Highly-structured, high specific surface area conductive carbon black based on high crystallinity, its preparation method, equipment, electrode paste, and secondary battery

Abstract

The present invention relates to the technical field of carbon black materials, and in particular to a high-structure, high-specific surface area conductive carbon black based on high crystallinity, and its preparation method, equipment, electrode paste, and secondary battery. For the high-structure, high-specific surface area conductive carbon black based on high crystallinity, the crystallinity of the carbon black is 42% to 51%, the BET specific surface area is 58 to 200 m<supgt;2< / supgt> / g, and the cOAN is 108 to 180 mL / 100 g. The conductive carbon black of the present invention takes into account high crystallinity, high structure, and high specific surface area. When used as a conductive agent, on the one hand, the high crystallinity endows it with excellent electrical conductivity and stability and improves the compatibility with the electrolyte. On the other hand, the structure has sufficient length, a perfect network structure, and the ability to absorb and retain liquid, and has good electrical conductivity, ion conduction ability, and dispersibility, which can significantly improve the battery performance.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon black materials, and in particular to a high-structure, high-specific surface area conductive carbon black with high crystallinity, a preparation method, equipment, electrode paste, and secondary battery thereof. Background Art

[0002] Carbon black is widely used as a high-quality conductive / heat-conducting additive in fields such as rubber and plastics, dry batteries, lead-acid batteries, microwave absorption materials, and secondary lithium batteries. Although the addition ratio of carbon black as an additive is not high, it can play key roles in conductivity, heat conduction, and functional solvent adsorption (electrolyte adsorption performance) in applications. Especially in lithium-ion batteries, it can improve the conductivity of active materials and promote the infiltration of electrolytes into active materials to enhance the battery performance.

[0003] During the production process of carbon black, primary particles will melt into larger three-dimensional space and chain-branch structure aggregates, called carbon black primary structures; aggregates with developed branched chains and void structures will further agglomerate into agglomerates through physical actions such as van der Waals forces. Compared with new conductive agents such as carbon nanotubes and graphene, the aggregates of carbon black particles have developed branched chains and void structures, which contribute to improving battery performance.

[0004] Although some special furnace carbon blacks have high surface areas and structures, during the preparation process of the products, heavy oil is used as the raw material, and impurities such as S / P / moisture will remain in the products, affecting the long-term stability of the batteries. And the reaction to produce furnace carbon black is an endothermic reaction, and natural gas needs to be added for aerobic combustion to maintain the heat required for the reaction, so there are many oxygen-containing functional groups, the reaction temperature is relatively low at 1400 - 2000°C, and the crystallinity of the products is relatively low; and water needs to be added to terminate the reaction, resulting in partial oxidation of the products and residual moisture, affecting the long-term stability.

[0005] In the existing process of preparing acetylene black by thermal cracking method, in order to improve the specific surface area and structure of the products, modified gases such as oxygen and water vapor need to be introduced to achieve this. However, this method will lead to the generation of oxygen-containing functional groups on the product surface, reducing the purity of the product and affecting the battery life when used in batteries. And the introduction of oxygen, water vapor, etc. reduces the reaction temperature, resulting in a decrease in the crystallinity of the products and restricting the basic property of its intrinsic electronic conductivity.

[0006] Therefore, it is of great significance to prepare conductive carbon black with high crystallinity, high structure, and high specific surface area without introducing oxygen-containing substances.

[0007] In view of this, the present invention is specifically proposed. Summary of the Invention

[0008] The object of the present invention is to provide a highly structured, high specific surface area conductive carbon black based on high crystallinity, and its preparation method, equipment, electrode paste, and secondary battery. Without introducing oxygen-containing substances, the carbon black obtained in the present invention has high crystallinity, high structure, and high specific surface area, and has good electrical conductivity and ion conduction ability.

[0009] To achieve the above object of the present invention, on the one hand, the present invention provides a highly structured, high specific surface area conductive carbon black based on high crystallinity. The crystallinity of the conductive carbon black is 42% - 51%, the BET specific surface area is 58 - 200 m 2 / g, and the cOAN is 108 - 180 mL / 100 g.

[0010] In a specific embodiment of the present invention, the OAN of the conductive carbon black is 240 - 350 mL / 100 g.

[0011] In a specific embodiment of the present invention, the structure change rate X of the conductive carbon black is 48.6% - 55%; wherein, the structure change rate X = (OAN - cOAN) / OAN.

[0012] In a specific embodiment of the present invention, the crystallinity of the conductive carbon black is 45% - 51%.

[0013] In a specific embodiment of the present invention, the crystallite size Lc of the conductive carbon black is

[0014] In a specific embodiment of the present invention, the average lattice spacing d(002) of the conductive carbon black is ≤ 0.3546 nm, such as 0.3503 - 0.3546 nm.

[0015] In a specific embodiment of the present invention, the average particle size of the primary particles of the conductive carbon black is 26 - 45 nm.

[0016] In a specific embodiment of the present invention, the average pore size of the conductive carbon black is 9.63 - 10.56 nm.

[0017] In a specific embodiment of the present invention, the volume of pores with a size of 2 - 50 nm measured by nitrogen desorption of the conductive carbon black is 0.1089 - 0.2851 cm 3 / g.

[0018] In a specific embodiment of the present invention, in the conductive carbon black, the proportion of the volume of pores with a size of 2 - 50 nm in the total pore volume is more than 86.87%, such as 86.87% - 90.6%.

[0019] On the other hand, the present invention provides a preparation method for any one of the above-mentioned conductive carbon blacks, including the following steps:

[0020] In an environment containing plasma and isolated from air, gaseous hydrocarbons undergo thermal cracking reactions under the action of a microwave plasma generator to form carbon black.

[0021] In a specific embodiment of the present invention, during the thermal cracking reaction process, the temperature of the plasma reaction zone is controlled to be 3000 - 3500 °C.

[0022] In a specific embodiment of the present invention, the gas flow direction of the gaseous hydrocarbons is arranged at an angle to the gas flow direction of the medium gas generating the plasma. Further, the angle is 30° - 45°.

[0023] In a specific embodiment of the present invention, the gaseous hydrocarbons include at least one of acetylene, toluene, benzene, ethylene, propylene, and butadiene. Further, the gaseous hydrocarbon is acetylene.

[0024] In a specific embodiment of the present invention, the medium gas generating the plasma includes at least one of hydrogen, nitrogen, and argon.

[0025] In a specific embodiment of the present invention, the flow rate ratio of the gaseous hydrocarbons to the medium gas generating the plasma is (4 - 13.5) : 1.

[0026] In a specific embodiment of the present invention, it further includes: introducing a cooling gas at the end of the reaction zone to cool the carbon black formed by the thermal cracking reaction and terminate the reaction. Further, the cooling gas includes at least one of hydrogen, nitrogen, and argon.

[0027] Another aspect of the present invention provides an apparatus for implementing the preparation method of carbon black described in any one of the above, including: a cracking furnace body, inside which a reaction chamber is formed; and, a microwave plasma generator;

[0028] The cracking furnace body forms a furnace head and a cooling part, and the outlet of the furnace head is connected to the inlet of the cooling part; two nozzles communicating with the reaction chamber and at least one first gas inlet pipe communicating with the reaction chamber are provided on the furnace head;

[0029] The microwave plasma generator is correspondingly arranged with the first gas inlet pipe to generate plasma in the reaction chamber.

[0030] In a specific embodiment of the present invention, it further includes at least one second gas inlet pipe communicating with the reaction chamber; the second gas inlet pipe is provided on the furnace head and is close to the outlet of the furnace head.

[0031] In a specific embodiment of the present invention, there are two said first gas inlet pipes, and the two said first gas inlet pipes are arranged oppositely on both sides of the furnace head. Further, the central axis of each said first gas inlet pipe forms an angle with the central axis of the furnace head. The angle is 45° to 60°.

[0032] In a specific embodiment of the present invention, there are two said second gas inlet pipes, and the two said second gas inlet pipes are arranged oppositely on both sides of the furnace head.

[0033] In a specific embodiment of the present invention, there are two said microwave plasma generators, and the two said microwave plasma generators are arranged oppositely on both sides of the furnace head.

[0034] On the other hand, the present invention provides an electrode paste, which includes any one of the above-mentioned conductive carbon blacks.

[0035] On the other hand, the present invention provides a secondary battery, which includes a positive electrode, a negative electrode, an electrolyte, and a separator; at least one of the positive electrode and the negative electrode is made of any one of the above-mentioned electrode pastes.

[0036] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0037] (1) The conductive carbon black of the present invention has both high crystallinity, high structure, and high specific surface area. When used as a conductive agent, on the one hand, the high crystallinity endows it with excellent conductivity, stability, and improved compatibility with the electrolyte. On the other hand, the structure has sufficient length, a perfect network structure, and the ability to absorb and retain liquid, having good conductivity, ion conduction ability, and dispersibility, and can significantly improve the battery performance;

[0038] (2) The preparation method of the conductive carbon black of the present invention is simple in operation and suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0040] Figure 1 It is a schematic structural diagram of the equipment for preparing conductive carbon black provided by the embodiment of the present invention;

[0041] Figure 2 It is a top view schematic diagram of the nozzle and the furnace head provided by the embodiment of the present invention;

[0042] Figure 3 Raman spectrum of the carbon black prepared in Example 1 of the present invention;

[0043] Figure 4 Raman spectrum of the carbon black prepared in Example 2 of the present invention;

[0044] Figure 5 Raman spectrum of the carbon black prepared in Example 3 of the present invention;

[0045] Figure 6 Raman spectrum of the carbon black prepared in Example 4 of the present invention;

[0046] Figure 7 Raman spectrum of the carbon black of Comparative Example 1;

[0047] Figure 8 XRD patterns of the carbon blacks of Examples 1-4 of the present invention and Comparative Example 1;

[0048] Figure 9 Test results of the rate performance of the batteries obtained by using the carbon blacks of Examples 1-4 of the present invention and Comparative Example 1 as conductive agents respectively.

[0049] Reference numerals:

[0050] 10 - cracking furnace body; 20 - microwave plasma generator; 11 - reaction chamber;

[0051] 12 - furnace head; 13 - nozzle; 14 - first gas inlet pipe;

[0052] 15 - second gas inlet pipe; 16 - cooling part; 17 - discharge port;

[0053] 131 - first nozzle; 132 - second nozzle. Detailed implementation manners

[0054] The technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific implementation manners. However, those skilled in the art will understand that the following described embodiments are some embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention. For those conditions not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. For the reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0055] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. These are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0056] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "mounted", "connected", "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0057] Carbon black is widely used as a high-quality conductive / heat-conductive additive in fields such as rubber and plastics, dry batteries, lead-acid batteries, microwave absorption materials, and secondary lithium batteries. However, for existing carbon black, in order to improve the specific surface area and structure of carbon black, oxygen-containing substances, etc. are usually introduced for modification. On the one hand, the introduction of oxygen-containing substances will generate oxygen-containing functional groups on the product surface, which will cause side reactions such as gas evolution during decomposition in the electrochemical system, affecting the battery life; on the other hand, the introduction of oxygen-containing substances, etc. reduces the reaction temperature, resulting in a decrease in the crystallinity of the product, restricting the intrinsic electronic conductivity of carbon black. This has led to the fact that existing conductive carbon black cannot simultaneously possess several characteristics of high crystallinity, high structure, and high specific surface area, directly affecting the further large-scale application of conductive carbon black.

[0058] Based on this, on the one hand, the present invention provides a high-structure, high-specific-surface conductive carbon black based on high crystallinity, with a crystallinity of 42% - 51%, a BET specific surface area of 58 - 200 m 2 / g, and a cOAN of 108 - 180 mL / 100g.

[0059] The conductive carbon black of the present invention combines high crystallinity, high structure, and high specific surface area. When used as a conductive agent, on the one hand, high crystallinity endows it with excellent conductive performance, stability, and improved compatibility with the electrolyte. On the other hand, the structure has sufficient length, a perfect network structure, and the ability to absorb and retain liquid, with good conductivity, ion conduction ability, and dispersibility, and can significantly improve the battery performance.

[0060] The crystallinity of carbon black can characterize its degree of graphitization, and the crystallinity is obtained from the ratio (S G / S G+D ) of the peak area measured as the G band to the sum of the peak areas of the G band and the D band in the Raman spectrum. The crystallinity of the conductive carbon black of the present invention can be 42% to 51%, such as 45% to 51%. Compared with the existing carbon black, the crystallinity is significantly improved, indicating that the conductive carbon black of the present invention has a high degree of graphitization. Therefore, when the conductive carbon black of the present invention is used as a conductive agent, its high degree of graphitization can improve the conductivity of the electrode active material or enhance the stability of the material to ensure the performance of the battery. In the conductive carbon black of the present invention, the crystallinity of the carbon black can be 42%, 44%, 45%, 46%, 49%, 51% or the range composed of any two of them.

[0061] Among them, the specific test method and test parameters of the Raman spectrum of the present invention are as follows:

[0062] Using a laser Raman spectroscopy device, several test objects are placed on a glass slide and scraped with a spatula multiple times to make it flat, and the test is carried out under the following test conditions: YAG laser (excitation wavelength): 514 nm, number of rulings: 600 gr / mm, filter: D0.6, objective magnification: 100 times, exposure time: 150 seconds, number of accumulations: 2 times.

[0063] The BET specific surface area is tested according to the method of GB / T 19587-2004. The BET specific surface area of carbon black can reflect the development of the pore structure of carbon black. The BET specific surface area of the conductive carbon black of the present invention is 58 - 200 m 2 / g. The BET specific surface area within the above range indicates that the conductive carbon black of the present invention has a developed pore structure and chain-branch structure, increasing the number of contact points with other substances (such as the active substance in the electrode), and enabling the full play of the conductivity of carbon black; at the same time, due to its percolation effect in the electrode material, it has a high conductivity endowment ability. In the conductive carbon black of the present invention, the BET specific surface area of the carbon black can be 58 m 2 / g, 61 m 2 / g, 77 m 2 / g, 85 m 2 / g, 100 m 2 / g, 120 m 2 / g, 140 m 2 / g, 145 m 2 / g, 160 m 2 / g, 200 m 2 / g or the range composed of any two of them.

[0064] cOAN is the compressed oil absorption number, which can characterize the carbon black structure in the compressed state of the carbon black material and is also a measure of the secondary structure of carbon black (under working conditions). It is measured by the standard method of "GB / T 3780.4-2017 Carbon Black - Part 4: Determination of Oil Absorption Value of Compressed Specimens". The retention of the carbon black structure in the compressed state indicates the stability of the carbon black structure against shear, grinding, impact, or rolling. The more void structures there are in the carbon black particles, the higher its structure and the better its ability to absorb and retain liquid. The higher the structure of the carbon black, the stronger its ability to form a conductive network through the cross-bridging connection of its developed chain-branch structure in the lithium-ion battery electrode, enabling the carbon black to reach the percolation threshold with a smaller addition amount. The conductive agent of high-structure carbon black has a good ability to absorb and retain liquid, which can increase the ion conduction path and improve the migration rate of lithium ions, thereby improving the battery performance. In the electrode, the carbon black concentration required to overcome the percolation threshold in the active material matrix usually depends on the cOAN, that is, it decreases with the increase of cOAN. The cOAN of the conductive carbon black of the present invention is 108-180 mL / 100 g. On the one hand, when the carbon black is used as a conductive agent, its structure has sufficient length, a perfect network structure, and the ability to absorb and retain liquid, enabling good electrical conductivity and ion conduction ability; on the other hand, the cOAN does not exceed 180 mL / 100 g, which can inhibit the aggregation of aggregates into larger agglomerates caused by the entanglement of aggregate structures with each other, resulting in good dispersibility. In the conductive carbon black of the present invention, the cOAN of the carbon black can be 108 mL / 100 g, 120 mL / 100 g, 130 mL / 100 g, 132 mL / 100 g, 140 mL / 100 g, 150 mL / 100 g, 160 mL / 100 g, 168 mL / 100 g, 170 mL / 100 g, 180 mL / 100 g or the range composed of any two of them.

[0065] In a specific embodiment of the present invention, the OAN of the conductive carbon black is 240-350 mL / 100 g.

[0066] During the formation of carbon black, at high temperatures, spherical primary particles are complexly arranged into branched or chain-like aggregates bonded by chemical bonds, forming the primary structure of carbon black; the primary structure is a structure formed by strong chemical bond forces between aggregates and belongs to a permanent structure; the aggregates are re-aggregated into larger agglomerates through electrostatic forces, forming the secondary structure of carbon black. The void volume generated by these aggregated carbon black aggregates is a measure of the carbon black structure and can be characterized by the oil absorption number (OAN), and the OAN is measured using the standard method of "GB / T 3780.2-2017 Carbon Black - Part 2: Determination of Oil Absorption Value". In the conductive carbon black of the present invention, the OAN of the carbon black can be 240 mL / 100 g, 245 mL / 100 g, 250 mL / 100 g, 260 mL / 100 g, 270 mL / 100 g, 280 mL / 100 g, 290 mL / 100 g, 300 mL / 100 g, 310 mL / 100 g, 320 mL / 100 g, 330 mL / 100 g, 338 mL / 100 g, 350 mL / 100 g or the range composed of any two of them.

[0067] In a specific embodiment of the present invention, the structure change rate X of the conductive carbon black is 48.6% - 55%; wherein, the structure change rate X = (OAN - cOAN) / OAN.

[0068] The larger the structure change rate of the carbon black, the larger the amount of aggregates destroyed when compressing the sample, that is, the structure of the carbon black is unstable, and the liquid absorption and liquid retention ability of the carbon black will be reduced; the smaller the structure change rate of the carbon black, it indicates that the carbon black material maintains most of its structural integrity after compression and maintains a good liquid absorption and liquid retention ability. It is found that the structure change rate of the carbon black cannot be too small. If the structure change rate of the carbon black is too small, the amount of aggregates or agglomerates destroyed when compressing the sample is small, reducing the dispersibility of the carbon black. The structure change rate of the conductive carbon black of the present invention is controlled within 48.6% - 55%, which can make the carbon black take into account the liquid absorption and liquid retention ability, conductivity and dispersibility, and thus when applied as a conductive agent to the electrode, the performance of the battery can be significantly improved. In the conductive carbon black of the present invention, the structure change rate of the carbon black can be 48.6%, 49%, 50%, 50.3%, 50.8%, 51.1%, 52%, 53%, 54%, 55%, 55% or the range composed of any two of them.

[0069] In a specific embodiment of the present invention, the average particle size of the primary particles of the conductive carbon black is 26 - 45 nm.

[0070] It should be noted that the primary particles of conductive carbon black are approximately spherical, and the average particle size of the primary particles of conductive carbon black is the value obtained by averaging the particle sizes measured from the photos taken by a transmission electron microscope or the like. In addition, the particle size is the circular equivalent diameter calculated from the area of the primary particles. In different embodiments, the average particle size of the primary particles of conductive carbon black can be 26 nm, 28 nm, 30 nm, 32 nm, 35 nm, 39 nm, 40 nm, 42 nm, 45 nm, or the range composed of any two of them.

[0071] In a specific embodiment of the present invention, the crystallite size Lc of the conductive carbon black is

[0072] The crystallite size Lc is a factor representing the crystallinity of a carbon material with a crystal structure, and can be calculated by the following Scherrer equation based on the X-ray diffraction data analyzed by X-ray diffraction (XRD).

[0073] Scherrer equation: Lc = 0.89λ / (βCosθ)

[0074] Wherein, 0.89 is the Scherrer constant, λ is the wavelength, θ is the angle at the peak of the d-spacing (002), and β is the full width at half maximum at the peak of the d-spacing (002).

[0075] The crystallite size Lc of the conductive carbon black of the present invention is significantly increased compared with the existing carbon black, indicating that the graphitization degree of the conductive carbon black of the present invention is higher than that of the existing carbon black. In the conductive carbon black of the present invention, the crystallite size Lc can be or the range composed of any two of them.

[0076] In a specific embodiment of the present invention, the average lattice spacing d(002) of the conductive carbon black ≤ 0.3546 nm, such as 0.3503 - 0.3546 nm.

[0077] The graphitization degree of the carbon material can also be characterized by its "d-spacing". The average lattice spacing d(002) of the present invention is defined as the average distance between adjacent hexagonal rings in the c-axis direction, and it is determined by the XRD (002) diffraction peak. The d(002) spacing can be calculated by the following formula according to Bragg's law:

[0078] d = λ / (2Sinθ)

[0079] Wherein: λ = the wavelength of the radiation source (for copper, λ is ), θ = the diffraction angle (in degrees) (peak 002), d = the distance between two carbon layer planes.

[0080] For those skilled in the art, carbon materials with a d-spacing of less than or equal to about 0.3500 nm are generally considered to be graphite carbon (0.3504 nm). The d(002) spacing of the conductive carbon black of the present invention is ≤0.3546 nm, such as 0.3503 - 0.3546 nm, which is greatly reduced compared to the d(002) spacing of existing carbon blacks and is close to the lattice spacing of graphite carbon, further indicating that the degree of graphitization of the carbon of the present invention is high. In different embodiments, the d(002) spacing of the conductive carbon black of the present invention can be 0.3503 nm, 0.351 nm, 0.3515 nm, 0.352 nm, 0.3525 nm, 0.353 nm, 0.3535 nm, 0.354 nm, 0.3544 nm, 0.3546 nm or the range composed of any two of them.

[0081] In a specific embodiment of the present invention, the average pore size of the conductive carbon black is 9.63 - 10.56 nm, such as it can be 9.63 nm, 9.7 nm, 9.8 nm, 9.9 nm, 10 nm, 10.04 nm, 10.56 or the range composed of any two of them.

[0082] In a specific embodiment of the present invention, for the conductive carbon black, the volume of pores with a size of 2 - 50 nm measured by nitrogen desorption is 0.1238 - 0.3147 cm 3 / g, such as it can be 0.1238 cm 3 / g, 0.14 cm 3 / g, 0.16 cm 3 / g, 0.18 cm 3 / g, 0.2 cm 3 / g, 0.25 cm 3 / g, 0.28 cm 3 / g, 0.3 cm 3 / g, 0.3031 cm 3 / g, 0.3147 cm 3 / g or the range composed of any two of them.

[0083] In a specific embodiment of the present invention, in the conductive carbon black, the proportion of the volume of pores with a size of 2 - 50 nm in the total pore volume is more than 86.87%, such as 86.87% - 90.6%. In different embodiments, the proportion of the volume of pores with a size of 2 - 50 nm in the total pore volume can be 86.87%, 87%, 87.99%, 88.5%, 89%, 89.13%, 90%, 90.6% or the range composed of any two of them.

[0084] In a specific embodiment of the present invention, in the conductive carbon black, the total pore volume is 0.1238 - 0.3147 cm 3 / g, such as 0.2624 to 0.3147 cm 3 / g. In different embodiments, the total pore volume of the conductive carbon black can be 0.1238 cm 3 / g, 0.145 cm 3 / g, 0.165 cm 3 / g, 0.185 cm 3 / g, 0.205 cm 3 / g, 0.255 cm 3 / g, 0.2624 cm 3 / g, 0.285 cm 3 / g, 0.3031 cm 3 / g, 0.3147 cm 3 / g or the range composed of any two of them.

[0085] The pore parameters of the present invention are tested according to the method of GB / T19587-2004. Specifically, the nitrogen adsorption method is used to test the pore size distribution. The sample is vacuum degassed at 250 °C for 2 h, and then at the temperature of liquid nitrogen (77 K), the adsorption and desorption performance of the sample for N2 is measured in the range of p / p0 0 to 1. The multi-point BET method is used to determine the specific surface area of the carbon black, the t-plot method is used to analyze the micropore area and micropore volume of the sample, and the DFT method (the QSDFT adsorption branch model of N2@77K in carbon slit pores) is used to calculate the pore size distribution of the carbon black. The pore volume of the conductive carbon black of the present invention can be as high as 0.3147 cm 3 / g, and the proportion of the mesopore (2 - 50 nm) pore volume is above 86.87%, indicating that the conductive carbon black of the present invention has a developed pore structure, endowing the conductive carbon black of the present invention with excellent liquid absorption and retention capabilities.

[0086] On the other hand, the present invention provides a preparation method for any one of the above conductive carbon blacks, comprising the following steps:

[0087] The gaseous hydrocarbon undergoes a thermal cracking reaction to form carbon black under the action of a microwave plasma generator in an environment containing plasma and isolated from air.

[0088] The preparation method of the conductive carbon black of the present invention uses a microwave plasma generator to generate plasma heating during pyrolysis to provide reaction heat, increase the temperature, which is more conducive to nucleation, increase the number of nucleations, that is, increase the number of particles in the nucleation mode, make the overall particle size of the formed primary particles smaller, contribute to the formation of chain-like high-structure carbon black with small particles, and is conducive to improving the graphitization degree of carbon black. The main driving forces for the agglomeration of carbon black particles in the reaction flow field are Brownian motion and turbulent effects. Turbulent agglomeration is the agglomeration behavior that occurs when particles move with the fluid in the flow field. During the formation and growth of carbon black particles, nucleation, surface growth, collision are directly related to the final morphology of the particle aggregates. The ambient temperature, pressure, flow characteristics and the type of pyrolysis raw materials directly affect the microscopic morphology and structural characteristics of the pyrolysis products. The production method adopted in the present invention has a higher reaction temperature, the fractal dimension of carbon black particles becomes smaller, has a more fluffy porous medium-like structure, the morphology of the agglomerates is more complex, and the structure of carbon black is improved.

[0089] At the same time, gaseous hydrocarbons will generate high-temperature soot during high-temperature pyrolysis. The medium gas for generating plasma generates plasma gas under the action of the microwave plasma generator, mixes with the high-temperature soot, dilutes the soot, reduces the collision and combination between carbon atoms, thereby inhibiting the growth of the primary particles and aggregates of carbon black.

[0090] In addition, the addition of the medium gas for generating plasma generates plasma gas under the action of the microwave plasma generator, so that there is a certain amount of atoms (such as hydrogen atoms) in the reaction zone, which can combine with the dangling bonds at the edges of the surface carbon clusters of carbon black, slow down and prevent the curling and closing of the carbon clusters to form a spherical surface of carbon black, thereby inhibiting the growth of the primary particles of carbon black and increasing the specific surface area and structure of carbon black. In addition, under the action of the microwave plasma generator, the formation of the plasma region expands the reaction formation region of carbon black, further increases the reaction time to extend the residence time of carbon black particles, increases the collision opportunity, and is conducive to the formation of a well-developed branched chain structure of carbon black.

[0091] In actual operation, gaseous hydrocarbons and air or oxygen can be pre-introduced into the system, first burned to raise the temperature of the reaction zone to a certain temperature (the temperature at which pyrolysis can occur, such as about 850 °C) to preheat the system; then stop introducing air or oxygen for a period of time, isolate the air in the environmental system, and then make the gaseous hydrocarbons undergo pyrolysis reaction under the action of the microwave plasma generator in an environment containing plasma and isolated from air.

[0092] In the specific embodiment of the present invention, during the pyrolysis reaction process, the temperature of the plasma reaction zone is controlled at 3000 - 3500 °C.

[0093] During the thermal cracking reaction process, the temperature of the plasma reaction zone can be assisted to be adjusted by a microwave plasma generator to 3000-3500 °C, so as to improve the graphitization degree of carbon black. For example, the temperature of the plasma reaction zone can be controlled at 3000 °C, 3100 °C, 3200 °C, 3300 °C, 3400 °C, 3500 °C or any range composed of any two of them.

[0094] In a specific embodiment of the present invention, the gas flow direction of the gaseous hydrocarbon and the gas flow direction of the medium gas for generating plasma are arranged at an angle. Further, the angle is 30°-45°.

[0095] By setting the angle, the existence of the reflux zone can be avoided and the reaction can be terminated. For example, in different embodiments, the angle can be 30°, 32°, 35°, 38°, 40°, 43°, 45° or any range composed of any two of them. In the subsequent specific embodiments, if no additional explanation is made, the angle here is 45°, but it is not limited thereto.

[0096] In a specific embodiment of the present invention, the gaseous hydrocarbon includes at least one of acetylene, toluene, benzene, ethylene, propylene and butadiene, and preferably acetylene.

[0097] In a specific embodiment of the present invention, the medium gas for generating plasma includes at least one of hydrogen, nitrogen and argon, and preferably hydrogen.

[0098] In a specific embodiment of the present invention, the flow rate ratio of the gaseous hydrocarbon to the medium gas for generating plasma is (4-13.5):1.

[0099] For example, in different embodiments, the flow rate ratio of the gaseous hydrocarbon to the medium gas for generating plasma can be 4:1, 6.7:1, 10:1, 12:1, 13.3:1, 13.5:1 or any range composed of any two of them.

[0100] In a specific embodiment of the present invention, it further includes: introducing a cooling gas at the end of the reaction zone to cool the carbon black formed by the thermal cracking reaction and terminate the reaction. Further, the cooling gas includes at least one of hydrogen, nitrogen and argon.

[0101] The present invention further introduces a cooling gas at the end of the reaction zone, cools the carbon black in the reaction zone and quickly blows it into the cooling part to terminate the excessive growth of the carbon black.

[0102] Another aspect of the present invention provides an apparatus for implementing the preparation method of any one of the above carbon blacks, as Figure 1 shown, including: a cracking furnace body 10, inside which a reaction cavity 11 is formed for carrying out a thermal cracking reaction, including the occurrence and termination of the thermal cracking; and, a microwave plasma generator 20. Among them, the cavity structure of the reaction cavity 11 can be adapted to the structure of the cracking furnace body 10.

[0103] The cracking furnace body 10 forms a furnace head part 12 and a cooling part 16, and the outlet of the furnace head part 12 is connected to the inlet of the cooling part 16. According to the illustration, the furnace head part 12 is used for thermally cracking the gaseous hydrocarbon raw material to prepare carbon black, and the cooling part 16 is formed at the outlet end of the furnace head part 12 and is used for cooling and collecting the carbon black. Further, the cracking furnace body 10 is provided with a discharge port 17 at one end of the reaction chamber 11 away from the furnace head part 12, that is, the discharge port 17 is arranged at the bottom of the cooling part 16. When the reaction is completed, the prepared carbon black leaves the reaction chamber 11 through the discharge port 17.

[0104] The furnace head part 12 is provided with two nozzles 13 communicating with the reaction chamber 11 and at least one first gas inlet pipe 14 communicating with the reaction chamber 11. The first gas inlet pipe 14 is used for introducing a medium gas for generating plasma into the reaction chamber 11.

[0105] As Figure 2 shown, the two nozzles 13 include a first nozzle 131 and a second nozzle 132. The first nozzle 131 is used for introducing oxygen or air or gaseous hydrocarbon into the reaction chamber 11, and the second nozzle 132 is used for introducing gaseous hydrocarbon into the reaction chamber 11. The first nozzle 131 and the second nozzle 132 are arranged on opposite sides of the furnace head part 12 and close to one end of the furnace head part 12. The central axes of the first nozzle 131, the second nozzle 132 and the furnace head part 12 are perpendicular. The spraying directions of the first nozzle 131 and the second nozzle 132 are opposite and tangent to the circumferential direction of the furnace head part 12, so that the gases transported by the first nozzle 131 and the second nozzle 132 generate less backflow and are evenly mixed on the inner wall of the furnace head part 12.

[0106] Further, the two nozzles 13 can respectively extend into the reaction chamber 11 to send the gas into the reaction chamber 11 to ensure the smooth progress of the thermal cracking reaction.

[0107] In actual operation, oxygen or air can be introduced through the first nozzle 131 first, and gaseous hydrocarbon can be introduced through the second nozzle 132. The combustion makes the furnace head part 12 reach a certain temperature (such as 850 °C) to preheat the cracking furnace; then, after cutting off the supply of oxygen or air for a period of time, gaseous hydrocarbon is introduced from the first nozzle 131 and the second nozzle 132. At the same time, a medium gas for generating plasma is introduced through the first gas inlet pipe 14, and the microwave plasma generator 20 is turned on to cause the cracking reaction.

[0108] The microwave plasma generator 20 is correspondingly arranged with the first gas inlet pipe 14 to generate plasma in the reaction chamber 11. The microwave plasma generator 20 acts on the furnace head part 12 to form a plasma region. The corresponding arrangement with the first gas inlet pipe 14 is more helpful for plasmaizing the medium gas for generating plasma and expanding the reaction formation region of carbon black.

[0109] In a specific embodiment of the present invention, two first gas inlet pipes 14 may be included, and the two first gas inlet pipes 14 are oppositely arranged on both sides of the furnace head 12. Further, the central axis of each first gas inlet pipe 14 forms an angle with the central axis of the furnace head 12. Further, the angle is 45° to 60°.

[0110] In different embodiments, the angle between the central axis of the first gas inlet pipe 14 and the central axis of the furnace head 12 may be 45°, 48°, 50°, 52°, 55°, 58°, 60° or a range composed of any two of them. In subsequent specific embodiments, if no additional description is made, the angle here is 45°, but it is not limited thereto.

[0111] In a specific embodiment of the present invention, two microwave plasma generators 20 may be included, and the two microwave plasma generators 20 are oppositely arranged on both sides of the furnace head 12. Further, the outlet of each microwave plasma generator 20 forms an angle with the central axis of the furnace head 12. The angle is 45° to 60°.

[0112] In different embodiments, the angle between the outlet of the microwave plasma generator 20 and the central axis of the furnace head 12 may be 45°, 48°, 50°, 52°, 55°, 58°, 60° or a range composed of any two of them. In subsequent specific embodiments, if no additional description is made, the angle here is 45°, but it is not limited thereto.

[0113] In actual operation, the type of the microwave plasma generator can be adjusted and selected according to actual needs, as long as the corresponding functions can be achieved. Specifically, the microwave plasma generator may include a magnetron, a circulator, a coupler, a tuner, a waveguide (such as a conical waveguide) and a resonator, etc., but it is not limited thereto.

[0114] In a specific embodiment of the present invention, at least one second gas inlet pipe 15 communicating with the reaction chamber 11 is further included; the second gas inlet pipe 15 is opened on the furnace head 12 and close to the outlet of the furnace head 12. The second gas inlet pipe 15 is used to introduce a cooling gas to cool the carbon black in the reaction zone and quickly blow it into the cooling part 16 to terminate the growth of the carbon black.

[0115] In a specific embodiment of the present invention, two second gas inlet pipes 15 may be included, and the two second gas inlet pipes 15 are oppositely arranged on both sides of the furnace head 12. Further, the central axis of each second gas inlet pipe 15 forms an angle with the central axis of the furnace head 12. The angle is 45° to 60°.

[0116] In different embodiments, the included angle between the central axis of the second gas inlet pipe 15 and the central axis of the furnace head 12 can be 45°, 48°, 50°, 52°, 55°, 58°, 60°, or the range composed of any two of them. In the subsequent specific embodiments, if there is no additional explanation, the included angle here is 45°, but it is not limited thereto.

[0117] Another aspect of the present invention provides an electrode paste, including any one of the above conductive carbon blacks.

[0118] When carbon black is used in the electrode paste, it can be used as the sole conductive material or used together with other conductive materials, and the mixing ratio of the co - use can be adjusted according to actual needs.

[0119] Another aspect of the present invention provides a secondary battery, including a positive electrode, a negative electrode, an electrolyte, and a separator; at least one of the positive electrode and the negative electrode is made of any one of the above electrode pastes.

[0120] Among them, the types of the positive electrode active material, the negative electrode active material, the electrolyte, and the separator can be adjusted according to actual needs and are not limited to a certain type. In the following embodiments, only one type of active material, electrolyte, and separator is used for illustrative purposes, rather than a limitation on these types.

[0121] Examples 1 - 4

[0122] Examples 1 - 4 provide a preparation method of a high - structure, high - specific - surface - area conductive carbon black based on high crystallinity, and the preparation is carried out using the equipment as Figure 1 shown, including the following steps:

[0123] (1) Feed acetylene gas at a flow rate of 30 Nm 3 / h and oxygen at a flow rate of 50 Nm 3 / h into the cracking furnace 10 together to make it burn and heat up to 850 °C to preheat the cracking furnace body 10; among them, oxygen is supplied through the first nozzle 131, and acetylene is supplied through the second nozzle 132.

[0124] (2) Continue to supply acetylene gas through the second nozzle 132; after cutting off the oxygen supply for a period of time to ensure that the air is isolated in the cracking furnace, and then supply acetylene gas from the first nozzle 131, and the flow rate of the acetylene gas is 80 - 200 Nm 3 / h; at the same time, supply hydrogen through the first gas inlet pipe 14, turn on the microwave plasma generator to generate plasma of hydrogen, and control the temperature of the plasma reaction zone at 3000 - 3500 °C, and the flow rate of the hydrogen gas is 15 - 20 Nm 3 / h.

[0125] (3) Acetylene is cracked and passes through a high-temperature plasma region to generate carbon black in the reaction chamber 11, and then is cooled and carried by hydrogen gas in the second gas inlet pipe 15 into the cooling section for cooling and collection, thereby preparing carbon black.

[0126] In the preparation methods of Examples 1 to 4, in step (2), the flow rates of acetylene gas and hydrogen gas and the temperature of the plasma reaction zone are shown in Table 1.

[0127] Table 1 Flow rate and temperature information of different examples

[0128]

[0129] Example 5

[0130] This example provides a method for preparing an electrode paste, including the following steps:

[0131] Weigh the positive electrode active material LiCoO2, polyvinylidene fluoride, and carbon black according to a mass ratio of 96:2:2, and mix them evenly in an appropriate amount of N-methylpyrrolidone to obtain an electrode paste; among them, the carbon black in each electrode paste is the conductive carbon black obtained in Examples 1 to 4, and the corresponding numbers of the obtained electrode pastes are Example 5-1, Example 5-2, Example 5-3, and Example 5-4, respectively.

[0132] Example 6

[0133] This example provides a method for preparing a battery, including the following steps:

[0134] Coat the electrode paste on a 20-μm-thick aluminum foil (current collector), dry, roll, and cut to make a positive electrode sheet; use a lithium metal sheet as the counter electrode, a separator (model: celgard 2500), and an electrolyte (1 mol / L lithium hexafluorophosphate dissolved in a volume ratio of 1:1:1 of dimethyl carbonate (DMC) / ethylene carbonate (EC) / ethyl methyl carbonate (EMC)) to prepare a button battery accordingly. Among them, the electrode pastes used in each button battery are the 4 electrode pastes prepared in Example 5, and the corresponding numbers of the obtained batteries are Example 6-1, Example 6-2, Example 6-3, and Example 6-4, respectively.

[0135] Comparative Example 1

[0136] Comparative Example 1 provides a commercially available carbon black.

[0137] Comparative Example 1 also provides an electrode paste. Referring to the preparation method of Example 5, the difference is only that the carbon black therein is replaced with an equal weight of commercially available carbon black, and the obtained electrode paste number is Comparative Example 1-1.

[0138] Comparative Example 1 also provided a battery. Referring to the preparation method of Example 6, the difference was only that the electrode paste was replaced with an equal weight of electrode paste Comparative Example 1-1, and the obtained battery was numbered Comparative Example 1-2.

[0139] Experimental Example 1

[0140] According to the standard method of "GB / T 3780.2-2017 Carbon black - Part 2: Determination of oil absorption number", the OAN and cOAN of carbon black in different examples and comparative examples were measured, and the structure change rate X (X=(OAN - cOAN) / OAN) was calculated. The specific results are shown in Table 2.

[0141] Table 2 OAN, cOAN and structure change rate of carbon black in different examples and comparative examples

[0142] Number OAN (mL / 100g) cOAN (mL / 100g) Structure change rate X Example 1 240 108 55.0％ Example 2 270 132 51.1％ Example 3 338 168 50.3％ Example 4 350 180 48.6％ Comparative Example 1 247 104 57.9％

[0143] As can be seen from Table 2, the cOAN of the conductive carbon black of the present invention is above 108 mL / 100 g, so that the structure of the carbon black has sufficient length, perfect network structure and liquid absorption and retention ability when used as a conductive agent, and good electrical conductivity and ion conduction ability can be obtained. The cOAN of the conductive carbon black of the present invention is below 180 mL / 100 g, which can inhibit the aggregation caused by the entanglement of aggregate structures with each other into larger agglomerates, and the dispersibility becomes good. Further, the structure change rate of the conductive carbon black of the present invention is 48.6% - 55%, which can make the carbon black take into account the liquid absorption and retention ability, electrical conductivity and dispersibility, and then improve the performance of the battery when applied to the electrode.

[0144] Further, according to the method of GB / T 19587-2004, the BET specific surface area and pore parameters of carbon black in different examples and comparative examples were tested. Specifically, the specific surface area and pore size distribution of carbon black were measured by the nitrogen adsorption method. The sample was vacuum degassed at 250 °C for 2 h, and then at the temperature of liquid nitrogen (77 K), the adsorption and desorption performance of the sample for N2 was measured in the range of p / p0 0 - 1. The multi-point BET method was used to determine the specific surface area of carbon black, the t-plot method was used to analyze the micropore area and micropore volume of the sample, and the DFT method (QSDFT adsorption branch model of N2@77K in carbon slit pores) was used to calculate the pore size distribution of carbon black. The specific results are shown in Table 3.

[0145] Table 3 BET specific surface area and pore parameters of carbon black in different examples and comparative examples

[0146]

[0147]

[0148] From the above data, it can be seen that the pore volume of the carbon black in the examples of the present invention is as high as 0.3147 cm3 / g, and the proportion of the mesopore (2 - 50 nm) pore volume is above 86.87% in each case, indicating a more developed mesoporous structure. The BET specific surface area can reflect the development of the void structure of carbon black. The BET specific surface area of the present invention is within the above range, indicating that the carbon black has a developed void structure and chain-branch structure, which increases the number of contact points with other substances (such as the active substances in the electrode), enabling the full play of the conductivity of the carbon black; at the same time, due to its percolation effect in the electrode material, it has a high conductivity endowment ability.

[0149] The average particle size of the primary particles of carbon black is a value obtained by averaging the particle sizes measured from the photos taken by a transmission electron microscope or the like. The average particle size of the primary particles of the conductive carbon black of the present invention is 26 - 45 nm. Specifically, the average particle sizes of the carbon black in Examples 1 - 4 are shown in Table 4 respectively.

[0150] Table 4 Average particle sizes of the primary particles of carbon black in different examples and comparative examples

[0151] Product / Parameter Average particle size of primary particles (nm) Example 1 45 Example 2 39 Example 3 32 Example 4 26

[0152] Experimental Example 2

[0153] Raman spectroscopy tests were carried out on the carbon black of different examples and comparative examples. The specific test method is as follows: Using a laser Raman spectroscopy device, several grains of the carbon black sample to be tested were placed on a glass slide and scraped with a spatula several times to make it flat, and the test was carried out under the following test conditions: YAG laser (excitation wavelength): 514 nm, number of rulings: 600 gr / mm, filter: D0.6, objective magnification: 100 times, exposure time: 150 seconds, number of accumulations: 2 times. Figures 3 to 7 They are the Raman spectra of the carbon black prepared in Examples 1 - 4 of the present invention and the carbon black of Comparative Example 1 respectively.

[0154] As can be seen from the figure, the Raman spectra of the corresponding carbon black have two characteristic peaks, namely the D Raman scattering peak and the G Raman scattering peak. Specifically, the Raman spectrum of carbon includes two main "resonance" bands at about 1340 cm -1 and 1580 cm -1 respectively, which are denoted as the "D" and "G" bands. Generally, it is considered that the D band is attributed to disordered sp 2 carbon and the G band is attributed to graphitic or "ordered" sp 2 carbon. Carbon black is characterized by its crystallinity with a graphitization degree, which is the ratio of the peak area measured as the G band to the sum of the peak areas of the G and D bands (S G / S G+D) Obtained. Measured by Raman spectroscopy, the crystallinities of the conductive carbon blacks prepared in Examples 1-4 of the present invention are 49%, 51%, 45%, and 42% respectively, while the crystallinity of the carbon black in Comparative Example 1 is 38%. It can be seen therefrom that the conductive carbon black prepared by the present invention can obtain a high degree of graphitization. Therefore, when the conductive carbon black of the present invention is used as a conductive agent, the high graphitization degree of the carbon black can improve the conductivity of the electrode active material or improve the stability of the material, and improve the compatibility with the electrolyte to ensure the performance of the battery.

[0155] Figure 8 XRD patterns of the carbon blacks of Examples 1-4 and Comparative Example 1 of the present invention. Graphite is a crystalline form of carbon in which carbon atoms have sp 2 hybrid bonds. The carbon atoms in graphite are arranged in substantially planar hexagonal rings, and the rings are stacked in an order such as ABAB or ABCABC. The XRD analysis of graphite shows main diffraction peaks of (002), (10), (004), and (110) planes. According to Figure 8 Calculated from the XRD data, the average lattice spacing d(002) of the conductive carbon blacks prepared in Examples 1-4 of the present invention are 0.3525 nm, 0.3503 nm, 0.3544 nm, and 0.3546 nm respectively, which are close to the lattice spacing of graphite carbon, consistent with the analysis results of Raman spectroscopy, indicating that the conductive carbon blacks prepared in Examples 1-4 of the present invention have excellent stability. In addition, the average lattice spacing d(002) of the carbon black in Comparative Example 1 is 0.3601 nm. The average lattice spacing d(002) of the carbon black in the examples of the present invention is greatly reduced compared with that of the carbon black in Comparative Example 1, indicating that the graphitization degree of the conductive carbon black of the present invention is significantly higher than that of the carbon black in Comparative Example 1.

[0156] Further calculated according to Figure 8 the XRD data, the crystallite sizes Lc of the conductive carbon blacks prepared in Examples 1-4 of the present invention are while the crystallite size Lc of the carbon black in Comparative Example 1 is The crystallite size Lc of the conductive carbon black of the present invention is greatly increased compared with that of the carbon black in Comparative Example 1, further indicating that the graphitization degree of the carbon black prepared by the present invention is higher than that of Comparative Example 1, which is consistent with the analysis of Raman spectroscopy and the average lattice spacing d(002).

[0157] Experimental Example 3

[0158] The parameters of the electrode slurries prepared in Example 5 and Comparative Example 1 were tested, and the test results are shown in Table 5.

[0159] Table 5 Test results of parameters of different electrode slurries

[0160] Electrode paste number Solid content / % Viscosity / mPa·S Example 5-1 71.93 8821 Example 5-2 71.39 7064 Example 5-3 62.67 7965 Example 5-4 59.49 7320 Comparative Example 1-1 71.36 8921

[0161] Among them, the above parameter testing method includes: using a battery slurry solid content detector, based on the principle of weight loss on drying, obtaining the solid content rate of the sample by the ratio of the weight of the dried sample after heating to the weight of the wet sample before heating, that is, measuring the solid content of each slurry; using an NDJ-9s viscosity tester, with a No. 3 rotor and a rotation speed of 12 revolutions per minute, measuring the viscosity of each electrode slurry at a temperature of 25°C.

[0162] According to the test results in Table 5, when the solid contents are not very different, the viscosities of the electrode slurries prepared from the carbon blacks of Examples 1 to 4 are significantly lower than those of the electrode slurry prepared from the carbon black of Comparative Example 1, which also shows that the conductive carbon blacks prepared in Examples 1 to 4 of the present invention have excellent dispersibility. When mixed with the active material and the binder, they are not easy to form aggregates, and are easily shear-dispersed during the dispersion treatment, thus forming an electrode slurry with a relatively low viscosity. At the same time, the shear of the prepared slurry can form a uniformly dispersed electrode slurry without seriously damaging the primary structure of the carbon black in the electrode slurry, which can greatly improve the characteristics of the corresponding secondary battery.

[0163] Further, performance tests were carried out on the batteries prepared in Example 6 and Comparative Example 1, and the test results are shown in Figure 9 . Among them, the test method for the rate performance of the battery includes: leaving the prepared battery to stand for 12 h, using a Neware battery test system, aging three times at a charge-discharge rate of 0.1C and a voltage range of 4.35 - 2.8V at 25°C, then charging at a rate of 0.5C, and discharging at rates of 0.2C, 0.5C, 1C, 2C, 3C, 5C, 6C, 8C, and 10C respectively, and carrying out the rate performance test in the voltage range of 4.35 - 2.8V.

[0164] According to Figure 9 the rate performance test results, the discharge capacities of the batteries numbered Example 6-1, Example 6-2, Example 6-3, and Example 6-4 at a rate of 10C are 88.41%, 89.11%, 93.4%, and 94.33% of the initial capacity respectively, and the discharge capacity of the battery numbered Comparative Example 1 at a rate of 10C is 82.73% of the initial capacity, indicating that the conductive carbon blacks prepared in Examples 1 to 4 of the present invention are uniformly dispersed in the battery chip and coated on the surface of lithium cobaltate. The high crystallinity makes the formed conductive network have stronger electronic conductivity, and the lower structure change rate makes the prepared carbon black have better liquid absorption and liquid retention capabilities, which is more conducive to lithium ion transmission and reduces the polarization degree inside the battery; the high-crystallinity conductive carbon black can reduce the side reactions of the internal electrolyte and lithium cobaltate in the battery, improve the compatibility with the electrolyte, and is more conducive to the battery capacity to play, thus improving the rate performance of the battery.

[0165] 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 foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and 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. Based on highly crystalline high-structure and high-specific surface area conductive carbon black, it is characterized in that, The crystallinity of the conductive carbon black is 42% to 51%, the BET specific surface area is 58 to 200 m 2 / g, and the cOAN is 108 to 180 mL / 100 g; The OAN of the conductive carbon black is 240-350 mL / 100 g; The structure change rate X of the conductive carbon black is 48.6%-55%; wherein, the structure change rate X = (OAN - cOAN) / OAN; The crystallite size Lc of the conductive carbon black is 18.82-29.09 Å; The high-structure, high-specific surface area conductive carbon black based on high crystallinity is prepared by thermal cracking reaction of gaseous hydrocarbons in an environment containing plasma and isolated from air; During the thermal cracking reaction process, the temperature of the plasma reaction zone is controlled at 3000-3500 °C; The gaseous hydrocarbon is at least one of acetylene, toluene, benzene, ethylene, propylene and butadiene.

2. The highly structured and high specific surface area conductive carbon black based on high crystallinity according to claim 1, wherein The crystallinity of the conductive carbon black is 45%-51%.

3. The highly structured and high specific surface area conductive carbon black based on high crystallinity according to claim 1, characterized in that, The average lattice spacing d(002) of the conductive carbon black is ≤ 0.3546 nm.

4. The highly structured and high specific surface area conductive carbon black based on high crystallinity according to claim 3, characterized in that, The average lattice spacing d(002) of the conductive carbon black is 0.3503-0.3546 nm.

5. The highly structured and high specific surface area conductive carbon black based on high crystallinity according to claim 1, characterized in that, The average particle size of the primary particles of the conductive carbon black is 26-45 nm.

6. The highly structured and high specific surface area conductive carbon black based on high crystallinity according to claim 1, characterized in that, Meet at least one of the following characteristics: (1) The average pore size of the conductive carbon black is 9.63-10.56 nm; (2) The volume of pores with a size of 2 to 50 nm measured by nitrogen desorption of the conductive carbon black is 0.1089 to 0.2851 cm 3 / g; (3) In the conductive carbon black, the proportion of the volume of pores with a size of 2-50 nm in the total pore volume is more than 86.87%.

7. The highly structured and high specific surface area conductive carbon black based on high crystallinity according to claim 6, characterized in that, In the conductive carbon black, the proportion of the volume of pores with a size of 2-50 nm in the total pore volume is 86.87%-90.6%.

8. The preparation method of the high-structure and high-specific surface area conductive carbon black based on high crystallinity according to any one of claims 1 to 7, characterized in that, Including the following steps: The gaseous hydrocarbon undergoes a thermal cracking reaction in an environment containing plasma and isolated from air under the action of a microwave plasma generator to form carbon black; During the thermal cracking reaction process, the temperature of the plasma reaction zone is controlled at 3000-3500 °C; The gaseous hydrocarbon is at least one of acetylene, toluene, benzene, ethylene, propylene and butadiene.

9. The preparation method according to claim 8, wherein The gas flow direction of the gaseous hydrocarbon is arranged at an angle with the gas flow direction of the medium gas generating the plasma.

10. The preparation method according to claim 9, characterized in that, The angle is 30°-45°.

11. According to the preparation method described in claim 8, characterized in that, The gaseous hydrocarbon is acetylene.

12. The preparation method according to claim 9, wherein, The medium gas generating the plasma includes at least one of hydrogen, nitrogen and argon.

13. The preparation method according to claim 9, characterized in that, The flow rate ratio of the gaseous hydrocarbon to the medium gas generating the plasma is (4-13.5):

1.

14. The preparation method according to claim 9, wherein Also includes: Cooling gas is introduced at the end of the reaction zone to cool the carbon black formed by the thermal cracking reaction and terminate the reaction.

15. The preparation method according to claim 14, wherein The cooling gas includes at least one of hydrogen, nitrogen and argon.

16. An apparatus for implementing the preparation method according to any one of claims 8 to 15, characterized in that, Including: A cracking furnace body, inside which a reaction chamber is formed; and, a microwave plasma generator; The cracking furnace body forms a furnace head and a cooling part, and the outlet of the furnace head is connected to the inlet of the cooling part; two nozzles communicating with the reaction chamber and at least one first gas inlet pipe communicating with the reaction chamber are provided on the furnace head; The microwave plasma generator is correspondingly arranged with the first gas inlet pipe to generate plasma in the reaction chamber.

17. The device according to claim 16, characterized in that, It also includes at least one second gas inlet pipe communicating with the reaction chamber; the second gas inlet pipe is provided on the furnace head and is close to the outlet of the furnace head.

18. The device according to claim 17, characterized in that, It includes two of the second gas inlet pipes, and the two second gas inlet pipes are oppositely arranged on two sides of the furnace head.

19. The device according to claim 16, characterized in that, It includes two of the first gas inlet pipes, and the two first gas inlet pipes are oppositely arranged on two sides of the furnace head.

20. The device according to claim 19, characterized in that, The central axis of each of the first gas inlet pipes forms an angle with the central axis of the furnace head.

21. The device according to claim 20, characterized in that, The angle is 45° to 60°.

22. The apparatus according to claim 16, characterized in that, It includes two of the microwave plasma generators, and the two microwave plasma generators are oppositely arranged on two sides of the furnace head.

23. An electrode paste, characterized in that, It includes the high-structure, high-specific surface area conductive carbon black based on high crystallinity according to any one of claims 1 to 7 or the high-structure, high-specific surface area conductive carbon black based on high crystallinity prepared by the preparation method according to any one of claims 8 to 15.

24. A secondary battery, characterized in that, It includes a positive electrode, a negative electrode, an electrolyte and a separator; at least one of the positive electrode and the negative electrode is made of the electrode paste according to claim 23.

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