Highly conductive carbon black, preparation method therefor, device, electrode, and secondary battery

Abstract

The present disclosure relates to the technical field of carbon black materials, and in particular relates to highly conductive carbon black, a preparation method therefor, a device, an electrode, and a secondary battery. The highly conductive carbon black has an average primary particle size of 20-40 nm; and the carbon black primary particles comprise spheres and graphene-like protruding pieces located on the surfaces of the spheres. The carbon black of the present disclosure has graphene-like protruding pieces on the surfaces of the spheres, allowing the carbon black to simultaneously have properties of both carbon black and graphene; node-to-surface contact can be formed between primary particles or with electrode material particles, thereby improving conductivity; and the present invention can significantly improve the conductivity of a slurry and an electrode.

Description

Carbon black with high conductivity, preparation method thereof, device and electrode, and secondary battery

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This disclosure claims priority and rights to the Chinese patent application with patent application number 202311792302.2 filed with the State Intellectual Property Office of China on December 25, 2023, and invention name “Carbon black with high conductivity, preparation method, equipment and electrode, and secondary battery thereof”, and incorporates the entire text of the patent application into this disclosure by reference. Technical Field

[0003] The present disclosure relates to the technical field of carbon black materials, and in particular to a carbon black with high conductivity, a preparation method thereof, a device, an electrode, and a secondary battery. Background Art

[0004] Conductive materials are typically added to the positive and / or negative electrodes of lithium-ion secondary batteries to improve conductivity. Typically, these materials primarily consist of point-type conductive materials, such as carbon black. Linear conductive materials, such as carbon nanotubes and carbon nanofibers, can also be added to further enhance the electrode's conductivity.

[0005] However, despite their excellent conductivity, linear conductive materials are often bundled and / or tangled, making them difficult to disperse evenly in electrode slurries. This can lead to poor uniformity in electrode resistance. To address this dispersibility issue, functional groups can be introduced into linear conductive materials. However, the introduction of functional groups can cause side reactions on the surface of the conductive material, making large-scale application in batteries difficult.

[0006] Graphene also has excellent electrical conductivity and can be used as a planar conductive material. However, the preparation process for single-layer graphene with high electrical conductivity is difficult and the production cost is high. When the graphene thickness exceeds a certain level or the planar size is too large, the excessive surface contact of the graphene can hinder the movement of electrolytes in the electrodes, leading to deterioration of battery performance.

[0007] In view of this, the present disclosure is proposed.

[0008] Summary of the Invention

[0009] The purpose of the present disclosure is to provide carbon black with high conductivity and its preparation method, equipment, electrode, and secondary battery. The carbon black disclosed in the present disclosure has the characteristics of both carbon black and graphene, can significantly improve the conductivity, and the preparation method is simple.

[0010] In order to achieve the above-mentioned purpose of the present disclosure, the present disclosure provides, on one hand, carbon black with high conductivity, wherein the average particle size of the primary particles of the carbon black is 20 to 40 nm;

[0011] The primary particles of the carbon black include a sphere and graphene-like sheet protrusions located on the surface of the sphere.

[0012] In a specific embodiment of the present disclosure, the graphene-like sheet protrusions are multilayer graphene. Furthermore, the number of layers of the multilayer graphene is ≤10, such as 2 to 8 layers.

[0013] In a specific embodiment of the present disclosure, the maximum distance between any two points in the graphene-like sheet protrusion is 10 to 50 nm.

[0014] In a specific embodiment of the present disclosure, the carbon black is acetylene black.

[0015] In a specific embodiment of the present disclosure, the graphene-like sheet protrusions are in-situ grown on the surface of the sphere.

[0016] In a specific embodiment of the present disclosure, the BET specific surface area of ​​the carbon black is 65 to 180 m 2 / g; DBP oil absorption value is 235~375cm 3 / 100g.

[0017] In a specific embodiment of the present disclosure, the carbon black has a 2D Raman spectrum at an excitation wavelength of 532 nm at 2648-2660 cm -1 The full width at half maximum (Δ2D) of the 2D Raman scattering peak in the range is 80-90 cm -1 The ratio of the peak intensity of the 2D Raman scattering peak to the peak intensity of the G Raman scattering peak is 0.55 to 0.87. Furthermore, the Raman crystallite plane size of the carbon black is

[0018] In a specific embodiment of the present disclosure, the crystallinity of the carbon black is 42% to 52%, such as 46% to 52%.

[0019] In a specific embodiment of the present disclosure, the powder resistivity of the carbon black is 0.13 to 0.206 Ω / cm.

[0020] Another aspect of the present disclosure provides a method for preparing any one of the above-mentioned carbon blacks, comprising the following steps:

[0021] Acetylene and methane undergo thermal cracking reaction in a hydrogen-containing and air-isolated environment to form carbon black;

[0022] The flow rates of acetylene, methane and hydrogen are regulated so that the molar ratio of H to C in the thermal cracking reaction zone is greater than 1.

[0023] In a specific embodiment of the present disclosure, the molar ratio of H to C in the thermal cracking reaction zone is 2 to 3.

[0024] In a specific embodiment of the present disclosure, the acetylene and methane gas flows are in opposite directions, and the hydrogen gas flow is arranged at an angle to the acetylene and methane gas flows. Furthermore, the angle is 45° to 60°.

[0025] In another aspect, the present disclosure provides an apparatus for implementing any one of the above-mentioned methods for preparing carbon black, comprising: a cracking furnace body having a reaction chamber formed therein;

[0026] The cracking furnace body is provided with two nozzles communicating with the reaction chamber, and the cracking furnace body is formed with a furnace head corresponding to the two nozzles; the furnace head is provided with at least one gas introduction pipe communicating with the reaction chamber;

[0027] The two nozzles include a first nozzle and a second nozzle.

[0028] In a specific embodiment of the present disclosure, two gas introduction pipes are included, and the two gas introduction pipes are arranged opposite to each other on both sides of the furnace head.

[0029] In a specific embodiment of the present disclosure, the central axis of the gas inlet pipe is arranged at an angle to the central axis of the furnace head, and the angle is preferably 30° to 45°.

[0030] Another aspect of the present disclosure provides an electrode comprising any one of the carbon blacks described above.

[0031] In another aspect, the present disclosure provides a secondary battery comprising a positive electrode, a negative electrode, an electrolyte, and a separator; at least one of the positive electrode and the negative electrode is any one of the electrodes described above.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] (1) The carbon black disclosed in the present invention has graphene-like protrusions on the surface of the sphere, and has the characteristics of both carbon black and graphene. It can form point-to-surface contact between primary particles or with electrode material particles, thereby improving the conductivity and significantly improving the conductivity of the slurry and the electrode.

[0034] (2) The method for preparing carbon black disclosed in the present invention has a simple process and relatively low production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0036] FIG1 is a schematic structural diagram of an apparatus for preparing highly conductive carbon black according to an embodiment of the present disclosure;

[0037] FIG2 is a schematic top view of a nozzle and a furnace head according to an embodiment of the present disclosure;

[0038] FIG3 is a transmission electron microscope image of the carbon black prepared in Example 1 of the present disclosure;

[0039] FIG4 is a partial enlarged view of the transmission electron microscope image of FIG3;

[0040] FIG5 is another partial enlarged view of the transmission electron microscope image of FIG3;

[0041] FIG6 is a Raman spectrum of the carbon black prepared in Example 1 of the present disclosure;

[0042] FIG7 is a Raman spectrum of the carbon black prepared in Example 2 of the present disclosure;

[0043] FIG8 is a Raman spectrum of the carbon black prepared in Example 3 of the present disclosure.

[0044] Reference numerals:

[0045] 10-cracking furnace body; 11-reaction chamber; 12-furnace head;

[0046] 13-nozzle; 14-gas inlet pipe; 15-discharge port;

[0047] 131 - first nozzle; 132 - second nozzle. DETAILED DESCRIPTION

[0048] The technical solutions of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, but those skilled in the art will understand that the embodiments described below are part of the embodiments of the present disclosure, rather than all of the embodiments, and are only used to illustrate the present disclosure, and should not be considered as limiting the scope of the present disclosure. Based on the embodiments in the present disclosure, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present disclosure. If specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0049] Carbon black, as a commonly used conductive material, is widely used in various industries, such as the field of secondary batteries. With the development requirements of the battery field, the conductive properties of carbon black need to be further improved.

[0050] In one aspect, the present disclosure provides carbon black having high electrical conductivity, wherein the average particle size of primary particles of the carbon black is 20 to 40 nm;

[0051] The primary particles of carbon black include spheres and graphene-like protrusions on the surface of the spheres.

[0052] The carbon black disclosed herein has graphene-like protrusions formed on the surface of the sphere, resembling solar prominences. The carbon black disclosed herein possesses both a carbon black core sphere and graphene-like protrusions, giving it the properties of both carbon black and graphene. This allows for point-to-point contact between primary particles or with electrode material particles, thereby improving electrical conductivity. This offers significant advantages over the point-to-point contact of conventional carbon black.

[0053] For example, in different embodiments, the average particle size of the primary particles of the carbon black disclosed herein may be 20 nm, 25 nm, 28 nm, 30 nm, 32 nm, 35 nm, 38 nm, 40 nm, or a range consisting of any two thereof.

[0054] It should be noted that the primary particles of the carbon black disclosed herein are approximately spherical, and the average particle size of the primary particles of the carbon black is the value obtained by averaging the particle sizes measured using a photograph taken with a transmission electron microscope, etc. Furthermore, the particle size is the circle-equivalent diameter calculated from the area of ​​the primary particles.

[0055] In a specific embodiment of the present disclosure, the graphene-like sheet protrusions are multilayer graphene. Furthermore, the number of layers of the multilayer graphene is ≤ 10, such as 2 to 8 layers.

[0056] The graphene-like sheet protrusions disclosed herein are multilayer graphene, and the number of layers of the multilayer graphene can be ≤10, ≤8, ≤5, ≤4, etc. Specifically, the number of layers of the multilayer graphene can be 2 layers, 3 layers, 4 layers, 5 layers, 6 layers, 7 layers, 8 layers or a range consisting of any two of them.

[0057] The number of graphene-like sheet protrusions on the surface of the sphere disclosed herein is ≥1, such as 1, 2, 3, 4, etc., and the specific number is not limited; when the number of graphene-like sheet protrusions located on the surface of the sphere is ≥2, the number of multilayer graphene layers of each graphene-like sheet protrusion can be independently selected from 2 to 8 layers, and can be the same or different.

[0058] When the number of multilayer graphene layers of the graphene-like sheet protrusions on the surface of the sphere meets the above requirements, the graphene sheet can exhibit unique flexibility, and can improve the surface contact between the graphene-like sheet protrusions and between the graphene-like sheet protrusions and the carbon black sphere, thereby improving conductivity.

[0059] In a specific embodiment of the present disclosure, the maximum distance between any two points in the graphene-like sheet protrusion is 10 to 50 nm.

[0060] For example, in various embodiments, the maximum distance between any two points on a graphene-like protrusion can be 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, or a range consisting of any two thereof. The maximum distance between any two points refers to the length L of the largest line segment between one point and another point on the graphene-like protrusion observed by transmission electron microscopy (TEM). Furthermore, the maximum value refers to the average value of L for 100 graphene-like protrusions observed by TEM.

[0061] In practice, the maximum distance between any two points on a specific graphene-like protrusion can be controlled by regulating the thermal cracking process, for example, by adjusting the flow rates of methane and hydrogen. The maximum distance between any two points on the graphene-like protrusions disclosed herein is much smaller than that on ordinary graphene. Because the graphene-like protrusions are smaller, they can effectively reduce the resistance to the movement of the electrolyte solution in the electrode, significantly reducing the ion hindrance effect and improving the smoothness of the diffusion of ions in the electrolyte in the electrode.

[0062] In a specific embodiment of the present disclosure, the carbon black is acetylene black.

[0063] In a specific embodiment of the present disclosure, graphene-like sheet protrusions are in-situ grown on the surface of the sphere.

[0064] Graphene-like sheet protrusions are formed on the surface of the sphere by in-situ growth, which ensures the stability of the bonding of the graphene-like sheet protrusions in the primary particles on the surface of the sphere and further improves the conductivity.

[0065] In a specific embodiment of the present disclosure, the BET specific surface area of ​​carbon black is 65 to 180 m 2 / g; DBP oil absorption value is 235~375cm 3 / 100g.

[0066] The BET specific surface area is tested according to the method of GB / T19587-2004. The more developed the microporous structure is, the larger the BET specific surface area is. That is, the BET specific surface area can reflect the development of the porous structure of carbon black. The BET specific surface area of ​​the carbon black disclosed in the present invention can be 65m 2 / g、85m 2 / g、100m 2 / g, 120m 2 / g, 140m 2 / g, 150m 2 / g, 160m 2 / g, 180m 2 / g or the range composed of any two of them, and the BET specific surface area is within the above range, which shows that the carbon black has a developed porous structure, which increases the number of contact points with other substances (such as active substances in the electrode) and can give full play to the conductivity of the carbon black; at the same time, due to its percolation effect in the electrode material, it has a high conductivity imparting ability.

[0067] The DBP oil absorption value is determined using the standard method of "GB / T 3780.2-2017 Carbon Black Part 2: Determination of Oil Absorption Value". The DBP oil absorption value is used to characterize the void volume within the carbon black aggregate. The larger the void volume of the carbon black aggregate, the larger its DBP oil absorption value, which means that the chain structure of the carbon black is more developed. The DBP oil absorption value of the carbon black disclosed in this disclosure can be 235cm 3 / 100g、250cm 3 / 100g、280cm 3 / 100g、300cm 3 / 100g、320cm 3 / 100g、340cm 3 / 100g、350cm 3 / 100g、375cm 3 / 100g or the range composed of any two thereof, and the DBP oil absorption value is within the above range, indicating that the carbon black disclosed in the present invention has a developed conductive network.

[0068] In the specific embodiment of the present disclosure, carbon black has a 2D Raman spectrum at an excitation wavelength of 532 nm at 2648-2660 cm -1 The full width at half maximum (Δ2D) of the 2D Raman scattering peak in the range is 80-90 cm -1 The ratio of the peak intensity of the 2D Raman scattering peak to the peak intensity of the G Raman scattering peak is 0.55 to 0.87. Furthermore, the Raman crystallite plane size of carbon black is

[0069] The specific 2D Raman spectroscopy test method and test parameters are as follows:

[0070] Using a laser Raman spectroscopy device, several particles of the carbon black sample to be tested were placed on a glass slide and scraped several times with a spatula to make it flat. The test was carried out under the following test conditions: YAG laser (excitation wavelength): 532 nm, number of lines: 600 gr / mm, filter: D0.6, objective lens magnification: 100 times, exposure time: 150 seconds, and accumulation times: 2 times.

[0071] 2D Raman spectroscopy can reveal the number of graphene layers, stacking pattern, and edge structure within graphene-like protrusions in carbon black. The Raman spectrum of graphene consists of several peaks, primarily the G Raman scattering peak, the D Raman scattering peak, and the 2D Raman scattering peak. The G Raman scattering peak is caused by the in-plane vibration of sp2 carbon atoms; the D Raman scattering peak is a graphene disorder vibration peak, reflecting structural defects or edges within the graphene sample; and the 2D Raman scattering peak is a second-order Raman peak of two-phonon resonance, reflecting the interlayer stacking pattern of carbon atoms within the graphene sample. The intensity of the G Raman scattering peak and the peak shape of the 2D Raman scattering peak can reflect the number of graphene layers. In addition to the different peak shapes of the 2D Raman scattering peak, the intensity of the G Raman scattering peak increases approximately linearly with the number of layers in the Raman spectra of graphene with different layer numbers.

[0072] The Raman spectrum of carbon includes a wavelength around 1340 cm -1 and 1580cm -1 The two main "resonance" bands at the center of the Raman spectrum are designated "D" and "G" bands. The Raman crystallite planar size (La) is measured by Raman spectroscopy. Regression analysis yields the following empirical relationship: La = 43.5 × (area of ​​the G band / area of ​​the D band), where La is calculated in angstroms. La can be used to characterize the crystal domains of carbon black and provide an indication of the degree of graphitization; higher La values ​​indicate a higher degree of graphitization.

[0073] For example, in different embodiments, in the 2D Raman spectrum of carbon black with an excitation wavelength of 532 nm, the peak position range of the 2D Raman scattering peak can be selected from but not limited to 2648 cm -1 、2650cm -1 、2652cm -1 、2655cm -1 、2658cm -1 、2660cm -1 or a range consisting of any two thereof; the full width at half maximum Δ2D corresponding to the 2D Raman scattering peak can be selected from but not limited to 80 cm -1 , 81cm -1 , 82cm -1 , 83cm -1 、84cm -1 , 85cm -1 , 86cm -1 , 87cm -1 , 88cm -1 , 89cm -1 , 90cm -1 Or the range of any two thereof; the peak intensity of the 2D Raman scattering peak (I 2D ) and the peak intensity of G Raman scattering peak (I G ) ratio I 2D / IG The Raman crystallite plane size of carbon black can be selected from but not limited to 0.55, 0.60, 0.63, 0.68, 0.70, 0.75, 0.80, 0.85, 0.87 or any two thereof; the Raman crystallite plane size of carbon black can be selected from but not limited to Or a range consisting of any two of them.

[0074] Through in-depth research, the inventors found that when the 2D Raman spectrum of carbon black meets the above conditions, the graphene-like sheet protrusions on the surface of the sphere have a suitable stacking method and number of layers, thereby further improving the conductivity of carbon black.

[0075] In a specific embodiment of the present disclosure, the crystallinity of the carbon black is 42% to 52%, such as 46% to 52%.

[0076] For example, in different embodiments, the crystallinity of carbon black may be 42%, 45%, 46%, 48%, 50%, 52%, or a range consisting of any two thereof.

[0077] The crystallinity of carbon black can reflect its graphitization degree, which is measured from Raman spectroscopy as the ratio of the intensity of the G band to the sum of the intensities of the G band and the D band (I G / I G+D A higher degree of graphitization further improves conductivity, and when used as a conductive material for batteries, it can improve battery capacity, etc.

[0078] In a specific embodiment of the present disclosure, the powder resistivity of carbon black is 0.13 to 0.206 Ω / cm.

[0079] For example, in different embodiments, the powder resistivity of carbon black may be 0.13 Ω / cm, 0.14 Ω / cm, 0.15 Ω / cm, 0.16 Ω / cm, 0.18 Ω / cm, 0.20 Ω / cm, 0.206 Ω / cm, or a range consisting of any two thereof.

[0080] Powder resistivity was measured using a semiconductor powder resistivity tester (Model FZ-2006). Test samples were prepared using a mold under a pressure of 83.5 kg. The carbon black disclosed herein possesses a specific structure, suitable graphene-like protrusion morphology, and a degree of graphitization, which can further reduce the powder resistivity and improve conductivity.

[0081] Another aspect of the present disclosure provides a method for preparing any of the above-mentioned carbon blacks, comprising the following steps:

[0082] Acetylene and methane undergo thermal cracking reaction in a hydrogen-containing and air-isolated environment to form carbon black;

[0083] The flow rates of acetylene, methane and hydrogen are regulated so that the molar ratio of H to C in the thermal cracking reaction zone is greater than 1.

[0084] In the carbon black preparation method disclosed herein, acetylene is thermally cracked to generate nucleation cores of acetylene black, which then grow. Simultaneously, the heat generated by the thermal cracking of acetylene causes methane to crack, form nuclei, and grow, and produces a certain amount of hydrogen atoms. In addition, hydrogen is supplied simultaneously, so that the reaction zone is rich in hydrogen atoms. The rich hydrogen atoms combine with dangling bonds at the edges of carbon clusters on the surface of acetylene black, slowing down and preventing the curling and closing of the carbon clusters to form a spherical surface of acetylene black, thereby forming graphene-like sheet protrusions on the acetylene black spheres.

[0085] In a specific embodiment of the present disclosure, the molar ratio of H to C in the thermal cracking reaction zone is 2 to 3.

[0086] For example, in various embodiments, the molar ratio of H to C in the pyrolysis reaction zone can be 2, 2.2, 2.5, 2.8, 3, or any two thereof. By regulating the molar ratio of H to C in the pyrolysis reaction zone within the above range, the reaction zone is made into a hydrogen-rich environment, further promoting the formation of graphene-like protrusions.

[0087] In actual operation, the flow rates of acetylene, methane, and hydrogen can be adjusted to ensure that the molar ratio of H to C in the thermal cracking reaction zone meets the corresponding conditions. For example, the flow rate ratio of acetylene, methane, and hydrogen can be 10:5: (4.6 to 17.3).

[0088] In a specific embodiment of the present disclosure, the gas flow directions of acetylene and methane are opposite; the gas flow direction of hydrogen is arranged at an angle to the gas flow directions of acetylene and methane.

[0089] By regulating the airflow direction of hydrogen, acetylene and methane to form a certain angle, the acetylene black generated by the cracking of acetylene and methane can quickly pass through the reaction zone, avoiding the existence of a reflux zone and terminating the reaction, further promoting the formation of graphene-like sheet protrusions on the acetylene black spheres.

[0090] In a specific embodiment of the present disclosure, the angle is 45° to 60°, such as 45°, 48°, 50°, 52°, 55°, 58°, 60°, or a range consisting of any two thereof.

[0091] In actual operation, acetylene gas and air can be introduced into the system in advance, and first burned to raise the temperature of the reaction zone to about 850°C (the temperature at which thermal cracking can occur). Then, after stopping the introduction of air for a period of time, the environmental system is isolated from air, and then acetylene and methane are subjected to thermal cracking reaction in an environment containing hydrogen and isolated from air.

[0092] In another aspect, the present disclosure provides an apparatus for implementing any of the aforementioned carbon black production methods, as shown in FIG1 , comprising a cracking furnace body 10 having a reaction chamber 11 formed therein for performing a thermal cracking reaction. The structure of the reaction chamber 11 can be adapted to that of the cracking furnace body 10 .

[0093] The cracking furnace body 10 is provided with two nozzles 13 in communication with the reaction chamber 11 for introducing gas into the reaction chamber 11. The two nozzles 13 can extend into the reaction chamber 11 to introduce gas into the reaction chamber 11 to ensure the smooth progress of the thermal cracking reaction.

[0094] The cracking furnace body 10 is formed with a furnace head 12 corresponding to the two nozzles 13 ; the furnace head 12 is provided with at least one gas introduction pipe 14 communicating with the reaction chamber 11 for introducing hydrogen into the reaction chamber 11 .

[0095] As shown in Figure 2, the two nozzles 13 include a first nozzle 131 and a second nozzle 132. The first nozzle 131 is used to introduce air or methane into the reaction chamber 11, while the second nozzle 132 is used to introduce acetylene into the reaction chamber 11. The first nozzle 131 and the second nozzle 132 are positioned on opposite sides of the furnace head 12, near one end of the furnace head 12, with the central axes of the first and second nozzles 131, 132 perpendicular to the central axis of the furnace head 12. The jets from the first and second nozzles 131, 132 are directed in opposite directions.

[0096] In actual operation, air can be introduced through the first nozzle 131 and acetylene gas can be introduced through the second nozzle 132 to cause combustion and heat up to a certain temperature (such as 850°C) to preheat the cracking furnace; then, after cutting off the air supply for a period of time, methane gas is supplied from the first nozzle 131 and hydrogen is introduced through the gas inlet pipe 14 to cause a thermal cracking reaction, and the carbon black is collected after cooling.

[0097] In a specific embodiment of the present disclosure, two gas introduction pipes 14 are included, and the two gas introduction pipes 14 are arranged opposite to each other on both sides of the furnace head 12 .

[0098] In actual operation, the cracking furnace body 10 may be provided with conventional heating components and temperature control components.

[0099] In the embodiment of the present disclosure, the central axis of the gas inlet pipe 14 is arranged at an angle to the central axis of the furnace head 12. Further, the angle is 30° to 45°. In subsequent embodiments, unless otherwise specified, the angle is 40°, but the present invention is not limited thereto.

[0100] By adjusting the angle between the central axis of the gas inlet pipe 14 and the central axis of the furnace head 12, the acetylene black generated by the cracking of acetylene and methane can pass through the reaction zone quickly, avoiding the existence of a reflux zone that would terminate the reaction, and further promoting the formation of graphene-like sheet protrusions on the acetylene black spheres.

[0101] In a specific embodiment of the present disclosure, the cracking furnace body 10 further includes a discharge port 15 , which is disposed at one end of the reaction chamber 11 away from the furnace head 12 . When the reaction is completed, the carbon black leaves the reaction chamber 11 through the discharge port 15 .

[0102] In the specific embodiment of the present disclosure, the cracking furnace body 10 further includes a heater (not shown), which is heated by induction heating or resistance heating, but is not limited thereto. The heater is used to heat the reaction zone of the reaction chamber 11 to maintain the smooth progress of the cracking reaction.

[0103] Another aspect of the present disclosure provides an electrode comprising any one of the above-mentioned carbon blacks.

[0104] Among them, carbon black is used as a conductive material in the preparation of electrodes. Carbon black can be used as the only conductive material or used together with other conductive materials.

[0105] In another aspect, the present disclosure provides a secondary battery comprising a positive electrode, a negative electrode, an electrolyte, and a separator; at least one of the positive electrode and the negative electrode is any one of the electrodes described above.

[0106] The positive electrode active material or the negative electrode active material can be adjusted according to actual needs and is not limited to a certain type. The following embodiments are illustrated by only one active material, rather than limiting the type of active material.

[0107] Examples 1 to 3

[0108] Examples 1 to 3 provide methods for preparing carbon black with high conductivity, which are prepared using the apparatus shown in FIG1 and include the following steps:

[0109] (1) Acetylene gas is heated at 10 Nm 3 / h flow rate and air at 60Nm 3 / h flow rate into the cracking furnace 10, so that it burns and heats up to 850°C to preheat the cracking furnace body 10; wherein, air is supplied through the first nozzle 131 and acetylene is supplied through the second nozzle 132.

[0110] (2) Continue to supply acetylene through the second nozzle 132, and cut off the air supply for a period of time to ensure that the cracking furnace is isolated from the air. Then, the heater is heated, and methane gas is supplied from the first nozzle 131. Hydrogen gas is supplied through the gas inlet pipe 14. The molar ratio of H to C in the reaction chamber 11 is controlled to be 2 to 3. After the thermal cracking reaction is carried out in the reaction chamber 11, the carbon black produced is collected after cooling.

[0111] In the preparation methods of Examples 1 to 3, in step (2), the flow rates of acetylene gas, methane gas and hydrogen gas are shown in Table 1.

[0112] Table 1 Flow information

[0113] Example 4

[0114] This embodiment provides a method for preparing an electrode slurry, comprising the following steps:

[0115] The positive electrode active material LiCoO2, polyvinylidene fluoride and carbon black were weighed in a mass ratio of 96:2:2, and mixed evenly in an appropriate amount of N-methylpyrrolidone to obtain an electrode slurry; wherein the carbon black in each electrode slurry was the carbon black obtained in Examples 1 to 3, and the corresponding electrode slurries were numbered as Example 4-1, Example 4-2, and Example 4-3, respectively.

[0116] Comparative Example 1

[0117] Comparative Example 1 provides a commercially available carbon black (SP).

[0118] Comparative Example 1 also provides an electrode slurry, which is prepared according to the method of Example 4, except that the carbon black therein is replaced with an equal weight of commercially available carbon black SP.

[0119] Comparative Example 2

[0120] Comparative Example 2 provides a carbon black, and the preparation method is the same as that of Example 1, except that: in step (2), no hydrogen is provided.

[0121] Comparative Example 2 also provides an electrode slurry, which is prepared according to the method of Example 4, except that the carbon black therein is replaced with an equal weight of the carbon black of Comparative Example 2.

[0122] Experimental Example 1

[0123] Figures 3 to 5 are transmission electron micrographs of the carbon black produced in Example 1 of the present disclosure. As can be seen from the figures, the primary particles of the carbon black disclosed herein are roughly spherical, with a structure comprising a sphere and graphene-like protrusions (similar to solar prominences) located on the sphere. Because the graphene-like protrusions on the surface of the carbon black spheres possess the properties of both carbon black and graphene, they can form point-to-point contact between the primary particles and with the electrode material particles, thereby improving conductivity. This offers significant advantages over the point-to-point contact of conventional conductive medium carbon black.

[0124] In addition, it can be seen from the transmission electron microscope image that the maximum distance between any two points in the graphene-like sheet protrusion is 10 to 50 nm.

[0125] Specifically, the sizes of the primary particles of carbon black in different embodiments and comparative examples, as well as the corresponding number of layers of graphene-like protrusions (the average number of layers of 100 graphene-like protrusions observed by transmission electron microscopy) and the maximum distance between any two points if they contain graphene-like protrusions, are shown in Table 2.

[0126] Table 2 Carbon black morphology information of different embodiments and comparative examples

[0127] As can be seen from Table 2, the average particle size of the primary particles of the carbon black disclosed in the present invention is 20-40 nm, the number of multilayer graphene layers in the graphene-like sheet protrusions is ≤10, and the maximum distance between any two points in the graphene-like sheet protrusions is 10-50 nm. Its structural characteristics give it obvious advantages over the point-to-point contact of traditional conductive medium carbon black.

[0128] Experimental Example 2

[0129] Raman spectroscopy tests were performed on the carbon black of different embodiments and comparative examples. The specific testing method was as follows: using a laser Raman spectroscopy device, several particles 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. The test was performed under the following test conditions: YAG laser (excitation wavelength): 532 nm, number of lines: 600 gr / mm, filter: D0.6, objective lens magnification: 100x, exposure time: 150 seconds, and accumulation times: 2 times.

[0130] The Raman spectra of Examples 1 to 3 are used to illustrate their characteristics. Figures 6 to 8 are the Raman spectra of the carbon black prepared in Examples 1 to 3 of the present disclosure, respectively. As can be seen from the figures, the Raman spectra of the carbon black prepared in the present disclosure have three characteristic peaks, namely, D Raman scattering peak, G Raman scattering peak and 2D Raman scattering peak. The carbon black prepared in Examples 1 to 3 has a peak at 2648-2660 cm -1 The full width at half maximum (FWHM) of the 2D Raman scattering peaks appearing in the range of -1, 80cm -1 , 85cm -1 Among them, the 2D Raman scattering peak is a symmetrical sharp single peak, and the peak position of the 2D Raman scattering peak is lower than that of general bulk graphite (about 2710 cm -1 ) shifts to the left, which is the characteristic peak of graphene that is different from bulk graphite. This also proves the existence of graphene-like sheet protrusions in the carbon black disclosed in the present invention, which is consistent with the TEM result.

[0131] In addition, there is a strong correlation between the 2D Raman scattering peak and the structure and stacking mode of the graphene layer. Generally, the fewer the number of graphene layers, the sharper and more symmetrical the 2D Raman scattering peak. The 2D Raman scattering peak of the carbon black prepared in the present disclosure has symmetry, and I 2D / I G The I of conventional high-quality single-layer graphene is 0.55, 0.87, and 0.70 respectively. 2D / I G As the ratio decreases, the number of graphene layers increases, but the Raman scattering of the graphite layer on the surface of the carbon black sphere is removed, and the contribution of the Raman scattering of the carbon black prepared by the present invention to the G peak of the Raman spectrum is reduced. 2D / I G is 0.55~0.87, indicating that the number of graphene-like protrusions in carbon black is small, which is consistent with the TEM results. 2D / I G When the π / π is 0.55 to 0.87, the graphene-like sheet protrusions of carbon black can exhibit the unique flexibility of the graphene sheet, and can improve the surface contact between the graphene-like sheet protrusions and between the graphene-like sheet protrusions and the carbon black spheres, so that the carbon black can have excellent conductivity.

[0132] Further calculations were made through Raman spectra, and the La of the carbon blacks prepared in Examples 1 to 3 were This indicates that the carbon black prepared in the present invention has a high degree of graphitization.

[0133] At the same time, the degree of graphitization of carbon black was further characterized by crystallinity. Raman spectroscopy showed that the crystallinity of the carbon black prepared in Examples 1 to 3 was 46%, 52%, and 42%, respectively, further demonstrating that the carbon black prepared in the present disclosure can achieve a high degree of graphitization. Therefore, when it is used as a conductive material in a battery, its high conductivity can improve the battery capacity and electrical characteristics.

[0134] The characteristic information of carbon black of different embodiments and comparative examples of the present disclosure obtained based on Raman spectroscopy is shown in Table 3.

[0135] Table 3 Characteristic information of different embodiments and comparative examples

[0136] As shown in Table 3, the carbon black of the present disclosure further satisfies the 2D Raman spectrum with an excitation wavelength of 532 nm, and has a wavelength of 2648-2660 cm -1 The full width at half maximum (Δ2D) of the 2D Raman scattering peak in the range is 80-90 cm -1 ; The ratio of the peak intensity of the 2D Raman scattering peak to the peak intensity of the G Raman scattering peak is 0.55 to 0.87; La is The crystallinity is 42% to 52%, indicating that the number of graphene layers, stacking mode and edge structure in the graphene-like sheet protrusions in the carbon black disclosed herein meet certain conditions, which is conducive to further improving the conductive properties of carbon black.

[0137] Experimental Example 3

[0138] The BET specific surface area of ​​the carbon black of different embodiments and comparative examples was tested in accordance with GB / T19587-2004; the powder resistivity of the carbon black of different embodiments and comparative examples was tested using a semiconductor powder resistivity tester (model FZ-2006), and the test samples were prepared using a mold under a pressure of 83.5 kg; the DBP oil absorption value of the carbon black of different embodiments and comparative examples was determined using the standard method of "GB / T 3780.2-2017 Carbon Black Part 2: Determination of Oil Absorption". The specific test results are shown in Table 4.

[0139] Table 4 Test results of BET specific surface area, powder resistivity and DBP oil absorption value of different embodiments and comparative examples

[0140] As shown in Table 4, the carbon black disclosed herein has a high BET specific surface area, indicating a well-developed porous structure. This increases the number of contact points between the carbon black and other materials, such as the active material in the electrode, enabling full utilization of the carbon black's conductive properties. Furthermore, the carbon black disclosed herein has a low powder resistivity, indicating significantly improved conductivity compared to similar conductive materials. The DBP oil absorption value, which measures the void volume within the carbon black aggregates, indicates that the carbon black disclosed herein has a well-developed branched structure and a well-developed conductive network.

[0141] The powder resistivity of the electrode slurries in Example 4 and Comparative Examples 1-2 was further tested. The specific testing method included: drying each electrode slurry at 130° C. under vacuum conditions for 3 h and crushing to obtain powder; then using a semiconductor powder resistivity tester (model FZ-2006) for testing. The test sample was prepared using a mold under a pressure of 83.5 kg. The test results are shown in Table 5.

[0142] Table 5 Powder resistivity of different electrode slurries

[0143] The test results above demonstrate that the powder resistivity of the electrode material produced using the carbon black disclosed herein is significantly lower than that of the electrode material produced using the carbon black from the comparative example. This demonstrates that the carbon black disclosed herein has a graphene-like protrusion structure, which helps increase surface contact between the active material and the carbon black, and between the carbon blacks themselves, significantly improving the conductivity of the slurry and electrode material.

[0144] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present disclosure, rather than to limit them. Although the present disclosure has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present disclosure. Industrial Applicability

[0145] The carbon black disclosed in the present invention has the properties of both carbon black and graphene, and can form point-to-surface contact between primary particles or with electrode material particles, thereby improving the conductivity and significantly improving the conductivity of the slurry and the electrode. In addition, the preparation method is simple and has good industrial application prospects.

Claims

1. Carbon black with high electrical conductivity, characterized in that, The average particle size of the primary particles of the carbon black is 20 to 40 nm; The primary particles of the carbon black include spheres and graphene-like sheet protrusions located on the surface of the spheres.

2. The carbon black with high conductivity according to claim 1, characterized in that, The graphene-like sheet protrusions are multi-layer graphene; Preferably, the number of layers of the multi-layer graphene ≤ 10; Preferably, the number of layers of the multi-layer graphene is 2 to 8 layers.

3. The carbon black with high conductivity according to claim 1 or 2, characterized in that, The maximum value of the distance between any two points in the graphene-like sheet protrusions is 10 to 50 nm.

4. The carbon black with high conductivity according to any one of claims 1 to 3, characterized in that, The carbon black is acetylene black.

5. The carbon black with high conductivity according to any one of claims 1 to 4, characterized in that, The graphene-like sheet protrusions grow in-situ on the surface of the spheres.

6. The carbon black with high conductivity according to any one of claims 1 to 5, characterized in that, The BET specific surface area of the carbon black is 65 to 180 m 2 / g; the DBP oil absorption value is 235 to 375 cm 3 / 100 g.

7. The carbon black with high conductivity according to any one of claims 1 to 6, characterized in that, The carbon black satisfies at least one of the following characteristics in the 2D Raman spectrum with an excitation wavelength of 532 nm: (1) The full width at half maximum Δ2D of the 2D Raman scattering peak in the range of 2648 - 2660 cm -1 is 80 - 90 cm -1 ; (2) The ratio of the peak intensity of the 2D Raman scattering peak to the peak intensity of the G Raman scattering peak is 0.55 to 0.87; (3) The Raman microcrystal plane size is 8. The carbon black with high conductivity according to any one of claims 1 to 7, characterized in that, The crystallinity of the carbon black is 42% to 52%; Preferably, the crystallinity of the carbon black is 46% to 52%.

9. The carbon black with high conductivity according to any one of claims 1 to 8, characterized in that, The powder resistivity of the carbon black is 0.13 to 0.206 Ω / cm.

10. The preparation method of the carbon black with high conductivity according to any one of claims 1 to 9, characterized in that, Comprising the following steps: Acetylene and methane are subjected to a thermal cracking reaction in an environment containing hydrogen and isolated from air to form carbon black; Among them, the flow rates of acetylene, methane, and hydrogen are adjusted so that the molar ratio of H to C in the thermal cracking reaction zone > 1.

11. The preparation method according to claim 10, characterized in that, The molar ratio of H to C in the thermal cracking reaction zone is 2 to 3.

12. The preparation method according to claim 10 or 11, characterized in that, The gas flow directions of the acetylene and the methane are opposite; the gas flow direction of the hydrogen is arranged at an angle to the gas flow directions of the acetylene and the methane; Preferably, the angle is 45° to 60°.

13. An apparatus for implementing the preparation method according to any one of claims 10 to 12, characterized in that, Comprising: A cracking furnace body, inside which a reaction chamber is formed; The cracking furnace body is provided with two nozzles communicating with the reaction chamber, and the cracking furnace body forms a furnace head corresponding to the two nozzles; at least one gas inlet pipe communicating with the reaction chamber is provided in the furnace head; The two nozzles include a first nozzle and a second nozzle.

14. The device according to claim 13, characterized in that, Two gas inlet pipes are included, and the two gas inlet pipes are oppositely arranged on both sides of the furnace head.

15. The device according to claim 12 or 13, characterized in that, The central axis of the gas inlet pipe is arranged at an angle to the central axis of the furnace head; Preferably, the angle is 30° to 45°.

16. An electrode, characterized in that, Comprising the carbon black according to any one of claims 1 to 9 or the carbon black prepared by the preparation method according to any one of claims 10 to 12.

17. A secondary battery, characterized in that, Comprising a positive electrode, a negative electrode, an electrolyte, and a separator; at least one of the positive electrode and the negative electrode is the electrode according to claim 16.

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