High-electrical-conductivity carbon black and preparation method therefor

Abstract

Disclosed in the present invention are high-electrical-conductivity carbon black and a preparation method therefor. The preparation method comprises: placing carbon black in a carrier, and subjecting same to Joule thermal transient high-temperature reaction in a low-pressure environment and an inert gas atmosphere to improve the electrical conductivity of the carbon black, wherein the carrier is selected from at least one of carbon cloth, carbon felt, carbon paper and graphite flakes or a metal having a melting point of 1400°C or above. The temperature of the Joule thermal transient high-temperature reaction is 1000-1700°C. In the method, the process for preparing the high-electrical-conductivity carbon black is simple, the universality is high, and new chemical pollution is not introduced.

Description

A kind of high conductive carbon black and preparation method thereof Technical Field

[0001] The invention relates to high-conductivity carbon black and a preparation method thereof, belonging to the technical field of conductive carbon black. Background Art

[0002] With the urgent need for a new energy revolution, energy storage technology has ushered in a historic opportunity for leapfrogging. Among the many energy storage technologies, secondary batteries have attracted significant attention due to their modularity. Currently, global lithium-ion battery production has reached unprecedented levels. Conductive agents, a crucial component of lithium-ion batteries, although they comprise a relatively small portion of the battery, significantly improve the conductivity of the positive and negative electrodes and reduce polarization, thus significantly impacting the actual performance of lithium-ion batteries.

[0003] The charging and discharging process of lithium-ion batteries requires the participation of lithium ions and electrons, which requires the battery electrodes to be mixed conductors of ions and electrons with good electrical conductivity. However, the current positive electrode active materials are mostly transition metal oxides or transition metal phosphates, such as LiCoO2, LiMn2O4 and LiFePO4, whose electronic conductivity is 10 −3 S / cm, 10 −4 S / cm and 10 −9 S / cm. The low electronic conductivity of the above materials significantly limits the cycle life and rate performance of the battery. Therefore, it is usually necessary to add a conductive agent to accelerate electron conduction at the interface between active materials and between active materials and current collectors, reducing the overall contact resistance within the electrode, reducing polarization, and improving the overall performance of the battery. Graphite-based negative electrode materials have slightly better conductivity, but they also require the addition of a conductive agent to maintain the stability of the negative electrode material's conductivity during cycling.

[0004] Conductive agents function in electrodes by providing pathways for electron movement. An appropriate conductive agent content results in higher discharge capacity and better cycle performance. Too low a content reduces the number of electron conduction pathways, hindering high-current charge and discharge. Poor conductivity requires a large addition, which reduces the relative content of active material and battery capacity, hindering the development and application of high-power, high-energy-density lithium-ion batteries. Therefore, improving the conductivity of conductive agents is crucial.

[0005] Generally speaking, conductive additives are divided into four categories: granular (e.g., carbon black (CB), zero-dimensional (0D)), highly branched (e.g., Ketjenblack), tubular (e.g., steam-grown carbon fibers and carbon nanotubes, one-dimensional (1D)), and lamellar (e.g., graphene, two-dimensional (2D)). Among these, CBs, represented by Super P, possess the lowest conductivity but also offer the most favorable cost and best processability (i.e., excellent dispersibility). According to electrode percolation theory, the percolation threshold of bulk electronic conductivity is inversely proportional to the spatial scalability of the conductive additive. Therefore, as the spatial dimensionality and degree of graphitization increase, the conductivity of conductive additives (such as Ketjenblack and high-aspect-ratio carbon nanotubes) continues to improve, but at the expense of higher costs and significantly increased dispersion difficulties. This dictates that zero-dimensional carbon black (CB) spherical nanoparticles remain the dominant component of current composite conductive additives. Therefore, improving the conductivity of carbon black is crucial. Summary of the Invention

[0006] The present invention provides a highly conductive carbon black and a preparation method thereof, which can effectively solve the above problems.

[0007] The present invention is achieved in that:

[0008] A method for preparing highly conductive carbon black, characterized in that the carbon black is placed in a carrier and subjected to a Joule heat transient high-temperature reaction in a low-pressure environment and an inert gas atmosphere to improve the conductivity of the carbon black; the carrier is selected from at least one of carbon cloth, carbon felt, carbon paper, and graphite sheet, or a metal with a melting point above 1400°C; and the temperature of the Joule heat transient high-temperature reaction is 1000-1700°C.

[0009] As a further improvement, the carbon black is selected from one or more of Super P, acetylene black, Ketjen black, KS-6, Super S, and 350 G.

[0010] As a further improvement, the metal is selected from one or more of tungsten, molybdenum, tantalum, zirconium and niobium.

[0011] As a further improvement, the low-pressure environment of the Joule heat transient high-temperature reaction is no more than 100 Pa.

[0012] As a further improvement, the operating voltage of the Joule heat transient high-temperature reaction is 10-200 V, and the operating current is 10-200 A.

[0013] As a further improvement, the voltage pulse duration of the Joule heat transient high temperature reaction is 0.1 to 500 s.

[0014] As a further improvement, the gas atmosphere is at least one of argon, nitrogen, helium, krypton, xenon, and radon.

[0015] As a further improvement, the carrier has a length of 5 to 20 cm and a width of 1 to 10 cm.

[0016] As a further improvement, the amount of carbon black used is 0.01-100 g / single batch.

[0017] A highly conductive carbon black prepared by the above method.

[0018] The beneficial effects of the present invention are:

[0019] This invention utilizes Joule heating transient high-temperature technology, which involves rapid heating and cooling, to precisely control the sample's structure based on structure-activity relationships. This technology can also improve the sample's conductivity by screening for its optimal degree of graphitization. This technique allows the synthesized material to be easily maintained in a metastable state (e.g., a high-entropy state) rather than a more thermodynamically stable configuration. Kinetically unfavorable reactions that are difficult to occur under normal conditions (e.g., furnace heating and cooling at atmospheric pressure) can be favored through ultrafast synthesis, allowing the materials synthesized using these methods to remain in a metastable state.

[0020] The present invention can improve the conductivity of the material without introducing new chemical pollution, has strong universality, and is applicable to different types of carbon black.

[0021] The present invention adopts Joule heat transient high temperature technology to overcome the slow heating and cooling speed (0~1 K s -1 ), it has long constant temperature period, low degree of manual intervention, small controllable space limitation, and is easy to achieve engineering amplification and large-scale processing, which is beneficial to improving the conductivity of the conductive agent and promoting the performance optimization of secondary batteries, and has important practical significance. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, 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 invention 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 paying any creative work.

[0023] FIG1 is a diagram showing the electrical conductivity of the carbon black of Sample 1 provided in Example 1 of the present invention after being modified by Joule heat.

[0024] FIG2 is a conductivity diagram of the carbon black of Sample 1 provided in Example 1 of the present invention modified at different temperatures with the same pulse time.

[0025] FIG3 is a laser Raman spectrum of the carbon black of Sample 1 provided in Example 1 of the present invention modified at different temperatures with the same pulse time.

[0026] FIG4 is a conductivity diagram of the carbon black of Sample 1 provided in Example 1 of the present invention modified at the same temperature with different pulse times.

[0027] FIG5 is a conductivity diagram of the carbon black of Sample 2 provided in Example 2 of the present invention after being modified by Joule heat.

[0028] FIG6 is a diagram showing the electrical conductivity of the carbon black of Sample 3 provided in Example 3 of the present invention after being modified by Joule heat.

[0029] FIG7 is a conductivity diagram of the carbon black of Sample 1 provided in Comparative Example 1 of the present invention after being modified by Joule heat.

[0030] FIG8 is a laser Raman spectrum of the carbon black of Sample 1 provided in Comparative Example 1 of the present invention after being modified by Joule heat. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the invention for which protection is sought, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0032] An embodiment of the present invention provides a method for preparing highly conductive carbon black. The carbon black is placed in a carrier and subjected to a Joule heat transient high-temperature reaction in a low-pressure environment and an inert gas atmosphere to improve the conductivity of the carbon black. The carrier is selected from at least one of carbon cloth, carbon felt, carbon paper, and graphite sheet, or a metal with a melting point above 1400°C. The temperature of the Joule heat transient high-temperature reaction is 1000-1700°C.

[0033] The embodiments of the present invention utilize the mechanism of rapid heating and rapid cooling of Joule heat transient high-temperature technology to precisely regulate the structure of the carbon black sample based on the structure-activity relationship, and can improve the conductivity of the sample by screening the optimal degree of graphitization of the carbon black sample.

[0034] The carrier serves as a container for the powdered carbon black sample, generating heat and providing electrical continuity, ensuring more uniform heating of the carbon black, increasing its degree of graphitization and, consequently, its electrical conductivity. The carrier is required to be non-reactive with the carbon black, resist melting during Joule heating transients, and resist fusing with the carbon black at graphitization temperatures. The reason for selecting at least one of carbon materials, such as carbon cloth, carbon felt, carbon paper, or graphite sheets, over carbon nanotubes is that carbon nanotubes readily fuse with carbon black at high temperatures, reducing the degree of graphitization of the carbon black itself. The Joule heating transient high-temperature reaction temperature should be neither too low nor too high. Temperatures below 1000°C make graphitization of the carbon black difficult, while temperatures exceeding 1700°C cause the carrier to melt and penetrate into the graphitized carbon black, reducing its electrical conductivity. The optimal Joule heating transient high-temperature reaction temperature is 1500°C. Above 1500°C, the carbon black's degree of graphitization becomes excessive, leading to a decrease in electrical conductivity.

[0035] In some embodiments, the carbon black is selected from one or more of Super P, acetylene black, Ketjen black, KS-6, Super S, and 350 G.

[0036] In some embodiments, the metal is selected from one or more of tungsten, molybdenum, tantalum, zirconium, and niobium, or an alloy containing one or more of tungsten, molybdenum, tantalum, zirconium, and niobium.

[0037] In some embodiments, the low-pressure environment of the Joule heat transient high-temperature reaction is no greater than 100 Pa. In this low-pressure environment, when the carbon black melts at a transient high temperature, the carbon molecular clusters of the carbon black are more easily diffused under low pressure, and the spacing between adjacent crystal layers of the formed graphitized carbon black is closer to that of an ideal graphite crystal.

[0038] In some embodiments, the operating voltage of the Joule heat transient high temperature reaction is 10-200 V, and the operating current is 10-200 A. Under these voltage and current conditions, the transient high temperature that the instrument can reach is moderate, which is conducive to the graphitization of carbon black, thereby improving the conductivity of the sample.

[0039] In some embodiments, the voltage pulse duration of the Joule heat transient high temperature reaction is 0.1-500 s.

[0040] In some embodiments, the carrier has a length of 5 to 20 cm and a width of 1 to 10 cm. The size of the carrier is adjusted according to the amount of carbon black used to ensure uniform distribution of the carbon black and improve the degree of graphitization.

[0041] In some embodiments, the amount of carbon black used is 0.01~100 g / single batch. The amount of carbon black used in a single batch affects the uniformity of heating. If the amount used is greater than 100 g, it is difficult to heat evenly, resulting in unsatisfactory graphitization of carbon black.

[0042] In some embodiments, the gas atmosphere is at least one of argon, nitrogen, helium, krypton, xenon, and radon.

[0043] The embodiment of the present invention provides a highly conductive carbon black prepared by the above method.

[0044] Example 1

[0045] Sample 1 is a high-ash Super P., and its ash analysis is shown in Table 1. 0.5 g of sample 1 was evenly placed on a carrier carbon felt (10 cm long, 5 cm wide), which was then placed in the reaction chamber of a Joule heating device. A vacuum pump was activated to evacuate sample 1 to a low vacuum environment, and argon gas was then introduced to a pressure of 100 Pa.

[0046] Set the operating voltage to 80 V and the operating current to 55 A; start the pulse power supply to instantly heat sample 1 from room temperature to 1500°C under an inert atmosphere; maintain a voltage pulse at 1500°C for 20 seconds; disconnect the power supply, cool the material to room temperature, and then take it out to obtain modified conductive carbon black, referred to as 1500°C-20s.

[0047] Set the operating voltage to 80 V and the operating current to 50 A; start the pulse power supply to instantly heat sample 1 from room temperature to 1400°C under an inert atmosphere; maintain a voltage pulse at 1400°C for 20 seconds; disconnect the power supply, cool the material to room temperature, and then take it out to obtain modified conductive carbon black, referred to as 1400°C-20s.

[0048] Set the operating voltage to 80 V and the operating current to 55 A; start the pulse power supply to instantly heat sample 1 from room temperature to 1500°C under an inert atmosphere; maintain a voltage pulse at 1500°C for 5 s; disconnect the power supply, cool the material to room temperature, and then take it out to obtain modified conductive carbon black, referred to as 1500°C-5 s.

[0049] Table 1

[0050] ItemsUnitsStandardTargetLower LimitUpper LimitValueSample 1Ash%GBT / 37800.20.1

[0051] The conductivity diagrams of the original sample 1 and the modified sample 1 are shown in Figure 1. It can be observed from Figure 1 that the conductivity of the original sample 1 is lower than that of commercial carbon black, but the conductivity of the sample 1 modified by Joule heat is significantly improved compared with the original sample 1 and is higher than that of commercial carbon black, indicating that Joule heat treatment can effectively improve the conductivity of conductive carbon black.

[0052] Conductivity tests were conducted on samples treated at 1500°C for 20 seconds and 1400°C for 20 seconds, and the conductivity spectra are shown in Figure 2. Analysis of the conductivity spectra shows that the conductivity of the samples treated at different temperature pulses for the same duration, as measured by Joule heating, is significantly improved compared to the original sample 1 and is greater than that of commercial carbon black. However, the degree of improvement in carbon black conductivity varies with treatment temperature.

[0053] The conductivity tests were carried out at 1500℃-5s and 1500℃-20s, and the conductivity spectra are shown in Figure 3. Analysis of the conductivity spectra shows that the conductivity of the samples after Joule heating at the same temperature pulse for different times is significantly improved compared with the original samples, and is greater than the conductivity of commercial carbon black. However, the degree of improvement in the conductivity of carbon black varies with different pulse times.

[0054] Raman tests were performed on the 1500℃-20s sample and the 1400℃-20s sample, and the Raman spectra are shown in Figure 4. The Raman spectra analysis shows that compared with the original sample 1, the sample after Joule heat treatment at 1400℃-20s has a larger peak at 2680 cm in the Raman spectrum. -1 A 2D peak gradually forms at the 1400°C-20 s Joule heat treatment, indicating an increase in the degree of graphitization of the material after Joule heat treatment. Combined with conductivity spectrum 4, it can be observed that compared to the original sample, the conductivity of the sample after Joule heat treatment at 1400°C-20 s is significantly improved, indicating that increasing the temperature is beneficial to increasing the degree of graphitization and thus the conductivity of the sample. As the temperature increases to 1500°C, the proportion of the sample's 2D peak increases, but the conductivity of the sample after Joule heat treatment at 1500°C-20 s is lower than that of the sample after Joule heat treatment at 1400°C-20 s. This indicates that the higher the degree of graphitization, the better. Instead, there is a turning point. Before this turning point, as the temperature increases, the degree of graphitization increases, and the conductivity of the sample increases. After this turning point, as the temperature increases, the sample becomes over-graphitized, and the conductivity decreases.

[0055] Example 2

[0056] Sample 2 is low-ash Super P., and its ash analysis is shown in Table 2. 1.0 g of Sample 2 was evenly placed on a carrier carbon felt (10 cm long, 5 cm wide) and placed in the reaction chamber of a Joule heating device. A vacuum pump was activated to evacuate the carbon black in Sample 2 into a low vacuum environment, which was then filled with argon gas to a pressure of 100 Pa. The operating voltage was set to 75 V and the operating current to 45 A. A pulse power supply was activated to instantaneously heat Sample 2 from room temperature to 1300°C under an inert atmosphere. A voltage pulse was applied at 1300°C for 30 s. The power was disconnected, the material was cooled to room temperature, and then removed to obtain the modified conductive carbon black, referred to as 1300°C-30 s.

[0057] Table 2

[0058] ItemsUnitsStandardTargetLower LimitUpper LimitValueSample 2Ash%GBT / 37800.20.01

[0059] The conductivity graphs of the original sample 2 and the modified sample 2 are shown in Figure 5. As can be observed from Figure 5, the conductivity of the original sample 2 is lower than that of commercial carbon black, but the conductivity of the sample 2 modified by Joule heating is significantly improved compared to the original sample 2 and is higher than that of commercial carbon black, indicating that Joule heating treatment can effectively improve the conductivity of conductive carbon black.

[0060] Example 3

[0061] 1.0 g of acetylene black sample 3 was evenly placed on a carrier carbon felt (10 cm long, 5 cm wide), and loaded into the reaction chamber of a Joule heating device. The vacuum pump was started to evacuate the sample 3 to place it in a low vacuum environment, and argon was filled to a pressure of 100 Pa. The operating voltage was set to 45 V and the operating current to 35 A. The pulse power supply was started to instantly heat the sample 3 from room temperature to 1200°C under an inert atmosphere. A voltage pulse was continuously applied at 1200°C for 30 s. The power was disconnected, and the material was cooled to room temperature before being taken out to obtain the modified conductive carbon black, referred to as 1200°C-30 s.

[0062] The conductivity graphs of the original sample 3 and the modified sample 3 are shown in Figure 6. As can be observed from Figure 6, the conductivity of the original sample 3 is lower than that of commercial carbon black, but the conductivity of the sample 3 modified by Joule heating is significantly improved compared to the original sample 3 and is higher than that of commercial carbon black, indicating that Joule heating treatment can effectively improve the conductivity of conductive carbon black.

[0063] Comparative Example 1

[0064] The temperature was changed to 2000°C, and other operations were the same as in Example 1. As can be seen from Figure 8, after the Joule heating treatment at 2000°C for 20 s, the D peak of the sample was significantly weakened, the G peak increased sharply, and the 2D peak was obvious, indicating that the degree of graphitization of the sample was very high. However, as can be seen from Figure 7, the conductivity of the sample not only did not increase, but decreased, indicating that the higher the degree of graphitization, the better.

[0065] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for preparing highly conductive carbon black, characterized in that: Carbon black is placed in a carrier and subjected to a Joule heat transient high temperature reaction in a low pressure environment of no more than 100 Pa and an inert gas atmosphere to improve the conductivity of the carbon black; the carrier is selected from at least one of carbon cloth, carbon felt, carbon paper, and graphite sheet, or a metal with a melting point above 1400°C; the temperature of the Joule heat transient high temperature reaction is 1000-1700°C.

2. The method for preparing highly conductive carbon black according to claim 1, characterized in that: The carbon black is selected from one or more of acetylene black, Super P, Ketjen black, KS-6, Super S, and 350 G.

3. The method for improving the electrical conductivity of carbon black according to claim 1, characterized in that: The metal is selected from one or more of tungsten, molybdenum, tantalum, zirconium and niobium.

4. The method for preparing highly conductive carbon black according to claim 1, characterized in that: The operating voltage of the Joule heat transient high temperature reaction is 10-200 V, and the operating current is 10-200 A.

5. The method for preparing highly conductive carbon black according to claim 1, characterized in that: The voltage pulse duration of the Joule heat transient high temperature reaction is 0.1 to 500 s.

6. The method for preparing highly conductive carbon black according to claim 1, characterized in that: The gas atmosphere is at least one of argon, nitrogen, helium, krypton, xenon, and radon.

7. The method for preparing highly conductive carbon black according to claim 1, characterized in that: The carrier has a length of 5 to 20 cm and a width of 1 to 10 cm.

8. The method for preparing highly conductive carbon black according to claim 1, characterized in that: The amount of carbon black used is 0.01-100 g / batch.

9. A highly conductive carbon black prepared by the method according to any one of claims 1 to 8.

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