Group 14 Composite

Abstract

Particulate composite materials and devices containing same are provided.

Description

[Technical field]

[0001] Embodiments of the present invention generally relate to spherical composite particles and devices containing same that include elements of Group 14. These materials are produced by a process that includes hydrothermal carbonization of a polyol facilitated by a preferential exclusion agent, followed by chemical vapor impregnation (CVI).

[0002] The present invention generally relates to a method for producing silicon-carbon composite materials and compositions thereof. The silicon-carbon composite materials are produced by a series of processes including hydrothermal treatment, pyrolysis, and activation of carbon precursor materials to produce highly microporous carbon particles, followed by chemical vapor infiltration to produce silicon within the pores of the microconstituent carbon particles to obtain the final silicon-carbon composite particles. Suitable carbon precursors include, but are not limited to, sugars, other polyols, and combinations thereof.

[0003] Suitable porous scaffolds include, but are not limited to, porous carbon scaffolds, such as carbons having a pore volume that includes micropores (less than 2 nm), mesopores (2-50 nm), and / or macropores (greater than 50 nm). Chemical vapor infiltration (CVI) of silicon into the pores of a porous scaffold material is accomplished by exposing the porous scaffold to a silicon-containing gas (e.g., silane) at elevated temperatures.

[0004] 2. Description of Related Art Chemical vapor infiltration (CVI) is a process in which a gaseous substrate reacts within a porous scaffold material. This method can be employed to produce composite materials, such as silicon-carbon composites, where a silicon-containing gas decomposes at high temperatures within the porous carbon scaffold. This method can be employed to produce a variety of composite materials, but silicon-carbon (Si-C) composites are of particular interest. Such Si-C composites are useful as energy storage materials, for example as anode materials in lithium-ion batteries (LIBs). LIBs have the potential to replace devices currently used in many applications. For example, current automotive batteries are not suitable for the next generation of fully electric and hybrid electric vehicles due to the formation of irreversible and stable sulfates during discharge. Lithium-ion batteries, due to their capacity and other considerations, are a viable alternative to currently used lead-based systems.

[0005] For this reason, there continues to be strong interest in developing new LIB anode materials, especially silicon, which has a gravimetric capacity ten times that of conventional graphite. However, silicon exhibits large volume changes during cycling, leading to electrode degradation and instability at the solid electrolyte interface (SEI). The most common method of improvement is to reduce the particle size of silicon, e.g., D v、50 <150 nm, e.g. D v、50 <100 nm, e.g. D v、50 <50 nm, e.g. D v、50 <20 nm, e.g. D v、50 <10 nm, e.g. D v、50 <5 nm, e.g. D v、50 The most promising approaches are to produce nanoscale silicon as discrete particles or in a matrix, such as <2 nm. Thus far, techniques to produce nanoscale silicon include high-temperature reduction of silicon oxide, extensive particle reduction, multi-step toxic etching, and / or other costly methods. Similarly, common matrix approaches involve expensive materials such as graphene or nanographite and / or require complex processing and coating.

[0006] It is known from the scientific literature that non-graphitized (hard) carbons are useful as LIB anode materials (Liu Y, Xue, JS, Zheng T, Dahn, JR. Carbon 1996, 34:193-200; Wu, YP, Fang, SB, Jiang, YY. 1998, 75:201-206; Buiel E, Dahn JR. Electrochim Acta 1999 45:121-130). The basis for this improved performance is the disordered structure of the graphene layers. This disordered structure allows lithium ions to intercalate on both sides of the graphene planes, theoretically containing twice the stoichiometric amount of lithium ions as crystalline graphite. Moreover, in contrast to graphite, where lithiation only proceeds parallel to the stacked graphene planes, the disordered structure allows isotropic intercalation of lithium ions, thereby improving the rated capacity of the material. Despite these desirable electrochemical properties, amorphous carbon has not been widely deployed in commercial lithium-ion batteries, primarily due to its low FCE and low bulk density (<1 g / cc). Instead, amorphous carbon has been more commonly used as a low-mass additive and coating to other active material components in batteries to improve electrical conductivity and reduce surface side reactions.

[0007] In recent years, amorphous carbon as a LIB battery material has attracted much attention as a coating for silicon anode materials. Such silicon-carbon core-shell structures not only improve electrical conductivity but also buffer the expansion during silicon lithiation, which may improve cycling stability and minimize problems associated with particle crushing, segregation, and SEI integrity (Jung, Y, Lee K, Oh, S. Electrochim Acta 2007 52:7061-7067; Zuo P, Yin G, Ma Y. Electrochim Acta 2007 52:4878-4883; Ng SH, Wang J, Wexler D, Chew SY, Liu HK. J Phys Chem C 2007 111:11131-11138). The problem with this method is that there is no suitable silicon starting material that is compatible with the coating process, and there is no inherent void space in the carbon-coated silicon core-shell composite particles to accommodate the expansion of silicon during lithiation. This inevitably leads to a lack of cycle stability due to the destruction of the core-shell structure and SEI layer (Beattie SD, Larcher D, Morcrette M, Simon B, Tarascon, JM. J Electrochem Soc 2008 155:A158-A163).

[0008] An alternative to the core-shell structure is a structure in which amorphous and nano-sized silicon is homogeneously distributed within the pores of a porous carbon scaffold. Porous carbon has the following desirable properties: (i) the porosity of the carbon provides a void volume to accommodate the expansion of silicon upon lithiation, thus limiting the net composite particle expansion at the electrode level; (ii) the disordered graphene network enhances the electrical conductivity to silicon, thus resulting in faster charge / discharge rates; and (iii) the nanopore structure acts as a template for the synthesis of silicon, thereby determining its size, distribution and morphology.

[0009] To this end, the desired inverse hierarchical structure can be achieved by employing CVI, where a silicon-containing gas can completely permeate the nanoporous carbon and decompose into nano-sized silicon there. The CVI approach offers several advantages with respect to the silicon structure. One of them is that the nanoporous carbon provides nucleation sites for silicon growth while simultaneously determining the maximum particle shape and size. Confining the silicon growth within the nanoporous structure makes it less susceptible to cracking and crushing, and also reduces loss of contact due to expansion. Furthermore, the structure encourages the nano-sized silicon to remain as an amorphous phase. This property offers the opportunity to realize high charge / discharge rates, especially in combination with the silicon vicinity within the conductive carbon scaffold. The system provides a high-rate capable solid-state lithium diffusion pathway that delivers lithium ions directly to the nanoscale silicon interface. Another advantage of delivering silicon via CVI within the carbon scaffold is that it eliminates the unwanted crystalline Li 15 The first is to suppress the formation of the Si4 phase. Another advantage is that the CVI process creates voids inside the grains.

[0010] Thermogravimetric analysis (TGA) can be employed to measure the relative amount of silicon impregnated within the pores of the porous carbon. TGA can be used to assess the percentage of silicon present within the pores of the porous carbon relative to the total silicon present, i.e., silicon within the pores plus silicon on the particle surface. When silicon-carbon composites are heated under air, the samples begin to show an increase in mass from about 300°C to 500°C, reflecting the initial oxidation of silicon to SiO2. The samples then show a loss in mass as the carbon burns out, after which the samples show an increase in mass reflecting the resumption of the conversion of silicon to SiO2, increasing towards an asymptotic value as the temperature approaches 1100°C as the oxidation of silicon becomes complete. For this analysis, the minimum mass recorded for the sample heated from 800°C to 1100°C is considered to be the point at which the combustion of carbon is complete. Any increase in mass from that point onwards corresponds to the oxidation of silicon to SiO2, and the total mass at the completion of oxidation is SiO2. Therefore, the ratio of unoxidized silicon after carbon combustion to the total amount of silicon is given by the following formula: Z=1.875×[(M1100-M) / M1100]×100% [where M is the mass of the sample when oxidation is complete at 1100°C, and M is the minimum mass of the sample recorded when the sample is heated from 800°C to 1100°C.] It can be calculated by:

[0011] Without being bound by theory, the temperature at which silicon oxidizes under TGA conditions is related to the length scale of the oxide coating on silicon due to the diffusion of oxygen atoms through the oxide layer. Thus, silicon present within the carbon pores oxidizes at a lower temperature than silicon deposited on the particle surface, due to the necessarily thinner coating present on the particle surface. Thus, calculating Z allows a quantitative assessment of the fraction of silicon that is not impregnated within the voids of the porous carbon scaffold. Summary of the Invention [Problem to be solved by the invention]

[0012] In the present disclosure, compositions and methods of manufacture are disclosed for spherical and unimodal composite materials containing Group 14 elements. As used herein, "Group 14" refers to Group 14 (IVa) of the periodic table. The spherical composite particles are manufactured by fabricating primary micron-sized spherical and microporous carbon particles, and then fabricating nano-sized amorphous silicon within the pores of the spherical porous carbon scaffold particles. To this end, the fabrication of silicon is performed by chemical vapor impregnation (CVI). The employment of spherical carbon scaffold particles offers advantages over the prior art, for example, compared to the employment of secondary micron-sized porous carbon particles. Here, "primary micron-sized" as a descriptor of porous carbon scaffold particles refers to the case where the particles are synthesized as micron-sized particles at the time of their fabrication. For example, the particles at the time of their fabrication have a particle size distribution that includes particles from 1 μm to 100 μm. Of note, particle size reduction is not required prior to CVI processing to fabricate the final micron-sized composite particles. Additionally, as used herein, "secondary micron size" as a descriptor for porous carbon scaffold particles refers to when the achievement of micron-sized particles (e.g., achievement of particles having a particle size distribution that includes particles between 1 μm and 100 μm) is achieved by reduction in particle size after synthesis of the porous carbon scaffold material.

[0013] The employment of primary micron-sized porous carbon particles to make composite particles containing group 14 elements has many advantages as disclosed herein. One advantage is the elimination of a particle size reduction step, which can be achieved by abrasion-type milling methods described in the prior art, such as particle size reduction using hammer mills, ball mills, jet mills, or other abrasion type mills. Attrition milling to produce finely divided carbon scaffold particles can result in a broad particle size distribution, irregular and sawtooth morphology, and a large proportion of fines that can lead to challenges and inconsistencies in handling, processing, and performance of the particles for use in lithium-ion battery systems. The methods outlined herein describe the synthesis of micron-sized spherical carbon particles that avoid the need for milling. In some embodiments, the micron-sized spherical carbon particles are prepared as discrete particles and do not agglomerate. The spherical morphology and unimodal particle size distribution of the composite not only avoids the need for milling, but also leads to superior electrochemical properties due to minimization of particle surface area, and, without wishing to be bound by theory, avoids planar or point contacts that can increase particle resistance or undesirable reaction sites. [Means for solving the problem]

[0014] The disclosed composite material containing group 14 elements such as silicon and carbon has novel properties that solve the problem of providing amorphous and nano-sized silicon encapsulated in porous carbon. The silicon-carbon composite can be produced by chemical vapor impregnation to impregnate amorphous and nano-sized silicon into the pores of the porous scaffold. Suitable porous scaffolds include, but are not limited to, porous carbon scaffolds, such as carbons having a pore volume that includes micropores (less than 2 nm), mesopores (2-50 nm), and / or macropores (greater than 50 nm). Suitable precursors for carbon scaffolds include, but are not limited to, sugars and polyols, organic acids, phenolic compounds, crosslinkers, and amine compounds. Suitable composite materials include, but are not limited to, silicon materials. Silicon precursors include, but are not limited to, silicon-containing gases, such as silane, higher silanes (such as di-, tri-, and / or tetrasilane), and / or chlorosilanes (such as mono-, di-, tri-, and tetrachlorosilane), and mixtures thereof.CVI, which produces silicon in the pores of the porous scaffold material, is achieved by exposing the porous scaffold to a silicon-containing gas (e.g., silane) at high temperature.The porous carbon scaffold can be particulate porous carbon.

[0015] The important result of the present invention is to achieve the desired morphology of silicon, i.e. amorphous and nano-sized silicon.In addition, another important result is to impregnate silicon into the pores of porous carbon.Such materials, for example silicon-carbon composites, are useful as anode materials for energy storage devices, for example for lithium-ion batteries. [Brief description of the drawings]

[0016] [Figure 1] Relationship between Z and average Coulombic efficiency for various silicon-carbon composites. [Diagram 2]Differential capacity vs voltage plot for silicon-carbon composite 3 from the second cycle using a half cell. [Diagram 3] Differential capacity vs voltage plot for silicon-carbon composite 3 from cycle 2 to cycle 5 using a half cell. [Figure 4] Plot of dQ / dV vs V for various silicon-carbon composites. [Diagram 5] Calculation example of φ for silicon-carbon composite 3. [Figure 6] Z vs φ plots for various silicon-carbon composites. [Figure 7] SEM of carbon scaffold 12, which contains primary spherical pyrolytic carbon particles produced by a hydrothermal condensation mechanism in the absence of a preferential scavenging agent. [Figure 8] SEM of various samples of primary spherical pyrolytic carbon particles produced by hydrothermal condensation mechanism in the presence of preferential rejection agent. [Figure 9] SEM of silicon-carbon composite 21. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Detailed Description In the following description, certain specific details are given to provide a thorough understanding of various embodiments. However, one of ordinary skill in the art will understand that the invention may be practiced without these details. In other instances, well-known structures are not shown or described in detail to avoid unnecessarily obscuring the description of the embodiments. Unless otherwise indicated, throughout this specification and the claims that follow, the word "comprise" and variations thereof, such as "comprises" and "comprising," are to be interpreted in an open and inclusive sense, i.e., "including but not limited to." Additionally, the headings provided herein are for convenience only and do not interpret the scope or meaning of the claimed invention.

[0018] Throughout this specification, a reference to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment. Thus, the appearance of the phrase "in one embodiment" or "in an embodiment" in various places throughout this specification do not necessarily all refer to the same embodiment. Moreover, particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. Also, as used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless otherwise indicated. It should also be noted that the term "or" is generally used in the sense of including "and / or" unless otherwise indicated.

[0019] A. Primary micron-sized porous carbon scaffold particles Conventional methods for producing porous carbon materials from polymer precursors are known in the art. For example, methods for producing carbon materials are described in U.S. Patent Nos. 7,723,262, 8,293,818, 8,404,384, 8,654,507, 8,916,296, 9,269,502, 10,590,277, and U.S. Patent Application Publication No. 16 / 745,197, the entire disclosures of which are incorporated herein by reference in their entirety for all purposes. To produce finely divided carbon scaffold particles, conventional methods for producing particles by a form of attrition grinding can result in a broad particle size distribution, irregular and sawtooth particle morphology, and a large proportion of fines that can cause challenges and inconsistencies in handling, processing, and performance in lithium-ion battery systems. The methods outlined herein describe the synthesis of finely divided spherical carbon particles that avoid the need for grinding. In some embodiments, the finely divided spherical carbon particles are discrete, non-agglomerated particles.

[0020] In contrast to these conventional methods, another approach is disclosed herein that allows the synthesis of primary submicron or primary micron sized porous carbon scaffold particles. These particles exhibit a spherical morphology. Primary micron sized porous carbon particles can be produced by hydrothermal carbonization of a reaction mixture. The reaction mixture is thus an aqueous milieu containing a polyol and a preferential elimination agent to promote preferential elimination of the polyol, and is subjected to a high temperature sufficient to achieve hydrothermal char (HTC) to form spherical micron sized domains within the aqueous environment. Suitable polyols include, but are not limited to, poly(ethylene glycol) (PEG), sorbitol, mannitol, maltitol, xylitol, isomalt, lactitol, sucrose, fructose, furfural, glucose, citric acid, starch, cellulose, allulose, xantham gum, gum arabic, alginate, chitin, chitosan, and combinations thereof. In certain preferred embodiments, reducing sugars are used.

[0021] The concentration of the polyol may be, for example, 0.001M to 10M, for example, 0.01M to 10M, for example, 0.1M to 10M, for example, 0.5M to 5M. In certain embodiments, the reaction mixture may include a cross-linking agent. Suitable cross-linking agents include furfural, hexamethylenetetramine, formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, benzaldehyde, and combinations thereof. The concentration of the cross-linking agent may be, for example, 0.001M to 10M, for example, 0.01M to 10M, for example, 0.1M to 10M, or alternatively, 0.001M to 5M, for example, 0.01M to 5M, for example, 0.1M to 5M, for example, 0.1M to 1M.

[0022] The reaction mixture may include one or more co-solvents, including, but not limited to, alcohol, ethanol, methanol, tetrahydrofuran (THF), dimethylsulfoxide (DMSO), dimethylformamide (DMF), N-methylpyrrolidone, glycols, glymes, alkanes, ethers, and combinations thereof. In some embodiments, the reaction mixture may include one or more co-solvents, including, but not limited to, alcohol, ethanol, methanol, tetrahydrofuran (THF), dimethylsulfoxide (DMSO), dimethylformamide (DMF), N-methylpyrrolidone, glycols, glymes, alkanes, ethers, and combinations thereof. The volume ratio of co-solvent to water (V:V) may be, for example, 0.001:1 to 1000:1, for example, 0.01:1 to 100:1, for example, 0.1 to 10:1.

[0023] The reaction mixture includes a preferential exclusion agent. The preferential exclusion agent is defined as an agent that promotes the formation of spherical micron-sized domains within the aqueous environment that is subsequently converted to HTCs upon exposure of the reaction mixture to high temperatures over time. The preferential exclusion agent has the property that its presence precludes interactions between the polyol and the solvent and promotes polyol aggregation. Without wishing to be bound by theory, there are various mechanisms by which the preferential exclusion agent may provide preferential exclusion, including, but not limited to, ionic interactions and hydrogen bonding interactions. Examples of preferential exclusion agents include, but are not limited to, polyanionic species such as carboxymethylcellulose or polyacrylic acid. Other examples of preferential exclusion agents include ionic, nonionic, or zwitterionic surfactants. Examples of exemplary surfactants in this regard include Triton, SPAN, Pluronics, and the like.

[0024] The reaction mixture may be exposed to a time and temperature sufficient to form spherical particles consisting of HTC. The time to produce HTC may be, for example, 1 hour to 72 hours. The temperature may be, for example, 120°C to 300°C, for example, 140°C to 240°C, for example, 150°C to 250°C, for example, 160°C to 220°C. In certain embodiments, the reaction temperature is set below the temperature at which the surfactant begins to degrade or decompose. In preferred embodiments, the temperature to produce HTC is 170°C to 210°C, or 180°C to 200°C, or 180°C to 220°C. The ramp from ambient temperature to reaction temperature may be, for example, 1°C / min to 100°C / min, for example, 2°C / min to 50°C / min, for example, 5°C / min to 20°C / min.

[0025] The reaction to produce the HTC is carried out in a reactor, where the pressure can be, for example, from ambient to above ambient, for example, from 0.1 psig to 1000 psig, for example, from 1 psig to 1000 psig, for example, from 1 psig to 500, for example, from 100 psig to 500 psig. In a preferred embodiment, the reactor pressure is from 120 psig to 300 psig, or from 130 psig to 280 psig, for example, from 140 psig to 260 psig, for example, from 145 psig to 225 psig.

[0026] The reaction mixture can be stirred or otherwise mixed to promote the formation of spherical polyol-rich domains throughout the reaction mixture. This mixing can be accomplished in reactors known in the art, including stirring by magnetic bars or one or more seated paddles, sonication, vibration, reactor design (e.g., rotating / stator reactor design, etc.). The reactor geometry can be varied as known in the art, as can the reactor material (e.g., a closed stainless steel autoclave-type vessel with a Teflon liner, etc.). The reactor vessel in the preferred mode can have one or more ports for introducing components at various times during the course of the reaction. The reactor can be run in either batch or continuous mode. The progress of the reaction can be observed by removing samples and analyzing various properties such as viscosity, conductivity, absorbance (visible and / or UV wavelengths), size of suspended particles (e.g., by laser light scattering, as known in the art). Alternatively, the progress of the reaction can be observed on-line.

[0027] In certain embodiments, the aqueous reaction environment exhibits an acidic pH, such as pH 2 to pH 6, such as pH 2 to pH 4, or pH 4 to pH 5, or pH 5 to pH 6. In other certain embodiments, the aqueous reaction environment exhibits a basic pH, such as pH 8 to pH 14, such as pH 8 to pH 12, or pH 8 to pH 10, or pH 9 to pH 10. In other embodiments, the aqueous reaction environment exhibits a neutral pH, such as pH 6 to pH 8, such as pH 6 to pH 7, such as pH 7 to pH 8. The pH can be adjusted by addition of acids and / or bases as known in the art. In some embodiments, the pH can be adjusted using a volatile acid, such as acetic acid, and / or a volatile base, such as ammonium acetate. In some embodiments, a buffer system can be used to control the pH of the aqueous reaction environment, as known in the art. In some embodiments, agents used to adjust and / or control the pH of the aqueous reaction environment can also act as preferential excluding agents, such as amino acids.

[0028] The conductivity of the aqueous reaction environment may be, for example, 0 to 1000 mS / cm. The oxidation-reduction potential (ORP) of the aqueous reaction environment may be, for example, +2.87 V to -3.05 V. The viscosity of the aqueous reaction environment may be, for example, 0.1 cP to 1000 cP.

[0029] In some embodiments, the aqueous reaction environment may include catalyst particles, including, but not limited to, metals such as lithium. Other examples of catalysts in this regard include amorphous carbon, nano-sized and / or nano-structured carbons such as nano-graphite, carbon black, carbon nanotubes, and combinations thereof. In certain embodiments, the catalyst may be a silane / siloxane crosslinker, a persulfate, a hydroxide, or a combination thereof.

[0030] In certain embodiments, the aqueous reaction environment includes an electrochemical modifier. For example, in some embodiments, an electrochemical modifier in the form of metal particles, metal pastes, metal salts, metal oxides, or molten metals may be dissolved or suspended in the mixture in which the HTCs are produced.

[0031] In some embodiments, the electrochemical modifier is a lithium salt, such as, but not limited to, lithium fluoride, lithium chloride, lithium carbonate, lithium hydroxide, lithium benzoate, lithium bromide, lithium formate, lithium hexafluorophosphate, lithium iodate, lithium iodide, lithium perchlorate, lithium phosphate, lithium sulfate, lithium tetraborate, lithium tetrafluoride, and combinations thereof.

[0032] In certain embodiments, the electrochemical modifier comprises a metal, and the species includes, but is not limited to, aluminum isopropoxide, manganese acetate, nickel acetate, iron acetate, tin chloride, silicon chloride, and combinations thereof.In certain embodiments, the electrochemical modifier is a phosphate compound, and the species includes, but is not limited to, phytic acid, phosphoric acid, ammonium dihydrogen phosphate, and combinations thereof.In certain embodiments, the electrochemical modifier comprises silicon, and the species includes, but is not limited to, silicon powder, silicon nanotubes, polycrystalline silicon, nanocrystalline silicon, amorphous silicon, porous silicon, nanosized silicon, nanofeatured silicon, nanosized and nanofeatured silicon, silicin, and black silicon, and combinations thereof.

[0033] Electrochemical modifiers can be combined with various polymer systems either through physical mixing or chemical reaction with latent (or secondary) polymer functionality. Examples of latent polymer functionality include, but are not limited to, epoxide groups, unsaturation (double and triple bonds), acid groups, alcohol groups, amine groups, and basic groups. Crosslinks with latent functionality can occur through heteroatoms (e.g., vulcanization with sulfur, acid / base / ring-opening reactions with phosphoric acid), reactions with organic acids or bases (as described above), coordination to transition metals (including, but not limited to, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ag, Au), ring-opening or ring-closing reactions (rotaxanes, spiro compounds, etc.).

[0034] After production of the HTC, the resulting particles can be removed from the aqueous environment by methods known in the art, such as filtration, centrifugation, sedimentation, and any remaining water can be removed by subjecting the material to heat and / or vacuum to obtain dry HTC. The dry HTC is pyrolyzed to obtain a plurality of spherical primary submicron or micron sized porous pyrolytic carbon particles. The temperature and residence time of pyrolysis can vary, for example, the residence time can be 1 min to 10 min, 10 min to 30 min, 30 min to 1 h, 1 h to 2 h, 2 h to 4 h, 4 h to 24 h. The temperature may vary, for example pyrolysis temperatures may be 200° C.-300° C., 250° C.-350° C., 350° C.-450° C., 450° C.-550° C., 540° C.-650° C., 650° C.-750° C., 750° C.-1050° C., 750° C.-850° C., 850° C.-950° C., 950° C.-1050° C., 1050° C.-1150° C., 1150° C.-1250° C. Pyrolysis may be carried out in an inert gas, such as nitrogen or argon.

[0035] In some embodiments, carbon activation is further accomplished using an alternative gas to obtain a plurality of primary porous carbon particles with sufficient porosity to serve as scaffolds for the subsequent CVI reaction to produce silicon-carbon composites. In certain embodiments, pyrolysis and activation are combined. Suitable gases for accomplishing carbon activation can be defined as activated gases, including but not limited to carbon dioxide, carbon monoxide, water (steam), air, oxygen, and further combinations thereof. The temperature and residence time of activation can vary, for example, the residence time can be 1 minute to 10 minutes, 10 minutes to 30 minutes, 30 minutes to 1 hour, 1 hour to 2 hours, 2 hours to 4 hours, 4 hours to 24 hours. The temperature may vary, for example, between 200°C and 300°C, between 250°C and 350°C, between 350°C and 450°C, between 450°C and 550°C, between 540°C and 650°C, between 650°C and 750°C, between 750°C and 850°C, between 750°C and 1050°C, between 850°C and 950°C, between 950°C and 1050°C, between 1050°C and 1150°C, between 1150°C and 1250°C.

[0036] Either before pyrolysis, and / or after pyrolysis, and / or after activation, the carbon may undergo particle size reduction. Particle size reduction can be achieved by various techniques known in the art (e.g., jet milling) in the presence of various gases (e.g., air, nitrogen, argon, helium, supercritical steam, and other known gases). Other particle size reduction methods are also contemplated, such as grinding, ball milling, jet milling, water jet milling, and other methods known in the art. However, in a preferred embodiment, no further particle size reduction methods are performed since the HTC materials are already produced as a plurality of primary particles in the range suitable for use as scaffolds for producing silicon-carbon composites.

[0037] The particle size and size distribution of the primary porous carbon scaffold particles can be measured by various techniques known in the art and described based on volume fraction. In this regard, the Dv,50 of the carbon scaffold can be from 10 nm to 10 mm, such as from 100 nm to 1 mm, such as from 1 micrometer (μm) to 100 μm, such as from 2 μm to 50 μm, such as from 3 μm to 30 μm, such as from 4 μm to 20 μm, such as from 5 μm to 10 μm. In certain embodiments, the Dv,50 is less than 1 mm, such as less than 100 μm, such as less than 50 μm, such as less than 30 μm, such as less than 20 μm, such as less than 10 μm, such as less than 8 μm, such as less than 5 μm, such as less than 3 μm, such as less than 1 μm. In certain embodiments, Dv,100 is less than 1 mm, such as less than 100 μm, such as less than 50 μm, such as less than 30 μm, such as less than 20 μm, such as less than 10 μm, such as less than 8 μm, such as less than 5 μm, such as less than 3 μm, such as less than 1 μm. In certain embodiments, Dv,99 is less than 1 mm, such as less than 100 μm, such as less than 50 μm, such as less than 30 μm, such as less than 20 μm, such as less than 10 μm, such as less than 8 μm, such as less than 5 μm, such as less than 3 μm, such as less than 1 μm. In certain embodiments, Dv,90 is less than 1 mm, such as less than 100 μm, such as less than 50 μm, such as less than 30 μm, such as less than 20 μm, such as less than 10 μm, such as less than 8 μm, such as less than 5 μm, such as less than 3 μm, such as less than 1 μm. In certain embodiments, Dv,0 is greater than 10 nm, such as greater than 100 nm, such as greater than 500 nm, such as greater than 1 μm, such as greater than 2 μm, such as greater than 5 μm, such as greater than 10 μm. In certain embodiments, Dv,1 is greater than 10 nm, such as greater than 100 nm, such as greater than 500 nm, such as greater than 1 μm, such as greater than 2 μm, such as greater than 5 μm, such as greater than 10 μm. In certain embodiments, Dv,10 is greater than 10 nm, such as greater than 100 nm, such as greater than 500 nm, such as greater than 1 μm, such as greater than 2 μm, such as greater than 5 μm, such as greater than 10 μm.

[0038] In some embodiments, the surface area of ​​the porous carbon scaffold is greater than or equal to 400 m 2 / g, e.g. 500m2 / g, e.g. 750m 2 / g, e.g. 1000m 2 / g, e.g. 1250m 2 / g, e.g. 1500m 2 / g, e.g. 1750m 2 / g, e.g. 2000m 2 / g, e.g. 2500m 2 / g, e.g. 3000m 2 In other embodiments, the surface area of ​​the porous carbon scaffold may include greater than 500 m / g. 2 In some embodiments, the surface area of ​​the porous carbon scaffold can be less than 200-500 m / g. 2 In some embodiments, the surface area of ​​the porous carbon scaffold is between 100 and 200 m 2 In some embodiments, the surface area of ​​the porous carbon scaffold is between 50 and 100 m 2 In some embodiments, the surface area of ​​the porous carbon scaffold is between 10 and 50 m 2 In some embodiments, the surface area of ​​the porous carbon scaffold is greater than 10 m 2 / g.

[0039] In some embodiments, the pore volume of a primary porous carbon scaffold particle is less than or equal to 0.4 cm 3 / g, e.g. 0.5 cm 3 / g, e.g. 0.6 cm 3 / g, e.g. 0.7 cm 3 / g, e.g. 0.8 cm 3 / g, e.g. 0.9 cm 3 / g, e.g., 1.0 cm 3 / g, e.g. 1.1 cm 3 / g, e.g. 1.2 cm 3 / g greater than 1.4, e.g. 1.6 cm 3 / g, e.g. 1.8 cm 3 / g, e.g., 2.0 cm 3 In other embodiments, the pore volume of the porous silicon scaffold is greater than 0.5 cm3 Less than 0.1 cm, for example 3 / g~0.5cm 3 / g. In certain other embodiments, the pore volume of the porous silicon scaffold is less than 0.01 cm 3 / g~0.1cm 3 In yet another embodiment, the pore volume is 0.001 cm 3 / g~0.01cm 3 / g.

[0040] In some other embodiments, the primary porous carbon scaffold particles are between 0.2 and 2.0 cm 3 In certain embodiments, the carbon comprises an amorphous activated carbon having a pore volume of 0.4 to 1.5 cm. 3 In certain embodiments, the carbon is an amorphous activated carbon having a pore volume of 0.5 to 1.2 cm. 3 In certain embodiments, the carbon is an amorphous activated carbon having a pore volume of 0.6 to 1.0 cm3 / g. 3 / g pore volume.

[0041] In other embodiments, the primary porous carbon scaffold particles have a density of 1.0 g / cm 3 Less than, for example, 0.8 g / cm 3 Less than, for example, 0.6 g / cm 3 Less than, for example, 0.5 g / cm 3 Less than, for example, 0.4 g / cm 3 Less than, for example, 0.3 g / cm 3 Less than, for example, 0.2 g / cm 3 Less than, for example, 0.1 g / cm 3 Including tap density less than.

[0042] The surface functionality of the primary porous carbon scaffold particles can vary. One characteristic that can predict surface functionality is the pH of the porous carbon scaffold. The porous carbon scaffolds of the present disclosure include pH values ​​from less than 1 to about 14, such as less than 5, 5 to 8, or greater than 8. In some embodiments, the pH of the porous carbon can be less than 4, less than 3, less than 2, or less than 1. In other embodiments, the pH of the porous carbon is about 5 to 6, about 6 to 7, about 7 to 8, or 8 to 9, or 9 to 10. In still other embodiments, the pH is high and the pH of the porous carbon is greater than 8, greater than 9, greater than 10, greater than 11, greater than 12, or greater than 13.

[0043] The pore volume distribution of the primary porous carbon scaffold particles can vary. For example, the percentage of micropores can include less than 30%, such as less than 20%, such as less than 10%, such as less than 5%, such as less than 4%, such as less than 3%, such as less than 2%, such as less than 1%, such as less than 0.5%, such as less than 0.2%, such as less than 0.1%. In certain embodiments, the porous carbon scaffold has no detectable micropore volume.

[0044] The mesopores that make up the primary porous carbon scaffold particles can vary. For example, the % mesopores can include less than 30%, such as less than 20%, such as less than 10%, such as less than 5%, such as less than 4%, such as less than 3%, such as less than 2%, such as less than 1%, such as less than 0.5%, such as less than 0.2%, such as less than 0.1%. In certain embodiments, the porous carbon scaffold has no detectable mesopore volume.

[0045] In some embodiments, the pore volume distribution of the porous carbon scaffold comprises more than 50% macropores, such as more than 60% macropores, such as more than 70% macropores, such as more than 80% macropores, such as more than 90% macropores, such as more than 95% macropores, such as more than 98% macropores, such as more than 99% macropores, such as more than 99.5% macropores, such as more than 99.9% macropores.

[0046] In certain preferred embodiments, the pore volume of the primary porous carbon scaffold particles comprises a blend of micropores, mesopores, and macropores. Thus, in certain embodiments, the porous carbon scaffold comprises 0-20% micropores, 30-70% mesopores, and less than 10% macropores. In other certain embodiments, the porous carbon scaffold comprises 0-20% micropores, 0-20% mesopores, and 70-95% macropores. In certain other embodiments, the porous carbon scaffold comprises 20-50% micropores, 50-80% mesopores, and 0-10% macropores. In certain other embodiments thereof, the porous carbon scaffold comprises 40-60% micropores, 40-60% mesopores, and 0-10% macropores. In other specific embodiments, the porous carbon scaffold comprises 80-95% micropores, 0-10% mesopores, and 0-10% macropores. In other specific embodiments, the porous carbon scaffold comprises 0-10% micropores, 30-50% mesopores, and 50-70% macropores. In other specific embodiments, the porous carbon scaffold comprises 0-10% micropores, 70-80% mesopores, and 0-20% macropores. In other specific embodiments, the porous carbon scaffold comprises 0-20% micropores, 70-95% mesopores, and 0-10% macropores. In other specific embodiments, the porous carbon scaffold comprises 0-10% micropores, 70-95% mesopores, and 0-20% macropores.

[0047] In certain embodiments, the % of pore volume in the primary porous carbon scaffold particle representing pores of 100-1000 A (10-100 nm) comprises more than 30% of the total pore volume, such as more than 40% of the total pore volume, such as more than 50% of the total pore volume, such as more than 60% of the total pore volume, such as more than 70% of the total pore volume, such as more than 80% of the total pore volume, such as more than 90% of the total pore volume, such as more than 95% of the total pore volume, such as more than 98% of the total pore volume, such as more than 99% of the total pore volume, such as more than 99.5% of the total pore volume, such as more than 99.9%.

[0048] In certain embodiments, the pycnometry density of the primary porous carbon scaffold particles is about 1 g / cc to about 3 g / cc, such as about 1.5 g / cc to about 2.3 g / cc. In other embodiments, the scaffold density is about 1.5 cc / g to about 1.6 cc / g, about 1.6 cc / g to about 1.7 cc / g, about 1.7 cc / g to about 1.8 cc / g, about 1.8 cc / g to about 1.9 cc / g, about 1.9 cc / g to about 2.0 cc / g, about 2.0 cc / g to about 2.1 cc / g, about 2.1 cc / g to about 2.2 cc / g, or about 2.2 cc / g to about 2.3 cc / g, about 2.3 cc / g to about 2.4 cc / g, such as about 2.4 cc / g to about 2.5 cc / g.

[0049] B. Production of Silicon by Chemical Vapor Impregnation (CVI) Chemical vapor deposition (CVD) is a method in which a substrate provides a solid surface containing the first component of the composite, and a gas is pyrolyzed on the solid surface to provide the second component of the composite. Such a CVD approach can be used, for example, to produce a Si-C composite material in which the silicon particles are coated on their outer surfaces. Alternatively, chemical vapor impregnation (CVI) is a method in which a substrate provides a porous scaffold containing the first component of the composite, and a gas is pyrolyzed within the pores of the porous scaffold material to provide the second component of the composite.

[0050] In one embodiment, silicon is generated in the pores of the porous carbon scaffold by subjecting the porous carbon particles to a silicon-containing precursor gas at high temperature in the presence of a silicon-containing gas, preferably silane, and decomposing the gas to silicon. The silicon-containing precursor gas can be mixed with other inert gases, such as nitrogen gas. The temperature and time of the treatment can vary, for example, the temperature can be 200-900°C, such as 200-250°C, such as 250-300°C, such as 300-350°C, such as 300-400°C, such as 350-450°C, such as 350-400°C, such as 400-500°C, such as 500-600°C, such as 600-700°C, such as 700-800°C, such as 800-900°C, such as 600-1100°C.

[0051] The gas mixture may include 0.1-1% silane and the remaining inert gas. Alternatively, the gas mixture may include 1%-10% silane and the remaining inert gas. Alternatively, the gas mixture may include 10%-20% silane and the remaining inert gas. Alternatively, the gas mixture may include 20%-50% or less silane and the remaining inert gas. Alternatively, the gas mixture may include more than 50% silane and the remaining inert gas. Alternatively, the gas may be essentially 100% silane gas. Suitable inert gases include, but are not limited to, hydrogen, nitrogen, argon, and combinations thereof.

[0052] The pressure of the CVI process can vary. In some embodiments, the pressure is atmospheric. In some embodiments, the pressure is less than atmospheric. In some embodiments, the pressure is greater than atmospheric.

[0053] C. Physical and Electrochemical Properties of Silicon-Carbon Composites Without wishing to be bound by theory, it is believed that the nano-sized silicon achieved as a result of filling a particular desired pore volume structure of a porous carbon scaffold (e.g., silicon filling pores in the 5-1000 nm or other range as disclosed elsewhere herein), along with the advantageous properties of the other components of the composite including low surface area, low pycnometric density, results in a composite material with different advantageous properties, e.g., electrochemical performance when the composite constitutes the anode of a lithium ion energy storage device.

[0054] In certain embodiments, the embedded silicon particles embedded within the composite include nano-sized features that may have a characteristic length scale of less than 1 μm, preferably less than 300 nm, preferably less than 150 nm, preferably less than 100 μm, preferably less than 50 nm, preferably less than 30 nm, preferably less than 15 nm, preferably less than 10 nm, preferably less than 5 nm.

[0055] In certain embodiments, the silicon embedded in the composite is spherical. In other certain embodiments, the porous silicon particles are non-spherical, such as rod-like or fibrous structures. In some embodiments, the silicon is present as a layer that coats the inside of the pores in the porous carbon scaffold. The depth of this silicon layer can vary, for example, the depth can be 5 nm to 10 nm, such as 5 nm to 20 nm, for example 5 nm to 30 nm, for example 5 nm to 33 nm, for example 10 nm to 30 nm, for example 10 nm to 50 nm, for example 10 nm to 100 nm, for example 10 to 150 nm, for example 50 nm to 150 nm, for example 100 to 300 nm, for example 300 to 1000 nm.

[0056] In some embodiments, the embedded silicon in the composite is nano-sized and resides within the pores of the porous carbon scaffold. For example, the embedded silicon can be impregnated and deposited by CVI or other suitable methods into pores within porous carbon particles including pore sizes of 5-1000 nm, e.g., 10-500 nm, e.g., 10-200 nm, e.g., 10-100 nm, e.g., 33-150 nm, e.g., 20-100 nm. Other ranges of carbon pore sizes in terms of fractional pore volume, whether micropores, mesopores, or macropores, are also envisioned.

[0057] In some embodiments, the pore volume distribution of the carbon scaffold can be described as the number or volume distribution of pores, as determined as known in the art based on gas sorption analysis, such as nitrogen gas sorption analysis. In some embodiments, the pore size distribution can be expressed in terms of the pore size at or below which a certain percentage of the total pore volume exists. For example, the pore size at which 10% or less of the pores exist can be expressed as DPv10.

[0058] The DPv10 of the porous carbon scaffold can vary, for example the DPv10 can be from 0.01 nm to 100 nm, such as from 0.1 nm to 100 nm, for example from 1 nm to 100 nm, for example from 1 nm to 50 nm, for example from 1 nm to 40 nm, for example from 1 nm to 30 nm, for example from 1 nm to 10 nm, for example from 1 nm to 5 nm.

[0059] The DPv50 of the porous carbon scaffold may vary, for example the DPv50 may be from 0.01 nm to 100 nm, such as from 0.1 nm to 100 nm, for example from 1 nm to 100 nm, for example from 1 nm to 50 nm, for example from 1 nm to 40 nm, for example from 1 nm to 30 nm, for example from 1 nm to 10 nm, for example from 1 nm to 5 nm. In other embodiments, the DPv50 is from 2 to 100, for example from 2 to 50, for example from 2 to 30, for example from 2 to 20, for example from 2 to 15, for example from 2 to 10.

[0060] The DPv90 of the porous carbon scaffold may vary, for example the DPv90 may be 0.01 nm to 100 nm, for example 0.1 nm to 100 nm, for example 1 nm to 100 nm, for example 1 nm to 50 nm, for example 1 nm to 50 nm, for example 1 nm to 40 nm, for example 1 nm to 30 nm, for example 1 nm to 10 nm, for example 1 nm to 5 nm. In other embodiments, the DPv50 is 2 nm to 100 nm, for example 2 nm to 50 nm, for example 2 nm to 30 nm, for example 2 nm to 20 nm, for example 2 nm to 15 nm, for example 2 nm to 10 nm.

[0061] In some embodiments, the DPv90 is less than 100 nm, such as less than 50 nm, such as less than 40 nm, such as less than 30 nm, such as less than 20 nm, such as less than 15 nm, such as less than 10 nm. In some embodiments, the carbon scaffold comprises a pore volume with more than 70% micropores (and a DPv90 less than 100 nm, such as a DPv90 less than 50 nm, such as a DPv90 less than 40 nm, such as a DPv90 less than 30 nm, such as a DPv90 less than 20 nm, such as a DPv90 less than 15 nm, such as a DPv90 less than 10 nm, such as a DPv90 less than 5 nm, such as a DPv90 less than 4 nm, such as a DPv90 less than 3 nm). In other embodiments, the carbon scaffold comprises a pore volume with more than 80% micropores and a DPv90 of less than 100 nm, such as a DPv90 of less than 50 nm, such as a DPv90 of less than 40 nm, for example a DPv90 of less than 30 nm, such as a DPv90 of less than 20 nm, for example a DPv90 of less than 15 nm, such as a DPv90 of less than 10 nm, for example a DPv90 of less than 5 nm, such as a DPv90 of less than 4 nm, for example a DPv90 of less than 3 nm.

[0062] The DPv99 of the porous carbon scaffold may vary, for example the DPv99 may be from 0.01 nm to 1000 nm, such as from 0.1 nm to 1000 nm, for example from 1 nm to 500 nm, for example from 1 nm to 200 nm, for example from 1 nm to 150 nm, for example from 1 nm to 100 nm, for example from 1 nm to 50 nm, for example from 1 nm to 20 nm. In other embodiments, the DPv99 is from 2 nm to 500 nm, for example from 2 nm to 200 nm, for example from 2 nm to 150 nm, for example from 2 nm to 100 nm, for example from 2 nm to 50 nm, for example from 2 nm to 20 nm, for example from 2 nm to 15 nm, for example from 2 nm to 10 nm.

[0063] The embodiments of the composites disclosed herein with highly durable intercalation of lithium improve the properties of any electrical energy storage device, such as lithium ion batteries.In some embodiments, the silicon-carbon composites disclosed herein exhibit Z less than 10, such as Z less than 5, such as Z less than 4, such as Z less than 3, such as Z less than 2, such as Z less than 1, such as Z less than 0.1, such as Z less than 0.01, such as Z less than 0.001.In certain embodiments, Z is 0.

[0064] In certain preferred embodiments, the silicon-carbon composite preferably comprises a low Z in combination with other desired physicochemical and / or electrochemical properties, or in combination with one or more other desired physicochemical and / or electrochemical properties. Table 1 provides a description of certain embodiments of the combination of properties of silicon-carbon composites. Surface area can be determined as known in the art, for example, by nitrogen gas sorption analysis. Silicon content can be determined as known in the art, for example, by TGA. Property Z can be determined from TGA according to the present disclosure. First cycle efficiency can be determined as known in the art, for example, calculated based on the first cycle charge / discharge capacity in a full cell or half cell. For example, first cycle efficiency can be determined in a voltage window of 5 mV to 0.8 V, or alternatively in a half cell in a voltage window of 5 mV to 1.5 V. The reversible capacity may be described as the maximum reversible capacity or maximum capacity and may be determined, for example, in a half-cell in a voltage window of 5 mV to 0.8 V, alternatively 5 mV to 1.5 V, as known in the art.

[0065] Table 1. Silicon-carbon composite embodiments with embodied properties [Table 1]

[0066] According to Table 1, silicon-carbon composites can include a variety of combinations of properties. For example, silicon-carbon composites can have Z less than 10, 100m 2 / g, a first cycle efficiency of greater than 80%, and a reversible capacity of at least 1300 mAh / g. For example, silicon-carbon composites can have a Z of less than 10, a 100m 2 / g, a first cycle efficiency of greater than 80%, and a reversible capacity of at least 1600 mAh / g. For example, silicon-carbon composites can have a Z of less than 10, a dc of less than 20 m 2For example, silicon-carbon composites can have a surface area of ​​less than 10, a first cycle efficiency of greater than 85%, and a reversible capacity of at least 1600 mAh / g. 2 For example, silicon-carbon composites can have a surface area of ​​less than 10, a first cycle efficiency of greater than 85%, and a reversible capacity of at least 1600 mAh / g. 2 For example, silicon-carbon composites can have a surface area of ​​less than 10, a first cycle efficiency of greater than 90%, and a reversible capacity of at least 1600 mAh / g. 2 / g, a first cycle efficiency of greater than 90%, and a reversible capacity of at least 1800 mAh / g.

[0067] In some embodiments, the TGA onset temperature is higher than a similar silicon-carbon composite made from a non-polyol precursor. Without being bound by theory, the higher TGA onset temperature may result in less gasification of the silicon-carbon composite when used as an anode material in a battery anode (e.g., a lithium ion battery anode or a lithium silicon battery anode).

[0068] Table 2. TGA onset temperatures for silicon-carbon composites [Table 2]

[0069] In some embodiments, the silicon-carbon composite has a TGA onset temperature greater than 600° C. In yet other embodiments, the silicon-carbon composite has a TGA onset temperature between 300° C. and 400° C.; between 400° C. and 500° C.; or between 500° C. and 600° C. In some embodiments, the silicon-carbon composite has a TGA onset temperature greater than 600° C.

[0070] In addition to including a carbon scaffold that also includes the properties described within this disclosure, the silicon-carbon composite may include a combination of the aforementioned properties. Thus, Table 2 provides a description of certain embodiments of the combination of properties for silicon-carbon composites.

[0071] Table 3. Silicon-carbon composite embodiments with embodied properties [Table 3]

[0072] As used herein, "microporosity," "mesoporosity," and "macroporosity" refer to the percentage of micropores, mesopores, and macropores, respectively, relative to the total pore volume. For example, a carbon scaffold having 90% microporosity is a carbon scaffold in which 90% of the total pore volume of the carbon scaffold is formed by micropores.

[0073] According to Table 3, silicon-carbon composites can include a variety of combinations of properties. For example, silicon-carbon composites can have Z less than 10, 100m 2 / g surface area, greater than 80% first cycle efficiency, at least 1600 mAh / g reversible capacity, 15% to 85% silicon content, 0.2 to 1.2 cm 3 / g of carbon scaffold total pore volume, where the scaffold pore volume includes more than 80% micropores, less than 20% mesopores, and less than 10% macropores. For example, a silicon-carbon composite can have a Z of less than 10, a Z of less than 20m 2 / g surface area, greater than 85% first cycle efficiency, at least 1600 mAh / g reversible capacity, 15% to 85% silicon content, 0.2 to 1.2 cm 3 / g of total pore volume of the carbon scaffold, where the scaffold pore volume includes more than 80% micropores, less than 20% mesopores, and less than 10% macropores. For example, a silicon-carbon composite can have a Z of less than 10, a 10m2 / g surface area, greater than 85% first cycle efficiency, and at least 1600 mAh / g reversible capacity, 15% to 85% silicon content, 0.2 to 1.2 cm 3 / g of total pore volume of the carbon scaffold, where the scaffold pore volume includes more than 80% micropores, less than 20% mesopores, and less than 10% macropores. For example, a silicon-carbon composite can have a Z of less than 10, a 10m 2 / g surface area, greater than 90% first cycle efficiency, and at least 1600 mAh / g reversible capacity, 15% to 85% silicon content, 0.2 to 1.2 cm 3 / g of total pore volume of the carbon scaffold, where the scaffold pore volume includes more than 80% micropores, less than 20% mesopores, and less than 10% macropores. For example, a silicon-carbon composite can have a Z of less than 10, a 10m 2 / g surface area, greater than 90% first cycle efficiency, and at least 1800 mAh / g reversible capacity, 15% to 85% silicon content, 0.2 to 1.2 cm 3 / g of total pore volume of the carbon scaffold, where the scaffold pore volume includes more than 80% micropores, less than 20% mesopores, and less than 10% macropores.

[0074] Also, according to Table 3, the silicon-carbon composite may include a carbon scaffold having more than 80% micropores, a silicon content of 30-60%, an average Coulombic efficiency of 0.9969 or more, and a Z of less than 10. For example, the silicon-carbon composite may include a carbon scaffold having more than 80% micropores, a silicon content of 30-60%, an average Coulombic efficiency of 0.9970 or more, and a Z of less than 10. For example, the silicon-carbon composite may include a carbon scaffold having more than 80% micropores, a silicon content of 30-60%, an average Coulombic efficiency of 0.9975 or more, and a Z of less than 10. For example, the silicon-carbon composite may include a carbon scaffold having more than 80% micropores, a silicon content of 30-60%, an average Coulombic efficiency of 0.9980 or more, and a Z of less than 10. For example, a silicon-carbon composite may include a carbon scaffold having greater than 80% micropores, a silicon content of 30-60%, an average Coulombic efficiency of 0.9985 or greater, and a Z of less than 10. For example, a silicon-carbon composite may include a carbon scaffold having greater than 80% micropores, a silicon content of 30-60%, an average Coulombic efficiency of 0.9990 or greater, and a Z of less than 10. For example, a silicon-carbon composite may include a carbon scaffold having greater than 80% micropores, a silicon content of 30-60%, an average Coulombic efficiency of 0.9995 or greater, and a Z of less than 10. For example, a silicon-carbon composite may include a carbon scaffold having greater than 80% micropores, a silicon content of 30-60%, an average Coulombic efficiency of 0.9970 or greater, and a Z of less than 10. For example, a silicon-carbon composite may include a carbon scaffold having greater than 80% micropores, a silicon content of 30-60%, an average Coulombic efficiency of 0.9999 or greater, and a Z of less than 10.

[0075] Without wishing to be bound by theory, it is believed that the loading of silicon into the pores of the porous carbon traps porosity within the porous carbon scaffold particles, resulting in inaccessible volumes, e.g., volumes inaccessible to nitrogen gas. Thus, the silicon-carbon composite has a mass fraction of 2.1 g / cm 3Less than, for example, 2.0 g / cm 3 Less than, for example, 1.9 g / cm 3 Less than, for example, 1.8 g / cm 3 Less than, for example, 1.7 g / cm 3 Less than, for example, 1.6 g / cm 3 Less than, for example, 1.4 g / cm 3 Less than, for example, 1.2 g / cm 3 Less than 1.0g / cm 3 It may exhibit a pycnometric density of less than 0.1.

[0076] In some embodiments, the silicon-carbon composite has a density of 1.7 g / cm 3 ~2.1g / cm 3 , e.g. 1.7g / cm 3 ~1.8g / cm 3 , 1.8g / cm 3 ~1.9g / cm 3 , e.g. 1.9g / cm 3 ~2.0g / cm 3 , e.g. 2.0g / cm 3 ~2.1g / cm 3 In some embodiments, the silicon-carbon composite may exhibit a pycnometric density of 1.8 g / cm 3 ~2.1g / cm 3 In some embodiments, the silicon-carbon composite may exhibit a pycnometric density of 1.8 g / cm 3 ~2.0g / cm 3 In some embodiments, the silicon-carbon composite may exhibit a pycnometric density of 1.9 g / cm 3 ~2.1g / cm 3 It may exhibit a pycnometric density of

[0077] The composite, which exhibits extremely durable intercalation of lithium, has a pore volume of 0.01 cm 3 / g~0.2cm 3 In certain embodiments, the pore volume of the composite material may be less than 0.01 cm 3 / g~0.15cm 3 / g, for example 0.01 cm 3 / g~0.1cm3 / g, e.g. 0.01 cm 3 / g~0.05cm 2 / g.

[0078] The particle size distribution of the composites exhibiting very durable intercalation of lithium is important in determining both power performance and volumetric capacity. Improved packing can increase volumetric capacity. In one embodiment, the distribution is either Gaussian with a single peak, bimodal, or multimodal (more than two distinct peaks, e.g., trimodal). The composite particle size characteristics can be described by D0 (smallest particle size in the distribution), Dv50 (average particle size), and Dv100 (largest particle size). The optimum combination of particle packing and performance can be some combination of the following size ranges. Particle size reduction in such embodiments can be performed by jet milling in the presence of various gases, including, for example, air, nitrogen, argon, helium, supercritical water vapor, and other gases known in the art, as known in the art.

[0079] In one embodiment, the Dv0 of the composite material can be from 1 nm to 5 microns. In another embodiment, the Dv0 of the composite material is from 5 nm to 1 micron, such as from 5 to 500 nm, such as from 5 to 100 nm, such as from 10 to 50 nm. In another embodiment, the Dv0 of the composite is from 500 nm to 2 microns, or from 750 nm to 1 μm, or from 1 to 2 μm, or from microns to 2 microns. In another embodiment, the Dv0 of the composite is from 2 to 5 μm, or greater than 5 μm.

[0080] In some embodiments, the Dv50 of the composite is between 5 nm and 20 μm. In other embodiments, the Dv50 of the composite is between 5 nm and 1 μm, such as between 5 and 500 nm, such as between 5 and 100 nm, such as between 10 and 50 nm. In other embodiments, the Dv50 of the composite is between 500 nm and 2 μm, between 750 nm and 1 μm, or between 1 and 2 μm. In yet other embodiments, the Dv50 of the composite is between 1 and 1000 μm, such as between 1 and 100 μm, such as between 1 and 10 μm, such as between 2 and 20 μm, such as between 3 and 15 μm, or such as between 4 and 8 μm. In certain embodiments, the Dv50 is greater than 20 μm, such as greater than 50 μm, such as greater than 100 μm.

[0081] The span (Dv50) / (Dv90-Dv10), where Dv10, Dv50 and Dv90 represent the particle size at 10%, 50% and 90% of the volume distribution, can be, for example, from 100 to 10, from 10 to 5, from 5 to 2, from 2 to 1; in some embodiments, the span can be less than 1. In certain embodiments, the particle size distribution of the composite comprising carbon and porous silicon materials can be multimodal, e.g., bimodal, or trimodal.

[0082] The surface functionality of the presently disclosed composite materials, which exhibit very durable intercalation of lithium, may be modified to obtain desired electrochemical properties. One property that may predict surface functionality is the pH of the composite material. The presently disclosed composite materials include pH values ​​from less than 1 to about 14, such as less than 5, 5 to 8, or greater than 8. In some embodiments, the pH of the composite material is less than 4, less than 3, less than 2, or even less than 1. In other embodiments, the pH of the composite material is about 5 to 6, about 6 to 7, about 7 to 8, or 8 to 9, or 9 to 10. In still other embodiments, the pH of the composite material is high, with a pH greater than 8, greater than 9, greater than 10, greater than 11, greater than 12, or even greater than 13.

[0083] The silicon-carbon composite may contain varying amounts of carbon, oxygen, hydrogen, and nitrogen as measured by gas chromatography CHNO analysis. In one embodiment, the carbon content of the composite is 98% by weight or more, or even 99.9% by weight or more, as measured by CHNO analysis. In another embodiment, the carbon content of the silicon-carbon composite is about 10-90%, such as 20-80%, such as 30-70%, such as 40-60%.

[0084] In some embodiments, the silicon-carbon composite material comprises a nitrogen content of 0-90%, such as 0.1-1%, for example 1-3%, such as 1-5%, for example 1-10%, such as 10-20%, for example 20-30%, for example 30-90%.

[0085] In some embodiments, the oxygen content is 0-90%, such as 0.1-1%, for example 1-3%, for example 1-5%, for example 1-10%, for example 10-20%, for example 20-30%, for example 30-90%.

[0086] Silicon-carbon composites may also incorporate electrochemical modifiers selected to optimize the electrochemical performance of the unmodified composite. The electrochemical modifiers may be incorporated into the pore structure and / or on the surface of the porous carbon scaffold, into embedded silicon, or into the final layer of carbon, or into a conductive polymer, coating, or anywhere else. For example, in some embodiments, the composite includes a coating of electrochemical modifier (e.g., silicon or Al2O3) on the surface of the carbon material. In some embodiments, the composite includes more than about 100 ppm of electrochemical modifier. In certain embodiments, the electrochemical modifier is selected from iron, tin, silicon, nickel, aluminum, and manganese.

[0087] In certain embodiments, the electrochemical modifier comprises an element having a lithiation potential of 3 to 0 V versus lithium metal (e.g., silicon, tin, sulfur). In other embodiments, the electrochemical modifier comprises a metal oxide having a lithiation potential of 3 to 0 V versus lithium metal (e.g., iron oxide, molybdenum oxide, titanium oxide). In still other embodiments, the electrochemical modifier comprises an element that does not lithiate at 3 to 0 V versus lithium metal (e.g., aluminum, manganese, nickel, metal phosphates). In still other embodiments, the electrochemical modifier comprises a nonmetallic element (e.g., fluorine, nitrogen, hydrogen). In still other embodiments, the electrochemical modifier comprises any of the aforementioned electrochemical modifiers, or any combination thereof (e.g., tin-silicon, nickel-titanium oxide).

[0088] The electrochemical modifier can be provided in any form. For example, in some embodiments, the electrochemical modifier comprises a salt. In other embodiments, the electrochemical modifier comprises one or more elements in elemental form, such as iron, tin, silicon, nickel, or manganese. In other embodiments, the electrochemical modifier comprises one or more elements in oxidized form, such as iron oxide, tin oxide, silicon oxide, nickel oxide, aluminum oxide, or manganese oxide.

[0089] The electrochemical properties of the composite material may be modified, at least in part, by the amount of electrochemical modifier in the material, where the electrochemical modifier is an alloy material such as silicon, tin, indium, aluminum, germanium, gallium, etc. Thus, in some embodiments, the composite material comprises 0.10%, at least 0.25%, at least 0.50%, at least 1.0%, at least 5.0%, at least 10%, at least 25%, at least 50%, at least 75%, at least 90%, at least 95%, at least 99%, or at least 99.5% electrochemical modifier.

[0090] The particle size of the composite material may expand upon lithiation, compared to the non-lithiation state. For example, the expansion coefficient is defined as the ratio of the average particle size of the composite material containing the porous silicon material upon lithiation divided by the average particle size under non-lithiation conditions. As described in the art, this expansion coefficient can be relatively large for previously known non-optimal silicon-containing materials, such as about 4 times (corresponding to a 400% volume expansion upon lithiation). The inventors have invented a composite material containing a porous silicon material that can exhibit a lower degree of expansion (for example, the expansion coefficient can be 3.5-4, 3.0-3.5, 2.5-3.0, 2.0-2.5, 1.5-2.0, 1.0-1.5).

[0091] It is envisioned that the composite material in certain embodiments contains a portion of trapped pore volume, i.e., void volume that is inaccessible to nitrogen gas as detected by nitrogen gas adsorption measurements. Without wishing to be bound by theory, this trapped pore volume is important in that it provides a volume through which silicon can expand upon lithiation.

[0092] In certain embodiments, the ratio of the trapped void volume to the silicon volume containing the composite particles is 0.1:1 to 10:1. For example, the ratio of the trapped void volume to the silicon volume containing the composite particles is 1:1 to 5:1, or 5:1 to 10:1. In embodiments, the ratio of the trapped void volume to the silicon volume containing the composite particles is 2:1 to 5:1, or about 3:1 to effectively accommodate the maximum expansion of silicon upon lithiation.

[0093] In some embodiments, the composite particles have an average sphericity (as defined herein) of at least 0.5, or at least 0.55, hi other embodiments, the average sphericity is at least 0.65, at least 0.7, at least 0.75, or at least 0.8.

[0094] Highly accurate two-dimensional projections of micron-scale particles can be obtained by scanning electron microscopy (SEM) or by dynamic image analysis, where the shadow cast by the particle is recorded by a digital camera. The term "sphericity" as used herein is understood as the ratio of the area of ​​the particle image to the area of ​​a circle (obtained from such imaging techniques) having the same circumference. Thus, the sphericity S of an individual particle is given by:

number

number

[0095] In certain embodiments, the electrochemical performance of the composites disclosed herein is tested in half cells; alternatively, the performance of the composites disclosed herein with highly durable intercalation of lithium is tested in full cells (e.g., full cell coin cells, full cell pouch cells, prism cells, or other battery configurations known in the art). Anode compositions including the composites disclosed herein with highly durable intercalation of lithium can further include various species known in the art. Additional formulation components include, but are not limited to, conductive additives such as conductive carbon (e.g., Super C45, Super P, Ketjen Black carbon, etc.), conductive polymers, binders such as styrene-butadiene rubber sodium carboxymethylcellulose (SBR-Na-CMC), polyvinylidene difluoride (PVDF), polyimide (PI), polyacrylic acid (PAA), and combinations thereof. In certain embodiments, the binder can include lithium ions as counterions.

[0096] Other species that make up the electrode are known in the art. The weight percent of active material in the electrode can vary, for example, 1-5%, for example, 5-15%, for example, 15-25%, for example, 25-35%, for example, 35-45%, for example, 45-55%, for example, 55-65%, for example, 65-75%, for example, 75-85%, for example, 85-95%. In some embodiments, the active material comprises 80-95% of the electrode. In certain embodiments, the amount of conductive additive in the electrode can vary, for example, 1-5%, for example, 5-15%, for example, 15-25%, for example, 25-35%. In some embodiments, the amount of conductive additive in the electrode is 5-25%. In certain embodiments, the amount of binder can vary, for example, 1-5%, 5-15%, for example, 15-25%, for example, 25-35%. In certain embodiments, the amount of conductive additive in the electrode is 5-25%.

[0097] The silicon-carbon composite material may be pre-lithiated as known in the art. In certain embodiments, the pre-lithiation is accomplished electrochemically, for example in a half cell, before assembling the lithiated anode comprising the porous silicon material into a full-cell lithium-ion battery. In certain embodiments, the pre-lithiation is accomplished by doping the cathode with a lithium-containing compound, for example a lithium-containing salt. Suitable lithium salts in this context include, but are not limited to, for example, dilithium tetrabromonickelate(II), dilithium tetrachloride(II), lithium azide, lithium benzoate, lithium bromide, lithium carbonate, lithium chloride, lithium cyclohexanebutyrate, lithium fluoride, lithium formate, hexafluoroarsenate(V), lithium hexafluorophosphate, lithium hydroxide, lithium iodate, lithium iodide, lithium metaborate, lithium perchlorate, lithium phosphate, lithium sulfate, lithium tetraborate, lithium tetrachloroaluminate, lithium tetrafluoroborate, lithium thiocyanate, lithium trifluoromethanesulfonate, lithium trifluoromethanesulfonate, and combinations thereof.

[0098] Anodes comprising silicon-carbon composites can be paired with various cathode materials to obtain full-cell lithium-ion batteries. Examples of suitable cathode materials are known in the art. Such cathode materials include, but are not limited to, LiCoO2 (LCO), LiNi 0.8 Co 0.15 Al 0.05 O2(NCA), LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (NMC), LiMn2O4 and its variants (LMO), and LiFePO4 (LFP).

[0099] In a full cell lithium ion battery including an anode further comprising a silicon-carbon composite material, the ratio of the cathode to the anode can vary. For example, the ratio of the cathode to the anode capacity can be 0.7 to 1.3. In certain embodiments, the ratio of the cathode to the anode capacity can be 0.7 to 1.0, such as 0.8 to 1.0, such as 0.85 to 1.0, such as 0.9 to 1.0, such as 0.95 to 1.0. In other embodiments, the ratio of the cathode to the anode capacity can be 1.0 to 1.3, such as 1.0 to 1.2, such as 1.0 to 1.15, such as 1.0 to 1.1, such as 1.0 to 1.05. In yet other embodiments, the ratio of the cathode to the anode capacity can be 0.8 to 1.2, such as 0.9 to 1.1, such as 0.95 to 1.05.

[0100] In a full-cell lithium-ion battery including an anode further including a silicon-carbon composite material, the voltage window during charging and discharging can vary. In this regard, the voltage window can vary as known in the art depending on various characteristics of the lithium-ion battery. For example, the selection of the cathode plays a role in the selected voltage window as known in the art. The voltage window can vary, for example, between 2.0V and 5.0V, for example, between 2.5V and 4.5V, for example, between 2.5V and 4.2V, with respect to the potential vs. Li / Li+.

[0101] In the full-cell lithium-ion battery that further comprises the anode of silicon-carbon composite material, the conditioning method of the cell can be various as known in the art.For example, conditioning can be achieved by one or more charge-discharge cycles at various speeds, for example at a speed slower than the desired cycle speed.As known in the art, the conditioning process can also include opening the lithium-ion battery, venting the gas generated inside during the conditioning process, and then resealing the lithium-ion battery.

[0102] In a full cell lithium ion battery including an anode further comprising a silicon-carbon composite material, the cycle rate can vary as known in the art, for example, C / 20 to 20C, for example, C10 to 10C, for example, C / 5 to 5C. In certain embodiments, the cycle rate is C / 10. In certain embodiments, the cycle rate is C / 5. In certain embodiments, the cycle rate is C / 2. In certain embodiments, the cycle rate is 1C. In certain embodiments, the cycle rate is 1C and periodically reduced in rate, for example, cycling at 1C and reducing the rate by C / 10 every 20th cycle. In certain embodiments, the cycle rate is 2C. In certain embodiments, the cycle rate is 4C. In certain embodiments, the cycle rate is 5C. In certain embodiments, the cycle rate is 10C. In certain embodiments, the cycle rate is 20C.

[0103] The first cycle efficiency of the composites disclosed herein with highly durable intercalation of lithium is determined by comparing the lithium inserted into the anode during the first cycle, prior to prior lithiation modification, with the lithium extracted from the anode during the first cycle. If insertion and extraction are equal, the efficiency is 100%. As is known in the art, the anode materials can be tested in half cells with lithium metal as the counter electrode and 1M LiPF6 1:1 ethylene carbonate:diethyl carbonate (EC:DEC) electrolyte using a commercially available polypropylene separator. In certain embodiments, the electrolyte can contain various additives known to improve performance (fluoroethylene carbonate (FEC) or other related fluorinated carbonate compounds), or ester co-solvents such as other electrolyte additives known to improve electrochemical performance (methyl butyrate, vinylene carbonate, and silicon-containing anode materials).

[0104] The coulombic efficiency can be averaged, for example, over cycle 7 to cycle 25 when tested in a half cell. The coulombic efficiency can be averaged, for example, over cycle 7 to cycle 20 when tested in a half cell. In certain embodiments, the average efficiency of the composite with very durable intercalation of lithium is greater than 0.9, or 90%. In certain embodiments, the average efficiency is greater than 0.95, or 95%. In other particular embodiments the average efficiency is 0.99 or more, such as 0.991 or more, such as 0.992 or more, for example 0.993 or more, such as 0.994 or more, for example 0.995 or more, such as 0.996 or more, for example 0.998 or more, such as 0.999 or more, such as 0.9991 or more, such as 0.9992 or more, for example 0.9993 or more, such as 0.9994 or more, for example 0.9995 or more, such as 0.9996 or more, for example 0.9997 or more, such as 0.9998 or more, such as 0.9999 or more.

[0105] In yet other embodiments, the present disclosure provides a composite material that exhibits highly durable intercalation of lithium, where when the composite material is incorporated into an electrode of a lithium-based energy storage device, the composite material has a volumetric capacity that is at least 10% greater than when the lithium-based energy storage device includes a graphite electrode. In some embodiments, the lithium-based energy storage device is a lithium-ion battery. In other embodiments, the composite material has a lithium-based energy storage device volumetric capacity that is at least 5%, at least 10%, or at least 15% greater than the volumetric capacity of a similar electrical energy storage device with a graphite electrode. In still other embodiments, the composite material has a lithium-based energy storage device volumetric capacity that is at least 20%, at least 30%, at least 40%, at least 50%, at least 200%, at least 100%, at least 150%, or at least 200% greater than the volumetric capacity of a similar electrical energy storage device with a graphite electrode.

[0106] The composite material may be pre-lithiated as known in the art. These lithium atoms may or may not be separated from the carbon. The number of lithium atoms (#Li) per six carbon atoms may be determined by the following method known to those skilled in the art: #Li=Q×3.6×MM / (C%×F) where Q is the lithium extraction capacity measured in mAh / g at voltages between 5 mV and 2.0 V versus lithium metal, MM is the molecular weight of 72 or 6 carbons, F is the Faraday constant 96500, and C% is the mass percent of carbon present in the structure as measured by CHNO or XPS. In Art:

[0107] The composite material may be characterized by the ratio of lithium atoms to carbon atoms (Li:C), which may be between about 0:6 and 2:6. In some embodiments, the Li:C ratio is between about 0.05:6 and about 1.9:6. In other embodiments, the maximum Li:C ratio, where the lithium is in ionic form rather than metallic form, is 2.2:6. In other specific embodiments, the Li:C ratio is between about 1.2:6 and about 2:6, between about 1.3:6 and about 1.9:6, between about 1.4:6 and about 1.9:6, between about 1.6:6 and about 1.8:6, or between about 1.7:6 and about 1.8:6. In other embodiments, the Li:C ratio is greater than 1:6, greater than 1.2:6, greater than 1.4:6, greater than 1.6:6, or greater than 1.8:6. In other embodiments, the Li:C ratio is about 1.4:6, about 1.5:6, about 1.6:6, about 1.6:6, about 1.7:6, about 1.8:6, or about 2:6. In certain embodiments, the Li:C ratio is about 1.78:6.

[0108] In other specific embodiments, the composite material comprises a Li:C ratio of about 1:6 to about 2.5:6, about 1.4:6 to about 2.2:6, or about 1.4:6 to about 2:6. In yet other embodiments, the composite material does not necessarily contain lithium, but instead has a lithium uptake capacity (i.e., the ability to take up a certain amount of lithium when the material is cycled between, for example, two voltage conditions (for a lithium-ion half cell, exemplary voltage windows are 0V to 3V, e.g., 0.005V to 2.7V, e.g., 0.005V to 1V, e.g., 0.005V to 0.8V). Without wishing to be bound by theory, it is believed that the lithium uptake capacity of the composite materials contributes to their superior performance in lithium-based energy storage devices. The lithium uptake capacity is expressed as the ratio of lithium atoms taken up by the composite. In other specific embodiments, composite materials exhibiting highly durable intercalation of lithium comprise a lithium uptake capacity of from about 1:6 to about 2.5:6, from about 1.4:6 to about 2.2:6, or from about 1.4:6 to about 2:6.

[0109] In other specific embodiments, the lithium uptake capacity is about 1.2:6 to about 2:6, about 1.3:6 to about 1.9:6, about 1.4:6 to about 1.9:6, about 1.6:6 to about 1.8:6, or about 1.7:6 to about 1.8:6. In other embodiments, the lithium uptake capacity is greater than 1:6, greater than 1.2:6, greater than 1.4:6, greater than 1.6:6, or greater than 1.8:6. In other embodiments, the Li:C ratio is about 1.4:6, about 1.5:6, about 1.6:6, about 1.6:6, about 1.7:6, about 1.8:6, or about 2:6. In certain embodiments, the Li:C ratio is about 1.78:6.

[0110] Working Example Example 1. Preparation of silicon-carbon composites by CVI The properties of the carbon scaffold (Carbon Scaffold 1) used to fabricate the silicon-carbon composites are shown in Table 4. Carbon Scaffold 1 was used to fabricate silicon-carbon composites (Silicon-Carbon Composite 1) by CVI as follows. A mass of 0.2 g of amorphous porous carbon was placed in a 2" x 2" ceramic crucible and then placed in the center of a horizontal tube furnace. The furnace was sealed and continuously purged with nitrogen gas at 500 cubic centimeters per minute (ccm). The furnace temperature was increased at 20°C / min to a peak temperature of 450°C and allowed to equilibrate for 30 minutes. At this point, the nitrogen gas was shut off and then silane and hydrogen gas were introduced at flow rates of 50 ccm and 450 ccm, respectively, for a total residence time of 30 minutes. After the residence time, the silane and hydrogen were shut off and nitrogen gas was again introduced into the furnace to purge the internal atmosphere. Simultaneously, the furnace heat was shut off and cooled to ambient temperature. The finished Si-C material was then removed from the furnace. Table 4. Description of carbon scaffolds used in Example 1 [Table 4]

[0111] Example 2. Analysis of various silicon-composite materials Various carbon scaffold materials were used and characterized by nitrogen adsorption gas analysis to determine the specific surface area, total pore volume, and percentage of pore volume including micropores, mesopores, and macropores. The characterization data of the carbon scaffold materials are shown in Table 5. That is, Table 5 is all data of carbon scaffold surface area, pore volume, and pore volume distribution (micropore%, mesopore%, macropore%) determined by nitrogen adsorption analysis.

[0112] Table 5. Properties of various carbon scaffold materials. [Table 5]

[0113] The carbon scaffold samples listed in Table 5 were used to produce a variety of silicon-carbon composites employing the CVI methodology in a static bed configuration generally described in Example 1. The silicon-carbon samples were produced using process conditions that included silane concentrations ranging from 1.25% to 100%, diluent gases of nitrogen or hydrogen, and starting carbon scaffold masses ranging from 0.2 g to 700 g.

[0114] The surface area of ​​the silicon-carbon composite was determined. The silicon-carbon composite was also analyzed by TGA to determine the silicon content and Z. The silicon-carbon composite was also tested in a half-cell coin cell. The anode of the half-cell coin cell may include 60-90% silicon-carbon composite, 5-20% Na-CMC (as a binder) and 5-20% Super C 45 (as a conductivity enhancer), and the electrolyte may include 2:1 ethylene carbonate:diethylene carbonate, 1M LiPF6 and 10% fluoroethylene carbonate. The half-cell coin cell may be cycled at 25°C for 5 cycles at a rate of C / 5 followed by a rate of C / 10. The voltage may be cycled from 0V to 0.8V, and alternatively the voltage may be cycled from 0V to 1.5V. From the half-cell coin cell data, the maximum capacity and the average coulombic efficiency (CE) over the cycle range from cycle 7 to cycle 20 can be determined. The physicochemical and electrochemical properties of various silicon-carbon composites are shown in Table 6.

[0115] Table 6. Properties of various silicon-carbon materials [Table 6]

[0116] A plot of the average coulombic efficiency as a function of Z is shown in FIG. 1. As shown in FIG. 1, the average coulombic efficiency of silicon-carbon samples with low Z increased dramatically. In particular, it was observed that all silicon-carbon samples with Z less than 10.0 exhibited average coulombic efficiencies of 0.9941 or greater, and all silicon-carbon samples with Z greater than 10 (silicon-carbon composite sample 12 to silicon-carbon composite sample 16) had average coulombic efficiencies of 0.9909 or less. Without wishing to be bound by theory, the high coulombic efficiency in silicon-carbon samples with Z less than 10 provides excellent cycling stability in full-cell lithium-ion batteries. Further inspection of the table reveals the surprising and unexpected fact that the combination of silicon-carbon composites with Z less than 10 and carbon scaffolds containing microporosity of 70 or greater results in average coulombic efficiencies of 0.9950 or greater.

[0117] Thus, in a preferred embodiment, the silicon-carbon composite comprises a Z of less than 10, such as a Z of less than 5, such as a Z of less than 3, such as a Z of less than 2, such as a Z of less than 1, such as a Z of less than 0.5, such as a Z of less than 0.1, or a Z of 0.

[0118] In certain preferred embodiments, the silicon-carbon composite material comprises a Z of less than 10 and more than 70% micropores, such as a Z of less than 10 and more than 80% micropores, such as a Z of less than 10 and more than 90% micropores, such as a Z of less than 10 and more than 95% micropores, such as a Z of less than 5 and more than 70% micropores, such as a Z of less than 5 and more than 80% micropores, such as a Z of less than 5 and more than 90% micropores, such as a Z of less than 5. and more than 95% of the micropores, for example, having a Z of less than 3 and more than 70% of the micropores, for example, having a Z of less than 3 and more than 80% of the micropores, for example, having a Z of less than 3 and more than 90% of the micropores, for example, having a Z of less than 3 and more than 95% of the micropores, for example, having a Z of less than 2 and more than 70% of the micropores, for example, having a Z of less than 2 and more than 80% of the micropores, for example, having a Z of less than 2 and more than 90% of the micropores, for example, having a Z of less than 2 and more than 95% of the micropores. for example, Z less than 1 and more than 70% micropores, for example, Z less than 1 and more than 80% micropores, for example, Z less than 1 and more than 90% micropores, for example, Z less than 1 and more than 95% micropores, for example, Z less than 0.5 and more than 70% micropores, for example, Z less than 0.5 and more than 80% micropores, for example, Z less than 0.5 and more than 90% micropores, for example, Z less than 0.5 and more than 95% micropores. Micropores, for example, Z less than 0.1 and more than 70% micropores, for example, Z less than 0.1 and more than 80% micropores, for example, Z less than 0.1 and more than 90% micropores, for example, Z less than 0.1 and more than 95% micropores, for example, Z of 0 and more than 70% micropores, for example, Z of 0 and more than 80% micropores, for example, Z of 0 and more than 90% micropores, for example, Z of 0 and more than 95% micropores.

[0119] In certain preferred embodiments, the silicon-carbon composite comprises a carbon scaffold having a Z of less than 10 and >70% micropores, and the silicon-carbon composite comprises 15%-85% silicon and 100% carbon. 2 / g, e.g., Z less than 10 and >70% micropores, and silicon-carbon composites have 15%-85% silicon and 50m 2 / g, e.g., Z less than 10 and >70% micropores, and silicon-carbon composites have 15%-85% silicon and 30m 2 / g, e.g., Z less than 10 and >70% micropores, and silicon-carbon composites have 15%-85% silicon and 10m 2 / g, e.g., Z less than 10 and >70% micropores, and silicon-carbon composites have 15%-85% silicon and 5m 2 / g, e.g., Z less than 10 and >80% micropores, and silicon-carbon composites have 15%-85% silicon and 50m 2 / g, e.g., Z less than 10 and >80% micropores, and silicon-carbon composites have 15%-85% silicon and 30m 2 / g, e.g., Z less than 10 and >80% micropores, and silicon-carbon composites have 15%-85% silicon and 10m 2 / g, e.g., Z less than 10 and >80% micropores, and silicon-carbon composites have 15%-85% silicon and 5m 2 / g, e.g., Z less than 10 and >90% micropores, and silicon-carbon composites have 15%-85% silicon and 50m 2 / g, e.g., Z less than 10 and >90% micropores, and silicon-carbon composites have 15%-85% silicon and 30m 2 / g, e.g., Z less than 10 and >90% micropores, and silicon-carbon composites have 15%-85% silicon and 10m 2 / g, e.g., Z less than 10 and >90% micropores, and silicon-carbon composites have 15%-85% silicon and 5m 2 / g, e.g., Z less than 10 and >95% micropores, and silicon-carbon composites have 15%-85% silicon and 50m 2 / g, e.g., Z less than 10 and >95% micropores, and silicon-carbon composites have 15%-85% silicon and 30m 2 / g, e.g., Z less than 10 and >95% micropores, and silicon-carbon composites have 15%-85% silicon and 10m 2 / g, e.g., Z less than 10 and >95% micropores, and silicon-carbon composites have 15%-85% silicon and 5m 2 / g.

[0120] In certain preferred embodiments, the silicon-carbon composite comprises a carbon scaffold having a Z of less than 10 and >70% micropores, and the silicon-carbon composite comprises 30%-60% silicon and 100% carbon. 2 / g, e.g., Z less than 10 and >70% micropores, and silicon-carbon composites have 30%-60% silicon and 50m 2 / g, e.g., Z less than 10 and >70% micropores, and silicon-carbon composites have 30%-60% silicon and 30m 2 / g, e.g., Z less than 10 and >70% micropores, and silicon-carbon composites have 30%-60% silicon and 10m 2 / g, e.g., Z less than 10 and >70% micropores, and silicon-carbon composites have 30%-60% silicon and 5m 2 / g, e.g., Z less than 10 and >80% micropores, and silicon-carbon composites have 30%-60% silicon and 50m 2 / g, e.g., Z less than 10 and >80% micropores, and silicon-carbon composites have 30%-60% silicon and 30m 2 / g, e.g., Z less than 10 and >80% micropores, and silicon-carbon composites have 30%-60% silicon and 10m 2 / g, e.g., Z less than 10 and >80% micropores, and silicon-carbon composites have 30%-60% silicon and 5m 2 / g, e.g., Z less than 10 and >90% micropores, and silicon-carbon composites have 30%-60% silicon and 50m 2 / g, e.g., Z less than 10 and >90% micropores, and silicon-carbon composites have 30%-60% silicon and 30m 2 / g, e.g., Z less than 10 and >90% micropores, and silicon-carbon composites have 30%-60% silicon and 10 m 2 / g, e.g., Z less than 10 and >90% micropores, and silicon-carbon composites have 30%-60% silicon and 5m 2 / g, e.g., Z less than 10 and >95% micropores, and silicon-carbon composites have 30%-60% silicon and 50m 2 / g, e.g., Z less than 10 and >95% micropores, and silicon-carbon composites have 30%-60% silicon and 30m 2 / g, e.g., Z less than 10 and >95% micropores, and silicon-carbon composites have 30%-60% silicon and 10m 2 / g, e.g., Z less than 10 and >95% micropores, and silicon-carbon composites have 30%-60% silicon and 5m 2 / g.

[0121] In certain preferred embodiments, the silicon-carbon composite comprises a carbon scaffold having a Z of less than 10 and >80% micropores, and the silicon-carbon composite comprises 30%-60% silicon, 30% carbon, 50% SiO2, and 50% SiO2. 2 For example, silicon-carbon composites include carbon scaffolds with Z less than 10 and >80% micropores, and silicon-carbon composites include 30%-60% silicon, 30% carbon, and 10% carbon. 2 For example, silicon-carbon composites include carbon scaffolds with Z less than 10 and >80% micropores, and silicon-carbon composites include 30%-60% silicon, 30% carbon, and 10% carbon. 2 For example, silicon-carbon composites include carbon scaffolds with Z less than 10 and >80% micropores, and silicon-carbon composites include 30%-60% silicon, 30% carbon, and 10% carbon. 2 For example, silicon-carbon composites include carbon scaffolds with Z less than 10 and >80% micropores, and silicon-carbon composites include 30%-60% silicon, 30% carbon, and 10% silicon. 2 For example, silicon-carbon composites include carbon scaffolds with Z less than 10 and >80% micropores, and silicon-carbon composites include 30%-60% silicon, 30m 2For example, silicon-carbon composites include carbon scaffolds with Z less than 10 and >80% micropores, and silicon-carbon composites include 30%-60% silicon, 30% carbon, and 10% silicon. 2 For example, silicon-carbon composites include carbon scaffolds with Z less than 10 and >80% micropores, and silicon-carbon composites include 30%-60% silicon, 30% carbon, and 10% silicon. 2 / g and an average coulombic efficiency of 0.9999 or greater.

[0122] Example 3. dV / dQ in various silicon-carbon materials. Differential capacity curves (dQ / dV vs. voltage) are often used as a non-destructive tool to understand the phase transitions as a function of voltage in lithium battery electrodes (Loveridge, MJ et al. Towards High Capacity Li-Ion Batteries Based on Silicon-Graphene Composite Anodes and Sub-micron V-doped LiFePO4 Cathodes. Sci. Rep. 6, 37787; doi: 10.1038 / srep37787 (2016); MN Obrovac et al. Li15Si4Formation in Silicon Thin Film Negative Electrodes, Journal of The Electrochemical Society,163 (2) A255-A261 (2016); Q.Pan et al. Improved electrochemical performance of micro-sized SiO-based composite anode by prelithiation of stabilized lithium metal powder, Journal of Power Sources 347 (2017) 170-177). The first cycle lithiation behavior depends inter alia on the crystallinity of the silicon and the oxygen content.

[0123] After the first cycle, conventional amorphous silicon materials in the art show two specific phase transition peaks in the dQ / dV vs. V plot during lithiation, and correspondingly, two specific phase transition peaks in the dQ / dV vs. V plot during delithiation. During lithiation, one peak corresponding to the lithium-poor Li-Si alloy phase occurs at 0.2-0.4 V, and another peak corresponding to the lithium-rich Li-Si alloy phase occurs below 0.15 V. During delithiation, one delithiation peak corresponding to the extraction of lithium occurs below 0.4 V, and another peak occurs between 0.4 V and 0.55 V. When the Li15Si4 phase is formed during lithiation, it is delithiated at about 0.45 V, appearing as a very narrow sharp peak.

[0124] FIG. 2 shows the dQ / dV vs. voltage curves for cycle 2 of the silicon-carbon composite corresponding to silicon-carbon composite 3 of Example 1. Silicon-carbon composite 3 contains a Z of 0.6. For ease of identification, the plot is divided into regimes I, II, IV, V, and VI. Regimes I (0.8V-0.4V), II (0.4V-0.15V), and III (0.15V-0V) contain the lithiation potentials, and regimes IV (0V-0.4V), V (0.4V-0.55V), and VI (0.55V-0.8V) contain the delithiation potentials. As mentioned above, conventional amorphous silicon-based materials exhibit phase transition peaks in two regimes of lithiation potentials (regimes II and III) and two regimes of delithiation potentials (regimes IV and V).

[0125] As seen in Figure 2, the dQ / dV vs. voltage curves reveal the surprising and unexpected result that the silicon-carbon composite 3 with Z of 0.6 contains two additional peaks in the dQ / dV vs. voltage curve, namely, regime I of the lithiation potential and regime VI of the delithiation potential. All six peaks are reversible and are observed in the next cycle, as shown in Figure 3.

[0126] Without wishing to be bound by theory, such trimodal behavior in the dQ / dV vs. V curves is novel and also reflects a novel morphology of silicon.

[0127] In particular, the novel peaks observed in Regime I and Regime VI are more pronounced in certain scaffold matrices and are completely absent in other samples representing the prior art (silicon-carbon composite samples with Z>10, see discussion and table below).

[0128] Figure 4 shows the dQ / dV vs V curves for silicon-carbon composite 3, where new peaks in regime I and regime VI are evident compared to silicon-carbon composite 15, silicon-carbon composite 16 and silicon-carbon composite 14. All three have Z greater than 10 and their dQ / dV vs V curves lack the peaks in regime I and regime VI.

[0129] Without being bound by theory, these novel peaks observed in regime I and regime VI are related to the properties of the silicon impregnated in the porous carbon scaffold, i.e., the interaction of lithium with silicon impregnated in the porous carbon scaffold by CVI. To provide a quantitative analysis, we define the parameter φ, calculated as peak I normalized with respect to peak III, as follows: φ = (maximum peak height of dQ / dV in regime 1) / (maximum peak height of dQ / dV in regime 3) [where dQ / dV is measured in a half-cell coin cell, regime 1 is 0.8V-0.4V, regime 3 is 0.15V-0V; the half-cell coin cell is fabricated as known in the art.]. When the Si-C sample exhibited graphite-related peaks in regime III of the differential curve, the D-factor calculations excluded Li-Si-related phase transition peaks in favor of them. For example, a half-cell coin cell includes an anode containing 60-90% silicon-carbon composite, 5-20% SBR-Na-CMC, and 5-20% Super C 45. An example of the calculation of φ for silicon-carbon composite 3 is shown in Figure 5. In this case, the maximum peak height in regime I is -2.39, which is seen at a voltage of 0.53V. Similarly, the maximum peak height in regime III is -9.71 at 0.04V. In this case, φ can be calculated using the formula above, giving φ=-2.39 / -9.71=0.25. The values ​​of φ were determined from data for half-cell coin cells for the various silicon-carbon composites shown in Example 2. These data are summarized in Table 7. Table 7 also includes first cycle efficiency data measured in half-cell coin cells cycled at 0.8 V at 5 mV.

[0130] Table 7. Properties of various silicon-carbon scaffold materials. [Table 7] These bracketed data for first cycle efficiency were measured in a voltage window from 5mV to 1.5V.

[0131] The data in Table 7 reveal an unexpected relationship between decreasing Z and increasing φ. All silicon-carbon composites with Z<10 had a φ of 0.13 or more, and all silicon-carbon composites with Z>10 had a φ of less than 0.13. In fact, all silicon-carbon composites with Z greater than 10 had a φ=0. This relationship is also shown in FIG. 6. Without being bound by theory, silicon materials with a φ of 0.10 or more, such as a φ of 0.13 or more, such as a φ of 0.15 or more, such as a φ of 0.20 or more, such as a φ of 0.25 or more, such as a φ of 0.30 or more, correspond to novel morphologies of silicon. Alternatively, silicon materials with a φ>0 correspond to novel morphologies of silicon. Silicon-carbon composites with silicon with a φ of 0.10 or more, such as a φ of 0.13 or more, such as a φ of 0.15 or more, such as a φ of 0.20 or more, such as a φ of 0.25 or more, such as a φ of 0.30 or more, correspond to novel silicon-carbon composites. Separately, silicon-carbon composites with φ>0 correspond to novel silicon-carbon composites.

[0132] In certain embodiments, the silicon-carbon composite comprises φ≧0.1, φ≧0.11, φ≧0.12, φ≧0.13, φ≧0.14, φ≧0.15, φ≧0.16, φ≧0.17, φ≧0.18, φ≧0.19, φ≧0.20, φ≧0.24, φ≧0.24, φ≧0.25, φ≧0.30, or φ≧0.35. In some embodiments, φ>0. In some embodiments, φ≧0.001, φ≧0.01, φ≧0.02, φ≧0.05, φ≧0.1, φ≧0.11, or φ≧0.12.

[0133] In certain embodiments, the silicon-carbon composite comprises a carbon scaffold having a Z of less than 10 and a microporosity of greater than 70%, and the silicon-carbon composite comprises 30% to 60% silicon and 100% carbon. 2 / g and φ of 0.1 or greater, e.g., carbon scaffolds having Z less than 10 and microporosity greater than 70%, and silicon-carbon composites having 30% to 60% silicon and 50m 2 / g and φ of 0.1 or greater, e.g., carbon scaffolds having Z less than 10 and microporosity greater than 70%, and silicon-carbon composites having 30% to 60% silicon and 30m 2 / g and φ of 0.1 or greater, e.g., carbon scaffolds having Z less than 10 and microporosity greater than 70%, and silicon-carbon composites having 30% to 60% silicon and 10 m 2 / g and φ of 0.1 or greater, e.g., carbon scaffolds having Z of less than 10 and microporosity of greater than 70%, and silicon-carbon composites having 30% to 60% silicon and 5m 2 / g and a φ of 0.1 or greater.

[0134] In certain embodiments, the silicon-carbon composite comprises a carbon scaffold having a Z of less than 10 and a microporosity of greater than 70%, and the silicon-carbon composite comprises 40% to 60% silicon and 100% carbon. 2 / g and φ of 0.1 or greater, e.g., carbon scaffolds having Z of less than 10 and microporosity of greater than 70%, and silicon-carbon composites having 40%-60% silicon and 50m 2 / g and φ of 0.1 or greater, e.g., carbon scaffolds having Z of less than 10 and microporosity of greater than 70%, and silicon-carbon composites having 40% to 60% silicon and 30m 2 / g and φ of 0.1 or greater, e.g., carbon scaffolds having Z less than 10 and microporosity greater than 70%, and silicon-carbon composites having 40%-60% silicon and 10 m 2 / g and φ of 0.1 or greater, e.g., carbon scaffolds having Z of less than 10 and microporosity of greater than 70%, and silicon-carbon composites having 40% to 60% silicon and 5m 2 / g and a φ of 0.1 or greater.

[0135] In certain embodiments, the silicon-carbon composite comprises a carbon scaffold having a Z of less than 10 and a microporosity of greater than 70%, and the silicon-carbon composite comprises 30% to 60% silicon and 100% carbon. 2 / g and φ greater than 0, for example, carbon scaffolds having Z less than 10 and microporosity greater than 70%, and silicon-carbon composites having 30% to 60% silicon and 50m 2 / g and φ greater than 0, for example, carbon scaffolds having Z less than 10 and microporosity greater than 70%, and silicon-carbon composites having 30% to 60% silicon and 30m 2 / g and φ greater than 0, for example, carbon scaffolds having Z less than 10 and microporosity greater than 70%, and silicon-carbon composites having 30% to 60% silicon and 10 m 2 / g and φ greater than 0, e.g., carbon scaffolds having Z less than 10 and microporosity greater than 70%, and silicon-carbon composites having 30% to 60% silicon and 5m 2 / g and φ greater than 0.

[0136] In certain embodiments, the silicon-carbon composite comprises a carbon scaffold having a Z of less than 10 and a microporosity of greater than 70%, and the silicon-carbon composite comprises 40% to 60% silicon and 100% carbon. 2 / g and φ greater than 0, e.g., carbon scaffolds having Z less than 10 and microporosity greater than 70%, and silicon-carbon composites having 40% to 60% silicon and 50m 2 / g and φ greater than 0, for example, carbon scaffolds having Z less than 10 and microporosity greater than 70%, and silicon-carbon composites having 40% to 60% silicon and 30m 2 / g and φ greater than 0, for example, carbon scaffolds having Z less than 10 and microporosity greater than 70%, and silicon-carbon composites having 40% to 60% silicon and 10 m 2 / g and φ greater than 0, for example, carbon scaffolds having Z less than 10 and microporosity greater than 70%, and silicon-carbon composites having 40% to 60% silicon and 5m 2 / g and φ greater than 0.

[0137] In certain embodiments, the silicon-carbon composite comprises a carbon scaffold having a Z of less than 10 and a microporosity of greater than 80%, and the silicon-carbon composite comprises 30% to 60% silicon and 100% carbon. 2 / g and φ of 0.1 or greater, e.g., carbon scaffolds having Z of less than 10 and microporosity of greater than 80%, and silicon-carbon composites having 30% to 60% silicon and 50m 2 / g and φ of 0.1 or greater, e.g., carbon scaffolds having Z of less than 10 and microporosity of greater than 80%, and silicon-carbon composites having 30% to 60% silicon and 30m 2 / g and φ of 0.1 or greater, e.g., carbon scaffolds having Z less than 10 and microporosity greater than 80%, and silicon-carbon composites having 30% to 60% silicon and 10 m 2 / g and φ of 0.1 or greater, e.g., carbon scaffolds having Z of less than 10 and microporosity of greater than 80%, and silicon-carbon composites having 30% to 60% silicon and 5m 2 / g and a φ of 0.1 or greater.

[0138] In certain embodiments, the silicon-carbon composite comprises a carbon scaffold having a Z of less than 10 and a microporosity of greater than 80%, and the silicon-carbon composite comprises 40% to 60% silicon and 100% carbon.2 / g and φ of 0.1 or greater, e.g., carbon scaffolds having Z of less than 10 and microporosity of greater than 80%, and silicon-carbon composites having 40%-60% silicon and 50m 2 / g and φ of 0.1 or greater, e.g., carbon scaffolds having Z of less than 10 and microporosity of greater than 80%, and silicon-carbon composites having 40%-60% silicon and 30m 2 / g and φ of 0.1 or greater, e.g., carbon scaffolds having Z less than 10 and microporosity greater than 80%, and silicon-carbon composites having 40%-60% silicon and 10 m 2 / g and φ of 0.1 or greater, e.g., carbon scaffolds having Z of less than 10 and microporosity of greater than 80%, and silicon-carbon composites having 40% to 60% silicon and 5m 2 / g and a φ of 0.1 or greater.

[0139] In certain embodiments, the silicon-carbon composite comprises a carbon scaffold having a Z of less than 10 and a microporosity of greater than 80%, and the silicon-carbon composite comprises 30% to 60% silicon and 100% carbon. 2 / g and φ greater than 0, e.g., carbon scaffolds having Z less than 10 and microporosity greater than 80%, and silicon-carbon composites having 30% to 60% silicon and 50m 2 / g and φ greater than 0, for example, carbon scaffolds having Z less than 10 and microporosity greater than 80%, and silicon-carbon composites having 30% to 60% silicon and 30m 2 / g and φ greater than 0, for example, carbon scaffolds having Z less than 10 and microporosity greater than 80%, and silicon-carbon composites having 30% to 60% silicon and 10 m 2 / g and φ greater than 0, e.g., carbon scaffolds having Z less than 10 and microporosity greater than 80%, and silicon-carbon composites having 30% to 60% silicon and 5m 2 / g and φ greater than 0.

[0140] In certain embodiments, the silicon-carbon composite comprises a carbon scaffold having a Z of less than 10 and a microporosity of greater than 80%, and the silicon-carbon composite comprises 40% to 60% silicon and 100% carbon. 2 / g and φ greater than 0, e.g., carbon scaffolds having Z less than 10 and microporosity greater than 80%, and silicon-carbon composites having 40% to 60% silicon and 50m 2 / g and φ greater than 0, for example, carbon scaffolds having Z less than 10 and microporosity greater than 80%, and silicon-carbon composites having 40% to 60% silicon and 30m 2 / g and φ greater than 0, e.g., carbon scaffolds having Z less than 10 and microporosity greater than 80%, and silicon-carbon composites having 40% to 60% silicon and 10 m 2 / g and φ greater than 0, e.g., carbon scaffolds having Z less than 10 and microporosity greater than 80%, and silicon-carbon composites having 40% to 60% silicon and 5m 2 / g and φ greater than 0.

[0141] In certain embodiments, the silicon-carbon composite comprises a carbon scaffold having a Z of less than 10 and a microporosity of greater than 90%, and the silicon-carbon composite comprises 30% to 60% silicon and 100% carbon. 2 / g and φ of 0.1 or greater, e.g., carbon scaffolds having Z of less than 10 and microporosity of greater than 90%, and silicon-carbon composites having 30% to 60% silicon and 50m 2 / g and φ of 0.1 or greater, e.g., carbon scaffolds having Z of less than 10 and microporosity of greater than 90%, and silicon-carbon composites having 30% to 60% silicon and 30m 2 / g and φ of 0.1 or greater, e.g., carbon scaffolds having Z less than 10 and microporosity greater than 90%, and silicon-carbon composites having 30% to 60% silicon and 10 m 2 / g and φ of 0.1 or greater, e.g., carbon scaffolds having Z of less than 10 and microporosity of greater than 90%, and silicon-carbon composites having 30% to 60% silicon and 5m 2 / g and a φ of 0.1 or greater.

[0142] In certain embodiments, the silicon-carbon composite comprises a carbon scaffold having a Z of less than 10 and a microporosity of greater than 90%, and the silicon-carbon composite comprises 40% to 60% silicon and 100% carbon. 2 / g and φ of 0.1 or greater, e.g., carbon scaffolds having Z of less than 10 and microporosity of greater than 90%, and silicon-carbon composites having 40% to 60% silicon and 50% carbon. 2 / g and φ of 0.1 or greater, e.g., carbon scaffolds having Z of less than 10 and microporosity of greater than 90%, and silicon-carbon composites having 40% to 60% silicon and 30m 2 / g and φ of 0.1 or greater, e.g., carbon scaffolds having Z of less than 10 and microporosity of greater than 90%, and silicon-carbon composites having 40%-60% silicon and 10 m 2 / g and φ of 0.1 or greater, e.g., carbon scaffolds having Z of less than 10 and microporosity of greater than 90%, and silicon-carbon composites having 40% to 60% silicon and 5m 2 / g and a φ of 0.1 or greater.

[0143] In certain embodiments, the silicon-carbon composite comprises a carbon scaffold having a Z of less than 10 and a microporosity of greater than 90%, and the silicon-carbon composite comprises 30% to 60% silicon and 100% carbon. 2 / g and φ greater than 0, e.g., carbon scaffolds having Z less than 10 and microporosity greater than 90%, and silicon-carbon composites having 30% to 60% silicon and 50m 2 / g and φ greater than 0, for example, carbon scaffolds having Z less than 10 and microporosity greater than 90%, and silicon-carbon composites having 30% to 60% silicon and 30m 2 / g and φ greater than 0, for example, carbon scaffolds having Z less than 10 and microporosity greater than 90%, and silicon-carbon composites having 30% to 60% silicon and 10 m 2 / g and φ greater than 0, e.g., carbon scaffolds having Z less than 10 and microporosity greater than 90%, and silicon-carbon composites having 30% to 60% silicon and 5m 2 / g and φ greater than 0.

[0144] In certain embodiments, the silicon-carbon composite comprises a carbon scaffold having a Z of less than 10 and a microporosity of greater than 90%, and the silicon-carbon composite comprises 40% to 60% silicon and 100% carbon. 2 / g and φ greater than 0, e.g., carbon scaffolds having Z less than 10 and microporosity greater than 90%, and silicon-carbon composites having 40% to 60% silicon and 50m 2 / g and φ greater than 0, e.g., carbon scaffolds having Z less than 10 and microporosity greater than 90%, and silicon-carbon composites having 40% to 60% silicon and 30m 2 / g and φ greater than 0, for example, carbon scaffolds having Z less than 10 and microporosity greater than 90%, and silicon-carbon composites having 40% to 60% silicon and 10 m 2 / g and φ greater than 0, e.g., carbon scaffolds having Z less than 10 and microporosity greater than 90%, and silicon-carbon composites having 40% to 60% silicon and 5m 2 / g and φ greater than 0.

[0145] In certain embodiments, the silicon-carbon composite comprises a carbon scaffold having a Z of less than 10 and a microporosity of greater than 95%, and the silicon-carbon composite comprises 30% to 60% silicon and 100% carbon. 2 / g and φ of 0.1 or greater, e.g., carbon scaffolds having Z of less than 10 and microporosity of greater than 95%, and silicon-carbon composites having 30% to 60% silicon and 50m 2 / g and φ of 0.1 or greater, e.g., carbon scaffolds having Z less than 10 and microporosity greater than 95%, and silicon-carbon composites having 30% to 60% silicon and 30m 2 / g and φ of 0.1 or greater, e.g., carbon scaffolds having Z less than 10 and microporosity greater than 95%, and silicon-carbon composites having 30% to 60% silicon and 10 m 2 / g and φ of 0.1 or greater, e.g., carbon scaffolds having Z of less than 10 and microporosity of greater than 95%, and silicon-carbon composites having 30% to 60% silicon and 5m 2 / g and a φ of 0.1 or greater.

[0146] In certain embodiments, the silicon-carbon composite comprises a carbon scaffold having a Z of less than 10 and a microporosity of greater than 95%, and the silicon-carbon composite comprises 40% to 60% silicon and 100% carbon.2 / g and φ of 0.1 or greater, e.g., carbon scaffolds having Z of less than 10 and microporosity of greater than 95%, and silicon-carbon composites having 40% to 60% silicon and 50% carbon. 2 / g and φ of 0.1 or greater, e.g., carbon scaffolds having Z of less than 10 and microporosity of greater than 95%, and silicon-carbon composites having 40% to 60% silicon and 30m 2 / g and φ of 0.1 or greater, e.g., carbon scaffolds having Z of less than 10 and microporosity of greater than 95%, and silicon-carbon composites having 40%-60% silicon and 10 m 2 / g and φ of 0.1 or greater, e.g., carbon scaffolds having Z of less than 10 and microporosity of greater than 95%, and silicon-carbon composites having 40% to 60% silicon and 5m 2 / g and a φ of 0.1 or greater.

[0147] In certain embodiments, the silicon-carbon composite comprises a carbon scaffold having a Z of less than 10 and a microporosity of greater than 95%, and the silicon-carbon composite comprises 30% to 60% silicon and 100% carbon. 2 / g and φ of 0.1 or greater, e.g., carbon scaffolds having Z of less than 10 and microporosity of greater than 95%, and silicon-carbon composites having 30% to 60% silicon and 50m 2 / g and φ of 0.1 or greater, e.g., carbon scaffolds having Z less than 10 and microporosity greater than 95%, and silicon-carbon composites having 30% to 60% silicon and 30m 2 / g and φ of 0.1 or greater, e.g., carbon scaffolds having Z less than 10 and microporosity greater than 95%, and silicon-carbon composites having 30% to 60% silicon and 10 m 2 / g and φ of 0.1 or greater, e.g., carbon scaffolds having Z of less than 10 and microporosity of greater than 95%, and silicon-carbon composites having 30% to 60% silicon and 5m 2 / g and a φ of 0.1 or greater.

[0148] In certain embodiments, the silicon-carbon composite comprises a carbon scaffold having a Z of less than 10 and a microporosity of greater than 95%, and the silicon-carbon composite comprises 40% to 60% silicon and 100% carbon. 2 / g and φ greater than 0, e.g., carbon scaffolds having Z less than 10 and microporosity greater than 95%, and silicon-carbon composites having 40% to 60% silicon and 50m 2 / g and φ greater than 0, e.g., carbon scaffolds having Z less than 10 and microporosity greater than 95%, and silicon-carbon composites having 40% to 60% silicon and 30m 2 / g and φ greater than 0, for example, carbon scaffolds having Z less than 10 and microporosity greater than 95%, and silicon-carbon composites having 40% to 60% silicon and 10 m 2 / g and φ greater than 0, e.g., carbon scaffolds having Z less than 10 and microporosity greater than 95%, and silicon-carbon composites having 40% to 60% silicon and 5m 2 / g and φ greater than 0.

[0149] In certain embodiments, the silicon-carbon composite comprises a carbon scaffold having a Z of less than 10 and a microporosity of greater than 80%, and the silicon-carbon composite comprises 30% to 60% silicon and 30% carbon. 2For example, the silicon-carbon composite includes a carbon scaffold having a Z of less than 10 and a microporosity of greater than 80%, and the silicon-carbon composite includes a carbon scaffold having a Z of 30% to 60% silicon and a microporosity of 30% to 50% silicon. 2 For example, the silicon-carbon composite includes a carbon scaffold having a Z of less than 10 and a microporosity of greater than 80%, and the silicon-carbon composite includes a carbon scaffold having a Z of 30% to 60% silicon and a microporosity of 30% to 50% silicon. 2 For example, the silicon-carbon composite includes a carbon scaffold having a Z of less than 10 and a microporosity of greater than 80%, and the silicon-carbon composite includes a carbon scaffold having a Z of 30% to 60% silicon and a microporosity of 30% to 50% silicon. 2 For example, silicon-carbon composites include carbon scaffolds having Z less than 10 and microporosity greater than 80%, and silicon-carbon composites include 30% to 60% silicon and 30% carbon. 2 For example, silicon-carbon composites include carbon scaffolds having Z less than 10 and microporosity greater than 80%, and silicon-carbon composites include 30% to 60% silicon and 30% carbon. 2 For example, the silicon-carbon composite includes a carbon scaffold having a Z of less than 10 and a microporosity of greater than 80%, and the silicon-carbon composite includes a carbon scaffold having a Z of 30% to 60% silicon and a microporosity of 30% to 50% silicon. 2 For example, silicon-carbon composites include carbon scaffolds having Z less than 10 and microporosity greater than 80%, and silicon-carbon composites include 30% to 60% silicon and 30% carbon. 2These include a surface area of ​​less than 0.01 / g, a diameter of 0.15 or greater, and an average coulombic efficiency of 0.9999 or greater.

[0150] In certain embodiments, the silicon-carbon composite comprises a carbon scaffold having a Z of less than 10 and a microporosity of greater than 80%, and the silicon-carbon composite comprises 30% to 60% silicon and 30% carbon. 2 For example, the silicon-carbon composite includes a carbon scaffold having a Z of less than 10 and a microporosity of greater than 80%, and the silicon-carbon composite includes a carbon scaffold having a Z of 30% to 60% silicon and a microporosity of 30% to 50%. 2 For example, the silicon-carbon composite includes a carbon scaffold having a Z of less than 10 and a microporosity of greater than 80%, and the silicon-carbon composite includes a carbon scaffold having a Z of 30% to 60% silicon and a microporosity of 30% to 50% silicon. 2 For example, the silicon-carbon composite includes a carbon scaffold having a Z of less than 10 and a microporosity of greater than 80%, and the silicon-carbon composite includes a carbon scaffold having a Z of 30% to 60% silicon and a microporosity of 30% to 50% silicon. 2 For example, the silicon-carbon composite includes a carbon scaffold having a Z of less than 10 and a microporosity of greater than 80%, and the silicon-carbon composite includes a carbon scaffold having a Z of 30% to 60% silicon and a microporosity of 30% to 50% silicon. 2 For example, the silicon-carbon composite includes a carbon scaffold having a Z of less than 10 and a microporosity of greater than 80%, and the silicon-carbon composite includes a carbon scaffold having a Z of 30% to 60% silicon and a microporosity of 30% to 50%. 2For example, silicon-carbon composites include carbon scaffolds having Z less than 10 and microporosity greater than 80%, and silicon-carbon composites include 30% to 60% silicon and 30% carbon. 2 For example, the silicon-carbon composite includes a carbon scaffold having a Z of less than 10 and a microporosity of greater than 80%, and the silicon-carbon composite includes a carbon scaffold having a Z of 30% to 60% silicon and a microporosity of 30% to 50%. 2 These include a surface area of ​​less than 0.3 / g, a φ of 0.20 or greater, and an average coulombic efficiency of 0.9999 or greater.

[0151] In certain embodiments, the silicon-carbon composite comprises a carbon scaffold having a Z of less than 10 and a microporosity of greater than 80%, and the silicon-carbon composite comprises 30% to 60% silicon and 30% carbon. 2 For example, the silicon-carbon composite includes a carbon scaffold having a Z of less than 10 and a microporosity of greater than 80%, and the silicon-carbon composite includes a carbon scaffold having a Z of 30% to 60% silicon and a microporosity of 30% to 50%. 2 For example, the silicon-carbon composite includes a carbon scaffold having a Z of less than 10 and a microporosity of greater than 80%, and the silicon-carbon composite includes a carbon scaffold having a Z of 30% to 60% silicon and a microporosity of 30% to 50% silicon. 2 For example, the silicon-carbon composite includes a carbon scaffold having a Z of less than 10 and a microporosity of greater than 80%, and the silicon-carbon composite includes a carbon scaffold having a Z of 30% to 60% silicon and a microporosity of 30% to 50% silicon. 2For example, silicon-carbon composites include carbon scaffolds having Z less than 10 and microporosity greater than 80%, and silicon-carbon composites include 30% to 60% silicon and 30% carbon. 2 For example, silicon-carbon composites include carbon scaffolds having Z less than 10 and microporosity greater than 80%, and silicon-carbon composites include 30% to 60% silicon and 30% carbon. 2 For example, silicon-carbon composites include carbon scaffolds having Z less than 10 and microporosity greater than 80%, and silicon-carbon composites include 30% to 60% silicon and 30% carbon. 2 For example, the silicon-carbon composite includes a carbon scaffold having a Z of less than 10 and a microporosity of greater than 80%, and the silicon-carbon composite includes a carbon scaffold having a Z of 30% to 60% silicon and a microporosity of 30% to 50% silicon. 2 These include a surface area of ​​less than 0.3 / g, a φ of 0.25 or greater, and an average coulombic efficiency of 0.9999 or greater.

[0152] In certain embodiments, the silicon-carbon composite comprises a carbon scaffold having a Z of less than 10 and a microporosity of greater than 80%, and the silicon-carbon composite comprises 30% to 60% silicon and 30% carbon. 2 For example, the silicon-carbon composite includes a carbon scaffold having a Z of less than 10 and a microporosity of greater than 80%, and the silicon-carbon composite includes a carbon scaffold having a Z of 30% to 60% silicon and a microporosity of 30% to 50%. 2For example, the silicon-carbon composite includes a carbon scaffold having a Z of less than 10 and a microporosity of greater than 80%, and the silicon-carbon composite includes a carbon scaffold having a Z of 30% to 60% silicon and a microporosity of 30% to 50% silicon. 2 For example, the silicon-carbon composite includes a carbon scaffold having a Z of less than 10 and a microporosity of greater than 80%, and the silicon-carbon composite includes a carbon scaffold having a Z of 30% to 60% silicon and a microporosity of 30% to 50%. 2 For example, the silicon-carbon composite includes a carbon scaffold having a Z of less than 10 and a microporosity of greater than 80%, and the silicon-carbon composite includes a carbon scaffold having a Z of 30% to 60% silicon and a microporosity of 30% to 50%. 2 For example, the silicon-carbon composite includes a carbon scaffold having a Z of less than 10 and a microporosity of greater than 80%, and the silicon-carbon composite includes a carbon scaffold having a Z of 30% to 60% silicon and a microporosity of 30% to 50% silicon. 2 For example, the silicon-carbon composite includes a carbon scaffold having a Z of less than 10 and a microporosity of greater than 80%, and the silicon-carbon composite includes a carbon scaffold having a Z of 30% to 60% silicon and a microporosity of 30% to 50%. 2 For example, silicon-carbon composites include carbon scaffolds having Z less than 10 and microporosity greater than 80%, and silicon-carbon composites include 30% to 60% silicon and 30% carbon. 2 These include a surface area of ​​less than 0.3 / g, a diameter of 0.3 or greater, and an average coulombic efficiency of 0.9999 or greater.

[0153] Example 4. Preparation of primary spherical pyrolytic carbon particles in the absence of a preferential exclusion agent. Various samples were prepared according to Table 8. Sucrose was weighed into a Teflon-lined autoclave, followed by the addition of deionized water. The solution was stirred until the sucrose was completely dissolved, and then the autoclave was sealed and placed in a hot convection oven. The vessel was allowed to dwell at temperature. During this time, the reaction proceeds by a hydrothermal condensation mechanism. After dwelling, the vessel was removed from the oven and allowed to cool completely to room temperature. The lid was slowly opened to vent the residual vapor pressure, and brown particulate hydrothermal char (HTC) was collected from the vessel. The HTC was rinsed twice with deionized water on a filter, followed by over-drying at 80°C for 2 hours, followed by sieving through a 25 micron size sieve. The dried HTC was then loaded into an alumina crucible and pyrolyzed in a tube furnace at 900°C for 1 hour under a constant flow of nitrogen gas. The furnace was then cooled to room temperature to obtain pyrolyzed spherical carbon products.

[0154] Table 8. Preparation of various samples of primary spherical pyrolytic carbon particles without using preferential rejection agents. [Table 8]

[0155] Various samples of primary spherical pyrolytic carbon particles produced in the absence of a preferential exclusion agent were characterized as summarized in Table 9.

[0156] Table 9. Characteristics of various samples of primary spherical pyrolytic carbon particles in the absence of preferential rejection agents. [Table 9]

[0157] Example 5. Preparation of primary spherical pyrolytic carbon particles in the presence of a preferential exclusion agent. Various samples were prepared according to Table 10. Sucrose was weighed into a Teflon-lined autoclave and deionized water containing various amounts of polyacrylic acid (PAA) as a preferential rejection agent was added. The solution was stirred until the sucrose was completely dissolved, then the autoclave was sealed and placed in a hot convection oven. The vessel was allowed to dwell at that temperature. During this time, the reaction proceeds by a hydrothermal condensation mechanism. After the dwell, the vessel was removed from the oven and cooled completely to room temperature. The lid was slowly opened to vent the residual vapor pressure, and brown particulate hydrothermal char (HTC) was collected from the vessel. The HTC was rinsed twice with deionized water on a filter, followed by over-drying at 80°C for 2 hours, followed by sieving through a 25 micron size sieve. The dried HTC was then loaded into an alumina crucible and pyrolyzed in a tube furnace at 900°C for 1 hour under a constant flow of nitrogen gas. The furnace was then cooled to room temperature to obtain pyrolyzed spherical carbon products.

[0158] Table 10. Preparation of primary spherical pyrolytic carbon particle samples in the presence of preferential rejection agents [Table 10]

[0159] As can be seen from the data in the table, the overall yields for samples produced in the presence of preferential rejection agents tended to be higher, up to 7.4% for carbon scaffold 14. The Dv1, Dv50 and Dv99 for carbon scaffold 13 were 1.6 μm, 9.5 μm and 33.0 μm, respectively, and the Dv1, Dv50 and Dv99 for carbon scaffold 14 were 1.6 μm, 8.6 μm and 40.4 μm, respectively.

[0160] FIG. 8 shows SEM of various samples according to Example 5. The SEM images revealed that the addition of PAA as a preferential exclusion agent controlled the morphology and particle size of the carbon scaffold particles. At the lowest amount of added PAA, i.e., 1000:1 sucrose:PAA (lower left diagram of FIG. 8, carbon scaffold 16), the particles were dimpled and most particles were 6-13 μm in size. When the PAA loading was increased to 800:1 sucrose:PAA (lower right diagram of FIG. 8, carbon scaffold 13), the particles became smoother and most particles were 2.3-2.9 μm in size. When the PAA loading was further increased to 400:1 sucrose:PAA (upper right diagram of FIG. 8, carbon scaffold 14), the particles became smoother and most particles were 2.3-2.9 μm in size. Finally, at the highest PAA loading of 100:1 sucrose:PAA (top left panel of FIG. 8, carbon scaffold 15), the particles were no longer spherical but showed a highly irregular morphology.

[0161] In certain embodiments, the polyol:surfactant ratio is greater than 1000:1. In some embodiments, the polyol:surfactant ratio is between 1000:1 and 800:1. In still other embodiments, the polyol:surfactant ratio is between 800:1 and 600:1, between 600:1 and 500:1, between 500:1 and 400:1, between 400:1 and 300:1, between 300:1 and 200:1, between 200:1 and 100:1. In some embodiments, the polyol:surfactant ratio is less than 100:1.

[0162] Example 6. Preparation of primary spherical activated carbon particles. Carbon scaffold 13, carbon scaffold 14, and carbon scaffold 16 were activated with steam to increase the available porosity, producing scaffold sample 17, scaffold sample 18, and scaffold sample 19. In a typical experiment, 1 g of pyrolyzed material was placed in an alumina crucible, which was then placed in the central hot zone of a horizontal tube furnace. The furnace was purged with nitrogen gas flow (~500 sccm) flowing through a bubbler (a flask heated to a set temperature of 200 °C) upstream of the furnace containing distilled water. This acted as a steam source to activate the carbon via the C+H2O=>CO+H2 reaction. The temperature of the furnace was increased to 900 °C at 10 °C / min and held for various times. The furnace was then cooled ambiently and samples were removed for analysis. A summary of the samples and their properties is shown in Table 11.

[0163] Table 11. Preparation of primary spherical activated carbon particle samples in the presence of preferential rejection agents [Table 11]

[0164] Example 7. Preparation of primary spherical group 14 composite particles. Carbon scaffold 13 was subjected to CVI using silane gas to deposit silicon within the carbon porosity. The resulting material was silicon-carbon composite 21, whose properties are summarized in Table 12. In a typical experiment, 0.2 g of activated material was placed in an alumina crucible, which was then placed in the central hot zone of a horizontal tube furnace. After purging with nitrogen gas flow (approximately 500 sccm) for 10 min, it was ramped to 475 °C at 20 °C / min, and the furnace temperature was stabilized at the peak temperature for 30 min, after which the gas flow was time-switched to a 1.3 mol% SiH4 / N2 gas mixture at 580 sccm for 1.75 h. After deposition, the gas was switched back to pure nitrogen and the furnace was allowed to cool to ambient. Once the furnace temperature reached less than 60 °C, samples were taken for analysis.

[0165] Table 12. Properties of silicon-carbon composite 21 [Table 12]

[0166] The measured particle size distribution of silicon-carbon composite 21 was very similar to that of the starting carbon scaffold 13; Dv1 was 0.8 μm, Dv50 was 10.3 μm, and Dv99 was 48.7 μm, respectively. An SEM of silicon-carbon composite 21 is shown in FIG.

[0167] Example 8. Preparation of primary spherical activated carbon particles in the absence of a preferential exclusion agent. Primary spherical activated carbon particles were produced according to Table 13. Sucrose was weighed into a Teflon-lined autoclave and deionized water was added. Samples were prepared without preferential rejection agents. The solution was stirred until sucrose was completely dissolved, then the autoclave was sealed and placed in a hot convection oven. The vessel was allowed to dwell at that temperature. During this time, the reaction proceeds by a hydrothermal condensation mechanism. After dwelling, the vessel was removed from the oven and cooled completely to room temperature. The lid was slowly opened to vent the residual vapor pressure, and the particulate hydrothermal char (HTC) was removed from the vessel. The HTC was rinsed twice with deionized water on the filter and then dried at 80°C for over 2 hours. The dried HTC was then loaded into an alumina crucible and pyrolyzed in a tube furnace at 900°C for 1 hour under a constant flow of nitrogen gas. The furnace was then cooled to room temperature to obtain the pyrolyzed spherical carbon product.

[0168] Table 13. Preparation of pyrolyzed and activated primary spherical carbon particle samples [Table 13]

[0169] After pyrolysis, the particles were activated with steam to increase the accessible porosity. In a typical experiment, 1 g of pyrolyzed material was placed in an alumina crucible, which was then placed in the central hot zone of a horizontal tube furnace. The furnace was purged with nitrogen gas flow (approximately 500 sccm) flowing through a bubbler (a flask heated to a set temperature of 200 °C) upstream of the furnace containing distilled water. This acted as a steam source to activate the carbon via the C+H2O=>CO+H2 reaction. The temperature of the furnace was increased at 10 °C / min to 900 °C and held for various times. The furnace was then ambient cooled and samples were removed for analysis.

[0170] Following steam activation, the activated carbon scaffolds listed in Table 13 were used to produce a variety of silicon-carbon composites using the CVI process in a static bed configuration generally described in Example 1. The physicochemical properties of the resulting silicon-carbon composites are shown in Table 14, along with a comparison of silicon-carbon composites obtained from non-polyol precursor materials designated as silicon-carbon composites C1 and C2.

[0171] Table 14. Properties of primary spherical Si-C composite particles [Table 14]

[0172] The resulting silicon-carbon composites were uniform in appearance, had no visible particle agglomerations, and had a soft texture. Without being bound by theory, in some instances, polyol-based Si-C composites had lower surface areas after silicon CVI compared to Si-C composites made from non-polyol precursors, as shown in Table 14. In some cases, the surface area was less than 1.0 m 2 / g, but was less than 0.5m 2 / g.

[0173] Silicon-carbon composites 22 and 23 were also tested following the methods generally described in Example 2. The physicochemical and electrochemical properties of these silicon-carbon composites are shown in Table 15.

[0174] Table 15. Properties of primary spherical Si-C composite particles [Table 15]

[0175] DETAILED DESCRIPTION OF THE EMBODIMENTS Embodiment 1. A Group 14 composite comprising a plurality of primary particles comprising the Group 14 elements silicon and carbon, the particles exhibiting a spherical morphology and having a Dv50 of 10 μm or less, a Z of less than 10, and a φ of 0.15 or greater, where φ=(maximum peak height in Regime I dQ / dV) / (maximum peak height in Regime III dQ / dV), where dQ / dV is measured in a half-cell coin cell, with Regime I being between 0.8V and 0.4V, and Regime III being between 0.15V and 0V.

[0176] Embodiment 2. A Group 14 composite comprising a plurality of primary particles comprising the Group 14 elements silicon and carbon, the particles exhibiting a spherical morphology and having a Dv50 of 10 μm or less, a Z of less than 10, and a φ of 0.2 or greater, where dQ / dV is measured in a half-cell coin cell, with Regime 1 being between 0.8 V and 0.4 V, and Regime III being between 0.15 V and 0 V.

[0177] Embodiment 3. A Group 14 composite comprising a plurality of primary particles comprising the Group 14 elements silicon and carbon, the particles exhibiting a spherical morphology and having a Dv50 of 10 μm or less, a Z of less than 10, and a φ of 0.3 or greater, where dQ / dV is measured in a half-cell coin cell, where Regime 1 is between 0.8 V and 0.4 V, and Regime III is between 0.15 V and 0 V.

[0178] Embodiment 4. (a) a plurality of porous carbon primary particles derived from a polyol, wherein the plurality of porous carbon particles exhibit a spherical morphology; (b) silicon impregnated within the pores of the porous carbon primary particles; (c) Dv50 of 10 μm or less; (d) Z of less than 10; and (e) phi (φ) of 0.15 or more, wherein dQ / dV is measured in a half-cell coin cell, and regime 1 is 0.8V to 0.4V, and regime III is 0.15V to 0V. Group 14 composites including:

[0179] Embodiment 5. The Group 14 composite of embodiment 4, wherein φ is 0.2 or greater.

[0180] Embodiment 6. The Group 14 composite of embodiment 4, wherein φ is 0.3 or greater.

[0181] Embodiment 7. The Group 14 composite of any one of embodiments 1-6, having a Dv50 of 5 μm or less.

[0182] Embodiment 8. The Group 14 composite of any one of embodiments 1-7, wherein each of the porous carbon primary particles is a discrete, non-agglomerated particle.

[0183] Embodiment 9. The Group 14 composite of any one of embodiments 1-8, wherein Z is less than 5.

[0184] Embodiment 10. Another 50m 2 10. The Group 14 composite of any one of embodiments 1-9, comprising a surface area of ​​less than 100 nm / g.

[0185] Embodiment 11. The Group 14 composite of any one of embodiments 1 to 10, comprising: (a) 0.6 cm 3 / g total pore volume; (b) a volume fraction of micropores of 20-50% and a volume fraction of mesopores of 50-80%; and (c) a pore volume in which the proportion of the pore volume of 10 nm or less out of the total pore volume of 5 nm to 20 μm is at least 75%. Group 14 composites further including:

[0186] Embodiment 12. The Group 14 composite of any one of embodiments 1 to 11, wherein the weight percentage of silicon relative to the porous carbon primary particles is 10% to 80%.

[0187] Embodiment 13. A Group 14 composite comprising a plurality of primary particles comprising Group 14 elements silicon and carbon, the particles comprising 30-60% silicon by weight, the particles exhibiting a spherical morphology and having a Dv50 of 10 μm or less, a Z of less than 10, and a φ of 0.15 or greater, where dQ / dV is measured in a half-cell coin cell, where Regime 1 is between 0.8 V and 0.4 V, and Regime III is between 0.15 V and 0 V.

[0188] Embodiment 14. A Group 14 composite comprising a plurality of primary particles comprising Group 14 elements silicon and carbon, the particles comprising 30-60% silicon by weight, the particles exhibiting a spherical morphology and having a Dv50 of 10 μm or less, a Z of less than 10, and a φ of 0.2 or greater, where dQ / dV is measured in a half-cell coin cell, where Regime 1 is between 0.8 V and 0.4 V, and Regime III is between 0.15 V and 0 V.

[0189] Embodiment 15. A Group 14 composite comprising a plurality of primary particles comprising Group 14 elements silicon and carbon, the particles comprising 30-60% silicon by weight, the particles exhibiting a spherical morphology and having a Dv50 of 10 μm or less, a Z of less than 10, and a φ of 0.3 or greater, where dQ / dV is measured in a half-cell coin cell, where Regime 1 is between 0.8 V and 0.4 V, and Regime III is between 0.15 V and 0 V.

[0190] Embodiment 16. A method for producing a semiconductor device comprising: (a) a plurality of primary particles comprising group 14 elements silicon and carbon, wherein the plurality of particles have a sphericity of at least 0.5, and each particle comprises a carbon scaffold; (b) 30% to 60% by weight silicon; (c) a Dv50 of 10 μm or less; (d) a Z of less than 10; and (e) a phi (φ) of 0.15 or more, wherein dQ / dV is measured in a half-cell coin cell, where regime 1 is 0.8V to 0.4V, and regime III is 0.15V to 0V. Group 14 composites including:

[0191] Embodiment 17. (a) a carbon comprising a polyol-derived porous carbon scaffold, further comprising: (i) amorphous carbon, (ii) a pore volume in which more than 70% of the pore volume is composed of pores having a diameter of less than 2 nm, and (iii) a Dv90 of less than 50 nm; (b) silicon, comprising: (i) amorphous and nano-sized silicon embedded within the pore volume of the porous carbon scaffold; and (c) a Group 14 composite, further comprising: (i) 30% to 60% silicon by weight; (ii) a Dv50 of 10 μm or less; (iii) a Z of less than 10; and (iv) a phi (φ) of 0.15 or more, where dQ / dV is measured in a half-cell coin cell, where regime 1 is 0.8V to 0.4V, and regime III is 0.15V to 0V. Group 14 composites including:

[0192] Embodiment 18. The Group 14 composite of any of embodiments 1-10 and embodiments 12-17, further comprising a carbon scaffold comprising a pore volume comprising greater than 70% microporosity.

[0193] Embodiment 19. The Group 14 composite of any of embodiments 1-10 and embodiments 12-17, further comprising a carbon scaffold comprising a pore volume comprising greater than 80% microporosity.

[0194] Embodiment 20. The Group 14 composite of any of embodiments 1-10 and embodiments 12-17, further comprising a carbon scaffold comprising a pore volume that comprises greater than 90% microporosity.

[0195] Embodiment 21. The Group 14 composite of any one of embodiments 1-20, comprising a capacity of greater than 900 mA / g.

[0196] Embodiment 22. The Group 14 composite of any one of embodiments 1-20, comprising a capacity of greater than 1300 mA / g.

[0197] Embodiment 23. The Group 14 composite of any one of embodiments 1-20, comprising a capacity of greater than 1600 mA / g.

[0198] Embodiment 24. The Group 14 composite of any one of embodiments 1-23, comprising an average coulombic efficiency of 0.9970 or greater.

[0199] Embodiment 25. The Group 14 composite of any one of embodiments 1-23, comprising an average coulombic efficiency of 0.9980 or greater.

[0200] Embodiment 26. The Group 14 composite of any one of embodiments 1-23, comprising an average coulombic efficiency of 0.9985 or greater.

[0201] Embodiment 27. The Group 14 composite of any one of embodiments 1-23, comprising an average coulombic efficiency of 0.9990 or greater.

[0202] Embodiment 28. The Group 14 composite of any one of embodiments 1-23, comprising an average coulombic efficiency of 0.9995 or greater.

[0203] Embodiment 29. The Group 14 composite of any one of embodiments 1-23, comprising an average coulombic efficiency of 0.9995 or greater.

[0204] Embodiment 30. The Group 14 composite of any one of embodiments 1-23, comprising an average coulombic efficiency of 0.9999 or greater.

[0205] Embodiment 31. The Group 14 composite of any one of embodiments 1-30, wherein the primary particles have an average sphericity of at least 0.5, at least 0.55, at least 0.65, at least 0.7, at least 0.75, or at least 0.8.

[0206] Embodiment 32. The Group 14 composite of any one of embodiments 1-31, comprising a Group 14 composite whose primary particles do not require sieving or milling during their manufacture.

[0207] Embodiment 33. (a) a carbon comprising a porous carbon scaffold, comprising: (i) amorphous carbon, (ii) a pore volume in which more than 70% of the pore volume is in pores less than 2 nm in diameter, and (iii) a Dv90 of less than 50 nm; (b) silicon, comprising: (i) amorphous and nano-sized silicon embedded within the pore volume of the carbon scaffold; and (c) a composite, comprising: (i) by weight a composite comprising: 30% to 60% silicon; (ii) Dv50 of 10 μm or less; (iii) Z of less than 10; and (iv) φ of 0.15 or more, where φ=(maximum peak height in regime I, dQ / dV) / (maximum peak height in regime III, dQ / dV), where dQ / dV is measured in a half-cell coin cell, with regime 1 being 0.8 V to 0.4 V, and regime III being 0.15 V to 0 V. Group 14 composites including:

[0208] Embodiment 34. The Group 14 composite of any one of embodiments 1 to 33, comprising 30 m 2 / g of the Group 14 composite.

[0209] Embodiment 35. The Group 14 composite of any of embodiments 1-21 and embodiments 24-34, further comprising a capacity of 1300 mAh / g.

[0210] Embodiment 36. The Group 14 composite of any of embodiments 1-21 and embodiments 24-34, further comprising a maximum capacity of 1300 mAh / g as measured by a half-cell coin cell.

[0211] Embodiment 37. The Group 14 composite of any one of embodiments 1-6 and embodiments 8-36, wherein the composite has a Dv50 of 5 μm or less.

[0212] Embodiment 38. The Group 14 composite of any one of embodiments 1-8 and embodiments 10-37, wherein Z is less than 5.

[0213] Embodiment 39. The Group 14 composite of any one of embodiments 7-13 and embodiments 16-38, wherein phi (φ) is 0.2 or greater.

[0214] Embodiment 40. The Group 14 composite of any one of embodiments 7-13 and embodiments 16-38, wherein phi (φ) is 0.3 or greater.

[0215] Embodiment 41. The Group 14 composite of any one of embodiments 1 to 40, wherein the porous carbon scaffold has an average sphericity of 0.5 to 0.8.

[0216] Embodiment 42. An energy storage device comprising a Group 14 composite represented by any of Embodiments 1-41.

[0217] Embodiment 43. A lithium ion battery comprising a Group 14 composite represented by any of Embodiments 1-41.

[0218] Embodiment 44. A lithium silicon battery comprising a Group 14 composite represented by any of embodiments 1-41.

[0219] Embodiment 45. A method for making Group 14 composite particles, comprising the steps of: a. providing a polyol and an optional preferential rejection agent to an aqueous environment; b. heating the aqueous environment to 150°C-250°C to obtain a hydrothermal char; c. heating the hydrothermal char in the presence of an inert gas to 750°C-1050°C to obtain pyrolytic carbon particles; d. heating the pyrolytic carbon particles in the presence of an active gas to 750°C-1050°C to obtain primary activated carbon particles comprising a porous carbon skeleton; and e. heating the primary activated carbon particles in the presence of a silicon-containing gas to 350°C-450°C to impregnate silicon into the porous carbon skeleton, wherein each Group 14 particle has a sphericity of greater than 0.5; Manufacturing method.

[0220] Embodiment 46. A method for making Group 14 composite particles, comprising the steps of: a. providing a polyol and an optional preferential rejection agent in an aqueous environment; b. heating the aqueous environment to 150°C-250°C to obtain a hydrothermal char; c. heating the hydrothermal char to 750°C-1050°C in the presence of an inert gas to obtain pyrolytic carbon particles; d. heating the pyrolytic particles to 750°C-1050°C in the presence of an active gas to obtain primary activated carbon particles comprising a pore volume; and e. heating the primary activated carbon particles comprising a pore volume to 350°C-450°C in the presence of a silicon-containing gas to impregnate silicon within the porous carbon skeleton. Manufacturing method.

[0221] Embodiment 47. The method of embodiment 45 or 46, wherein the aqueous environment optionally comprises a co-solvent comprising one or more of an alcohol, an alkane, an ether, THF, DMSO, DMF, N-methylpyrrolidone, a glycol, and a glymp.

[0222] Embodiment 48. The method of any one of embodiments 45-47, wherein the aqueous environment is heated to a temperature below the decomposition temperature of the preferential exclusion agent.

[0223] Embodiment 49. The method of any of embodiments 45-48, wherein the aqueous environment can be mixed by stirring or other methods to promote the formation of spherical domains throughout.

[0224] Embodiment 50. The method of any one of embodiments 45 to 49, wherein the polyol is sucrose.

[0225] Embodiment 51. The method of any one of embodiments 45 to 50, wherein the preferential exclusion agent is Span 80, polyacrylic acid, Triton X, or a combination thereof.

[0226] Embodiment 52. The method of any one of embodiments 45 to 51, wherein the preferential exclusion agent is polyacrylic acid.

[0227] Embodiment 53. The method according to any one of embodiments 45 to 52, wherein the ratio of polyol to preferential exclusion agent (polyol: preferential exclusion agent) is 1000:1 or less.

[0228] Embodiment 54. The method according to any one of embodiments 45 to 53, wherein the inert gas is nitrogen.

[0229] Embodiment 55. The method of any one of embodiments 45 to 54, wherein the active gas is carbon dioxide, steam, or a combination thereof.

[0230] Embodiment 56 The method of any one of embodiments 45 to 55, further comprising agitating the aqueous environment.

[0231] Embodiment 57. The method of any one of embodiments 45-56, wherein the silicon-containing gas deposits silicon on at least a portion of the surface of the primary activated carbon particles.

[0232] Embodiment 58. The method of any one of embodiments 45 to 57, wherein the ratio Z of the silicon moieties not impregnated within the porous carbon skeleton to the silicon moieties impregnated within the porous carbon skeleton is less than 10.

[0233] Embodiment 59. The method of any one of embodiments 45-58, wherein the silicon impregnated within the porous carbon skeleton comprises deposition of silicon nanoparticles within the internal skeleton of activated carbon particles.

[0234] Embodiment 60. The method of any one of embodiments 45-59, wherein the pyrolytic carbon particles are discrete or non-agglomerated particles and no sieving is required.

[0235] Embodiment 61. The method of any one of embodiments 45-60, wherein the Group 14 composite particles are discrete or non-agglomerated particles and no sieving is required.

[0236] Embodiment 62. The method of any one of embodiments 45-59, wherein both the pyrolyzed particles and the Group 14 composite particles are discrete or non-agglomerated particles, and no sieving is required.

[0237] Embodiment 63. The method of any one of embodiments 45-61, wherein the Group 14 particles further comprise two or more discrete Group 14 particles, and the discrete Group 14 particles are non-agglomerated.

[0238] Embodiment 64. The primary activated carbon has a pore volume of at least 0.6 cm 3 / g.

[0239] Embodiment 65. The method of any one of embodiments 45 to 64, wherein the silicon-containing gas is introduced by chemical vapor infusion (CVI).

[0240] Embodiment 66 The method of any one of embodiments 45 to 65, wherein the silicon-containing gas is a silane.

[0241] Embodiment 67. The method of any one of embodiments 45-66, further comprising casting the slurry containing the Group 14 particles to produce an anode electrode.

[0242] From the foregoing, it will be appreciated that, although specific embodiments of the invention have been described herein for purposes of illustration, various modifications may be made without deviating from the spirit and scope of the invention. Accordingly, the invention is not limited except as by the appended claims.

[0243] This application claims the benefit of the filing date under 35 U.S.C. § 119 of U.S. Provisional Application No. 63 / 218,786, filed July 6, 2021, the entire contents of which are incorporated herein by reference.

Claims

1. The following steps: a. Providing a polyol and an optional preferential exclusion agent in an aqueous environment; b. Heating the aqueous environment at 150 to 250 °C to produce a hydrothermal char; c. Heating the hydrothermal char to 750 °C to 1050 °C in the presence of an inert gas to produce pyrolytic carbon particles; d. Heating the pyrolytic carbon particles to 750 °C to 1050 °C in the presence of an active gas to produce primary activated carbon particles containing a porous carbon skeleton; and e. Heating the primary activated carbon particles to 350 °C to 450 °C in the presence of a silicon-containing gas to impregnate the porous carbon skeleton with silicon, wherein each particle of the Group 14 composite particles has a sphericity greater than 0.5, a method for producing Group 14 composite particles.

2. The production method according to claim 1, wherein the aqueous environment optionally contains a co-solvent containing one or more of alcohol, alkane, ether, THF, DMSO, DMF, N-methylpyrrolidone, glycol, and glyme.

3. The production method according to claim 1, wherein the aqueous environment is heated to a temperature below the decomposition temperature of the preferential exclusion agent.

4. The production method according to claim 1, wherein the polyol is sucrose.

5. The production method according to claim 1, wherein the preferential exclusion agent is present in the environment, and the preferential exclusion agent is Span 80, polyacrylic acid, Triton X, or a combination thereof.

6. The production method according to claim 5, wherein the ratio of the polyol to the preferential exclusion agent (polyol:preferential exclusion agent) is 1000:1 or less.

7. The production method according to claim 1, wherein the inert gas is nitrogen.

8. The production method according to claim 1, wherein the active gas is carbon dioxide, water vapor, or a combination thereof.

9. The production method according to claim 1, further comprising stirring the aqueous environment.

10. The production method according to claim 1, wherein the silicon-containing gas deposits silicon on at least a part of the surface of the primary activated carbon particles.

11. The production method according to claim 10, wherein the ratio Z of the silicon portion impregnated in the porous carbon skeleton to the silicon portion not impregnated in the porous carbon skeleton is less than 10.

12. The production method according to claim 11, wherein impregnating the porous carbon skeleton with silicon includes depositing silicon nanoparticles on the internal skeleton of the activated carbon particles.

13. The manufacturing method according to claim 1, wherein the Group 14 composite particles further include two or more discrete Group 14 particles, and the discrete Group 14 particles are non-aggregating.

14. The pore volume of the primary activated carbon is at least 0.6 cm ３ / g, and the manufacturing method according to claim 1.

15. The manufacturing method according to claim 1, wherein the silicon-containing gas is introduced by chemical vapor infiltration (CVI).

16. The manufacturing method according to claim 1, wherein the silicon-containing gas is silane.

17. The manufacturing method according to claim 1, further including casting a slurry containing Group 14 particles to manufacture an anode electrode.

18. The following: (a) A plurality of porous carbon primary particles derived from polyol, wherein the plurality of porous carbon primary particles exhibit a spherical morphology; (b) Silicon infiltrated into the pores of the porous carbon primary particles; (c) Dv50 is 10 μm or less; (d) Z < 10; and (e) phi (φ) ≧ 0.15 or more, where dQ / dV is measured in a half-cell coin cell, regime I is 0.8 V to 0.4 V, and regime III is 0.15 V to 0 V. A Group 14 composite including the above.

19. The Group 14 composite according to claim 18, wherein Dv50 is 5 μm or less.

20. The Group 14 composite according to claim 18, wherein each of the porous carbon primary particles is a discrete non-aggregating particle.

21. The Group 14 composite according to claim 18, wherein Z < 5.

22. The Group 14 composite according to claim 18, wherein φ ≧ 0.

2.

23. The Group 14 composite according to claim 18, wherein φ ≧ 0.

3.

24. The following: (f) 0.6 cm ３ / g or more total pore volume; (g) A volume fraction of micropores of 20% to 50% and a volume fraction of mesopores of 50% to 80%; and (h) A volume fraction of pores of 10 nm or less, including at least 75% of the total pore volume in the range of 5 nm to 20 μm. The Group 14 composite according to claim 18, further including the above.

25. The Group 14 composite according to claim 18, wherein the weight percentage of silicon with respect to the porous carbon primary particles is 10% to 80%.

26. A Group 14 composite including carbon and silicon, the following: (a) Carbon including a porous carbon scaffold derived from polyol, the following: (i) Amorphous carbon, (ii) A pore volume composed of pores having a diameter of less than 2 nm, with more than 70%, and (iii) Dv90 of less than 50 nm. Carbon further including the above. (b) The following: (i) Amorphous nano-sized silicon embedded within the pore volume of a porous carbon scaffold silicon, including; and (c) The following: (i) 30 to 60 wt% silicon (ii) Dv50 is 10 μm or less (iii) Z < 10, and (iv) phi (φ) ≥ 0.15, where dQ / dV is measured in a half-cell coin cell, regime I is 0.8 V to 0.4 V, and regime III is 0.15 V to 0 V further comprising a Group 14 composite is a Group 14 composite.

27. 30 m ２ The Group 14 composite of claim 26, further comprising a surface area of less than / g.

28. The Group 14 composite according to claim 26, further comprising a maximum capacity of 1300 mAh / g measured by a half-cell coin cell.

29. The Group 14 composite according to claim 26, wherein Dv50 is 5 μm or less.

30. The Group 14 composite according to claim 26, wherein Z < 5.

31. The Group 14 composite according to claim 26, wherein phi (φ) is 0.2 or more.

32. The Group 14 composite according to claim 26, wherein phi (φ) is 0.3 or more.

33. The Group 14 composite according to claim 26, wherein the porous carbon scaffold has an average sphericity of 0.5 to 0.

8.

34. An energy storage device comprising the Group 14 composite according to claim 26.

35. The energy storage device according to claim 34, which is a lithium-silicon battery or a lithium-ion battery.

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