Silicon-carbon composites for lithium-ion battery anodes

Abstract

Silicon-carbon composite structures include silicon entities occupying pores in carbon black supports, wherein a ration of OAN: BET surface area for the carbon black support is in a range from 0.1 to 10 and a mass of silicon per 100g of carbon black is less than or equal to 0.75 * OAN. The silicon-carbon composites may have a carbon coating. The silicon-carbon composite structures can be prepared by CVD techniques or mechanical mixing and can be used in LIB anodes.

Description

Docket: 2023613PCT2 TITLE Silicon-Carbon Composites for Lithium-Ion Battery Anodes CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit under 35 USC 119 of U.S. Provisional Application No. 63 / 569,448, filed on March 25, 2024, U.S. Provisional Application No. 63 / 573,919, filed on April 3, 2024, and U.S. Provisional Application No. 63 / 631,030, filed on April 8, 2024, and claims priority to International Patent Application No. PCT / US2025 / 011511, filed on January 14, 2025, French Patent Application No. 2500376 filed on January 14, 2025, and Belgian Patent Application No. 20255035 filed on January 14, 2025, the disclosures of which are hereby incorporated herein by reference in their entirety. BACKGROUND

[0002] Lithium-ion batteries (LIBs) are commonly used sources of electrical energy for numerous applications ranging from electronic devices to electric vehicles. A lithium-ion battery typically includes a negative electrode and a positive electrode in an arrangement that allows lithium ions and electrons to move to and from the electrodes during charging and discharging. An electrolyte solution in contact with the electrodes provides a conductive medium in which the ions can move. To prevent direct reaction between the electrodes, an ion- permeable separator is used to physically and electrically isolate the electrodes. During operation, electrical contact is made to the electrodes, allowing electrons to flow through the device to provide electrical power, and lithium ions to move through the electrolyte from one electrode to the other.

[0003] Most commercially available lithium-ion batteries have anodes that contain graphite, a material capable of incorporating lithium through an intercalation mechanism. Typically, lithium is added to the graphite anode during the charging cycle and removed as the battery is used. Other anode materials used in addition to or alternatively to graphite include lithium titanate, tin oxide, silicon (Si) and SiOx(with x typically being 1.04, 1.06, etc.).Docket: 2023613PCT2

[0004] Silicon has received attention due to its relatively low cost, high abundance, environmentally friendly properties and, importantly, its high energy density. While silicon can increase the energy density of LIB anodes, it also presents significant challenges. For instance, silicon undergoes significant expansions and contractions during charge and discharge cycles, leading to reduced cycle life and reduced energy density after cycling. SUMMARY

[0005] A need exists, therefore, for materials and techniques that can address at least some of the problems encountered when designing silicon-containing anodes. Silicon-carbon composites can address some of the problems, wherein silicon is present in pores or cavities of a carbon structure (for example, a carbon black structure) that acts as a support or “scaffold” since it supports and contains the silicon.

[0006] In many of its aspects, the disclosure relates to materials that include carbon and silicon, as well as anodes and batteries containing such materials. Further aspects of the disclosure relate to techniques for manufacturing silicon-carbon materials that can be used in LIB or other applications.

[0007] In one embodiment, the disclosure features a silicon-carbon composite in which a carbon black support can accommodate, within its pores, the expansion and contraction of silicon entities (e.g., silicon nanoparticles), as Li diffuses in and out of the anode during each cycle. For example, silicon-carbon composites disclosed herein may include a carbon black support and silicon in pores of the carbon black support, wherein a ratio of OAN (oil adsorption number): BET (Brunauer-Emmett-Teller surface area) for the carbon black support is in a range from 0.1 to 10, wherein OAN is measured by ASTM D2414-23A and is reported in ml per 100g of carbon and BET is measured by ASTM D6556-21, and a mass in gf silicon per 100g of carbon black support is less than or equal to 0.75 * OAN. Silicon-carbon composites having these features can improve the performance of LIB. For example, balancing the OAN (which can be correlated to void or pore volume in a carbon black support) with the amount of silicon in the pores to leave room for volume expansion of the silicon while not leaving so much room as to degrade energy density. Also, balancing the ratio of OAN to BET can minimize the formation of a solid electrolyte interface (SEI) caused by contact of electrolyte with the carbon blackDocket: 2023613PCT2 support. SEI decreases the amount of lithium in the LIB and thereby can diminish energy capacity.

[0008] In some embodiments, the silicon-carbon composites may be made by exposing the carbon black support to a silicon-containing precursor at temperatures sufficient to decompose the precursor and deposit silicon within the pores of the carbon black pellets. In other embodiments, the silicon-carbon composites may be made by mechanically combining the carbon black support with silicon nanoparticles to form the silicon-carbon composite.

[0009] The porous carbon supports can consist of, consist essentially of, or comprise carbon black (CB). In specific implementations, the carbon support is a CB entity formed of CB aggregates held together by various means such as, for example, covalent bonds resulting from graphitization, incorporation of a polymeric or inorganic binder, van der Waals forces, hydrogen bonds, electrostatic forces, or other species, e.g., a metal oxide that functions to bind the aggregates to each other. In some embodiments, the porous carbon supports can consist of, consist essentially of, or comprise graphite. In some embodiments, the porous carbon supports can consist of, consist essentially of, or comprise a combination of graphite and carbon black.

[0010] Some of the techniques that can be employed to prepare the silicon-carbon composite involve heating a Si-containing precursor to a temperature sufficiently high to decompose the precursor and deposit elemental Si inside the carbon supports. In one embodiment, silicon is introduced by chemical vapor deposition (CVD), using a silane-type precursor, for example.

[0011] The carbon black supports can be prepared by comminuting CB pellets before, during or after the introduction of the silicon entities. In addition to CB, the pellets and / or the supports can contain other ingredients, such as binders, single and / or multi-wall carbon nanotubes, and / or metal oxides, to name a few.

[0012] In typical situations, starting pellets will have a size larger than that of the porous carbon support used to prepare the silicon-carbon composite structures. For instance, the starting pellets can be larger than 100 micron, larger than 500 microns or larger than 1 millimeter (mm). In one example, the starting pellets have a size within a range from about 100 microns to about 1 mm or more.Docket: 2023613PCT2

[0013] The carbon black supports, obtained, for example, by jet milling CB pellets, can have a size between about 1 and about 25 microns. Finished product structures of silicon-carbon can have a particle size within a range from about 1 to about 25 microns. In one example, the size of the carbon black support or silicon-carbon composite structures for LIB applications is between about 1 and about 25 microns, for example a D50 particle size by volume in a range from 1 to 25 microns, or from 5 to 25 microns.

[0014] In some embodiments, the carbon supports and / or the pellets employed to prepare them are heat treated to graphitize the CB, for example.

[0015] While it is important for the carbon supports to provide enough void volume for the expansion of the silicon during lithiation, allowing too much void volume represents wasted space that otherwise could be filled with silicon entities. Accordingly, further embodiments seek to balance the need for sufficient void volume to accommodate both the silicon entities themselves as well as their expansion, while also maximizing the amount of silicon and, as a result, the energy density of the composite.

[0016] The empty volume available in the carbon black supports can be estimated approximately from the oil adsorption number (OAN). In many of its aspects, the disclosure features porous carbon supports that have an OAN within a range of from 32 to 400 ml / 100 g of carbon, for example from about 200 to about 300 ml / 100 g of carbon).

[0017] Illustrative silicon-carbon composites will contain enough carbon to form a porous carbon support framework that is interconnected to give it strength and conductivity. Silicon amounts are important for bringing about a desired high energy density. In one implementation the ratio of carbon to silicon in the silicon-carbon material is about 1:1 by mass. More generally, the mass ratio of carbon to silicon is within a range from about 20:80 to about 80:20, or about 40:60 to about 60:40.

[0018] Silicon-carbon composites that contain silicon entities deposited or infiltrated within the porous carbon support can be used as additives in LIB applications. In such an environment, however, the possible formation of a solid electrolyte interface (SEI) can lead to decreased Li amounts in the system, reducing energy capacity.Docket: 2023613PCT2

[0019] One approach for addressing this challenge relies on lowering the CB surface area, e.g., by selecting CBs with larger primary CB particles. In some examples, the CB employed has a BET surface area within a range from 3.2 to 400 m2 / g, for example from 80 to 130 m2 / g.

[0020] Another approach involves keeping the high surface area of the carbon support (e.g., carbon black, graphite, or a combination of the two) and of the silicon supported on the carbon protected inside the silicon-carbon composite entity. In specific examples, access to the interior surface area of carbon and silicon is blocked by sealing the pores at the surface of the silicon- carbon structure. The sealing of surface pores can be accomplished by one or more coating operations. For example, the pores can be sealed or “capped” by coating with silicon, silicon oxide, and / or carbon. In one embodiment, the process is conducted sequentially, for instance, by first closing the surface pores with silicon, then coating the overall entity with carbon. In many implementations, silicon capping is carried out after depositing silicon entities, e.g., silicon nanoparticles, into the porous carbon supports. Carbon coating can be conducted by CVD, using a suitable carbon-bearing precursor such as propylene. The apparent surface area (the interior surface area of the pellet not accessed) can be, for example, less than 30 m2 / g, less than 25 m2 / g, less than 20 m2 / g, less than 15 m2 / g, less than 10 m2 / g, less than 5 m2 / g, or less than 2 m2 / g.

[0021] Practicing embodiments of the disclosure presents many benefits. Using CB, for example, can bring about attractive mechanical properties, electrical conductivity and electrochemical compatibility with Li ion battery chemistry, at a relatively low cost. Using graphite fines, for example fines having a particle size of less than or equal to 1 micron, takes advantage of a relatively abundant and low-cost material. Adding silicon, in a silicon-carbon composite such as described herein (e.g., structures (particles) of 50:50 carbon to silicon) can contribute significant energy to an electrode due to the high energy density of silicon compared to graphite. In addition to bringing about energy densities that are higher than those of graphite, silicon can be a cost-effective component, widely available and environmentally friendly. In some cases, the silicon employed is provided from readily available dry sources, such as, for instance, silane gas (SiH4).

[0022] A starting material such as CB pellets can be a cost-effective source for preparing porous carbon supports. The pellets can be custom-made or can be commercially available inDocket: 2023613PCT2 desired CB specifications. In some cases, the pellets have already been heat-treated (e.g., annealed) and graphitized, simplifying the process described herein.

[0023] Capping the pores in the silicon-carbon composite can block external agents from reaching the interior of the product structures. A protective layer can prevent high surface CB particles in the product structures from coming into contact with the battery electrolyte and generating a solid electrolyte interface (SEI). Coating silicon-carbon composite structures, e.g., with a carbon layer, silicon layer, or silicon sub-oxide (SiOx, 0 < x < 2) layer, can protect high surface area CB and high surface area silicon within the composite from direct contact with the LIB electrolyte, thus reducing any irreversible uptake of silicon or minimizing SEI formation. In some implementations, silicon capping closes surface pores prior to coating with carbon, thus blocking the penetration of the carbon-containing precursor and any deposition of the carbon coating material within the interior of the composite. Pores capped with silicon also can be an indication that sufficient Si has been deposited. Carbon coating can reduce the surface energy of the agglomerates which can result in reduced water molecule adsorption, leading to easier processability and higher performance.

[0024] The above and other features of the disclosure, including various details of construction and combinations of parts, and other advantages, will now be more particularly described with reference to the accompanying drawings and pointed out in the claims. It will be understood that the particular method and device embodying the disclosure are shown by way of illustration and not as a limitation of the disclosure. The principles and features of this disclosure may be employed in various and numerous embodiments without departing from the scope of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In the accompanying drawings, reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale; emphasis has instead been placed upon illustrating the principles of the disclosure. Of the drawings:

[0026] FIG. 1 presents the Malvern AeroS dry powder % volume weighted PSD (particle size distribution) for three different lots of a commercial CB.Docket: 2023613PCT2

[0027] FIG.2 is a schematic illustration of a carbon black support;

[0028] FIG.3 is a schematic illustration of a silicon-carbon composite structure (particle) in which a carbon black support contains silicon entities, e.g., silicon nanoparticles;

[0029] FIG 4 is a scanning electron micrograph of a silicon-carbon composite particles with sizes ranging from roughly 1-25 microns;

[0030] FIG. 5 are scanning electron micrographs of a silicon-carbon composite particle showing a single porous structure of carbon supporting deposited silicon;

[0031] FIGS.6A and 6B are scanning electron micrographs (at different magnifications) of a silicon-carbon composite particle, the surface showing silicon (brighter spots) nanoparticles of roughly 10 nanometers in size and carbon;

[0032] FIG. 7 is a schematic illustration of a silicon-carbon composite particle, coated by silicon deposited at the surface of the composite particle;

[0033] FIG. 8 is a schematic diagram of a silicon-carbon composite, coated by carbon deposited at the surface of the composite particle;

[0034] FIG. 9 is a schematic illustration of a silicon-carbon composite particle coated by silicon and carbon at the surface of the composite particle.

[0035] FIG. 10 is a schematic illustration of a coated silicon-carbon composite having graphite, carbon black, carbon nanotubes and silicon nanoparticles.

[0036] FIG. 11 is a series of plots comparing the performance of composites prepared by mechanical mixing of silicon and carbon constituents, the performance of composites prepared by silicon infiltration using CVD and the performance of a control material that did not include silicon. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] The disclosure now will be described more fully hereinafter with reference to the accompanying drawings, in which illustrative embodiments of the disclosure are shown. This disclosure may, however, be embodied in many different forms and should not be construed asDocket: 2023613PCT2 limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0038] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. Also, all conjunctions used are to be understood in the most inclusive sense possible. Thus, the word "or" should be understood as having the definition of a logical "or" rather than that of a logical "exclusive or" unless the context clearly necessitates otherwise. Further, the singular forms and the articles "a", "an" and "the" are intended to include the plural forms as well, unless expressly stated otherwise. It will be further understood that the terms: includes, comprises, including and / or comprising, when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. Further, it will be understood that when an element, including component or subsystem, is referred to and / or shown as being connected or coupled to another element, it can be directly connected or coupled to the other element or intervening elements may be present.

[0039] It will be understood that although terms such as “first” and “second” are used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. Thus, an element discussed below could be termed a second element, and similarly, a second element may be termed a first element without departing from the teachings of the present disclosure.

[0040] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0041] The disclosure generally relates to electrochemical cells, in many cases for batteries such as, for instance, rechargeable LIBs. Typically, LIB batteries are named according to theDocket: 2023613PCT2 acronyms for the electroactive material employed to form the cathode, often an intercalation compound. Embodiments described herein can be practiced with or adapted to various types of lithium-ion batteries currently known in the art, such as LCO (lithium cobalt oxide), LMO (lithium manganese oxide), NCM (lithium nickel cobalt manganese oxide), NCA (lithium nickel cobalt aluminum oxide), LCP (lithium cobalt phosphate) , LFP (lithium iron phosphate), LMFP (lithium manganese iron phosphate), LFMP (lithium iron manganese phosphate), LFSF (lithium iron fluorosulfate) or LTS (lithium titanium sulfide), to name a few, or LIBs developed in the future.

[0042] In one of its aspects, the disclosure relates to a material that contains silicon and carbon, a silicon-carbon composite, for instance. A composite or composite particle, also referred to herein as a “composite structure” or a “composite entity” includes a carbon component, typically made of porous carbon supports (for example carbon black supports), and a silicon component, e.g., silicon entities such as, for example, silicon nanoparticles and / or silicon oxide nanoparticles.

[0043] The relative amounts of silicon and carbon present in the composite can vary, depending, for example, on the specific end-use or other factors. In some embodiments, the disclosure addresses not only the energy density improvements associated with the presence of silicon in LIB anodes, but also the challenges presented by the high expansion and shrinkage of silicon during cycling.

[0044] The high theoretical specific capacity for silicon (about 4,200 mAh / g based on theformation of the Li22Si5 alloy) is about 10 times higher than that of conventional carbon-basedanodes (typically about 372 mAh / g for graphite). (For pristine silicon, the capacity is 3600mAh / g.) A 50:50 silicon-carbon composite would introduce into the anode a structure with an energy density that is 5 times that of graphite.

[0045] During operation, however, the uptake of Li can result in a silicon volume expansion of up to 400%, with significant volume shrinkage occurring during lithium extraction. Even when silicon is not typically completely lithiated during cycling, the volume expansion can be more than twice its initial volume.Docket: 2023613PCT2

[0046] In some of the silicon-carbon materials described herein, a porous carbon support (scaffolding or matrix) accommodates not only silicon entities, but also the expansion- contraction characterizing these entities during cycling.

[0047] To illustrate, a close packing of spheres of carbon provides about 25% open volume, a value too low for containing both enough silicon for the desired energy density and enough free space for its volume expansion. In contrast, the void volume inside some materials (many high-structure carbon blacks, for example) can be as high as five or more times the volume of the material itself (e.g., the carbon black).

[0048] Allowing too much void volume, however, can represent a wasted opportunity for Si loading. Thus, there is an optimum void volume that is sufficient to contain the silicon itself and its expansion during cycling, without leaving excess unoccupied volume (which would reduce the energy density in the resulting anode).

[0049] Considering a case in which ratios of masses and volumes are: 33% silicon by volume, to provide a higher energy density for the final composite material; 33% carbon by volume, to form a porous support framework that is interconnected to give it strength and conductivity; and 33% open space by volume, the 33 free volume % available does not allow for full Si expansion of up to 400% during Li uptake.

[0050] In contrast, in a case providing sufficient void volume, silicon is deposited such that the fully lithiated silicon fills all the void volume, resulting in a silicon-carbon composite that is, roughly: 20% carbon by volume and 80% fully lithiated silicon by volume when expanded by 400%, so that the void space is completely filled, or 20% unexpanded silicon by volume. Based on densities, this corresponds to 50 wt% Si in the silicon-carbon composite, a silicon:carbon ratio of 1:1.

[0051] Accordingly, some of the silicon-carbon composites described herein have a mass ratio of silicon to carbon within a range from about 40:60 to about 60:40. In specific implementations, the silicon to carbon mass ratio is about 50:50, a ratio that provides a sufficiently high energy density by virtue of the relatively high silicon content. In other embodiments, the silicon-carbon composites described herein may have a mass ratio of silicon to carbon in a range from about 20:80 to about 80:20, about 30:70 to about 70:30, about 40:60Docket: 2023613PCT2 to about 60:40, about 45:55 to about 55:45, about 50:50, or any and all ranges and subranges therebetween. While other ratios can be selected, a much higher silicon content can result in insufficient carbon structure to support the silicon. On the other hand, a much lower silicon content can lead to an increased surface area of the carbon black and lower energy density due to the lower silicon content.

[0052] In one embodiment, the carbon component in the silicon-carbon material described herein consists of, consists essentially of, or comprises carbon black (CB), graphite, or a combination of carbon black and graphite.

[0053] Generally, CBs are materials that exist in the form of aggregates, which, in turn, are formed of CB primary particles. In most cases, primary particles do not exist independently of the CB aggregate. While the primary particles can have a mean primary particle diameter within the range of from about 10 nanometers (nm) to about 50 nm, e.g., from about 10 nm to about 15 nm; from about 10 nm to about 20 nm; from about 10 nm to about 25 nm; from about 10 nm to about 30 nm; or from about 10 nm to about 40 nm, the aggregates can be considerably larger. CB aggregates have fractal geometries and are often referred in the art as CB “particles” (not to be confused with the “primary particles” discussed above). Typically, the aggregates have significant internal volume corresponding to the spaces between the primary particles in the aggregate. CB aggregates can form larger structures, referred to herein as CB “agglomerates”.

[0054] Many types of CB are produced in a furnace-type reactor by pyrolyzing a hydrocarbon feedstock (FS) with hot combustion gases to produce combustion products containing particulate CB. Characteristics of a given CB often depend upon the conditions of manufacture and may be altered or modified, e.g., by changes in temperature, pressure, FS, residence time, quench temperature, throughput, and / or other parameters. Carbon black can also be produced using acetylene-based processes.

[0055] As known in the art, CBs can be described by certain properties determined according to procedures, often standardized protocols, well known in the art. For instance, CBs can be characterized by their Brunauer-Emmett-Teller (BET) surface area, measured, for example, according to ASTM D6556-21; by their oil adsorption number (OAN), determined,Docket: 2023613PCT2 for instance, according to ASTM D 2414-23A; or by their statistical thickness surface areas (STSAs), a property that can be determined by ASTM D 6556-21.

[0056] For a given CB, it may also be of interest, in some cases, to specify the ratio of its STSA to its BET surface area (STSA:BET ratio).

[0057] Crystalline domains of CBs can be characterized by an Lacrystallite size, as determined by Raman spectroscopy. Lais defined as 43.5 × (area of G band / area of D band). The crystallite size can give an indication of the degree of graphitization, where a higher Lavalue correlates with a higher degree of graphitization. Raman measurements of Lawere based on Gruber et al., "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 about 1340 cm-1and 1580 cm-1, denoted as the “D” and “G” bands, respectively. It is generally considered that the D band is attributed to disordered sp2carbon, and the G band to graphitic or “ordered’ sp2carbon. Using an empirical approach, the ratio of the G / D bands and an Lameasured by X-ray diffraction (XRD) are highly correlated, and regression analysis gives the empirical relationship: La= 43.5 × (area of G band / area of D band), in which Lais calculated in Angstroms. Thus, a higher Lavalue corresponds to a more ordered crystalline structure.

[0058] The crystalline domains can be characterized by a Lccrystallite size. The Lccrystallite size was determined by X-ray diffraction using an X-ray diffractometer (PANalytical X’Pert Pro, PANalytical B.V.), with a copper tube, tube voltage of 45 kV, and a tube current of 40 mA. A sample of carbon black particles was packed into a sample holder (an accessory ofthe diffractometer), and measurement was performed over angle (2 ) range of 10° to 80°, at aspeed of 0.14° / min. Peak positions and full width at half maximum values were calculated by means of the software of the diffractometer. For measuring-angle calibration, lanthanum hexaboride (LaB6) was used as an X-ray standard. From the measurements obtained, the Lccrystallite size was determined using the Scherrer equation: Lc (Å) = K* / ( *cos ), where K isthe shape factor constant (0.9); is the wavelength of the characteristic X-ray line of Cu K 1(1.54056 Å); is the peak width at half maximum in radians; and is determined by taking halfDocket: 2023613PCT2of the measuring angle peak position (2 ). In some embodiments, the carbon black support hasan Lc crystallite size of less than or equal to 42, 40, 35, 30, 25, 20, or 14 Angstroms. In some embodiments, the carbon black support has an Lc crystallite size in a range from 14 to 42, 14 to 40, 14 to 35, 14 to 30, 14 to 25, 20 to 42, 20 to 40, 20 to 35, 20 to 30, 25 to 42, 25 to 40, 25 to 35, 30 to 42, 30 to 40, 35 to 42, 35 to 40 Angstroms, or any and all ranges or subranges therebetween as these Lc indicate the carbon black support is subjected to a heat treatment of less than 1800 Celsius.

[0059] Surface cleanliness can be described by the surface energy (SEP) of the CB, a property that can be determined by Dynamic Vapor (Water) Sorption (DVS) or water spreading pressure (described, for instance in US Patent No.10,886,535 B2, issued on January 5, 2021 to Korchev et al. and incorporated herein by this reference). Lower surface energies typically correspond to lower surface concentrations of oxygen-containing groups.

[0060] Mean pore diameters and pore volumes can be determined in accordance with the techniques described in E.P. Barrett, L.G. Joyner, P. P. Halenda, J. Am. Chem. Soc. 1951, 73, 373-380 (BJH method).

[0061] Other techniques that can be used to study CBs include Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). FTIR spectroscopy is particularly useful for determining the nature of surface functional groups, while SEM / TEM techniques help to visualize the size and morphology of the particles. XPS is often used to determine the elemental composition of a material and TGA can provide information on the decomposition and oxidation characteristics of carbons.

[0062] Malvern laser diffraction techniques can be employed to measure particle size and particle size distributions, for example the D50 particle size by volume. Malvern instruments measure particles within specific ranges by measuring the intensity of light scattered when a laser beam passes through a dispersed particulate sample. Malvern instruments operated with flowing gas can approximate the conditions in fluidized beds where flow gas suspends the agglomerates. The Malvern laser diffraction technique used herein to test materials was with a Mastersizer 3000 (available from Malvern Panalytical) with Aero S attachment, following theDocket: 2023613PCT2 procedure in the Mastersizer 3000 Basic Guide published August 6, 2024. Equipment settings were set per the table below. A 2mm diameter sieve screen was installed on the Aero S hopper prior to adding the sample. During measurement, Aero S feed rate was manually adjusted to ensure an average obscuration of ~3%.Docket: 2023613PCT2

[0063] In some embodiments, the D50 particle size by volume of the carbon black support or silicon-carbon composite may be greater than 1 micron, greater than 5 microns, greater than 6 microns, greater than 7 microns, greater than 8 microns, greater than 9 microns, greater than 10 microns, or greater than 15 microns. In some embodiments, the D50 particle size by volume of the carbon black support or the silicon-carbon composite may be in a range from 1 to 25 microns, 1 to 20 microns, 1 to 15 microns, 5 microns to 25 microns, 5 microns to 20 microns, 5 microns to 15 microns, 6 microns to 25 microns, 6 microns to 20 microns, 6 microns to 15 microns, 7 microns to 25 microns, 7 microns to 20 microns, 7 microns to 15 microns, 8 microns to 25 microns, 8 microns to 20 microns, 8 microns to 15 microns, 9 microns to 25 microns, 9 microns to 20 microns, 9 microns to 15 microns, 10 microns to 25 microns, 10 microns to 20 microns, or any and all ranges and subranges therebetween.

[0064] In some embodiments, the carbon black support employed in the silicon-carbon material described herein is a hard agglomerate of CB aggregates. The porosity of such an agglomerate corresponds to the porosity inside (within) the primary particles, the space inside the aggregate structures (formed from the primary particles) and the space between aggregates. The pores in the primary particles are smaller than the size of the primary particles, typically less than 10 nm. These small pores have a small overall pore volume percentage and cannot support much silicon by mass fraction. Inter-aggregate pores (pores between aggregates in the agglomerate) can be within a range of from about 10 nm to about 500 nm, whereas intra- aggregate pores (pores between primary particles within the aggregate) can be within a range of from about 10 nm to about 500 nm.

[0065] The overall porosity of the CB agglomerates can be determined by considering the oil adsorption number (OAN) characterizing the porous carbon supports, OAN representing the number of cubic centimeters of dibutyl phthalate (DBP) or paraffin oil absorbed by 100 g of carbon black under specified conditions according to ASTM D-2414-23A.

[0066] As discussed above, one important goal for LIB anode applications is to provide sufficient empty volume for silicon expansion during cycling, while maximizing silicon occupancy of the pores, and thus the energy density of the resulting electrode.Docket: 2023613PCT2

[0067] Using OAN to approximate the amount of void volume in a carbon agglomerate can help determine a theoretical maximum silicon loading that can fit within the pores at full lithiation. In one example, for every 100g of carbon there is a volume of approximately 45 cm3of carbon, and the OAN can be used to convert to a volume % carbon. Theoretically, all the remaining volume in the porous carbon could be filled by lithiated silicon (with no space left for electrolyte). Considering a fully lithiated silicon (that can expand by 400% or so) gives a maximum volume to be allowed for silicon. Based on density, this can be converted to a maximum Si weight % (wt %).

[0068] Commercial CB specifications provide a wide array of properties including various values of OAN. In one embodiment, the silicon-carbon composite described herein is prepared using a CB that has an OAN corresponding to a relatively high Si capacity. For example, a CB having an OAN of 216 ml / 100g, LITX HP for example, allows for 55 wt% Si, a weight % that is close to the weight % of a desired 50:50 silicon-carbon product. Table 1 below compares two porous carbon supports that employ different CB specifications, showing that the one characterized by a higher OAN will have a higher Si capacity than the Si capacity available when using a CB with a lower OAN. Table 1

[0069] More generally, OAN values of 200 to 300 ml / cm3give roughly a volume of 2-3 cm3per gram of carbon aggregate. Considering a carbon density of 2.26 g / cm3, such a CB can provide ample room to contain, not only the silicon entities themselves, but also the expansion and contraction of these entities during cycling.Docket: 2023613PCT2

[0070] Thus, in specific embodiments of the disclosure, the porous carbon supports (before any silicon is infiltrated into the supports), have an OAN within a range of from about 32 to about 400 ml per 100g of carbon, for example, from 32 to: 250, 275, 300, 325, 350, 375, 400 ml per 100g of carbon, from 50 to: 250, 275, 300, 325, 350, 375, 400 ml per 100g of carbon, from 100 to: 250, 275, 300, 325, 350, 375, 400 ml per 100g of carbon, from 150 to: 250, 275, 300, 325, 350, 375, 400 ml per 100g of carbon from 200 to: 220, 240, 260, 280, 300, 325, 350, 375, 400 ml / 100g of carbon; or from 220 to: 240, 260, 280, 300, 325, 350, 375, 400 ml / 100g of carbon; or from 240 to: 260, 280, 300, 325, 350, 375, 400 ml / 100g of carbon; or from 260 to: 280, 300, 325, 350, 375, 400 ml / 100g of carbon; or from 280 to: 300, 325, 350, 375, 400 ml / 100g of carbon, from 300 to: 325, 350, 375, 400 ml per 100g of carbon, from 325 to: 350, 375, 400 ml per 100g of carbon, or 350 to: 375, 400 ml per 100g of carbon, or any and all ranges and subranges therebetween.

[0071] Another factor that can be considered is the surface area (SA) of the porous carbon supports. During operation, the carbon can come into contact with the electrolyte employed in the LIB, leading to the possible formation of a solid electrolyte interphase (SEI). The SEI takes up Li, thus decreasing the amount of Li in the system and reducing energy capacity.

[0072] SEI formation can be more pronounced for carbon having large surface areas. For example, a carbon black with surface area of 250 m2 / g can introduce large surface areas into an anode. In comparison, graphite has a much lower surface area, e.g., very roughly about 1 m2 / g (for illustrative purposes). On a 1 g basis, replacing 0.5 g of the graphite with 0.5 g CB (having a surface area of 250 m2 / g) increases the surface area by 125 m2 / g.

[0073] Various measures can be taken to address this challenge. One approach relates to reducing the surface area, e.g., by using larger primary particles (typically providing lower surface area).

[0074] Accordingly, one embodiment employs a porous carbon support having a BET surface area within a range of from about 3.2 to about 400 m2 / g, such as, for instance, from 3.2 to: 100, 150, 200, 250, 300, 350, 400 m2 / g, from 50 to: 100, 150, 200, 250, 300, 350, 400 m2 / g from 80 to: 90, 100, 120, 150, 200, 250, 300, 350, 400 m2 / g; or from 90 to: 100, 110, 120, 130, 150, 200, 250, 300, 350, 400 m2 / g; or from 100 to: 110, 120, 130, 150, 200, 250, 300, 350, 400Docket: 2023613PCT2 m2 / g; or from 110 to: 120, 130, 150, 200, 250, 300, 350, 400 m2 / g; or from 120 to: 130, 150, 200, 250, 300, 350, 400 m2 / g; from 150 to: 200, 250, 300, 350, 400 m2 / g; from 200 to: 250, 300, 350, 400 m2 / g; from 250 to: 300, 350, 400 m2 / g or any and all ranges and subranges therebetween. In one example, the carbon support consists of CB having a BET of about 100 m2 / g.

[0075] In some implementations, the carbon inside (within) the porous carbon black support is graphitized to increase its crystallinity, a property that (as noted above) can be measured by Raman spectroscopy. For commercial carbon blacks, graphitization is often conducted post CB manufacture, in a heat-treating process, typically at relatively high temperatures (e.g., annealing). Heat treatment techniques that can be employed are described, for instance, in U.S. Patent Nos. 9,287,565; 10,135,071; and 10,971,730. These patents are incorporated herein by this reference in their entirety.

[0076] In specific examples, the CB employed in the porous carbon black supports described herein is a CB that has already been graphitized. In others, the CB is graphitized at some point during the overall process used to prepare the silicon-carbon composite material described herein. It is also possible to employ CB that has not been graphitized.

[0077] Along with an increase in crystallinity, a possible consequence of the heat treatment (characterized by parameters such as heating temperatures, time intervals employed, protocols for ramping to and / or maintaining a certain temperature, etc.) is a reduction or elimination of porosity within primary carbon particles. This can be advantageous in some cases where a lower SA is desired.

[0078] In the absence of heat treatment and graphitization, the primary particles forming the CB aggregate can themselves contain porosity. If present, porosity within primary particles contributes to the overall porosity of the agglomerates and this contribution is reflected by the higher surface area of the porous carbon supports. Carbons without internal surface area are preferred when no heat treatment is used and a lower surface area is desired.

[0079] In specific examples, the porous carbon black support contains less than 100, less than 50, less than 25, less than 10 or less than 5 parts per million (ppm) metal impurities. Typically, levels of inductively coupled plasma (ICP) metals, individually or collectively, suchDocket: 2023613PCT2 as cobalt, chromium, copper, manganese, nickel, iron are no greater than 100, no greater than 50, not greater than 25, no greater than 10 or no greater than 5 ppm.

[0080] In many cases, the ash content is less than 0.1% by weight.

[0081] Some properties for three different CB specifications, namely A, B and C, which could be considered for preparing the carbon black supports are shown in Table 2 below. Table 2*Metal: Co, Cr, Cu, Mn, Ni.

[0082] In one implementation, a binder is added to hold the carbon aggregates together, and / or strengthen the carbon black support. In some embodiments, the binder may include, but is not limited to, polyacrylic acids, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), carboxymethylcellulose (CMC), another binder typically used in Li ion battery cathodes or anodes, or any combination thereof.

[0083] In some embodiments, the CB or carbon black support has a % crystallinity of at least 22%, for example, from 23% to 55%, such as within a range of from about 23 to about: 30, 35, 40, 45, 50, 55%; or from about 30 to about: 35, 40, 45, 50, 55%; or from about 35 to about: 40, 45, 50, 55%; or from about 40 to about: 45, 50, 55%; of from about 45 to about 50, 55%.

[0084] In one example, the CB or carbon black support has an Lacrystallite size of at least 14 Å, for example, from 14 Å to 50 Å. For instance, the CB can have an La crystallite size of from about 14 Å to : about 20, about 30, about 40, about 50 Å, from about 17 Å to: about 20, about 30, about 40, about 50 Å; or from about 20 Å to about 30, to about 40, to about 50 Å; or from about 30 Å to: about 40, about 50 Å; or from about 40 to about 50 Å.Docket: 2023613PCT2

[0085] Examples of commercially available CBs that can be utilized to prepare the silicon- carbon material described herein include LITX® HP, high purity carbon blacks, Denka carbon black from Denka, Japan, or other acetylene carbon blacks that can be pelletized or unpelletized and then used as described herein. Carbon blacks from Imerys also can be employed.

[0086] In some implementations, the carbon black support consists of, consists essentially of, or comprises a mixture (blend) of carbon blacks. The CB types in the blend can differ with respect to their BET, OAN and / or other properties.

[0087] Further implementations relate to a carbon black support that includes CB (provided as a single CB specification or in a blend) in combination with carbon nanotubes (CNTs), a type of material that can impart good electrical conductivity, thermal conductivity, and mechanical properties. When used in lithium-ion battery electrodes, CNTs can enhance battery performance such as power, cycle life and / or energy density.

[0088] As known in the art, CNTs are carbonaceous materials, typically hydrophobic, characterized by at least one sheet of sp2-hybridized carbon atoms bonded to each other to form a honey-comb lattice that forms a cylindrical or tubular structure. The carbon atoms in a carbon nanotube are arranged in a hollow (e.g., cylindrical) structure, having a length that generally is greater than the radial diameter. In many cases, the CNTs are characterized by a high aspect ratio, with lengths typically more than 100 times the diameter.

[0089] Both single and multiple walled CNTs can be used, as can mixtures of two or more different types of CNTs. Single walled CNTs (SWCNTs) can be thought of as an allotrope of sp2-hybridized carbon similar to fullerenes. The structure is a cylindrical tube including six- membered carbon rings. Double walled carbon nanotubes (DWCNTs) tend to have properties similar to SWCNTs. Multi walled CNTs (MWCNTs) have several tubes in concentric cylinders. The number of these concentric walls may vary, e.g., from 2 to 25 or more. Typically, the diameter of MWNTs may be 10 nm or more, in comparison to 0.7 to 2.0 nm for typical SWCNTs.

[0090] Based on chirality, CNTs are classified into armchair, zigzag and chiral nanotubes.

[0091] CNTs can be characterized by properties such as length, diameter, aspect ratio, surface area (BET, for example), bulk density, tapped density, particle size distribution (PSD),Docket: 2023613PCT2 to name a few. In many embodiments, the CNT-material employed has a 97% or higher CNT purity. Typically, anionic, cationic or metal impurities are low, e.g., in the parts per million (ppm) range. Often, the CNTs require no further additives to counteract Van der Waals’ forces.

[0092] If present in a porous carbon support, CNTs can be identified and / or characterized by techniques such as electron microscopy, including transmission electron microscopy (TEM) and scanning electron microscopy (SEM), for example. Raman spectroscopy and / or thermogravimetric analysis can be employed in some cases. For instance, the number of walls present (if MWCNTs are employed) can be determined by transmission electron microscopy (TEM), at a magnification sufficient for analyzing the number of walls in a particular case. Since CNTs are known to contain fair amounts of catalyst and other residuals, these species can be detected by techniques such as SEM, TEM, inductively coupled plasma atomic emission spectroscopy or ICP-AES.

[0093] In many implementations, the CNTs employed are conventional (also referred to as “ordinary”, “pristine” or “fresh”) CNTs, which often are provided in individualized form, as manufactured commercially, or, in some cases, as custom-synthesized or processed. Commercially available CNT materials that can be utilized include but are not limited to those available from Cabot Corporation under the tradename of ENERMAX® carbon nanotubes, from CNano under the FT trade name, from LG Chem under the Lucan trade name.

[0094] CNTs can be provided in any suitable amount, determined and / or optimized, for instance, by routine experimentation. In one example, the amount of CNTs in the porous carbon support is from about 0.1 to about 10 % by weight. In another example, the amount of CNTs in the porous carbon support is from about 1 to about 10 wt %. To illustrate, CNTs amounts can be within a range of from about 0.1 to about: 1, 2, 3, 4, 5, 6, 7, 8 or 9 wt %; from about 1 to about: 2, 3, 4, 5, 6, 7, 8 or 9 wt%; from about 2 to about: 3, 4, 5, 6, 7, 8, 9 or 10 wt %; from about 3 to about: 4, 5, 6, 7, 8, 9 or 10 wt %; from about 4 to about: 5, 6, 7, 8, 9 or 10 wt %; from about 5 to about: 6, 7, 8, 9 or 10 wt%; from about 6 to about: 7, 8, 9 or 10 wt %; from about 7 to about: 8, 9 or 10 wt %; from about: 8 to about 9 or 10 wt%; from about 9 to about 10 wt%.

[0095] The porous carbon supports can have any suitable shape. The shape can be defined by milling. Spheroidized supports, for example, can be obtained by gentle milling with mediaDocket: 2023613PCT2 to round off sharp corners. This can be done by similar methods as used for spheroidization of graphite for use in anodes.

[0096] Carbon black supports and silicon-carbon composites can have an average size or D50 particle size by volume within a range from about 1 to about 25 microns. In one implementation, supports have an average size of about 10 microns (μm) measured by Malvern optical scattering for entrained carbon black supports. For instance, carbon black supports can be dispersed into a flowing gas stream that carries the dispersed supports through the light scattering viewing volume. As an example, FIG. 1 shows Malvern Aero S dry powder volume % weighted particle size distribution (PSD) at a feed pressure of 0.5 bar, for CB samples from three different lots (at an average of five replicate runs per sample).

[0097] Carbon black supports and silicon-carbon composites with a D50 particle size by volume or an average particle size of about 1 to about 25 microns, and particularly supports of about 5 to 10 microns, are compatible with typical LIB anode applications. Other benefits associated with the size range described above include but are not limited to the ability to be fluidized in a fluidized bed used to carry out chemical vapor deposition of silicon and / or carbon. Smaller size entities can be entrained out of the fluidized bed reactor, while larger entities can cause rough films in anode layers and / or interfere with the coating processes used to make the anode layers.

[0098] Carbon black supports of a desired size can be custom-made or can be commercially available.

[0099] In one example, one or more types of carbon black and optional CNTs are ground together, to reduce their particle size, and combined. A binder (e.g., polyacrylic acid) can be employed in some cases. The resulting mixture of carbon constituents and optional binder can then be formed into pellets, by techniques such as pelletization, granulation using granulators, to name a few. The pellets can be jet milled to a suitable size, about 10 microns, in one example, to generate the carbon support structures.

[0100] In another example, carbon supports displaying a desired particle size distribution are obtained from readily available materials. For instance, the porous carbon supports can be, or can be obtained from CB pellets, as further described below.Docket: 2023613PCT2

[0101] A schematic representation of an illustrative carbon black support 10 is shown in FIG.2.

[0102] In some embodiments, the carbon black support may also include graphite. Natural as well as artificial / synthetic graphite can be employed, as can combinations of different types of graphite. The graphite employed may be characterized by one and, in many embodiments, more than one property, as further described below.

[0103] One important consideration in the selection of a suitable graphite material relates to its purity. Graphite, in particular natural graphite, often contains impurities such as, for instance, potassium, sodium, aluminum, iron, calcium, magnesium and / or silicate minerals. Since these species can have a negative effect on battery performance, specific implementations of the invention utilize graphite having a purity of at least 99 %, often at least 99.5%, or even at least 99.95 %.

[0104] In contrast to conventional graphite for LIB anode applications (which has a typical particle size of several microns, e.g., 10 microns or so), many embodiments of the carbon supports in the silicon-carbon composites described herein, are characterized by a porosity that can define and contain silicon particles of 100 nm, for instance. Using graphite particles that are too large (as typical in LIB anode graphite materials) would not provide sufficiently small porosity or enough pore volume between the graphite particles. Another factor to be considered is the overall particle size of the product silicon-carbon composite. These considerations point to graphite materials with a particle size no greater and often smaller than about 1 micron.

[0105] In illustrative examples, the graphite particles have a D50 particle size by volume, as measured by Malvern techniques described above, between about 0.1 and about: 0.2, 0.4, 0.6, 0.8 or 1.0 microns; between about 0.2 and about: 0.4, 0.6, 0.8 or 1.0 microns; between about 0.4 and about: 0.6, 0.8 or 1.0 microns; between about 0.6 and about: 0.8 or 1.0 microns; between about 0.8 and about 1 micron.

[0106] Also, in contrast to the mostly spherical graphite particles for LIB anode applications, many of the composites described herein include graphite particles that typically have irregular shapes, displaying, for example, jagged edges, (pointed) corners, deep indentations, and / or marked protrusions.Docket: 2023613PCT2

[0107] In specific embodiments, the graphite employed (having a particle size no greater than about 1 micron and often an irregular shape) is in the form of graphite “fines”, a byproduct in the manufacture of graphite anode LIB materials. For increased packing densities and thus higher energy densities, many manufacturing processes (aiming to prepare graphite particles of about 10 microns, for instance) include operations in which graphite particles are “rounded” (to remove corners, jagged edges, rough points, etc.) using special grinding machines. The chipped off graphite pieces produced during this operation constitute the graphite fines that can be employed in the composites described herein.

[0108] Among the various size cuts that can be obtained from graphite spherodization, particularly relevant here is a cut in the range of about 0.1 micron to about 1. Thus, in many cases, the graphite fines selected for preparing the composite are micron-size and smaller, yet usually larger than 100 nm (or 0.1 microns). However, other size cuts may be considered in some cases.

[0109] For some implementations, the fines utilized are obtained from processing a purified graphite material, such as used, for example, in a final rounding process to prepare an ultrahigh purity anode material. In some cases, the graphite employed is partially or completely coated with a pitch-derived carbon; this coating step is standard for graphite anode material synthesis.

[0110] Analytical techniques that can be relied upon to assess the graphite (often in the form of graphite fines) in the composite include but are not limited to scanning electron microscopy (SEM); X-ray diffraction (XRD), and / or Raman spectroscopy. Impurity concentrations can be determined by inductively coupled plasma atomic emission spectrophotometry (ICP-AES).

[0111] In some embodiments, the carbon in the carbon support may be all graphite, or may be a combination of graphite with carbon black and / or carbon nanotubes. For many applications, adding more graphite raises capacity of energy. Adding more CB, especially CB having a high structure, provides more pore volume. CBs can also have useful energy storage capacity. Adding more CNTs manages the Si expansion and contraction and provides intraparticle electrical conductivity. As part of some preparative approaches (further described below), the fines can be agglomerated (pelletized, for instance) to produce a carbon support having a D50Docket: 2023613PCT2 particle size by volume within a range from about 1 micron to about 25 microns, e.g., about 10 microns.

[0112] In one illustration, the carbon component present in a silicon-carbon composite may include graphite in a range from about 0% to about 100 wt %; CB within a range from about 0 to about 100%; and CNTs within a range from about 0 to about 25 wt %. Other compositions can contain higher loadings of CB and / or CNTs with a correspondingly lower graphite percentage. Many implementations aim to strike a balance between increased porosity due to increased amounts of CB and / or CNTs and gaining capacity from higher graphite amounts present in the composite.

[0113] In many embodiments, the carbon support, whether composed of carbon black, graphite, or a combination thereof is porous. Empty volume can be tailored to accommodate maximum Si loadings, while allowing for the Si volume changes during cycling. The porosity of the carbon support can be affected by the porosity of the constituents themselves, the size of the particles utilized, their shape (less spherical particles particle being less amenable to dense packing), surface energy, and / or other factors.

[0114] The second component in the composite, silicon, is in the form of silicon entities residing within pores of the carbon supports, e.g., in inter-aggregate pores and / or intra-aggregate pores. In implementations that employ porous primary particles, silicon entities also can occupy pores within the primary particles.

[0115] The silicon entities can have a particle size, as measured from SEM images, no greater than about 150 nm, such as, for instance, not greater than about 125, 100, 80, 70, 60, 50, 40, 30, 20, or 10 nm. In some embodiments, the silicon entities are silicon nanoparticles and / or silicon oxide nanoparticles, i.e., the particles are not greater and are often less than about 100 nm. For many applications, the silicon nanoparticles and / or silicon oxide nanoparticles have a size within a range of about 1 nanometer to about 100 nanometers. In specific examples, the silicon nanoparticles and / or silicon oxide nanoparticles are within a range of from about 10 to about: 20, 30, 40, 50 nm; or from about 20 to about: 30, 40, 50 nm; or from about 30 to about: 40, 50 nm; or from about 40 to about 50 nm.Docket: 2023613PCT2

[0116] While larger particles can be employed, selecting sizes at or below 100 nm renders the silicon particles less prone to cracking as they undergo their expansion and contraction during cycling.

[0117] The silicon entities can be discrete entities, disconnected from one another. It is also possible to have connectivity between at least some of the silicon entities. In some cases, the silicon forms, at least initially, a coating of nanoparticles within the internal pores of the support. This coating of nanoparticles of silicon on the carbon forming the porous support can evolve during battery operation as the Li enters and the silicon species move around. At higher loadings of silicon, it is possible to have, at least partially, a continuous coating of silicon on the carbon. This coating eventually may form small particles of silicon or may remain as a coating during subsequent processing and / or battery operation.

[0118] The silicon can be crystalline or amorphous, depending on the process employed to incorporate the silicon into the porous carbon supports. For example, amorphous silicon nanoparticles can be produced by silicon CVD using silane.

[0119] A schematic illustration of a structure in which silicon entities 12 are supported by carbon aggregates forming the porous carbon support 10 is shown in FIG.3.

[0120] The silicon can be introduced (infiltrated or deposited) into the porous carbon supports by various methods. One technique relies on chemical vapor deposition (CVD). In this approach, the carbon supports are exposed to a silicon precursor, e.g., silane (SiH4) gas, at relatively high temperatures, such as 500-600 degrees centigrade (ºC), for a time sufficient (often 1 to 10 seconds) to deposit silicon inside the porous carbon supports and produce a silicon-carbon composite at a desired silicon to carbon ratio, e.g., about a 50:50 ratio by mass. Scanning electron micrographs of carbon-silicon composite particles, where silicon nanoparticles were deposited onto porous carbon supports by CVD, using a silane gas precursor, are shown in FIGS.4, 5, 6A and 6B.

[0121] Other Si-containing precursors that can be utilized to generate the silicon component include silicon tetrachloride or tetrachlorosilane (SiCl4), trichlorosilane (SiCl3H), disilane (Si2Cl6), to name a few. Some Si-containing precursors may require higher deposition temperatures.Docket: 2023613PCT2

[0122] As known in the art, the precursor can be provided in a carrier gas such as, for instance, hydrogen or nitrogen.

[0123] The CVD process can be conducted continuously, semi-continuously or in batch mode, using a suitable apparatus e.g., an apparatus designed for particulate (powder) applications. Examples include but are not limited to fluidized beds, moving (entrained) beds, fixed beds, agitated beds, rotating tube furnaces, or other suitable reactors. In one example, the CVD operation is conducted for a time sufficient (often a minimum of 1 to 10 seconds) to deposit silicon inside the porous carbon scaffold and produce a composite at a desired silicon to carbon ratio, e.g., about a 50:50 ratio by mass. In some embodiments, when a fluidized bed is used, the minimum fluidization velocity is at least 0.1 cm / s, at least 0.5 cm / s, at least 1.0 cm / s, at least 2.0 cm / s, at least 3.0 cm / s, at least 4.0 cm / s, at least 5.0 cm / s, no more than 15.0 cm / s, no more than 14.0 cm / s, no more than 13.0 cm / s, no more than 12.0 cm / s, no more than 11.0 cm / s, no more than 10.0 cm / s, and any and all ranges and subranges therebetween.

[0124] Process parameters (e.g., precursor amounts, gas flow rates, time intervals, temperatures, complete (100%) or incomplete CVD yields, etc.) will typically depend on the equipment employed, starting materials, desired product properties and / or other factors, and can be determined by routine experimentation, modeling calculations, or prior experience.

[0125] In many cases, the CVD conditions employed are based on the Dahmkohler number (defined as the dimensionless ratio of a characteristic diffusion time to the reaction time). Whereas high values of the Da number indicate that the forward reaction is fast, low values indicate that the reaction is kinetically controlled. In specific implementations, the CVD process described herein is conducted at small Da numbers (e.g., <1, <0.5, <0.1). In such a Da number regime, the reaction rate is slow enough to allow silicon-containing species (SiH4, for instance) to penetrate fully into the carbon supports and deposit silicon uniformly throughout the pores of the carbon supports. The Da number characteristics can be controlled primarily through the temperature selected for the CVD process, the choice of precursor, additive gases, and / or other factors.Docket: 2023613PCT2

[0126] In one implementation, the reactor and / or process employed provides uniformity of concentration and temperature for exposing the carbon black support to the silicon-containing gas precursor.

[0127] In specific embodiments, the Si deposition inside a carbon black support is characterized as “uniform”, meaning that the center of the interior of the carbon black support (e.g., with a particle size of about 10 microns) has the same or nearly the same ratio of silicon to carbon as the ratio observed near the surface of the carbon black support. This can be measured by preparing a suitable cross section of the silicon-carbon product and using this cross section for Time-of-Flight Secondary Ion Mass Spectroscopy, XPS or other surface sensitive techniques.

[0128] The process described herein can include additional operations (steps) that can be conducted post-, during or pre-CVD. Post CVD steps, for example, can involve cooling and / or collecting the silicon-carbon structures, size reductions (by milling, for instance), coating using liquids such as pitch, spheroidization, or other product processing steps.

[0129] Other operations relate to obtaining a silicon-carbon composite of a desired average size. As noted above, the carbon black supports can be or can be derived from CB pellets. Such pellets can be available commercially or can be prepared using, for instance, high purity CB (e.g., with metal content below 10 ppm), by techniques known in the art.

[0130] In some cases, the starting pellets are too large compared to the desired product particle size (e.g., about 10 microns in some cases). For instance, the starting pellets can have an average size from about 100 microns to many thousands of microns. In specific examples, the starting pellets have a size within a range from less than 100 microns up to many millimeters such as from about 0.1 mm to about 5 mm.

[0131] The relatively large starting pellets and / or the relatively large product structures obtained by infiltrating silicon into these large pellets can be comminuted to the desired product size, e.g., an average size between 1 and 25 microns in a size reduction, e.g., grinding or milling operation. In some embodiments, the pellet can be reduced in size to have a carbon black support with a D50 particle size by volume to be in a range from 1 to 25 microns, 1 to 20 microns, 1 to 15 microns, 5 microns to 25 microns, 5 microns to 20 microns, 5 microns to 15Docket: 2023613PCT2 microns, 6 microns to 25 microns, 6 microns to 20 microns, 6 microns to 15 microns, 7 microns to 25 microns, 7 microns to 20 microns, 7 microns to 15 microns, 8 microns to 25 microns, 8 microns to 20 microns, 8 microns to 15 microns, 9 microns to 25 microns, 9 microns to 20 microns, 9 microns to 15 microns, 10 microns to 25 microns, 10 microns to 20 microns, or any and all ranges and subranges therebetween. Equipment that can be employed includes jet mills, ball mills, media mills or other dry milling equipment.

[0132] In one implementation, the size reduction step is performed prior to the CVD operation, and it is the smaller, fractured pellets that are exposed to the Si-containing precursor.

[0133] In another implementation, grinding is conducted post-CVD. A tradeoff for fluidized beds, for example, is the potential loss of smaller particles entrained in the gas. This loss can be reduced by conducting the CVD with larger pellets and comminuting the product particles after the silicon-carbon composite has been formed.

[0134] Size increases also can occur. For instance, in a fluidized bed, the porous carbon supports can be entrained in the flowing fluidizing gas and become “glued” together. These spontaneously formed agglomerates typically have sizes larger than those of the starting carbon supports. For instance, 10 microns porous carbon supports could potentially form silicon-carbon agglomerates as large as about 25, 50, 100 microns or even larger. This size increase can be addressed by a post CVD size reduction operation. Malvern optical techniques with the flowing gas can be used to provide useful information and possible correlations.

[0135] Size reductions or size increases can also take place at the same time as the exposure of the porous carbon supports to the Si precursor. For instance, larger carbon entities can collide with each other and result in size reduction. Smaller entities in a fluidized bed can spontaneously agglomerate and form larger entities that can be held together by the deposition of silicon.

[0136] In some embodiments, graphitization is conducted in a heat treating step that can be carried out before and / or after the size reduction operation. In one implementation, the starting pellets are already heat-treated, graphitized CB pellets. In another, heat treatment can be part of the process, with large pellets being heat treated prior to the size reduction step. In a further implementation, pellets are jet milled or comminuted before being heat treated and graphitized.Docket: 2023613PCT2 A further embodiment employs CB that has not been heat treated (e.g., annealed) and is not graphitized.

[0137] A different approach for preparing a composite containing carbon black, and / or graphite, and silicon and optionally CNTs employs a non-CVD technique. Surprisingly and unexpectedly, it was discovered that composites prepared by combining components mechanically, using wet or dry mixing techniques, compared favorably to CVD-produced composites. In this approach, Si entities could be incorporated in a carbonaceous scaffold by mechanical mixing, without losses in electrode performance. In other words, composites prepared by mechanically combining constituents, and without relying on CVD infiltration of silicon entities, performed as well as composite prepared by CVD techniques.

[0138] In one example, the carbon in the carbon support includes graphite fines or graphite fines in combination with a CB and / or CNTs. In another example, the carbon in the carbon support includes a CB, optionally in combination with CNTs, and no graphite. In embodiments, the carbon support is prepared by non-CVD techniques using 0-100% CB, 0-100% graphite, and 0-25% CNTs. A binder may be added in some cases.

[0139] The silicon can be derived from milling of metallurgical grade silicon or from other sources.

[0140] One non-CVD method for preparing a silicon-carbon composite relies on dry mixing. Suitable techniques that can be used or adapted include mechanical agitation, shaking, stirring, etc., and can rely on equipment such as jet mills, tube mills, acoustic mixers, extruders, planetary mixers, other mixing devices, e.g., laboratory-scale mixers, equipment suitable for pilot-scale evaluations, for full-scale industrial manufacturing and so forth.

[0141] If more than two ingredients are employed, the mixing operation can be conducted in one step, all constituents being added at the same time, or sequentially, with additional ingredients being combined with a pre-blend of fewer ingredients.

[0142] Stepwise sequences can employ one type of apparatus to conduct the first operation (e.g., preparing a pre-blend), and another type of apparatus in a subsequent mixing operation. The same is true for shear and / or other mixing parameters.Docket: 2023613PCT2

[0143] To illustrate, separate powders of silicon and / or CB and / or graphite fines, with optional CNTs, are mixed in dry form with an optional binder, such as, for instance, polyacrylic acids, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), carboxymethylcellulose (CMC), another binder typically used in Li ion battery cathodes or anodes, or any combination thereof.

[0144] A wet-mixing alternative involves forming a slurry, typically an aqueous slurry, composed of silicon nanoparticles and one or more carbon constituents, e.g., CB and / or graphite fines and optionally CNTs. The aqueous slurry can further include surface active agents, wetting agents, rheology modifiers, e.g., thickeners, defoamers and / or other components. In some cases, the aqueous slurry will include one or more dispersants or binders such as, for instance, poly(vinyl pyrrolidone), poly(vinylpyrrolidone-co- vinyl acetate), poly(vinyl butyral), poly(vinyl alcohol), poly(ethylene oxide), poly(propylene oxide), poly(propylene carbonate), cellulosic dispersants such as methyl cellulose, carboxymethyl cellulose, ethyl cellulose, hydroxymethyl cellulose and hydroxypropyl cellulose; polycarboxylic acid) such as poly (acrylic acid), polyacrylate, poly(methylacrylate), poly(acrylamide), amide wax, styrene maleic anhydride resins, octylphenol ethoxylate, or others known in the art.

[0145] The slurry is dispersed sufficiently for spray drying processing and can be fed into a spray dryer, with the machine atomizer generating droplets. Subjecting the droplets to a heated gas is typically followed by recovering the spray dried particles, which can be further processed (e.g., sorted, classified, milled, etc.) as needed. Slurry characteristics and / or operating conditions can be determined by routine experimentation, prior experience, and so forth.

[0146] Granulation systems represent yet another preparative approach that does not require CVD. In this approach, a binder is sprayed onto powdered feeds of combined carbon constituent(s) (e.g., CB and / or graphite fines and optional CNTs) and silicon nanoparticles, and the sprayed constituents are granulated into composite particles. Specific procedures and / or equipment that can be employed include granulators originally developed for the pharmaceutical, agricultural and / or other industries.

[0147] Mechanical mixing can be followed by further processing, including, for instance, operations aimed at obtaining a desired composite particle size (e.g., between about 1 and aboutDocket: 2023613PCT2 25 microns, roughly 10 microns in one example). In some embodiments, the mixture containing CB and silicon is pelletized and / or subjected to grinding to the desired size and classification. To illustrate, silicon-carbon structures obtained from the mechanical combination can be pelletized, dried, jet milled, and / or classified to provide composite particles of about 10 microns.

[0148] In one implementation, a solution of water, a binding agent, and, optionally, a dispersant is combined with the mixture of nanosilicon with the carbon materials. This can be followed by pelletizing in a drum pelletizer or a pin pelletizer. Thermal processing removes moisture from the pellets. The size of the dry pellets can be modified, as needed, by jet milling or other techniques known in the art. Sorting and / or classification steps can be conducted before and / or after jet milling.

[0149] The process described herein can include one or more coating operations in which the silicon-carbon composites or structures are covered (partially or completely) with silicon and / or with a material other than silicon.

[0150] As already noted, an important goal for the silicon-carbon composites described herein relates to reducing or minimizing the formation of a large surface area of SEI. Techniques that can be used alternatively or in addition to the carbon surface area considerations discussed above involve keeping the high surface area of the CB and of the silicon supported on the CB protected inside the silicon-carbon composite entity. In one approach, this is accomplished by sealing or “capping” the pores at the surface, thus blocking access to the interior surface area of carbon and silicon. Sealing or “capping” the pores can be conducted by coating the silicon- carbon composite particles with one or more of: silicon, silicon sub-oxide, or carbon. As used herein, the term “capping” refers to a process in which the CVD operation is continued until the silicon or a material other than silicon, e.g., carbon, deposits into outer (or surface) pores of the porous carbon supports to choke off the pores and eventually close off or “cap”) them.

[0151] Further to protecting the high surface area CB and silicon inside the composite, and thus reducing any irreversible uptake of silicon and / or minimizing SEI formation, capping also can block external agents from reaching the interior of the product structures.

[0152] Conditions for capping can be determined by routine experimentation, experience, modeling, or by other techniques.Docket: 2023613PCT2

[0153] In one approach, silicon is deposited into the interiors of the carbon supports and then the operation of the CVD system is shifted to higher temperatures and correspondingly higher silicon deposition rates. This increases the Dahmkohler number, e.g., to greater than 1, greater than 5, greater than 10. In turn, this results in a preferential Si deposition at the surface of the agglomerate. Illustrative processes are conducted with a Dahmkohler number based on particle size, silane diffusion coefficient in the gas phase, and a silane reaction rate that is less than unity; the CVD is continued for a time long enough to close the pores at the surface of the porous carbon supports by filling them in with silicon.

[0154] The schematic illustration of FIG. 7 shows a silicon coating 14 at the surface of a silicon-carbon composite particle (composed of porous carbon support 10 containing silicon entities 12, as shown in FIG.3).

[0155] In another implementation, the silicon-carbon composites are coated with a material other than silicon, carbon in one approach. FIG. 8, for instance, is a schematic representation in which carbon coating 16 is at the surface of the silicon-carbon composite particle of FIG. 3.

[0156] The carbon coating operation can be performed by CVD, utilizing a carbon- containing precursor such as, for instance, methane, natural gas, propane, butane, acetylene, ethylene, propylene, benzene, other saturated, unsaturated or aromatic hydrocarbons, or mixtures thereof.

[0157] In some embodiments, the silicon carbon composites can be coated with both silicon and with a material different from silicon, e.g., carbon. The capping process can be performed sequentially. For example, the pores can be closed using silicon, followed by coating the overall structure with carbon. A schematic representation of the resulting silicon-carbon composite particle, coated first with silicon layer 14, then with carbon layer 16 is presented in FIG.9.

[0158] In some embodiments, when the silicon-carbon composites include graphite, as schematic representation is shown in Fig.10 of a silicon-carbon composite particle 10 including graphite particles 12, which can be graphite fines, carbon black particles 14, carbon nanotubes 16, silicon nanoparticles 18 and coating 20 which seals (caps) surface pores thus protecting the interior 22 of silicon-carbon composite particle 10 from contact with battery electrolyte.Docket: 2023613PCT2

[0159] Conveniently, the carbon coating operation can be conducted in the same reactor that is employed to introduce silicon into the porous carbon support, optionally followed by silicon capping. Typically, this is done by switching feed gases (e.g., from silane to propane) and changing temperatures.

[0160] In one approach, relatively large pellets are ground to form the porous carbon supports described herein. Silicon is then deposited by CVD, e.g., to a 50% loading, optionally followed by silicon capping, then by carbon-coating (via CVD using a C-containing precursor, for example), to form partially or completely coated silicon-carbon structures.

[0161] In a different approach, the relatively larger pellets are first exposed to the Si- containing precursor in a CVD operation, followed by reducing the size of the silicon-carbon material, e.g., by grinding, to obtain silicon-carbon structures of the desired size, e.g., 10 micron, which are then covered (by CVD using a C-containing precursor, for example) with a carbon layer to form partially or completely coated silicon-carbon structures. In one implementation, this approach involves transferring the material to a size reduction apparatus, a jet mill, for instance. Once comminuted, the material can be returned to the CVD reactor for carbon coating.

[0162] In many cases, the thickness of the coating produced by the silicon and / or carbon coating operation will depend on the surface pores. In many cases, the pores at the surface of the porous carbon support are roughly 10-100 nm in size. To cap these surface pores may require deposition of material with a coating thickness greater than about 5-50 nm.

[0163] Capping operations can produce a coating or layer that covers 100% or nearly 100% of the silicon-carbon composite structure. Particles that are only partially covered with silicon and / or carbon, e.g., 90, 80, 70, 60, 50, 40, 30, 20, 10 percent or less, also can be prepared.

[0164] Techniques that can be employed to assess coating properties include but are not limited to BET surface area, cross sectional microscopy, elemental surface composition analysis such as by SIMS, Auger or XPS. A fully coated particle will block access to the high surface area within the entity, resulting in a low measured accessible surface area. Cross-sectional microscopy will show a continuous layer at the surface of the silicon-carbon entities. SIMS, Auger and XPS will show just the presence of silicon, for example, if the pores are closed by silicon.Docket: 2023613PCT2

[0165] In a specific embodiment, silicon-carbon composite structures are coated with a carbon layer using non-CVD techniques. For instance, the carbon coating can be formed by decomposing solid carbon-containing precursors that have been applied to the surfaces of composite particles (that include silicon, CB and optional CNTs). Illustrative implementations utilize materials that typically have higher carbon contents, such as, for instance, sugars, pitches, sol gels or tars.

[0166] In one approach, the silicon-containing composite particles are mixed with an aqueous solution of a sugar, e.g., glucose, sucrose, fructose, other polysaccharides or combinations of different sugar types.

[0167] Simple direct mixing, spray coating, dip-coating, granulator coating or other suitable techniques can be used, as known in the art. The coated particles can be dried to remove water, leaving a thin layer of sugar on their surfaces. The sugar-coated particles are then heated in an inert atmosphere (e.g., nitrogen, argon, etc.) at temperatures typically ranging from 400°C to 800°C. The pyrolysis process is conducted in an oxygen-free environment and involves the decomposition of the carbon-rich sugars which break down to form carbon, typically in a thin layer covering the substrate particles. The structure, porosity and / or other properties of the carbon layer can be controlled by varying the pyrolysis conditions, including temperature, heating rate, duration, and / or other process parameters.

[0168] Another approach involves pitch (a complex mixture of polycyclic aromatic hydrocarbons (PAHs) that can be derived from petroleum, coal tar, or synthetic sources). The high carbon content and thermoplastic behavior make pitch an excellent precursor for carbon coatings, offering good control over the properties of the final carbon layer, such as degree of graphitization, porosity, and electrical conductivity.

[0169] The pitch is typically applied to the substrate particles in a molten state or as a solution in an appropriate solvent. In many cases, the substrate particles are evenly coated with the pitch. If the pitch is applied in a solution, the solvent is evaporated, leaving a uniform pitch coating on the particles. The pitch-coated particles are heated in an inert atmosphere (nitrogen or argon, for instance) to temperatures typically between 600°C and 1000°C. In this process, known as “carbonization”, pitch is decomposed into a carbonaceous material. The temperatureDocket: 2023613PCT2 required to convert pitch to carbon for coating purposes will typically depend on the type of pitch used, desired properties of the carbon layer and / or other factors.

[0170] In more detail, different pitches (petroleum pitches, coal tar pitches or other types of pitches) have different compositions and therefore different thermal behaviors. Nevertheless, there is a general range of temperatures that can be considered effective for the conversion process. The pyrolysis of pitch typically begins at temperatures around 350°C to 400°C. This initial stage involves the evolution of volatile compounds and the formation of a more cross- linked structure. As the temperature increases, typically around 400°C to 500°C, the pitch begins to transform into a mesophase pitch. This mesophase is an important intermediate stage where the pitch starts to develop a more ordered, graphitic structure. The full carbonization of pitch, during which pitch fully loses its volatile components and develops a stable carbon structure, becoming transformed into a solid carbon material, usually occurs at higher temperatures, typically in the range of about 600°C to about 1000°C.

[0171] In some embodiments, the solid carbon containing precursor (for example, pitch) may contain carbon particles, such as carbon black, carbon nanotubes, carbon nanostructures, and combinations thereof. The carbon particles can be mixed at 5%, 10 wt% and up to 20 wt%. The carbon particles can improve the conductivity and adhesion with other particles. The carbon particles can also help to block surface pores on the composite particle.

[0172] In LIB applications, the silicon-carbon material described herein can represent the entire anode material or a portion thereof. In one embodiment, the silicon-carbon composite is used as an anode additive.

[0173] In anode applications, the silicon-carbon composite can be provided in combination with an electroactive material (also referred to herein as “active electrode material” or simply as “active material” or “AM”) such as graphite, e.g., natural graphite, artificial graphite (e.g., massive artificial graphite (MAG)) or blends of both. Mesocarbon microbead (MCMB), mesophase-pitch-based carbon fiber (MCF), vapor grown carbon fiber (VGCF) also can be employed. The silicon-carbon composite also can be added to active materials that include silicon, silicon-graphite composites, graphite containing nanosilicon (Si) or SiOxparticles, for example.Docket: 2023613PCT2

[0174] To illustrate, a graphite anode can employ a silicon-carbon composite such as described herein in an amount ranging from about 1 % by weight (wt %) to about 20 wt %, e.g., from about 1 to about 5, to about 10, to about 15, to about 20 wt%; or from about 5 to about 10, to about 15, to about 20 wt%; or from about 10 to about 15, to about 20 wt % or from about 15 to about 20 wt%.

[0175] In specific implementations, the ratio of silicon-carbon composite to graphite is 1:100, 1:50, 1:20, 1:10, 1:5 or 1:1.

[0176] Principles described herein also can be used with other active anode materials such as, for instance, those known or currently explored, or those to be developed in the future. Examples include but are not limited to: (a) intercalation / de-intercalation materials (e.g., carbon based materials, porous carbon, graphene, TiO2, Li4Ti5O12, and so forth); (b) alloy / de-alloy materials (e.g., Si, SiOx, doped Si, Ge, Sn, Al, Bi, SnO2, etc.); and (c) conversion materials (e.g., transition metal oxides (MnxOy, NiO, FexOy, CuO, Cu2O, MoO2, etc.), metal sulfides, metal phosphides and metal nitrides represented by the formula MxXy,where X = S, P, N)). Some examples employ alloys of silicon or germanium.

[0177] In another embodiment, the entire anode is made of the silicon-carbon composite material, obviating the need to include a separate electroactive material such as graphite, for instance.

[0178] It has been unexpectedly found the silicon-carbon composites that have (i) a ratio of OAN (oil adsorption number): BET (Brunauer-Emmett-Teller surface area) for the carbon black support is in a range from 0.1 to 10, wherein OAN is measured by ASTM D2414-23A and reported in ml per 100g of carbon and BET is measured by ASTM D6556-21, and / or (ii) a mass in g of silicon per 100g of carbon black support is less than or equal to 0.75 * OAN have benefits for use in anode compositions, for example for lithium-ion batteries. In some embodiments, the ratio of OAN:BET for the carbon black support may be in a range from 0.1 to 10, 0.1 to 9, 0.1 to 9, 0.1 to 7, 0.1 to 6, 0.1 to 5, 0.1 to 4, 0.1 to 3, 0.1 to 2, 0.1 to 1, 0.1 to less than 1, 0.2 to 10, 0.2 to 9, 0.2 to 9, 0.2 to 7, 0.2 to 6, 0.2 to 5, 0.2 to 4, 0.2 to 3, 0.2 to 2, 0.2 to 1, 0.2 to less than 1, 0.3 to 10, 0.3 to 9, 0.3 to 9, 0.3 to 7, 0.3 to 6, 0.3 to 5, 0.3 to 4, 0.3 to 3, 0.3 to 2, 0.3 to 1, 0.3 to less than 1, 0.4 to 10, 0.4 to 9, 0.4 to 9, 0.4 to 7, 0.4 to 6, 0.4 to 5, 0.4 to 4, 0.4 to 3, 0.4 to 2,Docket: 2023613PCT2 0.4 to 1, 0.4 to less than 1, 0.5 to 10, 0.5 to 9, 0.5 to 9, 0.5 to 7, 0.5 to 6, 0.5 to 5, 0.5 to 4, 0.5 to 3, 0.5 to 2, 0.5 to 1, 0.5 to less than 1, 1 to 10, 1 to 9, 1 to 8, 1 to 7, 1 to 6, 1 to 5, 2 to10, 2 to 9, 2 to 8, 2 to 7, 2 to 6, 3 to 10, 3 to 9, 3 to 8, 3 to 7, 3 to 6, 4 to 10, 4 to 9, 4 to 8, 4 to 7, 5 to 10, 5 to 9, 5 to 8, 5 to 7, 6 to 10, 6 to 9, 6 to 8, 7 to 10, 7 to 9, 8 to 10, or any and all ranges and subranges therebetween. Balancing the ratio of OAN to BET can minimize the formation of a solid electrolyte interface (SEI) caused by contact of electrolyte with the carbon black support, which is important because SEI decreases the amount of lithium in the LIB and thereby can diminish energy capacity. Thus, minimized the formation of SEI can lead to improved energy capacity of an LIB. In some embodiments, that mass in g of silicon per 100g of carbon black support may be in a range from less than or equal to 0.75 * OAN to greater than or equal 0.5 *OAN, less than or equal to 0.75 * OAN to greater than or equal to 0.55 * OAN, less than or equal to 0.75 * OAN to greater than or equal 0.6 *OAN, less than or equal to 0.75 * OAN to greater than or equal to 0.65 * OAN, less than or equal to 0.7 * OAN to greater than or equal 0.5 *OAN, less than or equal to 0.7 * OAN to greater than or equal to 0.55 * OAN, less than or equal to 0.7 * OAN to greater than or equal 0.6 *OAN, less than or equal to 0.7 * OAN to greater than or equal to 0.65 * OAN, less than or equal to 0.65 * OAN to greater than or equal 0.5 *OAN, less than or equal to 0.65 * OAN to greater than or equal to 0.55 * OAN, less than or equal to 0.65 * OAN to greater than or equal 0.6 *OAN, less than or equal to 0.6 * OAN to greater than or equal to 0.5 * OAN, or any and all ranges and subranges therebetween. Balancing the OAN (which can be correlated to void volume in a carbon black support) with the amount of silicon in the pores to leave room for volume expansion of the silicon while not leaving so much room as to degrade energy density has the benefit of improved energy density for LIBs.

[0179] Thus, generally, the silicon-carbon composite can be provided in an anode in any suitable amount, depending on factors such as: the specific application, anode active material employed (if any), manufacturing process, the presence of other ingredients, to name a few. In specific implementations, the silicon-carbon composite is provided in an amount between about 20 and about 100 wt%. In some cases, silicon-carbon composites within a range of 20-50 % may be preferred over higher loadings of the composite.Docket: 2023613PCT2

[0180] In addition to the silicon-carbon composite and the anode active material (if an active material, e.g., graphite, is employed), anode compositions can further include other ingredients, such as, for example, conductive additives, e.g., conductive carbon additives (CCAs), binders, plasticizers, and / or other components. In many cases, binders are provided in relatively small amounts (a few, e.g., 2 to 3 wt % or from 0.1 to 5 wt%). For anode applications, the silicon- carbon composite particles disclosed herein are particularly compatible with a binder that consists of, consists essentially of, or comprises lithiated-polyacrylic acid (LiPAA) for the anode. Other binders can be utilized.

[0181] CCA is often provided in an amount of 1 wt % or less. Examples of CCAs include CB, which can be the same or different from the CB in the silicon-carbon composite, and / or carbon nanotubes (CNTs). One implementation uses single wall carbon nanotubes (SWCNTs), which can maintain good electrical contact with the graphite and with the silicon-carbon composites as dimensions change during anode operation.

[0182] An illustrative anode composition includes graphite, a silicon-carbon composite such as described herein, LiPAA binder and SWCNTs.

[0183] The silicon-carbon composite can be combined with the anode active material, e.g., graphite, using techniques presently known in the art or developed in the future. The resulting composition, in the form of a slurry, paste, a pourable particulate material, etc. can be employed in the manufacture of LIB anodes.

[0184] LIBs described herein further include a cathode, e.g., a LCO (lithium cobalt oxide), LMO (lithium manganese oxide), NCM (lithium nickel cobalt manganese oxide), NCA (lithium nickel cobalt aluminum oxide), LCP (lithium cobalt phosphate), LFP (lithium iron phosphate), LMFP (lithium manganese iron phosphate), LFSF (lithium iron fluorosulfate), LTS (lithium titanium sulfide) cathode. Materials such as these are generally referred to herein as “lithium transition metal compounds”, e.g., “lithium transition metal oxides”. In addition to cathode materials based on intercalation chemistry, e.g., typically involving chemical reactions that transfer a single electron, other types of cathode materials (having lithium ions inserted into FeF3, for instance) can transfer multiple electrons through more complex reaction mechanisms,Docket: 2023613PCT2 called conversion reactions. Other active cathode materials known in the art or developed in the future can be used.

[0185] Some embodiments utilize NCM (also referred to as “NMC”) or NCA cathode compositions. These materials are generally known to those skilled in the art. Moreover, many battery grade formulations in powder form (such as, for example, NCM 622) can be obtained commercially.

[0186] In more detail, NCM can be represented by the formula Li1+x(NiyCo1-y-zMnz)1-xO2, wherein x ranges from 0 to 1, y ranges from 0 to 1 (e.g., 0.3-0.8), and z ranges from 0 to 1 (e.g., 0.1-0.3). Examples of NCMs include Li1+x(Ni0.33Co0.33Mn0.33)1-xO2, Li1+x(Ni0.4Co0.3Mn0.3)1-xO2, Li1+x(Ni0.4Co0.2Mn0.4)1-xO2, Li1+x(Ni0.4Co0.1Mn0.5)1-xO2, Li1+x(Ni0.5Co0.1Mn0.4)1-xO2, Li1+x(Ni0.5Co0.3Mn0.2)1-xO2, Li1+x(Ni0.5Co0.2Mn0.3)1-xO2, Li1+x(Ni0.6Co0.2Mn0.2)1-xO2, Li1+x(Ni0.8Co0.1Mn0.1)1-xO2and Li1+x(Ni0.9C0.05Mn0.05)1-xO2.

[0187] NCA can be represented by the formula Li1+x(NiyCo1-y-zAlz)1-xO2, wherein x ranges from 0 to 1, y ranges from 0 to 1, and z ranges from 0 to 1. An example of an NCA is Li1+x(Ni0.8Co0.15Al0.05)1-xO2.

[0188] In addition to the two electrodes, a typical LIB comprises a suitable electrolyte. Examples include, for instance, ethylene carbonate-dimethyl carbonate-ethylmethyl carbonate (EC-DMC-EMC), vinylene carbonate (VC), LiPF6; ethylene carbonate-diethyl carbonate (EC- DEC, LiPF6; or (EC-DMC), LiPF6. Furthermore, electrolyte composition may contain special additives known to enhance the performance of SiOxor silicon comprising anodes, for example fluorinated carbonates, such as fluoroethylene carbonate and others. In the laboratory, a separator that absorbs electrolyte and prevents electrical contact between electrodes, while allowing diffusion of Li ions, can be a suitable glass fiber micro filter (for example, Whatman GF / A). Membrane separators made of polypropylene / polyethylene (for example, Celgard 2300) also can be used in some cases.

[0189] Anodes containing the silicon-carbon structures described herein can be incorporated into a lithium-ion battery according to methods known in the art, such as, for example, those described in "Lithium Ion Batteries Fundamentals and Applications", by Yuping Wu, CRCDocket: 2023613PCT2 press, (2015). In specific implementations, the batteries are coin type batteries such as, for example, 2032 coin-cells, 18650 cylindrical cells, pouch cells, and others.

[0190] Principles described herein can be used and / or adapted to the manufacture of other energy storage devices, such as, primary alkaline batteries, primary lithium batteries, nickel metal hydride batteries, sodium batteries, lithium sulfur batteries, lithium air batteries, and supercapacitors. Methods of making such devices are known in the art and are described, for example, in "Battery Reference Book", by TR Crompton, Newness (2000).

[0191] The electrodes and / or batteries containing silicon-carbon composites can be characterized by various techniques. Examples include but are not limited to electron microscopy, e.g., TEM, SEM, X-ray tomography, Raman spectrometry, and other suitable qualitative or quantitative analytical methods. Anode performance can be tested by procedures known in the art, or techniques adapted or developed. Suitable methods include, for instance, in-plane and thru plane electrode conductivity, electrochemical impedance spectroscopy (EIS), constant current charge-discharge, hybrid pulse power capability (HPPC), cycling. Mechanical evaluation techniques include peeling testing (e.g., 90°, 180°, T-peel, various fixtures), pull testing, and bending testing (mandrel experiments), to name a few.

[0192] The disclosure is further illustrated by the following non-limited examples. EXEMPLIFICATION Example 1

[0193] Samples were prepared by static bed reactor CVD using an Easy Tube® 3000 system from CVD Equipment. A thin layer of LITX® HP (Cabot Corporation) was placed on a quartz tray, and the tray was placed in the reactor. The reactor was pumped down to low pressure and purged with argon before heating to temperature. Once the reactor was at the designated temperature, silane (a silicon-containing precursor) was flowed through the reactor at a set rate and for a set time to allow silicon to deposit on the layer of LITX® HP and form a silicon- carbon composite. Process parameters are summarized in Table A below. For some of the samples below, a carbon coating was applied by increasing the reactor temperature and pressure and flowing ethylene (a carbon-containing precursor) at a set rate for a set time. Table ADocket: 2023613PCT2

[0194] Materials were characterized by thermogravimetric analysis (TGA), surface area (BET) and scanning electron microscopy (SEM).

[0195] Thermogravimetric analysis was performed on a TA Instrument Q600 horizontal TGA / DSC under air. The temperature was ramped at 10°C / min until 650°C, then held for at least two hours to allow all carbon to burn off, then the temperature was increased 10°C / min until 1300°C. By 1300°C there is no further weight change, all silicon was fully oxidized to SiO2. The weight of the silica can be used to determine the total Si wt% using the equation below: )

[0196] The value is reported as an average of three replicates.

[0197] The samples were examined via Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy (SEM / EDS) using a ZEISS Ultra Plus field emission scanning electron microscope equipped with an Oxford AZtec x-ray spectroscopy system. All images were acquired using split detector mode. The left-hand side of the images were acquired using an energy selective backscatter detector and the right-hand side of the images were collected using a InLens secondary electron detector. Backscattered electron images were formed by collecting reflected electrons emitted by elastic scattering of the electron beam. These images can reveal compositional differences in a sample, heavier elements (in this case silicon) will appear brighter than lighter elements. The particles were sprinkled on carbon tape for imaging.Docket: 2023613PCT2

[0198] Surface area was measured by BET on a Micromeritics TriStar 3030 Plus. Samples were outgassed at 200°C for 60 min under nitrogen flow; measured using partial pressure range 0.05 - 0.5 P / P0; and analyzed by BET theory. The results are summarized in Table B below, where the Control was not exposed to silane.

[0199] The OAN of the carbon support was measured by ASTM D2414-23A and was 231.7 ml per 100g of carbon for all the samples. Therefore, 0.75 * OAN was 173.8 and as can be seen in the table below all the carbon supports had a mass of silicon per 100 g of carbon black support was less than 0.75 * OAN. The BET surface area of the carbon support was measured by ASTM D6556-21 and was 89.1 m2 / g for all samples. The OAN / BET of the samples was 2.60. Table BExample 2

[0200] Coin cells were prepared using a 3-step mixing process with a Thinky ARE-310 mixer using the formulation in Table C below. Li-PAA binder was prepared by dissolving polyacrylic acid (MW:450k, Sigma Aldrich) in water, and adjusting to pH 7 with LiOH. Tuball SWCNTs and Li-PAA were mixed for 10 min at 2000 rpm. Water and the silicon-carbonDocket: 2023613PCT2 composite were added and mixed for 5 min at 2000 rpm. Graphite was added and the composition was mixed for 20 min, with rest steps to prevent the paste from overheating. Table C

[0201] The slurry was coated onto a 9 μm copper foil with a thickness of 150 microns using a doctor blade coater then dried and calendared to target a density of 1.3 g / cm3. The coated sheets were then punched to 15 mm discs. 2032 half-cell coin cells were assembled in a glove box under argon with lithium chips, Whatman GF / A glass fiber separators, 1 mm thick spacers, and 175 microliters (μL) of 1.0M LiPF6 in ethylene carbonate / dimethyl carbonate / diethyl carbonate (1:1:1 vol) + 10% fluoroethylene carbonate as the electrolyte. Half cells were tested on a Maccor tester at 25°C with one formation cycle at C / 20, a second formation cycle at C / 10, then cycling at C / 3. The results are shown in Table D below and indicate that the silicon-carbon composites significantly increased the initial capacity with respect to the Control and the cycling performance of the silicon-carbon composites was comparable or better than that of the Control. In addition, if one were to prepare a carbon coated silicon-carbon composite for use in making a half coin cell as described above, it would be expected that the carbon coating would slightly decrease the initial capacity as a result of the added carbon, but that it would lead to a higher first cycle efficiency and better capacity retention compared to a half cell with an uncoated silicon-carbon composite. In such instance, the carbon coating would be made by dissolving 10 mg coal tar pitch in 20 ml of tetrahydrofuran and then adding 50 mg of the silicon-carbon composite. It would be mixed vigorously, then allowed to evaporate and the pitch-coated silicon-carbon composite residue would be collected. In a furnace, the composite would be heated under air to 240 degrees Celsius at 5 degrees Celsius per minute and then would be soaked for three hours. Then, it would be heated at 1000 degrees Celsius for 1 hour under argon to carbonize the coating.Docket: 2023613PCT2 Table DExample 3

[0202] Performance of coin cells prepared using a silicon-carbon composite prepared by mechanical mixing (Sample 9), a silicon-carbon composite prepared by CVD of the silicon (Sample 1 described in Example 1 above), and a control (Control described in Example 1 above) that did not contain silicon were compared.

[0203] Coin cells were prepared using the same process as in Example 2 and the formulations in weight percent on a dry basis are listed below in Table E. In making Sample 9, the silicon-carbon composite was a blend of 13.1 wt% silicon (silicon nanoparticles (US Research Nanomaterials Inc.)) and 30.8 wt% carbon black support (conductive carbon black particles (LITX® HP, Cabot Corporation)). The OAN of the carbon support of Sample 9 was measured by ASTM D2414-23A and was 231.7 ml per 100g of carbon. The mass of silicon per 100 g of carbon in the carbon black support was 30 g. Therefore, 0.75 * OAN was 173.8 and therefore the carbon supports had a mass of silicon per 100 g of carbon black support less than 0.75 * OAN. The BET surface area of the carbon support for Sample 9 was measured by ASTM D6556-21 and was 89.1 m2 / g. The OAN / BET of the carbon black support for Sample 9 was 2.60.Docket: 2023613PCT2 TABLE E

[0204] Half-cell performance is summarized in the graph of FIG.11. Specifically shown is the discharge capacity (mAh / g) versus cycle behavior of half cells according to Control (dashes), Sample 1 (dots) and Sample 9 (solid line).

[0205] The CB-silicon mechanical mix, Sample 9 had a cell performance that was within error of the performance of the example where silicon was deposited onto the carbon support by CVD (Sample 1). Both showed a significant improvement in capacity compared to the control sample prepared without silicon (Control). ASPECTS

[0206] Aspect 1: A silicon-carbon composite comprising: a carbon black support; and silicon in pores of the carbon black support, wherein: a ratio of OAN (oil adsorption number): BET (Brunauer-Emmett-Teller surface area) for the carbon black support is in a range from 0.1 to 10, or 0.1 to less than 1, wherein OAN is measured by ASTM D2414-23A and is reported in ml per 100g of carbon and BET is measured by ASTM D6556-21, and a mass in g of silicon per 100g of carbon black support is less than or equal to 0.75 * OAN.

[0207] Aspect 2: The silicon-carbon composite of aspect 1, wherein the silicon-carbon composite has a D50 particle size by volume in a range from 5 to 25 microns.

[0208] Aspect 3: The silicon-carbon composite of aspect 1 or 2, wherein the silicon-carbon composite further comprises a coating of silicon, carbon, or a combination thereof.Docket: 2023613PCT2

[0209] Aspect 4: The silicon-carbon composite of any preceding aspect, wherein the pores of the carbon black support are capped.

[0210] Aspect 5: The silicon-carbon composite of any preceding aspect, wherein the carbon black support has a Lc crystallite size of less than or equal to 42 Angstroms.

[0211] Aspect 6: The silicon-carbon composite of any preceding aspect, wherein the carbon black support is not heat treated.

[0212] Aspect 7: The silicon-carbon composite of any preceding aspect, wherein the pores the carbon black support comprise inter-aggregate pores and intra-aggregate pores and the silicon is within the intra-aggregate pores and / or the inter-aggregate pores.

[0213] Aspect 7: The silicon-carbon composite of any preceding aspect, wherein the carbon black support contains less than 100 ppm metal impurities.

[0214] Aspect 8: The silicon-carbon composite of any preceding aspect, wherein the carbon black support has an OAN in a range from 32 to 400 ml per 100g of carbon.

[0215] Aspect 9: The silicon-carbon composite of any preceding aspect, wherein the carbon black support has a BET in a range from 3.2 to 400 m2 / g.

[0216] Aspect 10: The silicon-carbon composite of any preceding aspect further comprising graphite.

[0217] Aspect 11: The silicon-carbon composite of aspect 10, wherein the graphite comprises graphite particles having a particle size that is no greater than 1 micron.

[0218] Aspect 12: The silicon-carbon composite of any preceding aspect, wherein the carbon black supports are agglomerates of carbon black aggregates.

[0219] Aspect 13: The silicon-carbon composite of any preceding aspect, wherein the silicon comprises silicon nanoparticles or silicon oxide nanoparticles.

[0220] Aspect 14: The silicon-carbon composite of any preceding aspect, the silicon is in inter-aggregate pores and inter-aggregate pores of the carbon black support and the silicon is in the form of silicon entities that are unconnected.Docket: 2023613PCT2

[0221] Aspect 15: The silicon-carbon composite of any of aspects 1-14, wherein the silicon is in inter-aggregate pores and inter-aggregate pores of the carbon black support and the silicon is in the form of silicon entities and at least some of the silicon entities are interconnected.

[0222] Aspect 16: An anode composition comprising: the silicon-carbon composite of any preceding aspect as an anode active material.

[0223] Aspect 17: The anode composition of aspect 16, further comprising an additional anode active material.

[0224] Aspect 18: The anode composition of aspect 17, wherein the anode active material is graphite.

[0225] Aspect 19: The anode composition of any of aspects 16-18, further comprising carbon nanotubes.

[0226] Aspect 20: A lithium ion battery comprising the anode composition of any of aspects 16-19.

[0227] Aspect 21: A method for preparing a silicon-carbon composite, the method comprising: exposing a carbon black support to a silicon-containing precursor at temperatures sufficient to decompose the precursor and deposit silicon within pores of the carbon black support to produce a silicon-carbon composite, wherein: a ratio of OAN (oil adsorption number): BET (Brunauer-Emmett-Teller surface area) for the carbon black support is in a range from 0.1 to 10 or 0.1 to less than 1, wherein OAN is measured by ASTM D2414-23A and BET is measured by ASTM D6556-21, and a mass of silicon per 100g of carbon black support is less than or equal to 0.75 * OAN.

[0228] Aspect 22: The method of aspect 21, further comprising fluidizing the carbon black at a minimum fluidization velocity of at least 0.1 cm / s while exposing the carbon black support to the silicon-containing precursor.

[0229] Aspect 23: The method of aspect 21, wherein the method is conducted in a fluidized bed, moving bed, fixed bed, agitated bed or a rotating tube furnace.Docket: 2023613PCT2

[0230] Aspect 24: The method of any of aspects 21-23, wherein the method is conducted in an apparatus that provides uniform concentration and temperature conditions.

[0231] Aspect 25: The method of any of aspects 21-24, wherein the method is conducted with a Dahmkohler number based on particle size, precursor diffusion coefficient in the gas phase, and a precursor reaction rate that is less than unity.

[0232] Aspect 26: A method for preparing a silicon-carbon composite, the method comprising: mechanically combining a carbon black support with silicon nanoparticles to form a silicon- carbon composite, wherein: a ratio of OAN (oil adsorption number): BET (Brunauer-Emmett-Teller surface area) for the carbon black support is in a range from 0.1 to 10 or 0.1 to less than 1, wherein OAN is measured by ASTM D2414-23A and BET is measured by ASTM D6556-21, and a mass of silicon per 100g of carbon black support is less than or equal to 0.75 * OAN.

[0233] Aspect 27: The method of aspect 26, further comprising reducing the size of the silicon-carbon black composite.

[0234] Aspect 28: The method of aspect 26 or 27, further comprising mechanically combining carbon nanotubes with the carbon black support and silicon nanoparticles.

[0235] Aspect 29: The method of any of aspects 26-28, further comprising mechanically combining binder with the carbon black support and silicon nanoparticles.

[0236] Aspect 30: The method of any of aspects 27-29, wherein the mechanically combining comprises dry mixing of powders, wet mixing in a slurry, or granulating powders sprayed with a powder.

[0237] Aspect 31: The method of any of aspects 21-308, wherein the silicon-carbon composite has a D50 particle size by volume in a range from 5 to 25 microns.

[0238] Aspect 32: The method of any of aspects 21-31, wherein the carbon black support has a Lc crystallite size of less than or equal to 42 Angstroms.

[0239] Aspect 33: The method of any of aspects 21-332, wherein the carbon black support contains less than 100 ppm metal impurities.Docket: 2023613PCT2

[0240] Aspect 34: The method of any of aspects 21-33, wherein the carbon black support has an OAN in a range from 32 to 400 ml per 100g of carbon.

[0241] Aspect 35: The method of any of aspects 21-34, wherein the carbon black support has a BET in a range from 3.2 to 400 m2 / g.

[0242] Aspect 36: The method of any of aspects 21-35, wherein the pores of the carbon black support comprise inter-aggregate pores and intra-aggregate pores and the silicon is within the intra-aggregate pores and / or the inter-aggregate pores.

[0243] Aspect 37: The method of any of aspects 21-36, further comprises adding graphite to silicon-carbon composite.

[0244] Aspect 38: The method of aspect 37, wherein the graphite comprises graphite particles having a particle size that is no greater than 1 micron.

[0245] Aspect 39: The method of any of aspects 21-338, wherein the carbon black supports are prepared from carbon black pellets.

[0246] Aspect 40: The method of any of aspects 21-39, wherein the carbon black is graphitized.

[0247] Aspect 41: The method of any of aspects 21-39, wherein the carbon black is not graphitized or heat treated.

[0248] Aspect 42: The method of any of aspects 21-41, wherein the carbon black support is an agglomerate of carbon black aggregates.

[0249] Aspect 43: The method of any of aspects 21-42, wherein the silicon is in inter- aggregate pores and intra-aggregate pores of the silicon-carbon support and the silicon is in the form of discrete, unconnected silicon entities.

[0250] Aspect 44: The method of any of aspects 21-42, wherein the silicon is in inter- aggregate pores and intra-aggregate pores of the silicon-carbon support and the silicon is in the form of silicon entities, at least some of which are interconnected.

[0251] Aspect 45: The method of any of aspects 21-44, wherein the silicon deposited within the pores of the carbon black support is in the form of silicon nanoparticles.Docket: 2023613PCT2

[0252] Aspect 46: The method of any of aspects 21-45, wherein a mass ratio of silicon to carbon in the silicon-carbon composite is between 20:80 to 80:20.

[0253] Aspect 47: The method of any of aspects 21-46, further comprising capping pores of the silicon-carbon composite.

[0254] Aspect 48: The method of any of aspects 21-47, further comprising coating the silicon-carbon composite with silicon, carbon, or a combination thereof.

[0255] Aspect 49: The method of aspect 48, wherein the silicon-carbon composite is coated by chemical vapor deposition.

[0256] Aspect 50: The method of aspect 48, wherein the silicon-carbon composite is coated with carbon by a thermal decomposition of a carbon-containing precursor at a surface of the silicon-carbon.

[0257] Aspect 51: The method of aspect 48, wherein the carbon-containing precursor is a sugar, a pitch, a tar or a sol gel.

[0258] Aspect 52: The method of aspect 48, further comprising capping surface pores of the silicon-carbon composite with silicon, followed by carbon coating.

[0259] Aspect 53: The method of any of aspects 21-52, further comprising reducing a particle size of the carbon support or the silicon-carbon composite.

[0260] Aspect 54: The method of any of aspects 21-53, further comprising combining the silicon-carbon composite with a LIB anode active material.

[0261] Aspect 55: The method of any of aspects 21-54, further comprising preparing a LIB anode that includes the silicon-carbon composite.

[0262] Aspect 56: A method for preparing a silicon-carbon composite, the method comprising: mechanically combining graphite particles having a particle size no greater than 1 micron with silicon nanoparticles to form a silicon-carbon structure.

[0263] Aspect 57: The method of aspect 56 further comprising coating the silicon-carbon composite with a carbon layer to produce a coated silicon-carbon composite.Docket: 2023613PCT2

[0264] Aspect 58: A silicon-carbon composite made according to the process of aspect 56 or 57.

[0265] While this disclosure has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the disclosure encompassed by the appended claims.

Claims

Docket: 2023613PCT2 CLAIMS What is claimed is:

1. A silicon-carbon composite comprising: a carbon black support; and silicon in pores of the carbon black support, wherein: a ratio of OAN (oil adsorption number): BET (Brunauer-Emmett-Teller surface area) for the carbon black support is in a range from 0.1 to 10, wherein OAN is measured by ASTM D2414-23A and is reported in ml per 100g of carbon and BET is measured by ASTM D6556-21, and a mass in g of silicon per 100g of carbon black support is less than or equal to 0.75 * OAN.

2. The silicon-carbon composite of claim 1, wherein the ratio of the OAN:BET for the carbon black support is in a range from 0.1 to less than 1.

3. The silicon-carbon composite of claim 1 or 2, wherein the silicon-carbon composite has a D50 particle size by volume in a range from 5 to 25 microns.

4. The silicon-carbon composite of any preceding claim, wherein the silicon-carbon composite further comprises a coating of silicon, carbon, or a combination thereof.

5. The silicon-carbon composite of any preceding claim, wherein the pores of the carbon black support are capped.

6. The silicon-carbon composite of any preceding claim, wherein the carbon black support has a Lc crystallite size of less than or equal to 42 Angstroms.

7. The silicon-carbon composite of any preceding claim, wherein the carbon black support is not heat treated.

8. The silicon-carbon composite of any preceding claim, wherein the pores of the carbon black support comprise inter-aggregate pores and intra-aggregate pores and the silicon is within the intra-aggregate pores and / or the inter-aggregate pores.

9. The silicon-carbon composite of any preceding claim, wherein the carbon black support contains less than 100 ppm metal impurities.

10. The silicon-carbon composite of any preceding claim, wherein the carbon black support has an OAN in a range from 32 to 400 ml per 100g of carbon.Docket: 2023613PCT2 11. The silicon-carbon composite of any preceding claim, wherein the carbon black support has a BET in a range from 3.2 to 400 m2 / g.

12. The silicon-carbon composite of any preceding claim further comprising graphite.

13. The silicon-carbon composite of claim 12, wherein the graphite comprises graphite particles having a particle size that is no greater than 1 micron.

14. The silicon-carbon composite of any preceding claim, wherein the carbon black supports are agglomerates of carbon black aggregates.

15. The silicon-carbon composite of any preceding claim, wherein the silicon comprises silicon nanoparticles or silicon oxide nanoparticles 16. The silicon-carbon composite of any preceding claim, wherein the silicon is in inter- aggregate pores and inter-aggregate pores of the carbon black support and the silicon is in the form of silicon entities that are unconnected.

17. The silicon-carbon composite of any of claims 1-15, wherein the silicon is in inter- aggregate pores and inter-aggregate pores of the carbon black support and the silicon is in the form of silicon entities and at least some of the silicon entities are interconnected.

18. An anode composition comprising: the silicon-carbon composite of any preceding claim as an anode active material.

19. The anode composition of claim 18, further comprising an additional anode active material.

20. The anode composition of claim 19, wherein the anode active material is graphite.

21. The anode composition of any of claims 18-20, further comprising carbon nanotubes.

22. A lithium ion battery comprising the anode composition of any of claims 18-21.

23. A method for preparing a silicon-carbon composite, the method comprising: exposing a carbon black support to a silicon-containing precursor at temperatures sufficient to decompose the precursor and deposit silicon within pores of the carbon black support to produce a silicon-carbon composite, wherein: a ratio of OAN (oil adsorption number): BET (Brunauer-Emmett-Teller surface area) for the carbon black support is in a range from 0.1 to 10, wherein OAN is measured by ASTM D2414-23A and BET is measured by ASTM D6556-21, and a mass of silicon per 100g of carbon black support is less than or equal to 0.75 * OAN.Docket: 2023613PCT2 24. The method of claim 23, further comprising fluidizing the carbon black at a minimum fluidization velocity of at least 0.1 cm / s while exposing the carbon black support to the silicon-containing precursor.

25. The method of claim 23 or 24, wherein the method is conducted in a fluidized bed, moving bed, fixed bed, agitated bed or a rotating tube furnace.

26. The method of any of claims 23-25, wherein the method is conducted in an apparatus that provides uniform concentration and temperature conditions.

27. The method of any of claims 23-26, wherein the method is conducted with a Dahmkohler number based on particle size, precursor diffusion coefficient in the gas phase, and a precursor reaction rate that is less than unity.

28. A method for preparing a silicon-carbon composite, the method comprising: mechanically combining a carbon black support with silicon nanoparticles to form a silicon- carbon composite, wherein: a ratio of OAN (oil adsorption number): BET (Brunauer-Emmett-Teller surface area) for the carbon black support is in a range from 0.1 to 10, wherein OAN is measured by ASTM D2414-23A and BET is measured by ASTM D6556-21, and a mass of silicon per 100g of carbon black support is less than or equal to 0.75 * OAN.

29. The method of claim 28 further comprising reducing the size of the silicon-carbon black composite.

30. The method of claim 28 or 29 further comprising mechanically combining carbon nanotubes with the carbon black support and silicon nanoparticles.

31. The method of any of claims 28-40 further comprising mechanically combining binder with the carbon black support and silicon nanoparticles.

32. The method of any of claims 28-31, wherein the mechanically combining comprises dry mixing of powders, wet mixing in a slurry, or granulating powders sprayed with a powder.

33. The method of any of claims 23-32, wherein the ratio of the OAN:BET for the carbon black support is in a range from 0.1 to less than 1.

34. The method of any of claims 23-33, wherein the silicon-carbon composite has a D50 particle size by volume in a range from 5 to 25 microns.Docket: 2023613PCT2 35. The method of any of claims 23-34, wherein the carbon black support has a Lc crystallite size of less than or equal to 42 Angstroms.

36. The method of any of claims 23-35, wherein the carbon black support contains less than 100 ppm metal impurities.

37. The method of any of claims 23-36, wherein the carbon black support has an OAN in a range from 32 to 400 ml per 100g of carbon.

38. The method of any of claims 23-37, wherein the carbon black support has a BET in a range from 3.2 to 400 m2 / g.

39. The method of any if claims 23-38, wherein the pores of the carbon black support comprise inter-aggregate pores and intra-aggregate pores and the silicon is within the intra-aggregate pores and / or the inter-aggregate pores.

40. The method of any of claims 23-39, further comprises adding graphite to silicon-carbon composite.

41. The method of claim 40, wherein the graphite comprises graphite particles having a particle size that is no greater than 1 micron.

42. The method of any of claims 23-41, wherein the carbon black supports are prepared from carbon black pellets.

43. The method of any of claims 23-42, wherein the carbon black is graphitized.

44. The method of any of claims 23-43, wherein the carbon black is not graphitized or heat treated.

45. The method of any of claims 23-44, wherein the carbon black support is an agglomerate of carbon black aggregates.

46. The method of any of claims 23-45, wherein the silicon is in inter-aggregate pores and intra-aggregate pores of the silicon-carbon support and the silicon is in the form of discrete, unconnected silicon entities.

47. The method of any of claims 23-45, wherein the silicon is in inter-aggregate pores and intra-aggregate pores of the silicon-carbon support and the silicon is in the form of silicon entities, at least some of which are interconnected.

48. The method of any of claims 23-47, wherein the silicon deposited within the pores of the carbon black support is in the form of silicon nanoparticles.Docket: 2023613PCT2 49. The method of any of claims 23-48, wherein a mass ratio of silicon to carbon in the silicon-carbon composite is between 20:80 to 80:

20.

50. The method of any of claims 23-49, further comprising capping pores of the silicon- carbon composite.

51. The method of any of claims 23-50, further comprising coating the silicon-carbon composite with silicon, carbon, or a combination thereof.

52. The method of claim 51, wherein the silicon-carbon composite is coated by chemical vapor deposition.

53. The method of claim 51, wherein the silicon-carbon composite is coated with carbon by a thermal decomposition of a carbon-containing precursor at a surface of the silicon- carbon.

54. The method of claim 453, wherein the carbon-containing precursor is a sugar, a pitch, a tar or a sol gel.

55. The method of claim 51, further comprising capping surface pores of the silicon-carbon composite with silicon, followed by carbon coating.

56. The method of any of claims 23-56, further comprising reducing a particle size of the carbon support or the silicon-carbon composite.

57. The method of any of claims 23-57, further comprising combining the silicon-carbon composite with a LIB anode active material.

58. The method of any of claims 23-58, further comprising preparing a LIB anode that includes the silicon-carbon composite.

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