Efficient process for etching highly graphitic carbons

Abstract

A process for increasing the porosity of graphitic carbon black includes combining graphitic carbon black having a planar Raman size (La) of at least 20 Angstroms with at least 100 ppm of an alkaline earth element chosen from strontium, barium and a mixture of the two to form a mixture, and contacting the mixture with an etching agent at a temperature of 900-1400 °C until 2%-85% of the mass of the carbon black is lost.

Description

Title of the invention: Efficient process for etching highly graphitic carbons

[0001] CONTEXT OF THE INVENTION 1. Domain

[0002] The present invention discloses methods for engraving highly graphitic carbons and the engraved carbons thus produced. 2. Description of related art

[0003] Applications such as electric vehicles and renewable energy storage place high demands on lead-acid batteries in terms of improved cycle life under high-rate partial state of charge (HRPSoC) and high dynamic charge acceptance (DCA) conditions. The benefits of carbon additives for reducing negative plate sulfation and improving the cycle life and charge acceptance of valve-regulated lead-acid (VRLA) batteries have been demonstrated. Suitable carbon additives include carbon blacks. Carbon blacks are carbon materials with a unique hierarchical structure manufactured from a hydrocarbon feedstock in a high-temperature, high-efficiency process. The characteristics of carbon blacks, such as their morphology, purity, and surface properties, have been investigated in the context of lead-acid battery applications.

[0004] Highly graphitic carbon blacks, such as those produced from acetylene as a raw material or via at least partial graphitization of furnace carbon blacks, exhibit excellent thermal and electrical conductivity. In general, carbon blacks with a larger specific surface area exhibit higher conductivities. A high specific surface area is traditionally correlated with a small primary particle size. Although steam can be used to etch carbon particles, amorphous carbons are etched more efficiently than the graphitic regions of carbon particles. Thus, it is desirable to have a more efficient process for etching carbon black, particularly highly graphitic carbon blacks. Summary

[0005] In one embodiment, a carbon black has the following characteristics: a planar Raman size (La) of at least 21.5 angstroms, a cumulative pore volume of pores having a diameter of 2 nm–6 nm of at least 0.1 cm³ / g, and at least 200 ppm of strontium, barium, or both. The carbon black may have a BET specific surface area of ​​150 m² / g to 2000 m² / g. The carbon black may have a cumulative pore volume in cm³ / g of pores having a diameter of 2 nm-6 nm of at least 0.0004 (BET) to 0.048 (BET), where BET is the specific surface area BET according to ASTM 6556 with samples degassed at 300 °C for one hour under nitrogen flow and measurements performed over the nitrogen partial pressure range of 0.05-0.1 P / Po. Carbon black may have a crystallite size Le of at least 10 Angstroms.

[0006] In another embodiment, a method for increasing the porosity of graphitic carbon black comprises combining graphitic carbon black having a planar Raman size (La) of at least 20 Angstroms with at least 100 ppm of an alkaline earth element selected from strontium, barium, and a mixture of the two to form a mixture, and contacting the mixture with an etching agent at a temperature of 900–1400 °C until 2%–85% of the mass of the carbon black is lost. The graphitic carbon black, before contacting, may have a crystallite size Le of at least 10 Angstroms.

[0007] Contact can be made until the specific surface area BET of the carbon black is at least doubled, for example, at least tripled. The mass loss rate can be at least 10% higher than that obtained without the use of strontium or barium. The increase in pore volume of pores with a diameter of 2–6 nm can be at least 2.5% higher than that obtained without the use of strontium or barium. The etching agent can be selected from the group consisting of O2, O3, oxygen-containing acid, water (for example, vapor), CO2, and combinations of two or more of these.

[0008] In another embodiment, a process for producing porous graphitic carbon black comprises the thermal decomposition of a hydrocarbon feedstock to obtain graphitic carbon black and contacting the graphitic carbon black with an etching agent and at least 100 ppm of an alkaline earth element selected from strontium, barium, and a mixture of the two to form a mixture. The thermal decomposition and contacting can be carried out in a single reactor. The contacting can be carried out at a temperature of 1600 °C to 2700 °C. The etching agent can be selected from the group consisting of O2, O3, an oxygen-containing acid, water (e.g., steam), CO2, and combinations of two or more of these.

[0009] In another embodiment, the porous graphitic carbon black is incorporated into a cathode, a conductive plastic, a catalyst, a fuel cell catalyst, or a supercapacitor. DETAILED DESCRIPTION

[0010] In one embodiment, a method for increasing the porosity of graphitic carbon black comprises combining carbon black having a planar Raman size (La) of at least 20 Angstroms with at least 100 ppm of strontium and / or barium to form a mixture; and contacting the mixture with an oxidant and / or etching agent at a temperature of 900-1400 °C until 2%-85% of the mass of the carbon black is lost.

[0011] Graphitic carbon black can be any highly graphitic carbon black. For example, carbon black can be acetylene black. Examples of acetylene blacks include DENKA BLACK materials from Denka Company Ltd., AB50P acetylene black available from IRPC Public Company Limited, and acetylene blacks available from Orion Engineered Carbons GmbH, Polimax, and Soltex, Inc. Acetylene blacks from other sources not listed herein are also known to those skilled in the art and are suitable for use in the processes provided herein.

[0012] Alternatively or in addition, the graphitic carbon black may be a partially or fully graphitized furnace black. Furnace blacks are generally amorphous. However, their crystallinity can be increased by heating them under an inert atmosphere, for example, at a temperature of 1100 °C to 2000 °C. Suitable partially or fully graphitized furnace blacks can be produced using any of the processes described in documents WO2005028569, US4601887, US4351815, EPI 164651, US4160813, US11352536, US9017837, US9287565, US 10135071, and US 10971730, the full contents of which are incorporated herein by reference.

[0013] Alternatively or in addition, commercially available graphitic carbon blacks include Cabot Corporation's LITX® 50, LITX® 66, LITX® 200, LITX® 300, FCX® 80 and LITX® HP carbons; Imerys' C-NERGY™ C45, C-NERGY™ C65, Ensaco® 250G, Ensaco® 250P and SUPER P® products; Denka's Li-400, Li-250, Li-100 and Li-435 products; and Ketjen's EC300 and EC600 products.

[0014] Graphitic carbon black, before etching, can have a Raman planar size (La) of at least 20 Angstroms, for example, 20 to 80 Angstroms, for example, 25-70 Angstroms, 30 to 60 Angstroms or 35 to 55 Angstroms.

[0015] The Raman measurements of La (planar size) are based on "Raman studies of heat-treated carbon blacks", Carbon Vol. 32 (7), pp. 1377-1382, 1994, which is incorporated herein by reference. The Raman spectrum of carbon includes two major "resonance" bands at approximately 1340 cm⁻¹ and 1580 cm⁻¹, respectively designated as the "D" and "G" bands. The D band is generally considered to be attributed to disordered sp² carbon and the G band to graphitic or "ordered" sp² carbon. Using an empirical approach, the ratio of the G / D bands and the La measured by X-ray diffraction (XRD) are strongly correlated, and regression analysis gives the following empirical relationship: La = 43.5 x (G band area / area of band D), in which La is calculated in Angstroms. Thus, a higher value of La corresponds to a more ordered crystal structure.

[0016] Graphitic carbon black, before etching, may have any suitable BET specific surface area, as measured according to ASTM 6556 with samples degassed at 300 °C for one hour under a nitrogen flow and measurements taken over the nitrogen partial pressure range of 0.05–0.1 W / pH. For example, graphitic carbon black, before etching, may have a BET specific surface area of ​​50 to 1300 m² / g, for example, 50 to 400, 400 to 800, 800 to 1100, or 1100 to 1300 m² / g.

[0017] Alternatively or in addition, the graphitic carbon black, before etching, may exhibit a crystallite Le, as measured by X-ray diffraction, of at least 10 Angstroms, for example, at least 15 Angstroms, at least 17 Angstroms, 20 to 80 Angstroms, 25 to 70 Angstroms, or 25 to 65 Angstroms. The crystallite size Le was determined by X-ray diffraction using an X-ray diffractometer (PANalytical X'Pert Pro, PANalytical BV), with a copper tube, a tube voltage of 45 kV, and a tube current of 40 mA. A sample of carbon black particles was introduced into a sample holder (a diffractometer accessory) and the measurement was performed over an angle range (20) from 10° to 80°, at a rate of 0.14° / min. The peak positions and the full width at half maximum (FWHM) were calculated using the diffractometer software.For the calibration of the measurement angle, lanthanum hexaboride (LaB6) was used as an X-ray standard. From the measurements obtained, the crystallite size Le was determined using Scherrer's equation: Le (A) = K*X / ([3*cos 0), where K is the form factor constant (0.9); X is the wavelength of the characteristic CuKai X-ray line (1.54056 Å); [3 is the full width at half maximum in radians and 0 is determined by taking half the peak position of the measurement angle (20).

[0018] Alternatively or in addition, the graphitic carbon black, before etching, may have a surface energy (SE) of 10 mJ / m² or less, 9 mJ / m² or less, 8 mJ / m² or less, 7 mJ / m² or less, 6 mJ / m² or less, 5 mJ / m² or less, or 3 mJ / m² or less. In this same embodiment and in others, the partially crystallized carbon black has a surface energy (SE) greater than 0 mJ / m², greater than 1 mJ / m², greater than 2 mJ / m², greater than 3 mJ / m², greater than 4 mJ / m², greater than 5 mJ / m², greater than 6 mJ / m², greater than 7 mJ / m², greater than 8 mJ / m², or greater than 9 mJ / m². Namely, the surface energy of graphitic carbon black, before etching, can be in any range defined by any pair of upper and lower limits provided above.

[0019] The surface energy (SE) of a carbon black particle can be determined by measuring the adsorption of water vapor using a gravimetric instrument. The carbon black sample is placed on a microbalance in a chamber The sample is moist and allowed to equilibrate through a series of gradual changes in relative humidity. The change in mass is recorded. The increase in mass at equilibrium as a function of relative humidity is used to generate the vapor adsorption isotherm. The spreading pressure (in mJ / m²) for a sample is calculated using ire / BET, where: ire = RTjo p° rd In p R is the ideal gas constant, T is the temperature, T is the number of moles of water adsorbed, p° is the vapor pressure, and p is the partial pressure of the vapor at each progressive stage. The spreading pressure is related to the surface energy of the solid and indicates the hydrophobic / hydrophilic properties of the solid, with a lower surface energy (SE) corresponding to higher hydrophobicity.

[0020] The porosity and specific surface area of ​​graphitic carbon black can be increased by any oxidative etching process, for example, the processes described in US 10087330 or US 9017837, the full contents of which are incorporated by reference. The etching preferably comprises contacting a portion of the graphitic carbon black with one or more etching agents, for example, O2, O3, an oxygen-containing acid, water (for example, steam), or CO2, in the presence of a strontium and / or barium catalyst, as described below, under conditions that allow the graphitic carbon black to be etched, for example, by oxidative processes, and its porosity to be increased, in particular the volume of pores having a diameter of 2–6 nm. In some embodiments, the etching comprises a steam etching process.As used herein, the term "steam etching" means the etching of graphitic carbon black with an etching medium, wherein the etching medium comprises steam. For example, the etching agent may comprise at least 50% by weight of steam, at least 75% by weight of steam, at least 90% by weight of steam, or 100% of steam.

[0021] The etching is carried out in the presence of a strontium and / or barium-based catalyst. The strontium and / or barium may be introduced in the form of nitrate, hydroxide, acetate, chloride or another salt known to those skilled in the art. The catalyst can be introduced in an amount of 100 to 10,000 ppm relative to the graphitic carbon black, for example, 100 to 200 ppm, 200 to 300 ppm, 300 to 400 ppm, 400 to 500 ppm, 500 to 600 ppm, 600 to 700 ppm, 700 to 800 ppm, 800 to 900 ppm, 900 to 1000 ppm, 1000 to 1200 ppm, 1200 to 1400 ppm, 1400 to 1600 ppm, 1600 to 1800 ppm, 1800 to 2000 ppm, 2000 to 2200 ppm, 2200 to 2400 ppm, 2400 to 2600 ppm, 2600 to 2800 ppm, 2800 to 3000 ppm, 3000 to 3500 ppm, 3500 to 4000 ppm, 4000 to 4500 ppm, 4500 to 5000 ppm, 5000 to 6000 ppm, 6000 to 7000 ppm, 7000 to 8000 ppm, 8000 to 9000 ppm or 9000 to 10,000 ppm.

[0022] The catalyst can be introduced into the graphitic carbon black using any method known to those skilled in the art. For example, an aqueous solution of the catalyst can be used in a wet granulation process. Alternatively, an aqueous solution of the catalyst can be sprayed onto the graphitic carbon black, in a densified or undensified form, and then allowed to dry, leaving the catalyst on the surface of the carbon black.

[0023] Etching can be carried out in any suitable heating apparatus, for example, a rotary kiln, a multi-hearth furnace, a fluidized bed reactor, or any other heating apparatus known to those skilled in the art. During etching, the etching agent is passed through the furnace containing the graphitic carbon black. The etching agent is optionally associated with a diluent, a material that is passed through the heating apparatus primarily for a reason other than etching or oxidizing the graphitic carbon black raw material. For example, the diluent may include an inert gas, such as nitrogen or argon. Thus, a reaction gas passing through the heating apparatus may include only the etching agent or a mixture of the etching agent and the diluent.The ratio of etching agent to diluent can be adjusted to control the etching rate during the reaction, and / or the diluent can be used to allow temperature adjustments when etching the material is not desirable. For example, the diluent can be passed through a heater during process start-up or shutdown, while the heater is being heated or cooled, with the etching agent added to the reaction gas while the heater is at the desired etching temperature.

[0024] In the heating devices described above, etching can be carried out at temperatures from 700 °C to 1400 °C, for example from 900 °C to 1100 °C. The process temperature corresponds to the average temperature of the graphitic carbon black when the graphitic carbon black is brought into contact with the etching agent and the catalyst in order to increase the porosity of the graphitic carbon black.

[0025] Other process conditions that can be adjusted include the flow rate and / or velocity of the reaction gas. Ideally, the flow rate or velocity should not be so high as to carry the graphitic carbon away from the reactor. Those skilled in the art will know how to adjust the flow rate and / or velocity of the reaction gas to obtain favorable reaction conditions, for example, to induce the graphitic carbon in a fluidized bed reactor to behave in a fluidized manner. In some embodiments, for example, in a fluidized bed reactor, it may be necessary to perform the etching at high pressure. The mass ratio of the agent The cumulative etching rate relative to the starting quantity of graphitic carbon black can also be adjusted by modifying the reaction time, the mass loading of the starting graphitic carbon material, and the heating apparatus filling factor, as well as the flow rate, velocity, partial pressure of the etching agent, and the etching agent / diluent ratio of the reaction gas. Any of these process conditions, along with the reaction time and the amount of strontium and / or barium, can be adjusted to control the degree of etching of the graphitic carbon black.

[0026] Optionally, the process is carried out with dense or granulated graphitic carbon black. Dense or granulated carbon black can provide desirable flow and fluidization characteristics that facilitate the handling and / or transport of the graphitic carbon black during the various etching processes described herein. Any of a variety of conventional carbon black granulation techniques can be used to granulate ungranulated carbon black material and form a starting material for granulated carbon black. For example, the granules can be formed via wet granulation, in which a fine carbon black powder is introduced into a pin mixer with water and then mixed under high shear. Polymer or small-molecule binders can also be added to the water to improve the hardness or durability of the granules.Another granulation process is dry granulation, in which a fine carbon black powder is introduced into a large rotating drum where it is mixed with recycled (or seed) granules. The rotating action of the drum causes the fine powder to mix and incorporate into the granules. Alternatively, or in addition, a press or other densifying device such as a roller compactor can be used to densify the graphitic carbon black.

[0027] In some exemplary embodiments, the starting granulated carbon black material has an average pellet size greater than about 25 µm, for example, greater than about 50 µm, greater than about 100 µm, greater than about 200 µm, greater than about 500 µm, or greater than about 1 mm. In terms of ranges, the starting granulated carbon black material may have an average pellet size from about 10 µm to about 5 mm, for example, from about 100 µm to about 5 mm, or from about 200 µm to about 2 mm. The carbon black starting material may have a particle size distribution with 0% to 3% by weight of granules larger than 2 mm, 15% to 80% by weight between 1 and 2 mm, 15% to 80% by weight between 500 µm and 1 mm, 1% to 15% by weight between 250 µm and 500 µm, 0% to 10% by weight between 125 µm and 250 µm, and 0% to 5% by weight less than 125 µm.In this context, the particle size distribution and average size of the granules are determined. by passing the carbon black granules through a series of stacked vibrating screens with decreasing mesh sizes, and then measuring the mass collected on each screen in accordance with ASTM D1511-00, the entirety of which is incorporated herein by reference.

[0028] Preferably, the starting material of granulated graphitic carbon black is substantially free of carbon black fines, defined herein as the fraction of carbon black particles passing through a No. 120 mesh sieve, for example, having a pellet size of less than approximately 125 µm. In various possible embodiments, the starting material of granulated carbon black comprises less than approximately 15% by weight of carbon black fines, for example, less than approximately 10% by weight, less than approximately 5% by weight, or less than approximately 2% by weight of carbon black fines.

[0029] Alternatively or in addition, the etching can be carried out immediately after the formation of crystalline carbon black. For example, an etching agent, as well as strontium or barium, can be introduced into a carbon black reactor after the carbon black has formed. In this case, the temperature can be closer to the temperature at which the carbon black was formed, for example, at least 1600 °C, or from 1600 °C to 2500 °C, or from 2200 °C to 2700 °C. In some embodiments, after the decomposition of acetylene and the formation of carbon black, steam and strontium are introduced into the carbon black reactor to perform the carbon black etching. For example, the steam and strontium can be introduced into the reactor in a region downstream of a region in which the carbon black is formed.

[0030] Without being bound by any particular theory, it is thought that the etching process operates by removing carbon atoms from the surface and forming carbon monoxide and carbon dioxide gases, thereby reducing the mass of the graphitic carbon black. In some embodiments, up to 85% of the mass of the graphitic carbon black is removed, for example, from 2% to 5%, from 5% to 10%, from 10% to 50%, from 20% to 60%, from 30% to 85%, from 40% to 75%, from 50% to 65%, or from 60% to 85%. Alternatively or in addition, the BET surface area of ​​the etched carbon black may be at least 2 times that of the starting material, for example, at least 2.5 times that of the starting material, for example, from 2.5 times to 8 times, from 3 times to 7.5 times, from 3.5 times to 7 times, from 4 times to 6.5 times, from 4.5 times to 6 times, from 5 times to 7.5 times, or from 5.5 times to 8 times the BET surface area of ​​the starting material.

[0031] We unexpectedly discovered that strontium and barium improve the etching rate, both in the absence of a catalyst and in the use of lighter elements such as calcium. The use of strontium, barium, or a mixture of the two can modify the reaction rate. (mass loss rate) of at least 10% compared to an etch in which these elements are not used, for example from 10% to 80%, from 15% to 75%, from 20% to 65%, from 25% to 60% or from 30% to 55%. The change in reaction rate is calculated as follows: [(reaction rate with strontium and / or barium) - (reaction rate without strontium and / or barium)] / (reaction rate without strontium and / or barium).

[0032] Etching also increases the pore volume of the graphitic carbon black. However, the use of strontium and / or barium can increase the pore volume of pores with a diameter of 2–6 nm by at least 2.5% compared to the absence of these elements. For example, a strontium and / or barium catalyst can increase the pore volume of pores with a diameter of 2–6 nm by 2.5% to 210%, for example, by 5% to 150%, by 10% to 100%, or by 20% to 50%, compared to the etched graphitic carbon black without these elements. Therefore, the cumulative pore volume of pores with a diameter of 2–6 nm can be at least 0.1 cm³ / g, for example, by 0.1 cm³ / g to 0.6 cm³ / g or by 0.1 cm³ / g to 0.3 cm³ / g. Alternatively or in addition, the cumulative pore volume (in cm3 / g) of pores having a diameter of 2 nm-6 nm can be at least 0.0004 (BET) - 0.048, for example between 0.0004 (BET) - 0.048 and 0.6 cm3 / g.The average pore diameters and pore volumes can be determined in accordance with the techniques described in EP Barrett, LG Joyner, PP Halenda, J. Am. Chem. Soc. 1951, 73, 373-380 (method B JH).

[0033] Porous graphitic carbon black can retain its graphitic nature. For example, porous graphitic carbon black can have a planar Raman size (La) of at least 21.5 Angstroms, for example from 21.5 Angstroms to 45 Angstroms or from 21.5 Angstroms to 40 Angstroms.

[0034] Porous graphitic carbon black can have a specific surface area BET of 150 m2 / g to 2000 m2 / g, for example from 200 m2 / g to 400 m2 / g, from 400 m2 / g to 600 m2 / g, from 600 m2 / g to 800 m2 / g, from 800 to 1000 m2 / g, from 1000 m2 / g to 1200 m2 / g, from 1200 to 1400 m2 / g, from 1400 to 1600 m2 / g, from 1600 m2 / g to 1800 m2 / g or from 1800 m2 / g to 2000 m2 / g, or in any range defined by two of these limit points.

[0035] Alternatively or in addition, the porous graphitic carbon black may have a crystallite size Le of at least 10 Angstroms, for example, of at least 15 Angstroms, of at least 17 Angstroms, of 20 to 80 Angstroms, of 25 to 75 Angstroms or of 25 to 70 Angstroms.

[0036] Porous graphitic carbon black may exhibit improved powder resistivity compared to unetched graphitic carbon black. For example, porous graphitic carbon black may exhibit higher powder resistivity by mass, by volume, or both. Powder resistivity can be measured by a four-point process using a commercially available compact powder resistivity and density analyzer, for example the PRCD2100 instrument from IEST-Yuanneng Technology.

[0037] Porous graphitic carbon black may have a total concentration of strontium and barium of at least 100 ppm by mass, for example from 200 ppm to 500 ppm, from 500 to 1000 ppm, from 1000 to 2000 ppm, from 2000 to 3000 ppm, from 3000 to 5000 ppm, from 5000 to 10,000 ppm, from 10,000 to 15,000 ppm or from 15,000 to 20,000 ppm, for example from 100 ppm to 20,000 ppm.

[0038] Porous graphitic carbon black can be used in a variety of end applications. The combination of a high specific surface area, for example, of at least 150 m² / g, high porosity, for example, a cumulative pore volume of pores with a diameter of 2 nm–6 nm of at least 0.1 cm³ / g, and high crystallinity, for example, a planar Raman size (La) of at least 21.5 Angstroms, makes the porous graphitic carbon blacks supplied herein highly electrically conductive. Such carbon blacks can provide advantages in conductive plastics, electrodes for fuel cells such as direct methanol fuel cells (DMFCs) or hydrogen fuel cells, catalyst supports, for example, for fuel cell applications, and in supercapacitors.

[0039] In one embodiment, porous graphitic carbon black is used to form conductive plastics. Carbon black is highly electrically conductive and is therefore added to (normally non-conductive) plastics at sufficient levels to obtain a carbon black percolation network, thereby rendering the plastic part or film electrically conductive. In general, achieving electrical percolation at lower mass charges of carbon black can be advantageous, as it imparts other benefits to the plastic, such as viscosity, fracture toughness, adhesion, density, or other properties. The graphitic nature of carbon black can also increase the melt flow index (MFI), as disclosed in US patent 11732174, the entire contents of which are incorporated herein by reference, thereby increasing the processability of the plastics compared to less graphitic carbon blacks.

[0040] In another embodiment, the catalyst particles include a porous graphitic carbon black as provided herein, and an active phase deposited on the porous graphitic carbon black, which serves as a support phase for the active phase. For example, the catalyst particles can be formed in a sputtering conversion reactor, in which a liquid mixture is formed comprising carbon support particles, i.e., porous graphitic carbon black particles, an active phase precursor, and a liquid vehicle. The liquid mixture is sprayed at elevated temperatures under conditions that allow vaporization of the liquid vehicle and conversion of the active phase precursor into an active phase deposited on the carbon support particles. In other embodiments, the active phase is not fully formed during the spray conversion step, and another heat treatment is employed after spraying. Alternatively, wet precipitation processes can be used to form catalyst particles on the carbon black product.

[0041] In another embodiment, porous graphitic carbon black particles or catalyst particles prepared with porous graphitic carbon black are used to manufacture electrodes for fuel cells such as DMFCs or hydrogen fuel cells.In some embodiments, the particles are formulated into an ink that is deposited onto a carbon fabric or carbon paper or directly onto a membrane such as a polymer electrolytic membrane. Deposition can be accomplished by spray deposition, pen / syringe application, continuous or droplet inkjet printing, droplet deposition, spraying, flexography, lithography, gravure printing, other intaglio printing, and other methods.

[0042] Alternatively or in addition, porous graphitic carbon black can be used in silicon-carbon composites. These silicon-carbon composites are used in lithium-ion battery anodes to improve the cycling performance of silicon anodes. The carbon black in these composites is used to improve conductivity.Although crystalline carbon blacks are generally more conductive than amorphous carbon blacks, increasing the porosity of the carbon black significantly increases its conductivity. Crystallinity improves not only conductivity but also the durability of the carbon black particles. Furthermore, etched graphitic carbon black can serve as a scaffold and reservoir for the silicon phase to constrain and manage the expansion of the silicon particles during lithiation.

[0043] Alternatively or in addition, porous graphitic carbon black can be used to improve the stability of conductive additives in cathode materials used in high-voltage or high-temperature environments. Modifying the formulations of nickel-cobalt-manganese electrode materials, particularly increasing the proportion of nickel, increases the energy density of batteries based on these materials. The use of graphitic carbon blacks can improve the stability of conductive additives in cathode compositions for high-voltage batteries, and the porous graphitic carbon blacks supplied herein can offer increased conductivity compared to graphitic carbon blacks that have not been etched. Similarly, the combination of crystallinity and porosity of the carbon blacks supplied herein also improves stability under conditions operating at a higher temperature, for example between 50 and 70 °C rather than at a temperature closer to ambient temperature. EXAMPLES

[0044] Carbon black samples were prepared by weighing 100 g (for acetylene black) or 300 g (all other samples) of carbon black and placing them in a stainless steel tray approximately 30.5 cm x 29.3 cm (12 in x 8 in), resulting in a bed depth of approximately 1.3 cm (0.5 in). The tray was tareed, and a 30 wt. solution of strontium nitrate or calcium nitrate in deionized water was sprayed onto the carbon black in five aliquots. Between each addition, the sample was manually agitated for approximately 30 s to mix the coated top layer with the rest of the sample. Once the desired mass of catalytic solution had been added (indicated as the total amount of Sr or Ca in the examples below; the processing conditions used equimolar amounts of Sr or Ca), the sample was transferred into a suitable container for use with the rotary kiln.

[0045] Steam etching was performed in a rotary kiln with a working volume of two liters. The kiln was maintained at a constant heating setpoint of 1050 °C in standby mode. Before each experiment, the deionized water tank was filled, the steam generator was preheated to over 200 °C, and the incinerator indicator light was switched on. To steam etch a sample, carbon black was loaded into a loading / cooling collar. The kiln transported the carbon black from the collar into the hot zone, which was maintained at a setpoint of 1050 °C, with a nitrogen flow rate of 1 L / min, a steam flow rate of 100 g / h, and a tube rotation speed of 4.5 rpm. The run times varied depending on the sample reaction rate and the desired degree of etching, ranging from 1 to 15 hours.Once the operating time was over, the rotation of the furnace was reversed to transport the carbon out of the hot zone and back to the loading / cooling collar, where it was cooled for 30 min under nitrogen, then weighed. The degree of etching, expressed as a percentage, was (100*(Initial mass - Final mass) / Initial mass). Example 1

[0046] Samples of highly graphitic and amorphous carbon were steam-etched without a catalyst, using either a 0.0883 g / g carbon strontium nitrate solution or a 0.068 g / g carbon calcium nitrate solution. Cabot Corporation's FCX 80 and LITX HP conductive carbons are highly graphitic carbons with an acinar structure and substantially uniform primary particle size, while Cabot Corporation's CSX 960 and Spheron® 5000A carbon blacks are amorphous carbon blacks. AB50P acetylene black was densified by placing 100 g in a woven polyethylene filter bag and pressed twice in a hydraulic press at a force of 30 tonnes for 1 minute. Exp CB1 was produced by heat-treating Vulcan® XC72 carbon black (Cabot Corporation) at a temperature of 1300 °C to 1500 °C until an Le value of 46 Angstroms was obtained. Exp CB2 was produced by heat-treating CSX960 carbon black at a temperature of 1400 °C to 1600 °C until an Le value of 36 Angstroms was obtained. The same molar amounts of Sr and Ca were used in the catalyzed samples. The reaction time was adjusted to obtain a consistent degree of etching between the samples with added catalyst and the comparative samples without catalyst.If necessary, the etched samples were returned to the furnace for further etching to achieve the desired degree of etching, with the total etching time and final mass used in the reaction rate calculations. The etching results are shown in Tables 1 to 3 below. Specific surface area was measured according to ASTM D6556 with the samples degassed at 300 °C for one hour under a nitrogen flow, and measurements were taken over a nitrogen partial pressure range of 0.05–0.1 W / pH. The amount of strontium or calcium present on the etched black was measured by inductive plasma as follows. A 5–10 mg sample was incinerated using a muffle furnace, as described in ASTM D506. The resulting ash was combined with 2 mL of concentrated HCl, 0.5 mL of concentrated HNO3, and a small amount of reagent-grade water.The sample was then brought to 50 mL with yttrium as an internal standard and reagent-grade water, and analyzed using an Agilent ICP-OES model 5110 spectrometer. The moderate amounts of calcium present on the strontium-etched samples, and vice versa, likely resulted from contamination by residual materials in the reactor during previous experiments. Similar contamination could have occurred with samples etched without additives. The mean pore diameters and volumes were determined according to the techniques described in E.P. Barrett, L.G. Joyner, P.P. Halenda, J. Am. Chem. Soc. 1951, 73, 373–380 (BJH method). [Tables 1] Carbon sample % etching Additive Reaction rate (g / h) BET (m2 / g) La Ram an (ang) Le (ang) FCX80 0% None - 78 66.1 59.6 FCX80 82% None 17.2 261.7 25.5 66.1 FCX80 76% Sr 28.6 605.5 24.5 48.0 FCX80 76% Ca 16.4 309.7 21.9 Exp. CB1 0% None - 100 41.6 46.0 Exp. CB1 62% None 20.6 197.0 31.3 51.9 Exp. CB1 62% Sr 32.0 339.0 36.6 46.3 Exp. CB1 44% Ca 14.5 179.8 32.2 AB50P density 0% None - 79.8 38 29.5 AB50P density 57% None 28.6 426.5 24.8 31.2 AB50P density 63% Sr 31.4 536.8 23.4 29.7 AB50P density 53% Ca 26.7 408.6 26.3 Exp. CB2 0% None - 94 48.0 36.0 Exp. CB2 41% None 15.2 323.7 32.7 33.6 Exp. CB2 33% Sr 22.8 305.7 25.5 36.4 LITXHP 0% None - 95 27 20.7 LITXHP 61% None 22.8 441.3 28.3 25.8 LITXHP 61% Sr 27.2 425.6 25.9 23.2 CSX960 0% None - 125 14.5 15.3 CSX960 74% None 28.4 1122.7 18.6 12.4 CSX960 74% Sr 32.3 1301.8 18.9 11.1 Spheron 5000 A 0% None - 27.2 Spheron 5000 A 70% None 29.2 665.7 20.7 13.6 Spheron 5000 A 68% Sr 34.4 651.5 20.4 15.0

[0047] [Tables2] Carbon sample % etching Additive Sr on etched black (ppm) Ca on etched black (ppm) FCX80 0% None FCX80 82% None 995 17 FCX80 76% Sr 12973 54 FCX80 76% Ca 1974 9522 Exp. CB1 0% None Exp. CB1 62% None 339 66 Exp. CB1 62% Sr 5449 14 Exp. CB1 44% Ca 303 6244 AB50P densified 0% None AB50P densified 57% None 1373 22 AB50P densified 63% Sr 18644 42 AB50P densified 53% Ca 498 4146 Exp. CB2 0% None Exp. CB2 41% None 19 11 Exp. CB2 33% Sr 3988 3.4 LITXHP 0% None LITXHP 61% None 20 11 LITXHP 61% Sr 2836 5 CSX960 0% None CSX960 74% None 36 7 CSX960 74% Sr 1235 <5 Spheron 5000A 0% None Spheron 5000A 70% None 3794 385 Spheron 5000A 68% Sr 31590 170

[0048] [Tables3] Pore ​​volume (cm3 / g) per pore size (nm) Carbon sample % etching Additive < 2 nm 2-6 nm 6-10 nm 10-50 nm > 50 nm FCX80 0% None FCX80 82% None 0.008 0.092 0.046 0.17 0.31 FCX80 76% Sr 0.008 0.216 0.151 0.54 0.75 FCX80 76% Ca 0.009 0.104 0.08 0.31 0.49 Exp. CB1 0% None Exp. CB1 62% None 0.0 0.059 0.035 0.2 0.3 Exp. CB1 62% Sr 0.013 0.180 0.106 0.380 0.650 Exp. CB1 44% Ca 0.005 0.052 0.03 0.15 0.30 AB50P density 0% None AB50P density 57% None 0.013 0.163 0.089 0.21 0.24 AB50P density 63% Sr 0.012 0.185 0.093 0.22 0.25 AB50P density 53% Ca 0.012 0.146 0.09 0.21 0.24 Exp. CB2 0% None Exp. CB2 41% None 0.009 0.111 0.067 0.25 0.37 Exp. CB2 33% Sr 0.009 0.114 0.049 0.2 0.37 LITXHP 0% None LITXHP 61% None 0.011 0.147 0.115 0.41 0.55 LITXHP 61% Sr 0.012 0.151 0.045 0.19 0.36 CSX960 0% None CSX960 74% None 0.029 0.513 0.198 0.37 0.81 CSX960 74% Sr 0.04 0.547 0.107 0.38 0.67 Spheron 5000 A 0% None Spheron 5000 A 70% None 0.02 0.242 0.081 0.15 0.24 Spheron 5000 A 68% Sr 0.02 0.203 0.033 0.07 0.2

[0049] The results demonstrate that the use of strontium as a catalyst for the graphitic samples led to an increase in the etching rate compared to the use of calcium, which did not increase the etching rates compared to the comparative samples without a catalyst and resulted in a smaller specific surface area for a comparable degree of etching (mass loss). Example 2

[0050] Graphite flake samples exhibiting a Raman La well above 20 Å (Millipore Sigma) were steam-etched without a catalyst or with a strontium nitrate solution of 0.085 g / g carbon. The reaction times and results are shown in Table 4 below. [Tables 4] Carbon Sample % Etching Additive Reaction Time (h) Reaction Rate (g / h) Graphite Flakes 0% None Graphite Flakes 69% Sr 10 17.3 Graphite Flakes 12% None 10 3.1 Graphite Flakes 35% Sr 3 11.7 Graphite Flakes 7% None 3 6.7

[0051] During catalyst-free etching of graphite flake samples, no flame was visible at the furnace outlet. In contrast, a significant flame was observed at the furnace outlet with the use of strontium. It is thought that a substantial portion of the mass loss in the comparative graphite flake samples (without strontium) was due to binder loss, and not to the etching of the graphite. Regardless of the source of the mass loss, the use of strontium significantly increased the etching rate of the highly crystalline graphite.

[0052] The preceding description of various embodiments has been presented for illustrative and descriptive purposes. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Modifications and variations are possible in light of the above, or may be achieved through practical application of the invention. The embodiments have been chosen and described to explain the principles of the invention and its practical application, enabling those skilled in the art to use the invention in various embodiments and with various modifications as adapted to the particular intended use. It is understood that the scope of the invention is defined by the attached claims and their equivalents.

Claims

Demands

1. Carbon black having the following characteristics: a planar Raman size (La) of at least 21.5 Angstroms, a cumulative pore volume of pores having a diameter of 2 nm-6 nm of at least 0.1 cm3 / g, and at least 200 ppm of strontium, barium or both.

2. Carbon black according to claim 1, having a specific surface area B ET of 150 m2 / g to 2000 m2 / g.

3. Carbon black according to claim 1 or 2, having a cumulative pore volume in cm3 / g of pores having a diameter of 2 nm-6 nm of at least 0.0004 (BET) to 0.048, in which BET is the specific surface area BET according to ASTM 6556 with samples degassed at 300 °C for one hour under nitrogen flow and measurements carried out over the nitrogen partial pressure range 0.05-0.1 P / In.

4. Carbon black according to any one of claims 1 to 3, having a crystallite size Le of at least 10 Angstroms.

5. A process for increasing the porosity of graphitic carbon black, comprising: combining graphitic carbon black having a planar Raman size (La) of at least 20 angstroms with at least 100 ppm of an alkaline earth element selected from strontium, barium and a mixture of the two to form a mixture; and contacting the mixture with an etching agent at a temperature of 900-1400 °C until 2%-85% of the mass of the carbon black is lost.

6. A method according to claim 5, wherein the graphitic carbon black, before contacting, has a crystallite size Le of at least 10 angstroms.

7. A method according to claim 5 or 6, wherein the contacting is carried out until a specific BET surface area of ​​the carbon black is at least doubled, for example at least tripled.

8. A process according to any one of the preceding claims, wherein the mass loss rate is at least 10% higher than that obtained without the use of strontium or barium.

9. A method according to any one of the preceding claims, wherein the increase in pore volume of pores having a diameter of 2-6 nm is at least 2.5% greater than that obtained without the use of strontium or barium.

10. A method according to any one of the preceding claims, wherein the etching agent is selected from the group consisting of O2, O3, oxygen-containing acid, water (e.g., vapor), CO2 and combinations of two or more of these.

11. A process for producing porous graphitic carbon black, comprising: the thermal decomposition of the hydrocarbon feedstock to obtain graphitic carbon black; and contacting the graphitic carbon black with an etching agent and at least 100 ppm of an alkaline earth element selected from strontium, barium and a mixture of the two to form a mixture.

12. A method according to claim 11, wherein the thermal decomposition and contacting are carried out in a single reactor.

13. Method according to claim 11 or 12, wherein the contact is made at a temperature of 1600 °C to 2700 °C.

14. A method according to any one of claims 11 to 13, wherein the etching agent is selected from the group consisting of O2, O3, oxygen-containing acid, water (e.g., vapor), CO2 and combinations of two or more of these.

15. Porous graphitic carbon black produced by the process according to any one of claims 5 to 14.

16. Conductive plastic comprising porous graphitic carbon black according to any one of claims 1 to 4 and 15.

17. Fuel cell catalyst comprising porous graphitic carbon black according to any one of claims 1 to 4 and 15.

18. Supercapacitor comprising porous graphitic carbon black according to any one of claims 1 to 4 and 15.

19. Catalyst comprising porous graphitic carbon black according to any one of claims 1 to 4 and 15.

20. Cathode comprising porous graphitic carbon black according to any one of claims 1 to 4 and 15.