling further finely pulverizes the first mechanical grinding and spheroidization product to obtain spherical porous carbon with a target particle size and high dispersion.

[0075] According to embodiments of this application, the average primary particle size of the product obtained by the first mechanical grinding and spheroidizing is 10 μm to 100 μm, specifically within the range of 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, or any two of these ranges. Therefore, the processing efficiency is relatively high.

[0076] According to embodiments of this application, the average primary particle size of the carbon precursor obtained by the first airflow pulverization is 4 μm to 15 μm, specifically within the range of 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, or any two of these ranges. This allows for sufficient deagglomeration of the sintered product, which is beneficial for improving the dispersion of spherical porous carbon.

[0077] As an example, the carbon source can be placed in a crucible and transferred to a box furnace. After sintering at 300℃~600℃ for 1h~3h, the temperature is raised to 800℃~1600℃ for 5h~20h. After sintering, the carbon is mechanically crushed and spheroidized to obtain carbon particles with an average primary particle size of 10μm~100μm. Then, the particles are air-jet milled to obtain spherical carbon precursors with an average primary particle size of 4μm~15μm.

[0078] The classifier wheel frequency, feeding frequency, and induced draft fan frequency of the air jet mill can be 120Hz~180Hz, 1Hz~5Hz, and 5Hz~15Hz, respectively, and the air jet pressure is 0.2MPa~1.0MPa. This facilitates the efficient acquisition of carbon precursors with the target particle size.

[0079] S20: The carbon precursor is activated to obtain the spherical porous carbon.

[0080] The aforementioned steps result in a carbon precursor with almost no pores. Through activation treatment, a porous structure that meets the requirements can be formed on the carbon precursor.

[0081] According to an embodiment of this application, the activation process includes: preheating the carbon precursor under a protective atmosphere, and then performing a second sintering on the carbon precursor in the presence of an activator. Thus, the activator can etch the carbon precursor to form a porous structure.

[0082] According to embodiments of this application, the activator includes at least one selected from CO2, H2O, NH3, KOH, K2CO3, KHCO3, Na2CO3, NaOH, NaHCO3, NH4OH, NH4HCO3, (NH4)2CO3, LiOH, Li2CO3, LiHCO3, Ca(OH)2, Ba(OH)2, and Al(OH)3. Therefore, the etching effect is better, the etching rate is suitable and controllable, thus facilitating the acquisition of a porous structure that meets the requirements.

[0083] According to embodiments of this application, the preheating temperature is 300℃~500℃, specifically 300℃, 320℃, 350℃, 380℃, 400℃, 420℃, 450℃, 480℃, 500℃, or any range between two of these. Preheating can replace water vapor, oxygen, and other residual gases adsorbed in the micropores of the carbon precursor with a protective atmosphere (such as nitrogen), preventing water and oxygen from participating in the activation reaction process. Simultaneously, the preheating process provides thermal energy to the carbon precursor, accelerating the electronic transition rate of carbon atoms in the microstructure, increasing the reactivity of the carbon ring framework, and making the activation reaction process easier to occur.

[0084] According to an embodiment of this application, the preheating time is 1 hour to 4 hours, specifically 1 hour, 2 hours, 3 hours, 4 hours, or any range between two of these. Within this time range, sufficient preheating can be achieved without wasting time.

[0085] According to embodiments of this application, the flow rate of the activator is 10 scc to 100 scc, specifically 10 scc, 20 scc, 30 scc, 40 scc, 50 scc, 60 scc, 70 scc, 80 scc, 90 scc, 100 scc, or any range between two of these. This allows for etching of the carbon precursor at a suitable rate and adjustment of the microstructure of the target product, thereby facilitating the acquisition of spherical porous carbon with high sphericity and a suitable R-value.

[0086] According to embodiments of this application, the second sintering temperature is 600℃~1500℃, specifically 600℃, 700℃, 800℃, 900℃, 1000℃, 1100℃, 1200℃, 1300℃, 1400℃, 1500℃, or any range between two of these. Within the above temperature range, the activation process can be completed with high efficiency, while avoiding excessively violent reactions, ensuring safety and controllability.

[0087] According to an embodiment of this application, the second sintering time is 3h to 18h, specifically 3h, 5h, 8h, 10h, 12h, 15h, 18h, or any range between two of these. Within the above time range, the formed porous structure meets the usage requirements and is beneficial to improving the performance of the obtained spherical porous carbon.

[0088] As an example, the carbon precursor can be placed in a rotary kiln and protected with nitrogen gas. After preheating at 300℃~500℃ for 1h~4h, the activator is gasified and introduced into the rotary kiln at a flow rate of 10scc~100scc. The carbon is then sintered at 600℃~1500℃ for 3h~18h. After sintering, the carbon is deagglomerated by an air jet mill to obtain spherical porous carbon with an average primary particle size of 3μm~10μm.

[0089] A fourth aspect of this application provides a method for preparing the aforementioned spherical silicon-carbon composite material. According to an embodiment of this application, the method includes: depositing silicon material in the pores of the aforementioned spherical porous carbon to obtain a core; and depositing a carbon coating layer on at least a portion of the surface of the core to obtain the spherical silicon-carbon composite material. This method is convenient to operate, and the prepared silicon-carbon composite material can inherit the high sphericity and R-value of the spherical porous carbon, significantly improving the discharge specific capacity and initial coulombic efficiency. It also effectively reduces the volume expansion of the silicon-carbon composite material. Furthermore, the deposition forms a uniform and stable carbon coating layer, effectively preventing desilication caused by silicon material expansion, mitigating the excessive SEI film side reaction problem caused by desilication, and improving the cycle coulombic efficiency and cycle capacity of the silicon-carbon composite material. Moreover, the carbon coating layer formed by this method is uniform and thin, mitigating the conductivity reduction problem caused by conventional coating methods, reducing negative electrode impedance and polarization, and simultaneously improving the rate performance and discharge specific capacity of the silicon-carbon composite material.

[0090] According to embodiments of this application, the silicon material and the carbon coating layer are each obtained independently through chemical vapor deposition. This further enhances the overall performance of the silicon-carbon composite material.

[0091] It is understandable that there are no particular restrictions on the specific operations of depositing silicon materials and depositing carbon coatings, and they can be selected and adjusted according to actual needs.

[0092] As an example, spherical porous carbon can be placed in a fluidized bed feeder, the fluidized bed is purged with nitrogen and preheated at 200℃~400℃ for 1h~3h, and then the spherical porous carbon is purged into the fluidization zone under a nitrogen atmosphere and heated to 400℃~700℃ at a heating rate of 1℃ / min~10℃ / min. The silicon source (including but not limited to SiH4, Si2H6, Si3H8, SiHCl3, SiH2Cl2, SiH3Cl, Si2Cl6, SiF4, etc.) is vaporized and slowly introduced into the fluidized bed at a flow rate of 5scc~150scc. After chemical vapor deposition at 400℃~700℃ for 2h~24h, the silicon source passage is closed, and nitrogen is used to continue purging for 1h~3h. The product is then blown into a collection tank and allowed to cool naturally to obtain an intermediate. Then, the intermediate obtained above is placed in a rotary kiln and protected with nitrogen. After preheating at 100℃~300℃ for 1h~3h, a carbon source (including but not limited to CH4, C2H6, C3H8, C2H2, CO, CO2, etc.) is slowly introduced into the rotary kiln at a flow rate of 10scc~100scc. After chemical vapor deposition at 300℃~700℃ for 1h~12h, the carbon source passage is closed, and nitrogen is used to continue purging for 1h~3h. After cooling, the silicon-carbon composite material is obtained.

[0093] A fifth aspect of this application provides a negative electrode sheet. According to an embodiment of this application, the negative electrode sheet includes a negative electrode current collector and a negative electrode material layer disposed on at least one surface of the negative electrode current collector, the negative electrode material layer comprising the spherical silicon-carbon composite material described above. This negative electrode sheet has high specific capacity, is not prone to powder shedding or cracking, has high structural stability, and thus has a long cycle life.

[0094] As an example, the negative electrode material layer may include a negative electrode active material, a thickener, a negative electrode conductive agent, and a negative electrode binder, wherein the negative electrode current collector may be a metal foil, for example, a copper foil.

[0095] According to embodiments of this application, the negative electrode active material may include the silicon-carbon composite material described above.

[0096] According to embodiments of this application, the negative electrode binder in the negative electrode material layer may include, but is not limited to, at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethyl methacrylate (PMAA), and carboxymethyl chitosan (CMCS).

[0097] According to embodiments of this application, the negative electrode conductive agent in the negative electrode material layer may include, but is not limited to, at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0098] In a sixth aspect, this application provides a battery. According to embodiments of this application, the battery comprises the spherical silicon-carbon composite material described above or the negative electrode sheet described above. This battery exhibits high initial coulombic efficiency and specific capacity, and a long cycle life.

[0099] It is understood that there are no particular restrictions on the specific type of battery; it can be a primary battery or a secondary battery. The battery shape can be cylindrical, prismatic, or any other shape. Based on the outer packaging, the battery can be a hard-shell battery, a pouch battery, etc. According to the classification of active ions, the battery can be a lithium-ion battery or a sodium-ion battery, etc.

[0100] Typically, a battery can include a positive electrode, a negative electrode, an electrolyte, and a separator.

[0101] In some embodiments, the electrolyte in the battery described above can be a liquid electrolyte (i.e., an electrolyte solution) or a solid electrolyte.

[0102] In some embodiments, the electrolyte is a liquid electrolyte. In this case, the positive electrode, negative electrode, and separator can be fabricated into a battery cell using a winding or stacking process, and the battery cell and electrolyte can be housed in an outer package. During battery charging and discharging, active ions repeatedly insert and extract between the positive and negative electrodes. The electrolyte acts as a conductor of ions between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, primarily prevents short circuits between the positive and negative electrodes while allowing ions to pass through.

[0103] In some embodiments, the electrolyte is a solid electrolyte. In this case, the positive electrode, negative electrode, electrolyte, and separator can be fabricated into a battery cell using a winding or stacking process, and the battery cell can be housed in an outer package. The positive and negative electrodes are alternately stacked, and the electrolyte and separator are disposed between adjacent positive and negative electrodes.

[0104] In some embodiments, the positive electrode sheet includes a current collector and a positive electrode material layer disposed on at least one side of the current collector. In some embodiments, the positive electrode active layer may include a positive electrode binder, a positive electrode conductive agent, and a positive electrode active material, and may also include additives with specific functions and effects, such as thickeners, sodium supplements, film-forming additives, flame retardants, high-temperature / low-temperature stabilizers, etc., as needed.

[0105] In some embodiments, the positive current collector can be a metal current collector or a composite current collector. For example, metal current collectors include, but are not limited to, aluminum foil current collectors; composite current collectors may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. Composite current collectors can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0106] As an example, the positive electrode active material of the battery may include lithium nickel cobalt manganese oxide (including but not limited to NCM811, NCM613, NCM523, etc.), lithium cobalt oxide, lithium iron phosphate, lithium manganese iron phosphate, lithium manganese oxide, lithium nickel manganese oxide, lithium-rich manganese-based materials, or positive electrode active materials commonly used in the art.

[0107] As an example, the positive electrode binder in the positive electrode active layer may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0108] As an example, the positive electrode conductive agent in the positive electrode active layer may include at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0109] In some embodiments, the separator may be a separator known in the art that can be used in batteries and is stable to the electrolyte used, such as a polyethylene separator, a polypropylene separator, a polyethylene / polypropylene composite separator, etc.

[0110] According to embodiments of this application, a single-cell battery is provided, comprising the aforementioned spherical silicon-carbon composite material or the aforementioned negative electrode sheet. This single-cell battery exhibits high initial coulombic efficiency and specific capacity, and long cycle life.

[0111] According to an embodiment of this application, a battery module is provided. According to an embodiment of this application, the battery module includes the aforementioned spherical silicon-carbon composite material, the aforementioned negative electrode sheet, the aforementioned battery, or the aforementioned single cell. This battery module has high initial coulombic efficiency and specific capacity, and long cycle life.

[0112] According to an embodiment of this application, a battery pack is provided. According to an embodiment of this application, the battery pack includes the aforementioned spherical silicon-carbon composite material, the aforementioned negative electrode sheet, the aforementioned battery, the aforementioned single cell, or the aforementioned battery module. This battery pack exhibits high initial coulombic efficiency and specific capacity, and a long cycle life.

[0113] It is understood that the specific structures of individual cells, battery modules, and battery packs can refer to conventional technologies in this field, and will not be described in detail here.

[0114] In a seventh aspect, this application provides an electrical device. According to an embodiment of this application, the electrical device includes the aforementioned spherical silicon-carbon composite material, the aforementioned negative electrode sheet, the aforementioned battery, the aforementioned single cell, the aforementioned battery module, or the aforementioned battery pack. This electrical device possesses all the features and advantages of the aforementioned spherical silicon-carbon composite material, negative electrode sheet, battery, single cell, battery module, and battery pack, which will not be elaborated upon here.

[0115] According to embodiments of this application, the specific type of electrical equipment is not particularly limited and can be any device that uses a battery as a power source or energy storage unit. For example, electrical equipment includes, but is not limited to, electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), mobile terminals (e.g., mobile phones, laptops, game consoles, wearable devices, etc.), drones, aerospace equipment, satellites, ships, energy storage systems, etc.

[0116] It is understood that, in addition to the battery or battery pack mentioned above, the electrical equipment also includes necessary structures and components, all of which can be made with reference to conventional technologies. For example, an electric vehicle may include a body, chassis, tires, navigation system, radar system, steering system, braking system, lubrication system, cooling system, driving system, etc., which will not be described in detail here.

[0117] The embodiments of this application are described in detail below.

[0118] Example 1 Phenolic resin (sphericity 0.94, K 1.18) was placed in a crucible and transferred to a box furnace. After sintering at 450℃ for 1.5 h, the temperature was increased to 1000℃ and sintered for 8 h. Following sintering, the resin was mechanically crushed and spheroidized to obtain resin carbon particles with an average primary particle size of 12 μm. These particles were then subjected to air jet milling with the classifier wheel frequency, feeding frequency, and induced draft fan frequency set to 140 Hz, 3 Hz, and 12 Hz, respectively, and an air jetting pressure of 0.6 MPa. This yielded a spherical resin carbon precursor with an average primary particle size of 6.8 μm. This precursor was then placed in a rotary kiln under nitrogen protection and preheated at 380℃ for 2 h. Carbon dioxide gas was then introduced into the rotary kiln at a flow rate of 50 scc, and sintered at 1000℃ for 8 h. After sintering, the precursor was depolymerized using an air jet mill to obtain spherical porous carbon with an average primary particle size of 5.4 μm. Figure 3 The result is shown in the particle size distribution diagram.

[0119] Spherical porous carbon was placed in a fluidized bed feeder. The fluidized bed was purged with nitrogen and preheated at 275°C for 1.5 hours. Then, under a nitrogen atmosphere, the spherical porous carbon was purged into the fluidization zone and heated to 500°C at a heating rate of 5°C / min. Silane was slowly introduced into the fluidized bed at a flow rate of 50 scc. After 6 hours of chemical vapor deposition at 500°C, the silicon source pathway was shut off, and nitrogen purging continued for 2 hours. The product was then blown into a collection tank and allowed to cool naturally. The material was then quickly placed into a rotary kiln under nitrogen protection. After preheating at 150°C for 2 hours, acetylene gas was slowly introduced into the rotary kiln at a flow rate of 30 scc. After 4 hours of chemical vapor deposition at 600°C, the carbon source pathway was shut off, and nitrogen purging continued for 2 hours. After cooling, a silicon-carbon composite material was obtained. Figure 1 Its SEM image.

[0120] Example 2 The synthesis process of spherical porous carbon is the same as in Example 1.

[0121] Spherical porous carbon was placed in a fluidized bed feeder. The fluidized bed was purged with nitrogen and preheated at 250°C for 1.5 hours. Then, under a nitrogen atmosphere, the spherical porous carbon was purged into the fluidization zone and heated to 550°C at a heating rate of 5°C / min. Silane was slowly introduced into the fluidized bed at a flow rate of 50 scc. After 6 hours of chemical vapor deposition at 550°C, the silicon source pathway was shut off, and nitrogen purging continued for 2 hours. The product was then blown into a collection tank and allowed to cool naturally. After collection, the material was quickly placed in a rotary kiln and protected with nitrogen. After preheating at 150°C for 2 hours, acetylene gas was slowly introduced into the rotary kiln at a flow rate of 40 scc. After 3 hours of chemical vapor deposition at 600°C, the carbon source pathway was shut off, and nitrogen purging continued for 2 hours. After cooling, a silicon-carbon composite material was obtained.

[0122] Example 3 The synthesis process of spherical porous carbon is the same as in Example 1.

[0123] Spherical porous carbon was placed in a fluidized bed feeder. The fluidized bed was purged with nitrogen and preheated at 250°C for 1.5 hours. Then, under a nitrogen atmosphere, the spherical porous carbon was purged into the fluidization zone and heated to 580°C at a heating rate of 5°C / min. Silane was slowly introduced into the fluidized bed at a flow rate of 60 scc. After 5 hours of chemical vapor deposition at 580°C, the silicon source pathway was shut off, and nitrogen purging continued for 2 hours. The product was then blown into a collection tank and allowed to cool naturally. After collection, the material was quickly placed in a rotary kiln and protected with nitrogen. After preheating at 150°C for 2 hours, acetylene gas was slowly introduced into the rotary kiln at a flow rate of 50 scc. After 3 hours of chemical vapor deposition at 600°C, the carbon source pathway was shut off, and nitrogen purging continued for 2 hours. After cooling, a silicon-carbon composite material was obtained.

[0124] Example 4 The synthesis process of spherical porous carbon is the same as in Example 1.

[0125] Spherical porous carbon was placed in a fluidized bed feeder. The fluidized bed was purged with nitrogen and preheated at 250°C for 1.5 hours. Then, under a nitrogen atmosphere, the spherical porous carbon was purged into the fluidization zone and heated to 600°C at a heating rate of 5°C / min. Silane was slowly introduced into the fluidized bed at a flow rate of 60 scc. After 5 hours of chemical vapor deposition at 600°C, the silicon source pathway was shut off, and nitrogen purging continued for 2 hours. The product was then blown into a collection tank and allowed to cool naturally. After collection, the material was quickly placed in a rotary kiln and protected with nitrogen. After preheating at 150°C for 2 hours, acetylene gas was slowly introduced into the rotary kiln at a flow rate of 50 scc. After 3 hours of chemical vapor deposition at 600°C, the carbon source pathway was shut off, and nitrogen purging continued for 2 hours. After cooling, a silicon-carbon composite material was obtained.

[0126] Example 5 The phenolic resin (sphericity 0.92, K 1.25) was placed in a crucible and transferred to a box furnace. The synthesis process of the remaining spherical porous carbon was the same as in Example 1.

[0127] The synthesis process of the spherical silicon-carbon composite material is the same as in Example 3.

[0128] Example 6 The phenolic resin (sphericity of 0.85, K of 1.30) was placed in a crucible and transferred to a box furnace. The synthesis process of the remaining spherical porous carbon was the same as in Example 1.

[0129] The synthesis process of the spherical silicon-carbon composite material is the same as in Example 3.

[0130] Example 7 Phenolic resin (sphericity 0.95, K 1.18) was placed in a crucible and transferred to a box furnace. After sintering at 450°C for 1.5 hours, the temperature was raised to 700°C and sintered for 8 hours. After sintering, the resin was mechanically ground and spheroidized. The synthesis process of the remaining spherical porous carbon was the same as in Example 1.

[0131] The synthesis process of the spherical silicon-carbon composite material is the same as in Example 3.

[0132] Example 8 The phenolic resin (sphericity of 0.95, K of 1.18) was placed in a crucible and transferred to a box furnace. After sintering at 450°C for 1.5 hours, the temperature was raised to 1500°C and sintered for 8 hours. After sintering, the resin was mechanically ground and spheroidized. The synthesis process of the remaining spherical porous carbon was the same as in Example 1.

[0133] The synthesis process of the spherical silicon-carbon composite material is the same as in Example 3.

[0134] Example 9 Spherical glucose (sphericity of 0.94, K of 1.07) was placed in a crucible and transferred to a box furnace. The synthesis process of the remaining spherical porous carbon was the same as in Example 1.

[0135] The synthesis process of the spherical silicon-carbon composite material is the same as in Example 3.

[0136] Comparative Example 1 Similar to Example 3, the main difference is that mechanical grinding, crushing, shaping, and spheroidizing treatment was not performed. Figure 2 The image shows a SEM image of the obtained silicon-carbon composite material.

[0137] Comparative Example 2 Similar to Example 3, the main difference is that: spherical phenolic resin is placed in a crucible and transferred to a box furnace, sintered at 150°C for 1.5 hours, and then heated to 400°C for 8 hours to obtain porous carbon.

[0138] Performance testing: 1. SEM testing Morphological analysis was performed using a Zeiss Sigma 300 field emission scanning electron microscope (FET). The scanning voltage was 3 kV, and the magnifications were 3 k×, 5 k×, 10 k×, 30 k×, and 50 k×. The powder samples were adhered to conductive tape and dried in a vacuum drying oven before testing.

[0139] 2. Sphericity test Formula for the sphericity of arbitrary particles =

[0140] Vp is the particle volume, and Sp is the particle surface area.

[0141] By combining SEM images of spherical porous carbon with image processing techniques, and using the particle image analysis software Cellpose to process and analyze the SEM images of spherical porous carbon, the particle size and shape information of each particle can be obtained. That is, the particle volume and particle surface area of ​​spherical porous carbon can be directly output. Then, the particle volume and particle surface area of ​​300 particles of spherical porous carbon in the SEM image are statistically analyzed and the average value is calculated to obtain the sphericity.

[0142] 3. R-value test: The spherical silicon-carbon sample and α-alumina were mixed at a mass ratio of 1:1. The mixed sample was XRD tested using a Bruker XRD diffractometer D8 advance. The R-value is the ratio of the diffraction peak intensity of the (002) crystal plane to the derivative peak intensity of the (104) crystal plane of α-alumina.

[0143] 4. Total pore volume test: The total pore volume of the material was tested using the Micromeritics 3Flex three-station multi-functional gas adsorption instrument with carbon dioxide as the gas source.

[0144] 5. Specific surface area test: The specific surface area of ​​the material was tested using the Micromeritics 3Flex three-station multi-functional gas adsorption instrument with carbon dioxide as the gas source and the BET method.

[0145] 6. Micropore ratio test: Using the Micromeritics 3Flex three-station multi-functional gas adsorption instrument with carbon dioxide as the gas source, the proportion of micropores smaller than 2 nm in the sample was calculated using the NLDFT (Nonlocal Density Functional Theory) model.

[0146] 7. Average Particle Size Test: The particle size of the sample was measured using a Malvern Mastersizer 3000 laser particle size analyzer to obtain the D value. 10 D 50 D 90 Equal particle size results, and according to K=(D 90 -D 10 ) / D 50 The particle size concentration data were obtained.

[0147] 8. Compression strength test: According to the national standard GB / T 43091-2023 "Test method for compressive strength of powder", the SPFT single particle mechanical property testing system of Yuaneng Technology was used to randomly locate the sample and select monodisperse particles with similar particle size to conduct mechanical strength test to obtain the single particle compression strength test result.

[0148] 9. Pressure resistance test: According to the national standard GB / T 43091-2023 "Test method for compressive strength of powder", the SPFT single particle mechanical property testing system of Yuaneng Technology was used for testing. The pressure resistance result was calculated based on the compressive strength of random monodisperse samples and the force-bearing area of ​​the samples.

[0149] 10. Battery fabrication and testing Silicon-carbon anode material, conductive carbon black (SP), and binder (LA133) were weighed in an 8:1:1 ratio, then deionized water was added and stirred to form a black slurry. The slurry was coated onto copper foil using an automatic coating machine, and then dried in a pinhole drying oven at 80°C for 24 hours to obtain the anode sheet of the battery. A lithium sheet was used as the counter electrode for the half-cell, a 12μm PE film was used as the separator, and the electrolyte was 1M LiPF6-EC / DMC (volume ratio 1:1). CR2025 coin cells were assembled in a glove box. Electrochemical performance was tested using the Xinwei 3008 battery testing system under the following conditions: 10.1 Specific capacity and first-efficiency test: The assembled battery is placed in the Xinwei Battery Test Cabinet and charged to 4.2V at a current of 0.05C at room temperature of 25℃. After resting for 5 minutes, it is discharged to 2.0V at a current of 0.05C. The specific capacity and first-efficiency of the battery can be obtained. The test results are shown in Table 1.

[0150] 10.2 Room temperature cycle performance: The battery was installed in the Xinwei battery test cabinet and subjected to 300 cycles at room temperature of 25°C, with a current of 1C, an upper limit voltage of 4.2V, and a lower limit voltage of 2.5V. The ratio of the discharge capacity of the 300th cycle to the discharge capacity of the 1st cycle is the capacity retention rate of the battery after 300 room temperature cycles. The test results are shown in Table 1.

[0151] 10.3 1C / 0.05C Capacity Retention Rate: The assembled battery is placed in the Xinwei Battery Test Cabinet and tested at 0.05C and 1.0C at room temperature of 25℃ (the lithium insertion and delithiation rates are the same). The ratio of the delithiation capacity at 1.0C to the delithiation capacity at 0.05C is the 1C / 0.05C capacity retention rate.

[0152] Table 1: Parameters of Spherical Porous Carbon

[0153] Table 2: Parameters of Spherical Silicon-Carbon Composite Materials

[0154] Table 3: Battery Performance

[0155] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0156] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0157] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A spherical porous carbon, characterized in that, satisfy: The sphericity is 0.9~1.0; The R value is 0.7~0.9; Wherein, sphericity = V p S represents the particle volume of the spherical porous carbon. p The surface area of ​​the spherical porous carbon particles; The R value is the ratio of the diffraction peak intensity of the (002) crystal plane to the diffraction peak intensity of the α-alumina (104) crystal plane in the X-ray diffraction pattern of the spherical porous carbon.

2. The spherical porous carbon according to claim 1, characterized in that, satisfy: The sphericity is 0.92~1.0; The R value is 0.72~0.

80.

3. The spherical porous carbon according to claim 1, characterized in that, At least one of the following conditions must be met: The total pore volume is 0.3 mL / g to 1.2 mL / g, preferably 0.7 mL / g to 1.0 mL / g; Specific surface area is 300 m² 2 / g~2800 m 2 / g, preferably 1500 m 2 / g~2200 m 2 / g; The micropore content is 60%~95%, preferably 85%~90%; The average particle size is 3 μm to 10 μm, preferably 4 μm to 6 μm; The spherical porous carbon includes at least one of chemical-based carbon, biomass carbon, and sugar-based carbon; optionally, the chemical-based carbon includes at least one of resin carbon and pitch carbon, the biomass carbon includes at least one of coconut shell carbon, bamboo block carbon, and straw carbon, and the sugar-based carbon includes at least one of sucrose carbon, glucose carbon, and starch carbon.

4. A spherical silicon-carbon composite material, characterized in that, include: The core comprises spherical porous carbon and silicon material as described in any one of claims 1 to 3, wherein at least a portion of the silicon material is located in the pores of the spherical porous carbon; A carbon coating layer that covers at least a portion of the outer surface of the core.

5. The spherical silicon-carbon composite material according to claim 4, characterized in that, At least one of the following conditions must be met: The sphericity of the spherical silicon-carbon composite material is 0.9~1.0, preferably 0.92~1.0; The crush resistance of the spherical silicon-carbon composite material is 30 mN~60 mN, preferably 40 mN~50 mN; The spherical silicon-carbon composite material has a pressure resistance of 600 MPa to 1200 MPa, preferably 800 MPa to 1000 MPa.

6. The spherical silicon-carbon composite material according to claim 4 or 5, wherein at least one of the following conditions is met: The thickness of the carbon coating layer is 5 nm to 50 nm, preferably 5 nm to 20 nm; The specific surface area of ​​the spherical silicon-carbon composite material is 1 m². 2 / g~20 m 2 / g, preferably 1 m 2 / g~5 m 2 / g; The mass percentage of silicon in the spherical silicon-carbon composite material is 20% to 60%, preferably 45% to 55%. The mass percentage of carbon in the spherical silicon-carbon composite material is 40% to 80%, preferably 45% to 55%.

7. A method for preparing spherical porous carbon according to any one of claims 1 to 3, characterized in that, include: The carbon source is first sintered and first crushed to obtain a carbon precursor. The carbon precursor is activated to obtain the spherical porous carbon. The sphericity of the carbon source is 0.85~1.

0.

8. The method according to claim 7, characterized in that, The carbon source satisfies: K≤1.2,K=(D 90 -D 10 ) / D 50 。 9. The method according to claim 7 or 8, characterized in that, The first sintering includes a first-stage sintering and a second-stage sintering performed sequentially; The temperature of the first-stage sintering is 300~600℃, and the holding time of the first-stage sintering is 1~3h; the temperature of the second-stage sintering is 800~1600℃, and the holding time of the second-stage sintering is 5~20h.

10. The method according to any one of claims 7 to 9, characterized in that, The first pulverization includes sequential mechanical grinding and spheroidization followed by a first airflow pulverization, and satisfies at least one of the following conditions: The average primary particle size of the product obtained by the first mechanical grinding and spheroidizing process is 10 μm to 100 μm; The average primary particle size of the carbon precursor obtained by the first airflow pulverization is 4 μm to 15 μm.

11. The method according to any one of claims 7 to 10, characterized in that, The activation process includes: The carbon precursor is preheated under a protective atmosphere, and then subjected to a second sintering in the presence of an activator. The activation treatment satisfies at least one of the following conditions: The activator includes at least one of CO2, H2O, NH3, KOH, K2CO3, KHCO3, Na2CO3, NaOH, NaHCO3, NH4OH, NH4HCO3, (NH4)2CO3, LiOH, Li2CO3, LiHCO3, Ca(OH)2, Ba(OH)2, and Al(OH)3; The preheating temperature is 300℃~500℃; The preheating time is 1 hour to 4 hours; The flow rate of the activator is 10 scc to 100 scc; The second sintering temperature is 600℃~1500℃; The second sintering time is 3h~18h.

12. A method for preparing the spherical silicon-carbon composite material according to any one of claims 4 to 6, characterized in that, include: Silicon material is deposited in the pores of the spherical porous carbon as described in any one of claims 1 to 3 to obtain a core; A carbon coating layer is deposited on at least a portion of the surface of the core to obtain the spherical silicon-carbon composite material.

13. A negative electrode sheet, characterized in that, It includes a negative electrode current collector and a negative electrode material layer disposed on at least one side surface of the negative electrode current collector, wherein the negative electrode material layer includes the spherical silicon-carbon composite material according to any one of claims 4 to 6.

14. A battery, characterized in that, It includes the spherical silicon-carbon composite material according to any one of claims 4 to 6 or the negative electrode sheet according to claim 13.

15. An electrical appliance, characterized in that, It includes the spherical silicon-carbon composite material according to any one of claims 4 to 6, the negative electrode sheet according to claim 13, or the battery according to claim 14.

Images