Group 14 complex

Abstract

A particulate composite material and an apparatus comprising the particulate composite material are provided.

Description

background Technical Field

[0002] Embodiments of the present invention generally relate to spherical composite particles containing Group 14 elements and devices containing such particles. These materials are produced by a method comprising hydrothermal carbonization of a polyol promoted by a preferred exclusion agent and subsequent chemical vapor infiltration (CVI).

[0003] Embodiments of the present invention generally relate to methods for producing silicon-carbon composite materials and material compositions thereof. The silicon-carbon composite is produced by a sequence of hydrothermal treatment, pyrolysis, and activation of a carbon precursor material to produce highly microporous carbon particles, followed by chemical vapor infiltration to generate silicon within the pores of the microporous carbon particles, thereby producing the final silicon-carbon composite particles. Suitable carbon precursors include, but are not limited to, sugars and other polyols, and combinations thereof.

[0004] Suitable porous scaffolds include, but are not limited to, porous carbon scaffolds, such as carbon having pore volumes including micropores (less than 2 nm), mesopores (2 to 50 nm), and / or macropores (greater than 50 nm). Silicon chemical vapor infiltration (CVI) into the pores of the porous scaffold material is achieved by exposing the porous scaffold to a silicon-containing gas (e.g., silane) at elevated temperatures.

[0005] Related technical descriptions

[0006] Chemical vapor infiltration (CVI) is a method in which a gaseous substrate is reacted within a porous scaffold material. This method can be used to produce composite materials, such as silicon-carbon composites, where silicon-containing gases decompose within a porous carbon scaffold at high temperatures. While this method can be used to manufacture a variety of composite materials, particular attention is paid to silicon-carbon (Si-C) composites. Such Si-C composites have practical applications, such as as energy storage materials, for example, as anode materials in lithium-ion battery packs (LIBs). LIBs have the potential to replace devices currently used in many applications. For example, current lead-acid automotive battery packs are unsuitable for next-generation all-electric and hybrid electric vehicles due to the formation of irreversible, stable sulfates during discharge. Lithium-ion battery packs are a viable alternative to currently used lead-based systems due to their capacity and other considerations.

[0007] Therefore, there has been considerable interest in developing new LIB anode materials, particularly silicon, which has a 10-fold higher gravimetric capacity than conventional graphite. However, silicon exhibits large volumetric changes during cycling, leading to electrode degradation and solid electrolyte interphase (SEI) instability. The most common approach to improvement is to reduce the silicon particle size, for example, Dv50 < 150 nm, Dv50 < 100 nm, Dv50 < 50 nm, Dv50 < 20 nm, Dv50 < 10 nm, Dv50 < 5 nm, or Dv50 < 2 nm, either as discrete particles or within a matrix. To date, techniques for fabricating nanoscale silicon have involved high-temperature reduction of silicon oxides, coarse-grained particle refinement, multi-step toxic etching, and / or other costly methods. Similarly, common matrix methods involve expensive materials such as graphene or nanographite, and / or require complex processing and coating.

[0008] It is known from scientific literature that non-graphitizable (hard) carbon is advantageous as an anode material for LIBs (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). This improved performance is due to the disordered nature of the graphene layers, which allows Li ions to embed on either side of the graphene plane, thus theoretically allowing for a doubling of the stoichiometric content of Li ions relative to crystalline graphite. Furthermore, unlike graphite, where lithiation can only occur parallel to the stacked graphene planes, the disordered structure improves the rate capability of the material by allowing isotropic embedding of Li ions. Despite possessing these desirable electrochemical properties, amorphous carbon has not yet been widely adopted in commercial Li-ion battery packs, primarily due to its low free charge efficiency (FCE) and low bulk density (<1 g / cc). Instead, amorphous carbon has been more commonly used as a low-mass additive and coating for other active material components in battery packs to improve conductivity and reduce surface side reactions.

[0009] In recent years, amorphous carbon, as a material for LIB battery packs, has attracted considerable attention as a coating for silicon anode materials. Such silicon-carbon core-shell structures not only have the potential to improve conductivity but also to buffer the expansion of silicon during lithiation, thereby stabilizing its cycle stability and minimizing problems related to particle fragmentation, insulation, 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 C2007 111:11131–11138). Problems associated with this strategy include the lack of suitable silicon starting materials for coating processes and the inherent lack of engineered void spaces within carbon-coated silicon core-shell composite particles to accommodate silicon expansion during lithiation. This inevitably leads to cyclic stability failure due to the destruction of the core-shell structure and the SEI layer (Beattie SD, Larcher D, Morcrette M, Simon B, Tarascon, JM. J Electrochem Soc 2008 155: A158-A163).

[0010] An alternative to the core-shell structure is a structure in which amorphous nanoscale silicon is uniformly distributed within the pores of a porous carbon scaffold. Porous carbon possesses desirable properties: (i) carbon porosity provides pore volume to accommodate the expansion of silicon during lithiation, thereby reducing net composite particle expansion at the electrode level; (ii) the disordered graphene network provides increased conductivity for silicon, enabling faster charge / discharge rates; and (iii) the nanoporous structure acts as a template for silicon synthesis, thus defining its size, distribution, and morphology.

[0011] To this end, the desired reverse hierarchical structure can be achieved using CVI, where silicon-containing gas can completely permeate nanoporous carbon and decompose into nanoscale silicon within it. The CVI method offers several advantages in terms of silicon structures. One advantage is that nanoporous carbon provides nucleation sites for silicon growth, while also defining the maximum particle shape and size. Confining silicon growth within the nanoporous structure reduces susceptibility to breakage or fragmentation and contact losses due to expansion. Furthermore, this structure promotes the retention of the amorphous phase in the nanoscale silicon. This property provides high charge / discharge rates, especially when combined with the silicon-peripheral region within the conductive carbon scaffold. This system provides a high-rate solid-state lithium diffusion pathway capable of directly delivering lithium ions to the nanoscale silicon interface. Another benefit of providing silicon via CVI within the carbon scaffold is the suppression of undesirable Li crystallization. 15The formation of the Si4 phase. Another benefit is that the CVI method provides void space within the particles.

[0012] To measure the relative amount of silicon impregnated into the pores of porous carbon, thermogravimetric analysis (TGA) can be used. TGA can be used to assess the fraction of silicon residing within the pores of porous carbon relative to the total silicon present (i.e., the sum of silicon within the pores and on the particle surface). When the silicon-carbon composite is heated in air, the sample shows a mass increase starting at approximately 300°C to 500°C, reflecting the initial oxidation of silicon to SiO2; the sample then shows a mass loss as carbon is burned off; then the sample shows a mass increase, reflecting the continued conversion of silicon to SiO2, increasing to an asymptotic value near 1100°C, where silicon oxidation is complete. For the purposes of this analysis, it is assumed that the minimum mass recorded when the sample is heated from 800°C to 1100°C represents the point at which carbon is completely burned off. Any other mass increase beyond this point corresponds to the oxidation of silicon to SiO2, and the total mass at which oxidation is complete is SiO2. Therefore, the percentage of unoxidized silicon after carbon burn-off, expressed as a proportion of the total silicon, can be determined using the following formula:

[0013] Z=1.875x[(M1100-M) / M1100]x 100

[0014] Where M1100 is the mass of the sample when oxidation is completed at 1100℃, and M is the minimum mass recorded when the sample is heated from 800℃ to 1100℃.

[0015] Without being bound by theory, the temperature at which silicon is oxidized 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. Therefore, silicon residing within the carbon pores will oxidize at a lower temperature than silicon deposits on the particle surfaces, where a thinner coating is necessarily present. In this way, the calculation of Z is used to quantitatively assess the fraction of silicon not impregnated within the pores of the porous carbon scaffold.

[0016] Brief Overview

[0017] This document discloses compositions and methods for manufacturing spherical unimodal composite materials containing Group 14 elements. As used herein, “Group 14” refers to Group 14 (IVa) of the periodic table. Spherical composite particles are produced by generating primary micron-sized, spherical microporous carbon particles, followed by the generation of nanoscale amorphous silicon within the pores of the spherical porous carbon scaffold particles. For this purpose, silicon generation is achieved via chemical vapor infiltration (CVI). The use of spherical carbon scaffold particles offers advantages over existing techniques, such as those compared to the use of secondary micron-sized porous carbon particles. Herein, as a descriptor for porous carbon scaffold particles, “primary micron-sized” refers to the case where the particles are synthesized into micron-sized particles at the time of their generation, for example, particles containing a particle size distribution ranging from 1 μm to 100 μm at the time of their generation; notably, particle size reduction is not required before CVI processing to produce the final micron-sized composite particles. Furthermore, in this paper, as a descriptor for porous carbon scaffold particles, "secondary micron size" refers to the situation where micron-sized particles are generated by reducing the particle size after the synthesis of porous carbon scaffold materials (e.g., the generated particles have a particle size distribution including particles in the range of 1 μm to 100 μm).

[0018] Using primary micron-sized porous carbon particles to produce composite particles containing Group 14 elements offers numerous advantages as disclosed herein. One advantage is the elimination of the particle size reduction step, which can be achieved as described in the art, such as abrasive milling methods, for example using hammer mills, ball mills, jet mills, or other abrasive mills to reduce particle size. Abrasive milling to produce micronized carbon scaffold particles typically exhibits a wide particle size distribution, irregular serrated morphology, and predominantly fine powder, which can pose challenges and inconsistencies in the handling, processing, and performance of particles used in lithium-ion battery systems. The method outlined herein describes the synthesis of micron-sized spherical carbon particles that do not require milling. In some embodiments, the micron-sized spherical carbon particles are prepared as discrete particles and do not agglomerate. In addition to the elimination of milling as described above, the spherical morphology and unimodal particle size distribution of the composite material result in excellent electrochemical properties due to the minimization of particle surface area, and avoids planar or point contacts that could increase particle resistance or undesirable reaction sites without being bound by theory.

[0019] A composite comprising Group 14 elements such as silicon and carbon is disclosed, wherein the composite possesses novel properties that overcome the challenge of providing amorphous nanoscale silicon encased within porous carbon. The silicon-carbon composite can be prepared by chemical vapor infiltration to impregnate amorphous nanoscale silicon within the pores of a porous scaffold. Suitable porous scaffolds include, but are not limited to, porous carbon scaffolds, such as carbon having pore volumes including micropores (less than 2 nm), mesopores (2 to 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, crosslinking agents, and amine compounds. Suitable composite materials include, but are not limited to, silicon-containing materials. Precursors for silicon include, but are not limited to, silicon-containing gases, such as silanes, higher silanes (e.g., disilane, trisilane, and / or tetrasilane) and / or chlorosilanes (e.g., monochlorosilane, dichlorosilane, trichlorosilane, and tetrachlorosilane) and mixtures thereof. CVI is achieved by exposing the porous scaffold to a silicon-containing gas (e.g., silane) at elevated temperatures to generate silicon within the pores of the porous scaffold material. The porous carbon scaffold can be particulate porous carbon.

[0020] A key result in this regard is obtaining silicon in the desired form, namely amorphous nanoscale silicon, in the desired shape. Furthermore, another key result is the realization of silicon impregnation within the pores of porous carbon. Such materials, for example, silicon-carbon composites, have applications as anode materials for energy storage devices such as lithium-ion battery packs.

[0021] Brief description of the attached figures

[0022] Figure 1 The relationship between Z and average coulombic efficiency for various silicon-carbon composite materials.

[0023] Figure 2 Differential capacity versus voltage plot of silicon-carbon composite 3 using half-cell in the second cycle.

[0024] Figure 3 Differential capacity versus voltage plot for silicon-carbon composite 3 using half-cells from the 2nd to the 5th cycle.

[0025] Figure 4 dQ / dV versus V diagrams for various silicon-carbon composite materials.

[0026] Figure 5 Silicon-carbon composite 3 Calculation examples.

[0027] Figure 6 Z-pairs of various silicon-carbon composite materials picture

[0028] Figure 7SEM image of carbon support 12, which contains primary spherical pyrolytic carbon particles generated by hydrothermal condensation mechanism in the absence of a preferred exclusion agent.

[0029] Figure 8 SEM images of various samples of primary spherical pyrolytic carbon particles generated via hydrothermal condensation in the presence of exclusion agents.

[0030] Figure 9 SEM of silicon-carbon composite 21.

[0031] Detailed description

[0032] In the following description, certain specific details are set forth to provide a thorough understanding of various embodiments. However, those skilled in the art will understand that the invention can be practiced without these details. In other instances, structures generally known are not shown or described in detail to avoid unnecessarily obscuring the description of the embodiments. Unless the context otherwise requires, throughout the specification and appended claims, the word “comprise” and its variations (e.g., “comprises” and “comprising”) should be interpreted in an open-ended, inclusive sense, i.e., as meaning “including but not limited to”. Furthermore, the headings provided herein are for convenience only and do not constitute an explanation of the scope or meaning of the claimed invention.

[0033] Throughout this specification, the phrase "an embodiment" or "an embodiment" means that at least one embodiment includes a specific feature, structure, or characteristic relating to that embodiment. Therefore, the phrases "in one embodiment" or "in an embodiment" appearing throughout this specification do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. Additionally, as used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural indicators unless the context clearly specifies otherwise. It should also be noted that the term "or" generally carries the meaning of "and / or" unless the context clearly specifies otherwise. A. Primary micron-sized porous carbon scaffold particles

[0034] Conventional methods for preparing porous carbon materials from polymer precursors are known in the art. For example, methods for preparing 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 No. 16 / 745,197, the entire disclosure of which is incorporated herein by reference for all purposes. In those conventional methods, particles are produced by abrasive grinding to produce micronized carbon scaffold particles. This conventional approach typically results in a wide particle size distribution, irregular serrated particle morphology, and a predominance of fine powder, which can pose challenges and inconsistencies in the handling, processing, and performance of lithium-ion battery systems. The method outlined herein describes the synthesis of micronized spherical carbon particles that do not require grinding. In some embodiments, the micronized spherical carbon particles are discrete, non-agglomerated particles.

[0035] This paper discloses a different method for providing synthetic primary submicron or micron-sized porous carbon scaffold particles, compared to conventional methods. These particles exhibit a spherical morphology. Primary micron-sized porous carbon particles can be produced by hydrothermal carbonization of the reaction mixture. Therefore, the reaction mixture is an aqueous environment containing a polyol and a preferred exclusion agent that promotes the preferential exclusion of the polyol to form spherical micron-sized domains within the aqueous environment, subjecting it to elevated temperatures sufficient to produce hydrothermal char (HTC). Suitable polyols include, but are not limited to, poly(ethylene glycol) (PEG), sorbitol, mannitol, maltitol, xylitol, isomaltitol, lactitol, sucrose, fructose, furfural, glucose, citric acid, starch, cellulose, allulose, xanthan gum, gum arabic, alginate, chitin, chitosan, and combinations thereof. In some preferred embodiments, reducing sugars are used.

[0036] The concentration of the polyol can vary, for example, from 0.001M to 10M, for example, from 0.01M to 10M, for example, from 0.1M to 10M, for example, from 0.5M to 5M. In some embodiments, the reaction mixture may include a crosslinking agent. Suitable crosslinking agents include furfural, hexamethylenetetramine, formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, benzaldehyde, and combinations thereof. The concentration of the crosslinking agent can vary, for example, from 0.001M to 10M, for example, from 0.01M to 10M, for example, from 0.1M to 10M, or it may vary from 0.001M to 5M, for example, from 0.01M to 5M, for example, from 0.1M to 5M, for example, from 0.1M to 1M.

[0037] The reaction mixture may include one or more co-solvents, including but not limited to alcohols, ethanol, methanol, tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), dimethylformamide (DMF), N-methylpyrrolidone, ethylene glycol, ethylene glycol dimethyl ether, alkanes, ethers, and combinations thereof. In some embodiments, the reaction mixture may include one or more co-solvents, including but not limited to ethanol, methanol, tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), dimethylformamide (DMF), N-methylpyrrolidone, ethylene glycol, ethylene glycol dimethyl ether, and combinations thereof. The volume ratio (V:V) of the co-solvent to water may vary, for example from 0.001:1 to 1000:1, for example from 0.01:1 to 100:1, for example from 0.1 to 10:1.

[0038] The reaction mixture contains a size-limiting agent. A size-limiting agent is defined as a reagent that promotes the formation of spherical, micron-sized domains in an aqueous environment, which are subsequently converted to HTC over time after the reaction mixture is subjected to elevated temperatures. Size-limiting agents possess the property of facilitating the interaction between the polyol and the solvent, thereby promoting polyol aggregation. Without being bound by theory, a variety of different possible mechanisms exist in which the size-limiting agent provides preferential size restriction, including but not limited to ionic interactions and hydrogen bonding interactions. Exemplary size-limiting agents include, but are not limited to, polyionic substances, such as polyanionic substances like carboxymethyl cellulose or poly(acrylic acid). Another exemplary size-limiting agent includes ionic, nonionic, or amphoteric surfactants. Exemplary surfactants in this regard include Triton, SPAN, Pluronics, etc.

[0039] The reaction mixture can be subjected to sufficient time and temperature to form spherical particles containing HTC. The time for HTC production can vary, for example, from 1 hour to 72 hours. The temperature can vary, for example, from 120°C to 300°C, from 140°C to 240°C, from 150°C to 250°C, or from 160°C to 220°C. In some embodiments, the reaction temperature is set at or below the temperature at which the surfactant begins to degrade or decompose. In a preferred embodiment, the temperature used to produce HTC is 170°C to 210°C, or 180°C to 200°C, or 180°C to 220°C. The rate of increase from ambient temperature to the reaction temperature can vary, for example, from 1°C / min to 100°C / min, from 2°C / min to 50°C / min, or from 5°C / min to 20°C / min.

[0040] The reaction that produces HTC takes place within a reactor, where the pressure can vary, for example from ambient pressure to pressures above ambient pressure, such as 0.1 psig to 1000 psig, 1 psig to 1000 psig, 1 psig to 500 psig, or 100 psig to 500 psig. In a preferred embodiment, the reactor pressure is 120 psig to 300 psig, or 130 psig to 280 psig, such as 140 psig to 260 psig, or 145 psig to 225 psig.

[0041] 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 carried out in a reactor as is known in the art, including stirring by magnetic rods or one or more paddles, ultrasonication, vibration, and reactor designs such as rotary / stator reactor designs. The geometry of the reaction vessel can vary as is known in the art, as can the reactor material, such as a sealed stainless steel autoclave-type vessel with a Teflon lining. In a preferred configuration, the reactor vessel may have one or more ports for introducing components at different times during the reaction. The reactor can be operated in a batch or continuous manner. The progress of the reaction can be monitored by taking samples and analyzing various properties such as viscosity, conductivity, absorbance (visible and / or UV wavelengths), and the size of suspended particles (as is known in the art, e.g., by laser scattering). Alternatively, the reaction progress can be monitored online.

[0042] In some embodiments, the aqueous reaction environment exhibits an acidic pH, such as a pH range from pH 2 to pH 6, for example, pH 2 to pH 4, or pH 4 to pH 5, or pH 5 to pH 6. In some other embodiments, the aqueous reaction environment exhibits an alkaline pH, such as a pH range from pH 8 to pH 14, for example, 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 a pH range from pH 6 to pH 8, for example, pH 6 to pH 7, or pH 7 to pH 8. As is known in the art, the pH can be adjusted by adding an acid and / or a base. In some embodiments, volatile acids, such as acetic acid, and / or volatile bases, such as ammonium acetate, can be used to adjust the pH. In some embodiments, buffering systems can be used to control the pH of the aqueous reaction environment as is known in the art. In some embodiments, the reagents used to adjust and / or control the pH of the aqueous reaction environment can also act as exclusion agents, such as amino acids.

[0043] The conductivity of an aqueous reaction environment can vary, for example, from 0 to 1000 mS / cm. The oxidation-reduction potential (ORP) of an aqueous reaction environment can vary, for example, from +2.87 V to -3.05 V. The viscosity of an aqueous reaction environment can vary, for example, from 0.1 cP to 1000 cP.

[0044] In some embodiments, the aqueous reaction environment may contain catalyst particles, including but not limited to metals such as lithium. Other exemplary catalysts in this regard include amorphous carbon, nanographite, carbon black, nano-sized and / or nanostructured carbon such as carbon nanotubes, and combinations thereof. In some embodiments, the catalyst may be a silane / siloxane crosslinking agent, persulfate, hydroxide, or a combination thereof.

[0045] In some embodiments, the aqueous reaction environment contains an electrochemical modifier. For example, in some embodiments, the electrochemical modifier, in the form of metal particles, metal paste, metal salt, metal oxide, or molten metal, may be dissolved or suspended in the HTC-generating mixture.

[0046] 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 tetrafluoroborate, and combinations thereof.

[0047] In some embodiments, the electrochemical modifier comprises a metal, and exemplary substances include, but are not limited to, aluminum isopropoxide, manganese acetate, nickel acetate, ferric acetate, tin chloride, silicon chloride, and combinations thereof. In some embodiments, the electrochemical modifier is a phosphate compound, including but not limited to phytic acid, phosphoric acid, ammonium dihydrogen phosphate, and combinations thereof. In some embodiments, the electrochemical modifier comprises silicon, and exemplary substances include, but are not limited to, silicon powder, silicon nanotubes, polycrystalline silicon, nanocrystalline silicon, amorphous silicon, porous silicon, nanoscale silicon, nano-featured silicon, nanoscale and nano-featured silicon, silicyne, and black silicon, and combinations thereof.

[0048] Electrochemical modifiers can be combined with various polymer systems through physical mixing or through chemical reactions using latent (or minor) polymer functional groups. Examples of latent polymer functional groups include, but are not limited to, epoxy groups, unsaturated groups (double and triple bonds), acid groups, alcohol groups, amine groups, and basic groups. Crosslinking with latent functional groups can occur via heteroatoms (e.g., sulfidation with sulfur, acid / base / ring-opening reactions with phosphoric acid), reactions with organic acids or bases (as described above), coordination with 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, spirocyclic compounds, etc.).

[0049] After HTC is generated, the resulting multiple particles can be removed from the aqueous environment by methods known in the art, such as filtration, centrifugation, sedimentation, etc., and any residual water can be removed by subjecting the material to heating and / or vacuum to produce dried HTC. The dried HTC can be pyrolyzed to produce multiple spherical, primary submicron or micron-sized porous pyrolytic carbon particles. The pyrolysis temperature and residence time can be varied, for example, residence time can vary from 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, and 4 hours to 24 hours. The temperature can be varied; for example, the pyrolysis temperature can vary from 200°C to 300°C, 250°C to 350°C, 350°C to 450°C, 450°C to 550°C, 540°C to 650°C, 650°C to 750°C, 750°C to 1050°C, 750°C to 850°C, 850°C to 950°C, 950°C to 1050°C, 1050°C to 1150°C, and 1150°C to 1250°C. Pyrolysis can be carried out in an inert gas (such as nitrogen or argon).

[0050] In some embodiments, an alternative gas is used to further activate the carbon to produce multiple primary porous carbon particles with sufficient porosity to serve as a scaffold for subsequent CVI reactions to produce silicon-carbon composites. In some embodiments, pyrolysis and activation are combined. Suitable gases for achieving carbon activation can be defined as activating gases, including but not limited to carbon dioxide, carbon monoxide, water (steam), air, oxygen, and other combinations thereof. The activation temperature and residence time can be varied, for example, the residence time can vary from 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, and 4 hours to 24 hours. The temperature can vary, for example, from 200°C to 300°C, 250°C to 350°C, 350°C to 450°C, 450°C to 550°C, 540°C to 650°C, 650°C to 750°C, 750°C to 850°C, 750°C to 1050°C, 850°C to 950°C, 950°C to 1050°C, 1050°C to 1150°C, and 1150°C to 1250°C.

[0051] Before pyrolysis, and / or after pyrolysis, and / or after activation, the carbon particle size can be reduced. Particle size reduction can be achieved by various techniques known in the art, such as jet milling in the presence of various gases, including air, nitrogen, argon, helium, supercritical vapor, and other gases known in the art. Other particle size reduction methods are also contemplated, such as milling, 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 because the HTC material has been produced as multiple primary particles within a range suitable for use as a scaffold for the production of silicon-carbon composites.

[0052] The particle size and particle size distribution of primary porous carbon scaffold particles can be measured by various techniques known in the art and can be described based on fractional volume. In this regard, the Dv50 of the carbon scaffold can be 10 nm to 10 mm, for example 100 nm to 1 mm, for example 1 micrometer (“μm”) to 100 μm, for example 2 μm to 50 μm, for example 3 μm to 30 μm, for example 4 μm to 20 μm, for example 5 μm to 10 μm. In some embodiments, Dv50 is less than 1 mm, for example less than 100 μm, for example less than 50 μm, for example less than 30 μm, for example less than 20 μm, for example less than 10 μm, for example less than 8 μm, for example less than 5 μm, for example less than 3 μm, for example less than 1 μm. In some embodiments, Dv100 is less than 1 mm, for example, less than 100 μm, for example, less than 50 μm, for example, less than 30 μm, for example, less than 20 μm, for example, less than 10 μm, for example, less than 8 μm, for example, less than 5 μm, for example, less than 3 μm, for example, less than 1 μm. In some embodiments, Dv99 is less than 1 mm, for example, less than 100 μm, for example, less than 50 μm, for example, less than 30 μm, for example, less than 20 μm, for example, less than 10 μm, for example, less than 8 μm, for example, less than 5 μm, for example, less than 3 μm, for example, less than 1 μm. In some embodiments, Dv90 is less than 1 mm, for example, less than 100 μm, for example, less than 50 μm, for example, less than 30 μm, for example, less than 20 μm, for example, less than 10 μm, for example, less than 8 μm, for example, less than 5 μm, for example, less than 3 μm, for example, less than 1 μm. In some embodiments, Dv0 is greater than 10 nm, for example, greater than 100 nm, for example, greater than 500 nm, for example, greater than 1 μm, for example, greater than 2 μm, for example, greater than 5 μm, for example, greater than 10 μm. In some embodiments, Dv1 is greater than 10 nm, for example, greater than 100 nm, for example, greater than 500 nm, for example, greater than 1 μm, for example, greater than 2 μm, for example, greater than 5 μm, for example, greater than 10 μm. In some embodiments, Dv10 is greater than 10 nm, for example, greater than 100 nm, for example, greater than 500 nm, for example, greater than 1 μm, for example, greater than 2 μm, for example, greater than 5 μm, for example, greater than 10 μm.

[0053] In some implementations, the surface area of ​​the porous carbon scaffold may include greater than 400 m². 2 / g surface area, for example, greater than 500m 2 / g, for example, greater than 750m 2 / g, for example, greater than 1000m 2 / g, for example, greater than 1250m 2 / g, for example, greater than 1500m 2 / g, for example, greater than 1750m 2 / g, for example, greater than 2000m 2 / g, for example, greater than 2500m 2 / g, for example, greater than 3000m 2 / g. In other embodiments, the surface area of ​​the porous carbon scaffold can be less than 500m². 2 / g. In some embodiments, the surface area of ​​the porous carbon scaffold is 200 to 500 m². 2 / g. In some embodiments, the surface area of ​​the porous carbon scaffold is 100 to 200 m². 2 / g. In some embodiments, the surface area of ​​the porous carbon scaffold is 50 to 100 m². 2 / g. In some embodiments, the surface area of ​​the porous carbon scaffold is 10 to 50 m². 2 / g. In some embodiments, the surface area of ​​the porous carbon scaffold can be less than 10m². 2 / g.

[0054] In some implementations, the pore volume of the primary porous carbon scaffold particles is greater than 0.4 cm³. 3 / g, for example, greater than 0.5cm 3 / g, for example, greater than 0.6cm 3 / g, for example, greater than 0.7cm 3 / g, for example, greater than 0.8cm 3 / g, for example, greater than 0.9cm 3 / g, for example, greater than 1.0cm 3 / g, for example, greater than 1.1cm 3 / g, for example, greater than 1.2cm 3 / g, for example, greater than 1.4cm 3 / g, for example, greater than 1.6cm 3 / g, for example, greater than 1.8cm 3 / g, for example, greater than 2.0cm 3 / g. In other embodiments, the pore volume of the porous carbon scaffold is less than 0.5 cm³, for example, 0.1 cm³. 3 / g to 0.5cm 3 / g. In some other embodiments, the pore volume of the porous carbon scaffold is 0.01 cm³. 3 / g to 0.1cm 3 / g. In a further embodiment, the pore volume can be 0.001cm³. 3 / g to 0.01cm 3 / g.

[0055] In some other embodiments, the primary porous carbon scaffold particles contain pore volumes of 0.2 to 2.0 cm³. 3 / g of amorphous activated carbon. In some embodiments, the carbon has a pore volume of 0.4 to 1.5 cm³. 3 / g of amorphous activated carbon. In some embodiments, the carbon has a pore volume of 0.5 to 1.2 cm³. 3 / g of amorphous activated carbon. In some embodiments, the carbon has a pore volume of 0.6 to 1.0 cm³. 3 / g of amorphous activated carbon.

[0056] In some other embodiments, the primary porous carbon scaffold particles comprise less than 1.0 g / cm³. 3 The tap density, for example, is less than 0.8 g / cm³. 3 For example, less than 0.6 g / cm³ 3 For example, less than 0.5 g / cm³ 3 For example, less than 0.4 g / cm³ 3 For example, less than 0.3 g / cm³ 3 For example, less than 0.2 g / cm³ 3 For example, less than 0.1 g / cm³ 3 .

[0057] The surface functionality of primary porous carbon scaffold particles can vary. One property that can predict surface functionality is the pH of the porous carbon scaffold. The porous carbon scaffolds disclosed in this invention contain pH values ​​from less than 1 to about 14, for example, less than 5, 5 to 8, or greater than 8. In some embodiments, the pH of the porous carbon is less than 4, less than 3, less than 2, or even 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 other embodiments, the pH is high and the pH range of the porous carbon is greater than 8, greater than 9, greater than 10, greater than 11, greater than 12, or even greater than 13.

[0058] The pore volume distribution of the primary porous carbon scaffold particles can vary. For example, the percentage of micropores can be less than 30%, such as less than 20%, less than 10%, less than 5%, less than 4%, less than 3%, less than 2%, less than 1%, less than 0.5%, less than 0.2%, or less than 0.1%. In some embodiments, there is no detectable micropore volume in the porous carbon scaffold.

[0059] The mesopores constituting the primary porous carbon scaffold particles can vary. For example, the percentage of mesopores can be less than 30%, such as less than 20%, less than 10%, less than 5%, less than 4%, less than 3%, less than 2%, less than 1%, less than 0.5%, less than 0.2%, or less than 0.1%. In some embodiments, there is no detectable mesopore volume in the porous carbon scaffold.

[0060] In some embodiments, the pore volume distribution of the porous carbon scaffold includes more than 50% macropores, such as more than 60% macropores, more than 70% macropores, more than 80% macropores, more than 90% macropores, more than 95% macropores, more than 98% macropores, more than 99% macropores, more than 99.5% macropores, and more than 99.9% macropores.

[0061] In some preferred embodiments, the pore volume of the primary porous carbon scaffold particles comprises a mixture of micropores, mesopores, and macropores. Therefore, in some embodiments, the porous carbon scaffold comprises 0-20% micropores, 30-70% mesopores, and less than 10% macropores. In some other embodiments, the porous carbon scaffold comprises 0-20% micropores, 0-20% mesopores, and 70-95% macropores. In some other embodiments, the porous carbon scaffold comprises 20-50% micropores, 50-80% mesopores, and 0-10% macropores. In some other embodiments, the porous carbon scaffold comprises 40-60% micropores, 40-60% mesopores, and 0-10% macropores. In some other embodiments, the porous carbon scaffold comprises 80-95% micropores, 0-10% mesopores, and 0-10% macropores. In some other embodiments, the porous carbon scaffold comprises 0-10% micropores, 30-50% mesopores, and 50-70% macropores. In some other embodiments, the porous carbon scaffold comprises 0-10% micropores, 70-80% mesopores, and 0-20% macropores. In some other embodiments, the porous carbon scaffold comprises 0-20% micropores, 70-95% mesopores, and 0-10% macropores. In some other embodiments, the porous carbon scaffold comprises 0-10% micropores, 70-95% mesopores, and 0-20% macropores.

[0062] In some embodiments, the pore volume percentage of pores representing 100 to 1000 Å (10 to 100 nm) in the primary porous carbon scaffold particles is greater than 30% of the total pore volume, for example, greater than 40% of the total pore volume, for example, greater than 50% of the total pore volume, for example, greater than 60% of the total pore volume, for example, greater than 70% of the total pore volume, for example, greater than 80% of the total pore volume, for example, greater than 90% of the total pore volume, for example, greater than 95% of the total pore volume, for example, greater than 98% of the total pore volume, for example, greater than 99% of the total pore volume, for example, greater than 99.5% of the total pore volume, for example, greater than 99.9% of the total pore volume.

[0063] In some embodiments, the specific gravity density of the primary porous carbon scaffold particles is from about 1 g / cc to about 3 g / cc, for example, from about 1.5 g / cc to about 2.3 g / cc. In other embodiments, the scaffold density is from about 1.5 cc / g to about 1.6 cc / g, from about 1.6 cc / g to about 1.7 cc / g, from about 1.7 cc / g to about 1.8 cc / g, from about 1.8 cc / g to about 1.9 cc / g, from about 1.9 cc / g to about 2.0 cc / g, from about 2.0 cc / g to about 2.1 cc / g, from about 2.1 cc / g to about 2.2 cc / g, or from about 2.2 cc / g to about 2.3 cc / g, from about 2.3 cc to about 2.4 cc / g, for example, from about 2.4 cc / g to about 2.5 cc / g.

[0064] B. Silicon production via chemical vapor infiltration (CVI)

[0065] Chemical vapor deposition (CVD) is a method in which a substrate provides a solid surface comprising a first component of a composite, and a gas is thermally decomposed on the solid surface to provide a second component of the composite. For example, this CVD method can be used to produce Si-C composites, where silicon is coated on the outer surface of silicon particles. Alternatively, chemical vapor infiltration (CVI) is a method in which a substrate provides a porous scaffold comprising a first component of a composite, and a gas is thermally decomposed to enter the pores of the porous scaffold material (entering the pores) to provide the second component of the composite.

[0066] In one embodiment, silicon is generated within the pores of the porous carbon scaffold by subjecting porous carbon particles to a silicon-containing precursor gas at elevated temperatures and in the presence of a silicon-containing gas (preferably silane) to decompose the gas into silicon. The silicon-containing precursor gas may be mixed with other inert gases such as nitrogen. The process temperature and time can vary, for example, the temperature may be 200 to 900°C, such as 200 to 250°C, such as 250 to 300°C, such as 300 to 350°C, such as 300 to 400°C, such as 350 to 450°C, such as 350 to 400°C, such as 400 to 500°C, such as 500 to 600°C, such as 600 to 700°C, such as 700 to 800°C, such as 800 to 900°C, such as 600 to 1100°C.

[0067] The gas mixture may contain 0.1-1% silane and the balance inert gas. Alternatively, the gas mixture may contain 1%-10% silane and the balance inert gas. Alternatively, the gas mixture may contain 10% to 20% silane and the balance inert gas. Alternatively, the gas mixture may contain 20% to 50% silane and the balance inert gas. Alternatively, the gas mixture may contain more than 50% silane and the balance inert gas. Alternatively, the gas may be substantially 100% silane gas. Suitable inert gases include, but are not limited to, hydrogen, nitrogen, argon, and combinations thereof.

[0068] The pressure in the CVI method can vary. In some implementations, the pressure is atmospheric pressure. In some implementations, the pressure is below atmospheric pressure. In some implementations, the pressure is above atmospheric pressure.

[0069] C. Physicochemical and electrochemical properties of silicon-carbon composites

[0070] While not wishing to be bound by theory, it is believed that the realization of nanoscale silicon (e.g., silicon with pores filled to 5 to 1000 nm or other ranges as disclosed elsewhere herein) due to certain desired pore volume structures of porous carbon scaffolds, along with the advantageous properties of other components of the composite (including low surface area and low specific gravity), results in composite materials with different and advantageous properties (e.g., electrochemical performance when the composite constitutes the anode of a lithium-ion energy storage device).

[0071] In some embodiments, the embedded silicon particles within the composite include nanoscale features. These nanoscale features may preferably have a feature length scale of less than 1 μm, less than 300 nm, less than 150 nm, less than 100 μm, less than 50 nm, less than 30 nm, less than 15 nm, less than 10 nm, or less than 5 nm.

[0072] In some embodiments, the silicon embedded within the composite is spherical. In other embodiments, the porous silicon particles are non-spherical, such as rod-shaped or fibrous structures. In some embodiments, silicon exists as a layer encapsulating the interior of the pores within a porous carbon scaffold. The depth of this silicon layer can vary, for example, it can be 5 nm to 10 nm, such as 5 nm to 20 nm, such as 5 nm to 30 nm, such as 5 nm to 33 nm, such as 10 nm to 30 nm, such as 10 nm to 50 nm, such as 10 nm to 100 nm, such as 10 nm to 150 nm, such as 50 nm to 150 nm, such as 100 nm to 300 nm, such as 300 nm to 1000 nm.

[0073] In some embodiments, the silicon embedded within the composite is nanoscale and resides within the pores of the porous carbon scaffold. For example, the embedded silicon can be impregnated, deposited via CVI, or otherwise suitably introduced into the pores within the porous carbon particles, the pore sizes of which are 5 to 1000 nm, for example 10 to 500 nm, 10 to 200 nm, 10 to 100 nm, 33 to 150 nm, or 20 to 100 nm. Other ranges of carbon pore sizes with respect to fractional pore volumes are also envisioned, whether micropores, mesopores, or macropores.

[0074] In some embodiments, the pore volume distribution of the carbon scaffold can be described as the number or volume distribution of pores as known in the art based on gas adsorption analysis (e.g., nitrogen adsorption analysis). In some embodiments, the pore size distribution can be represented by the pore size at or below a certain percentage of the total pore volume. For example, 10% of the pores at or below a certain size can be represented as DPv10.

[0075] The DPv10 of the porous carbon scaffold can vary, for example, DPv10 can be 0.01nm to 100nm, for example 0.1nm to 100nm, for example 1nm to 100nm, for example 1nm to 50nm, for example 1nm to 40nm, for example 1nm to 30nm, for example 1nm to 10nm, for example 1nm to 5nm.

[0076] The DPv50 of the porous carbon scaffold can vary; for example, DPv50 can be from 0.01 nm to 100 nm, such as 0.1 nm to 100 nm, 1 nm to 100 nm, 1 nm to 50 nm, 1 nm to 40 nm, 1 nm to 30 nm, 1 nm to 10 nm, or 1 nm to 5 nm. In other embodiments, DPv50 is 2 to 100, such as 2 to 50, 2 to 30, 2 to 20, 2 to 15, or 2 to 10.

[0077] The DPv90 of the porous carbon scaffold can vary; for example, DPv90 can be 0.01 nm to 100 nm, such as 0.1 nm to 100 nm, 1 nm to 100 nm, 1 nm to 50 nm, 1 nm to 50 nm, 1 nm to 40 nm, 1 nm to 30 nm, 1 nm to 10 nm, or 1 nm to 5 nm. In other embodiments, DPv50 is 2 nm to 100 nm, such as 2 nm to 50 nm, 2 nm to 30 nm, 2 nm to 20 nm, 2 nm to 15 nm, or 2 nm to 10 nm.

[0078] In some implementations, DPv90 is less than 100nm, for example less than 50nm, for example less than 40nm, for example less than 30nm, for example less than 20nm, for example less than 15nm, for example less than 10nm. In some embodiments, the carbon scaffold comprises a pore volume greater than 70% of the micropores (and DPv90 is less than 100 nm, for example, DPv90 less than 50 nm, DPv90 less than 40 nm, DPv90 less than 30 nm, DPv90 less than 20 nm, DPv90 less than 15 nm, DPv90 less than 10 nm, DPv90 less than 5 nm, DPv90 less than 4 nm, or DPv90 less than 3 nm). In other embodiments, the carbon scaffold comprises a pore volume greater than 80% of the micropores and DPv90 is less than 100 nm, for example, DPv90 less than 50 nm, DPv90 less than 40 nm, DPv90 less than 30 nm, DPv90 less than 20 nm, DPv90 less than 15 nm, DPv90 less than 10 nm, DPv90 less than 5 nm, DPv90 less than 4 nm, or DPv90 less than 3 nm.

[0079] The DPv99 of the porous carbon scaffold can vary; for example, DPv99 can be 0.01 nm to 1000 nm, such as 0.1 nm to 1000 nm, such as 1 nm to 500 nm, such as 1 nm to 200 nm, such as 1 nm to 150 nm, such as 1 nm to 100 nm, such as 1 nm to 50 nm, such as 1 nm to 20 nm. In other embodiments, DPv99 is 2 nm to 500 nm, such as 2 nm to 200 nm, such as 2 nm to 150 nm, such as 2 nm to 100 nm, such as 2 nm to 50 nm, such as 2 nm to 20 nm, such as 2 nm to 15 nm, such as 2 nm to 10 nm.

[0080] The embodiments of the composites with extremely durable lithium intercalation disclosed herein improve the properties of any number of energy storage devices (e.g., lithium-ion battery packs). In some embodiments, the silicon-carbon composites disclosed herein exhibit a Z value less than 10, such as less than 5, less than 4, less than 3, less than 2, less than 1, less than 0.1, less than 0.01, or less than 0.001. In some embodiments, Z is 0.

[0081] In some preferred embodiments, the silicon-carbon composite comprises a desired low Z-value and a combination with another desired physicochemical and / or electrochemical property, or a combination with more than one other desired physicochemical and / or electrochemical property. Table 1 provides a description of some embodiments of the combination of properties of the silicon-carbon composite. Surface area can be determined as known in the art, for example by nitrogen adsorption analysis. Silicon content can be determined as known in the art, for example by TGA. Property Z can be determined by TGA according to this disclosure. First cycle efficiency can be determined as known in the art, for example, calculated based on the first cycle charge and discharge capacity in a full cell or half cell. For example, the first cycle efficiency can be determined in a half cell for a voltage window of 5 mV to 0.8 V, or alternatively, 5 mV to 1.5 V. Reversible capacity can be described as maximum reversible capacity or maximum capacity and can be determined as known in the art, for example, in a half cell for a voltage window of 5 mV to 0.8 V, or alternatively, 5 mV to 1.5 V.

[0082] Table 1. Implementation schemes of silicon-carbon composites with realized properties

[0083]

[0084]

[0085] According to Table 1, silicon-carbon composites can contain a variety of combinations of properties. For example, silicon-carbon composites can contain Z values ​​less than 10 and m values ​​less than 100. 2 A surface area of ​​ / g, a first-cycle efficiency greater than 80%, and a reversible capacity of at least 1300 mAh / g. For example, silicon-carbon composites can contain less than 10 Z and less than 100 m. 2 A surface area of ​​ / g, a first-cycle efficiency greater than 80%, and a reversible capacity of at least 1600 mAh / g. For example, silicon-carbon composites can contain less than 10 Z and less than 20 m. 2 A surface area of ​​ / g, a first-cycle efficiency greater than 85%, and a reversible capacity of at least 1600 mAh / g. For example, silicon-carbon composites can contain less than 10 Z and less than 10 m. 2 A surface area of ​​ / g, a first-cycle efficiency greater than 85%, and a reversible capacity of at least 1600 mAh / g. For example, silicon-carbon composites can contain less than 10 Z and less than 10 m. 2 A surface area of ​​ / g, a first-cycle efficiency greater than 90%, and a reversible capacity of at least 1600 mAh / g. For example, silicon-carbon composites can contain less than 10 Z and less than 10 m. 2 / g surface area, greater than 90% first cycle efficiency and at least 1800mAh / g reversible capacity.

[0086] In some implementations, the TGA onset temperature is higher than that of similar silicon-carbon composites made from non-polyol precursors. Without being bound by theory, a higher TGA onset temperature can result in less gas evolution in silicon-carbon composites when used as an anode material in battery packs (e.g., lithium-ion battery pack anodes or lithium-silicon battery pack anodes).

[0087] Table 2. TGA onset temperature of silicon-carbon composites

[0088]

[0089]

[0090] In some embodiments, the TGA onset temperature of the silicon-carbon composite is greater than 600°C. In other embodiments, the TGA onset temperature of the silicon-carbon composite is 300°C to 400°C; 400°C to 500°C; or 500°C to 600°C. In some embodiments, the TGA onset temperature of the silicon-carbon composite is greater than 600°C.

[0091] In addition to including a carbon scaffold with properties also described in this scheme, silicon-carbon composites may also include combinations of the aforementioned properties. Therefore, Table 3 provides descriptions of certain embodiments of combinations of properties in silicon-carbon composites.

[0092] Table 3. Implementation schemes of silicon-carbon composites with realized properties.

[0093]

[0094]

[0095] As used in this article, the percentages of "microporosity," "mesoporosity," and "macroporosity" refer to the percentages of micropores, mesopores, and macropores in the total pore volume, respectively. For example, a carbon scaffold with 90% microporosity is a carbon scaffold in which 90% of the total pore volume of the carbon scaffold is formed by micropores.

[0096] According to Table 3, silicon-carbon composites can contain a variety of combinations of properties. For example, silicon-carbon composites can include Z values ​​less than 10 and surface areas less than 100 m². 2 / g, first cycle efficiency greater than 80%, reversible capacity of at least 1600mAh / g, silicon content of 15%-85%, and total pore volume of carbon scaffold of 0.2-1.2cm³. 3 / g, wherein the pore volume of the support comprises >80% micropores, <20% mesopores, and <10% macropores. For example, silicon-carbon composites may include a Z of less than 10 and a surface area of ​​less than 20 m². 2 / g, first cycle efficiency greater than 85%, reversible capacity of at least 1600mAh / g, silicon content of 15%-85%, and total pore volume of carbon scaffold of 0.2-1.2cm³. 3 / g, wherein the pore volume of the support comprises >80% micropores, <20% mesopores, and <10% macropores. For example, silicon-carbon composites may include a Z of less than 10 and a surface area of ​​less than 10 m². 2 / g, first cycle efficiency greater than 85%, reversible capacity of at least 1600mAh / g, silicon content of 15%-85%, and total pore volume of carbon scaffold of 0.2-1.2cm³. 3 / g, wherein the pore volume of the support comprises >80% micropores, <20% mesopores, and <10% macropores. For example, silicon-carbon composites may include a Z of less than 10 and a surface area of ​​less than 10 m². 2 / g, first cycle efficiency greater than 90%, reversible capacity of at least 1600mAh / g, silicon content of 15%-85%, and total pore volume of carbon scaffold of 0.2-1.2cm³. 3 / g, wherein the pore volume of the support comprises >80% micropores, <20% mesopores, and <10% macropores. For example, silicon-carbon composites may include a Z of less than 10 and a surface area of ​​less than 10 m². 2 / g, first cycle efficiency greater than 90%, reversible capacity of at least 1800mAh / g, silicon content of 15%-85%, and total pore volume of carbon scaffold of 0.2-1.2cm³. 3 / g, wherein the pore volume of the support comprises >80% micropores, <20% mesopores and <10% macropores.

[0097] Also according to Table 3, silicon-carbon composites can contain carbon scaffolds with >80% micropores, 30-60% silicon content, ≥0.9969 average coulombic efficiency, and Z<10. For example, silicon-carbon composites can contain carbon scaffolds with >80% micropores, 30-60% silicon content, ≥0.9970 average coulombic efficiency, and Z<10. For example, silicon-carbon composites can contain carbon scaffolds with >80% micropores, 30-60% silicon content, ≥0.9975 average coulombic efficiency, and Z<10. For example, silicon-carbon composites can contain carbon scaffolds with >80% micropores, 30-60% silicon content, ≥0.9980 average coulombic efficiency, and Z<10. For example, silicon-carbon composites can contain carbon scaffolds with >80% micropores, 30-60% silicon content, ≥0.9985 average coulombic efficiency, and Z<10. For example, a silicon-carbon composite may contain a carbon scaffold with >80% microporosity, 30-60% silicon content, ≥0.9990 average coulombic efficiency, and Z<10. For example, a silicon-carbon composite may contain a carbon scaffold with >80% microporosity, 30-60% silicon content, ≥0.9995 average coulombic efficiency, and Z<10. For example, a silicon-carbon composite may contain a carbon scaffold with >80% microporosity, 30-60% silicon content, ≥0.9970 average coulombic efficiency, and Z<10. For example, a silicon-carbon composite may contain a carbon scaffold with >80% microporosity, 30-60% silicon content, ≥0.9999 average coulombic efficiency, and Z<10.

[0098] Without being bound by theory, the silicon filling within the pores of porous carbon traps the pores within the porous carbon scaffold particles, creating inaccessible volumes, such as those inaccessible to nitrogen. Therefore, silicon-carbon composites can exhibit a specific gravity density of less than 2.1 g / cm³. 3 For example, less than 2.0 g / cm³ 3 For example, less than 1.9 g / cm³ 3 For example, less than 1.8 g / cm³ 3 For example, less than 1.7 g / cm³ 3 For example, less than 1.6 g / cm³ 3 For example, less than 1.4 g / cm³ 3 For example, less than 1.2 g / cm³ 3 For example, less than 1.0 g / cm³ 3 .

[0099] In some implementations, the specific gravity density exhibited by the silicon-carbon composite material can be 1.7 g / cm³. 3 Up to 2.1 g / cm 3 For example, 1.7g.cm 3 Up to 1.8 g / cm 31.8g.cm 3 Up to 1.9 g / cm 3 For example, 1.9g.cm 3 Up to 2.0 g / cm 3 For example, 2.0g.cm 3 Up to 2.1 g / cm 3 In some implementations, the specific gravity density exhibited by the silicon-carbon composite material can be 1.8 g / cm³. 3 Up to 2.1 g / cm 3 In some implementations, the specific gravity density exhibited by the silicon-carbon composite material can be 1.8 g / cm³. 3 Up to 2.0 g / cm 3 In some implementations, the specific gravity density exhibited by the silicon-carbon composite material can be 1.9 g / cm³. 3 Up to 2.1 g / cm 3 .

[0100] The pore volume of lithium-intercalated composite materials exhibiting extremely high durability can be as low as 0.01 cm³. 3 / g to 0.2cm 3 / g. In some embodiments, the pore volume of the composite material can be 0.01 cm³. 3 / g to 0.15cm 3 / g, for example, 0.01cm 3 / g to 0.1cm 3 / g, for example 0.01cm 3 / g to 0.05cm 2 / g.

[0101] The particle size distribution of lithium-intercalated composites exhibiting extreme durability is important for determining both power performance and volumetric capacity. Volumetric capacity can increase with improved packing. In one embodiment, this distribution is a Gaussian distribution with a unimodal, bimodal, or multimodal (>2 distinct peaks, e.g., trimodal) shape. The particle size properties of the composite can be described by D0 (minimum particle size in the distribution), Dv50 (average particle size), and Dv100 (maximum size of the largest particle). The optimal combination of particle packing and performance will be a combination of some of the following size ranges. Particle size reduction in such embodiments can be carried out as is known in the art, for example by jet milling in the presence of various gases, including air, nitrogen, argon, helium, supercritical vapor, and other gases known in the art.

[0102] In one embodiment, the Dv0 of the composite material can be from 1 nm to 5 μm. In another embodiment, the Dv0 of the composite material is from 5 nm to 1 μm, for example, 5-500 nm, 5-100 nm, or 10-50 nm. In other embodiments, the Dv0 of the composite material is from 500 nm to 2 μm, or 750 nm to 1 μm, or 1-2 μm. In still other embodiments, the Dv0 of the composite material is 2-5 μm, or >5 μm.

[0103] In some embodiments, the composite material has a Dv50 of 5 nm to 20 μm. In other embodiments, the composite material has a Dv50 of 5 nm to 1 μm, for example, 5-500 nm, 5-100 nm, or 10-50 nm. In other embodiments, the composite material has a Dv50 of 500 nm to 2 μm, 750 nm to 1 μm, or 1-2 μm. In still other embodiments, the composite material has a Dv50 of 1 to 1000 μm, for example, 1-100 μm, 1-10 μm, 2-20 μm, 3-15 μm, or 4-8 μm. In some embodiments, Dv50 > 20 μm, for example, > 50 μm or > 100 μm.

[0104] The span (Dv50) / (Dv90-Dv10) (where Dv10, Dv50, and Dv90 represent the particle size at 10%, 50%, and 90% of the volumetric distribution) can vary, for example, from 100 to 10, from 10 to 5, from 5 to 2, and from 2 to 1; in some embodiments, the span can be less than 1. In some embodiments, the composite comprising the particle size distribution of carbon and porous silicon materials can be multimodal, such as bimodal or trimodal.

[0105] The surface functionality of the composite materials disclosed in this invention, exhibiting extremely durable lithium intercalation, can be modified to obtain the desired electrochemical properties. One property that can predict surface functionality is the pH of the composite material. The composite materials disclosed in this invention contain pH values ​​from less than 1 to about 14, for example, 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 other embodiments, the pH is high and the pH range of the composite material is greater than 8, greater than 9, greater than 10, greater than 11, greater than 12, or even greater than 13.

[0106] The silicon-carbon composite material may contain varying amounts of carbon, oxygen, hydrogen, and nitrogen as measured by gas chromatography-CHNO analysis. In one embodiment, the composite has a carbon content greater than 98 wt.% or even greater than 99.9 wt%, as measured by CHNO analysis. In another embodiment, the carbon content of the silicon-carbon composite is about 10-90%, for example 20-80%, for example 30-70%, for example 40-60%.

[0107] In some embodiments, the nitrogen content of the silicon-carbon composite material is 0-90%, for example 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%.

[0108] In some embodiments, the oxygen content is 0-90%, for example 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%.

[0109] Silicon-carbon composites can also be incorporated with electrochemical modifiers, selected to optimize the electrochemical properties of the unmodified composite. The electrochemical modifiers can be incorporated within the pore structure and / or surface of the porous carbon scaffold, within embedded silicon, or within the final carbon layer, or within the conductive polymer, within a coating, or in any other manner. For example, in some embodiments, the composite includes a coating of an electrochemical modifier (e.g., silicon or Al₂O₃) on the surface of the carbon material. In some embodiments, the composite contains more than about 100 ppm of the electrochemical modifier. In some embodiments, the electrochemical modifier is selected from iron, tin, silicon, nickel, aluminum, and manganese.

[0110] In some embodiments, the electrochemical modifier comprises an element (e.g., silicon, tin, sulfur) capable of lithiation at 3 to 0 V relative to lithium metal. In other embodiments, the electrochemical modifier comprises a metal oxide (e.g., iron oxide, molybdenum oxide, titanium oxide) capable of lithiation at 3 to 0 V relative to lithium metal. In other embodiments, the electrochemical modifier comprises an element that does not lithilate at 3 to 0 V relative to lithium metal (e.g., aluminum, manganese, nickel, metal phosphates). In other embodiments, the electrochemical modifier comprises a nonmetallic element (e.g., fluorine, nitrogen, hydrogen). In other embodiments, the electrochemical modifier comprises any one or any combination of the aforementioned electrochemical modifiers (e.g., tin-silicon, nickel-titanium oxide).

[0111] Electrochemical modifiers can be provided in various forms. 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 elemental 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.

[0112] The electrochemical properties of a composite material can be modified, at least in part, by the amount of an electrochemical modifier in the material, wherein the electrochemical modifier is an alloying material, such as silicon, tin, indium, aluminum, germanium, or gallium. Therefore, in some embodiments, the composite material contains at least 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% of the electrochemical modifier.

[0113] Compared to the non-lithiation state, the particle size of the composite material can expand during lithiation. For example, the expansion factor is defined as the ratio of the average particle size of the composite material containing porous silicon material during lithiation to the average particle size under non-lithiation conditions. As described in the art, this expansion factor can be relatively large for previously known suboptimal silicon-containing materials, for example, about 4X (corresponding to 400% volume expansion during lithiation). The inventors have discovered that composite materials containing porous silicon material can exhibit a lower degree of expansion, for example, the expansion factor can vary from 3.5 to 4, 3.0 to 3.5, 2.5 to 3.0, 2.0 to 2.5, 1.5 to 2.0, and 1.0 to 1.5.

[0114] It is conceivable that, in some embodiments, the composite material will contain a portion of the pore volume, i.e., the volume of voids inaccessible to nitrogen as detected by nitrogen adsorption measurements. Without being bound by theory, this pore volume is important because it provides the volume into which silicon can expand during lithiation.

[0115] In some embodiments, the ratio of the void volume to the silicon volume constituting the composite particle is from 0.1:1 to 10:1. For example, the ratio is from 1:1 to 5:1 or from 5:1 to 10:1. In some embodiments, to effectively accommodate the maximum expansion of silicon during lithiation, the ratio is from 2:1 to 5:1, or about 3:1.

[0116] In some embodiments, the composite particles have a mean sphericity of at least 0.5 or at least 0.55 (as defined herein). In other embodiments, the mean sphericity is at least 0.65, or at least 0.7, or at least 0.75, or at least 0.8.

[0117] Highly accurate two-dimensional projections of micron-scale particles can be obtained through scanning electron microscopy (SEM) or dynamic image analysis, where a digital camera is used to record the shadow cast by the particle projection. The term "sphericity" as used herein should be understood as the ratio of the area of ​​the particle projection (obtained from this type of imaging technique) to the area of ​​a circle, where the particle projection and the circle have the same circumference. Therefore, for a single particle, the sphericity S can be defined as:

[0118]

[0119] Where A m C is the measured area of ​​the particle projection. m This is the measured perimeter of the particle projection. The mean sphericity S of the particle group used in this paper... av Defined as:

[0120]

[0121] Where n represents the number of particles in the group. The average sphericity of the particle group is preferably calculated by two-dimensional projection of at least 50 particles.

[0122] In some embodiments, the electrochemical performance of the disclosed composites is tested in a half-cell; alternatively, the performance of the disclosed composites with extremely durable lithium intercalation is tested in a full cell (e.g., a full-cell button cell, a full-cell pouch cell, a prismatic cell, or other battery pack structures known in the art). As known in the art, anode compositions comprising the disclosed composites with extremely durable lithium intercalation may further comprise a variety of substances. Additional formulation components include, but are not limited to, conductive additives such as conductive carbon (e.g., Super C45, Super P, Ketjenblack carbon, etc.), conductive polymers, etc., binders such as styrene-butadiene rubber sodium carboxymethyl cellulose (SBR-Na-CMC), polyvinylidene fluoride (PVDF), polyimide (PI), polyacrylic acid (PAA), etc., and combinations thereof. In some embodiments, the binder may contain lithium ions as counterions.

[0123] Other substances constituting the electrode are known in the art. The percentage of active material in the electrode by weight can vary, for example, 1 to 5%, for example, 5 to 15%, for example, 15 to 25%, for example, 25 to 35%, for example, 35 to 45%, for example, 45 to 55%, for example, 55 to 65%, for example, 65 to 75%, for example, 75 to 85%, for example, 85 to 95%. In some embodiments, the active material constitutes 80 to 95% of the electrode. In some embodiments, the amount of conductive additive in the electrode can vary, for example, 1 to 5%, 5 to 15%, for example, 15 to 25%, for example, 25 to 35%. In some embodiments, the amount of active material in the electrode is 5 to 25%. In some embodiments, the amount of binder can vary, for example, 1 to 5%, 5 to 15%, for example, 15 to 25%, for example, 25 to 35%. In some embodiments, the amount of conductive additive in the electrode is 5 to 25%.

[0124] As is known in the art, silicon-carbon composite materials can be pre-lithiated. In some embodiments, pre-lithiation is electrochemically achieved, for example, in a half-cell, before assembling a lithium-ion anode containing porous silicon material into a full-cell lithium-ion battery pack. In some embodiments, pre-lithiation is achieved by doping a cathode with a lithium-containing compound, such as a lithium salt. Examples of suitable lithium salts herein include, but are not limited to, lithium(II) tetrabromonickel oxide, lithium(II) tetrachlorocopper oxide, lithium azide, lithium benzoate, lithium bromide, lithium carbonate, lithium chloride, lithium cyclohexanebutyrate, lithium fluoride, lithium formate, lithium hexafluoroarsenic(V) oxide, 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.

[0125] Anodes incorporating silicon-carbon composite materials can be paired with a variety of cathode materials to obtain full-cell lithium-ion battery packs. Examples of suitable cathode materials are known in the art. Examples of such cathode materials include, but are not limited to, LiCoO2 (LCO) and 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).

[0126] For full-cell lithium-ion battery packs that include an anode also comprising a silicon-carbon composite material, the cathode-anode pairing can be varied. For example, the cathode-to-anode capacity ratio can be varied from 0.7 to 1.3. In some embodiments, the cathode-to-anode capacity ratio can be varied from 0.7 to 1.0, such as 0.8 to 1.0, 0.85 to 1.0, 0.9 to 1.0, or 0.95 to 1.0. In other embodiments, the cathode-to-anode capacity ratio can be varied from 1.0 to 1.3, such as 1.0 to 1.2, 1.0 to 1.15, 1.0 to 1.1, or 1.0 to 1.05. In other embodiments, the cathode-to-anode capacity ratio can be varied from 0.8 to 1.2, such as 0.9 to 1.1 or 0.95 to 1.05.

[0127] For full-cell lithium-ion battery packs that include an anode comprising a silicon-carbon composite material, the voltage windows for charging and discharging can be varied. In this respect, the voltage window can be varied as is known in the art, depending on various properties of the lithium-ion battery pack. For example, the choice of cathode plays a role in the selected voltage window, as is known in the art. Examples of voltage windows, for example, vary from 2.0V to 5.0V, such as 2.5V to 4.5V, or 2.5V to 4.2V, depending on the potential variation relative to Li / Li+.

[0128] For a full-cell lithium-ion battery pack that also includes an anode comprising a silicon-carbon composite material, the battery conditioning strategy can vary as is known in the art. For example, conditioning can be accomplished by one or more charge and discharge cycles at various rates (e.g., at rates slower than the desired cycle rate). As is known in the art, the conditioning process can also include the steps of unsealing the lithium-ion battery pack, evacuating any gases generated therein during the conditioning process, and then resealing the lithium-ion battery pack.

[0129] For a full-cell lithium-ion battery pack including an anode that also comprises a silicon-carbon composite material, the cycle rate can vary as is known in the art, for example, the rate can be C / 20 to 20C, such as C10 to 10C, such as C / 5 to 5C. In some embodiments, the cycle rate is C / 10. In some embodiments, the cycle rate is C / 5. In some embodiments, the cycle rate is C / 2. In some embodiments, the cycle rate is 1C. In some embodiments, the cycle rate is 1C, wherein the rate is periodically reduced to a slower rate, such as cycling at 1C, wherein every 20th cycle uses a rate of C / 10. In some embodiments, the cycle rate is 2C. In some embodiments, the cycle rate is 4C. In some embodiments, the cycle rate is 5C. In some embodiments, the cycle rate is 10C. In some embodiments, the cycle rate is 20C.

[0130] The first cycle efficiency of the lithium-intercalated composite disclosed herein is determined by comparing the lithium intercalated into the anode during the first cycle with the lithium deintercalated from the anode during the first cycle (before pre-lithiation modification). The efficiency is 100% when intercalation and deintercalation are equal. As is known in the art, the anode material can be tested in a half-cell where the counter electrode is lithium metal, the electrolyte is 1M LiPF6 1:1 ethylene carbonate:diethyl carbonate (EC:DEC), and a commercially available polypropylene separator is used. In some embodiments, the electrolyte may contain various additives known to provide improved performance, such as fluoroethylene carbonate (FEC) or other related fluorinated carbonate compounds, or ester cosolvents such as methyl butyrate, vinylene carbonate, and other electrolyte additives known to improve the electrochemical performance of silicon-containing anode materials.

[0131] Coulombic efficiency can be averaged, for example, by averaging from cycle 7 to cycle 25 when tested in a half-cell. In some embodiments, the average efficiency of the complex with extremely durable lithium intercalation is greater than 0.9 or 90%. In some embodiments, the average efficiency is greater than 0.95 or 95%. In some other embodiments, the average efficiency is 0.99 or greater, such as 0.991 or greater, such as 0.992 or greater, such as 0.993 or greater, such as 0.994 or greater, such as 0.995 or greater, such as 0.996 or greater, such as 0.997 or greater, such as 0.998 or greater, such as 0.999 or greater, such as 0.9991 or greater, such as 0.9992 or greater, such as 0.9993 or greater, such as 0.9994 or greater, such as 0.9995 or greater, such as 0.9996 or greater, such as 0.9997 or greater, such as 0.9998 or greater, such as 0.9999 or greater.

[0132] In other embodiments, this disclosure provides a lithium-intercalation composite material exhibiting extremely durable performance, wherein when the composite material is incorporated into the electrodes of a lithium-based energy storage device, the volumetric capacity of the composite material is at least 10% greater than that of a lithium-based energy storage device including a graphite electrode. In some embodiments, the lithium-based energy storage device is a lithium-ion battery pack. In other embodiments, the volumetric capacity of the composite material in the lithium-based energy storage device is at least 5%, at least 10%, or at least 15% greater than the volumetric capacity of the same energy storage device having a graphite electrode. In other embodiments, the volumetric capacity of the composite material in the lithium-based energy storage device 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 the same energy storage device having a graphite electrode.

[0133] As is known in the art, the composite material can be pre-lithiated. These lithium atoms may or may not be separated from the carbon. The number of lithium atoms relative to 6 carbon atoms (#Li) can be calculated using techniques known to those skilled in the art:

[0134] #Li=Q x 3.6x MM / (C%x F)

[0135] Where Q is the lithium intercalation / deintercalation capacity relative to lithium metal at voltages between 5 mV and 2.0 V, measured in mAh / g; MM is the molecular weight of 72 or 6 carbons; F is the Faraday constant of 96,500; and C% is the mass percentage of carbon present in the structure as measured by CHNO or XPS.

[0136] The composite material can be characterized by a lithium to carbon atom ratio (Li:C), which can vary from about 0:6 to 2:6. In some embodiments, the Li:C ratio is from about 0.05:6 to about 1.9:6. In other embodiments, the maximum Li:C ratio in which lithium is in ionic rather than metallic form is 2.2:6. In some other embodiments, the Li:C ratio is from about 1.2:6 to about 2:6, from about 1.3:6 to about 1.9:6, from about 1.4:6 to about 1.9:6, from about 1.6:6 to about 1.8:6, or from about 1.7:6 to 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 even greater than 1.8:6. In even 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 a specific embodiment, the Li:C ratio is about 1.78:6.

[0137] In some other embodiments, the Li:C ratio of the composite material is 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 other embodiments, the composite material may not necessarily contain lithium, but rather possess lithium absorption capacity (i.e., the ability to absorb a certain amount of lithium), for example, when cycling the material between two voltage conditions (in the case of a lithium-ion half-cell, exemplary voltage windows are located between 0 and 3V, such as 0.005 to 2.7V, such as 0.005 to 1V, such as 0.005 to 0.8V). While not wishing to be bound by theory, it is believed that the lithium absorption capacity of composite materials contributes to their excellent performance in lithium-based energy storage devices. Lithium absorption capacity is expressed as the ratio of lithium atoms absorbed by the composite. In some other embodiments, the lithium absorption capacity of the composite material exhibiting extremely durable lithium intercalation is 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.

[0138] In some other embodiments, the lithium absorption 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 absorption capacity is greater than 1:6, greater than 1.2:6, greater than 1.4:6, greater than 1.6:6, or even greater than 1.8:6. In even 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 a specific embodiment, the Li:C ratio is about 1.78:6. Example

[0139] Example 1.

[0140] Silicon-carbon composite materials were prepared by CVI.

[0141] The properties of the carbon scaffold (carbon scaffold 1) used to prepare the silicon-carbon composite are shown in Table 4. Using carbon scaffold 1, the silicon-carbon composite (silicon-carbon composite 1) was prepared via CVI as follows: 0.2 g of amorphous porous carbon was placed in a 2 inch × 2 inch ceramic crucible and then placed in the center of a horizontal tube furnace. The furnace was sealed and continuously purged with nitrogen at 500 cubic centimeters per minute (ccm). The furnace temperature was increased to a peak temperature of 450 °C at 20 °C / min and allowed to equilibrate at this peak temperature for 30 minutes. At this point, the nitrogen was turned off, and silane and hydrogen were introduced at flow rates of 50 ccm and 450 ccm, respectively, for a total residence time of 30 minutes. After this residence time, the silane and hydrogen were turned off, and nitrogen was introduced into the furnace again to purge the internal atmosphere. Simultaneously, the furnace heat was turned off and allowed to cool to ambient temperature. The completed Si-C material was then removed from the furnace.

[0142] Table 4. Description of the carbon scaffold used in Example 1

[0143]

[0144] Example 2.

[0145] Analysis of various silicon composite materials.

[0146] Various carbon scaffold materials were used, and the carbon scaffold materials were characterized by nitrogen adsorption gas analysis to determine specific surface area, total pore volume, and the fraction of pore volume including micropores, mesopores, and macropores. The characterization data of the carbon scaffold materials are shown in Table 5, namely the data on carbon scaffold surface area, pore volume, and pore volume distribution (% micropores, % mesopores, and % macropores), all determined by nitrogen adsorption analysis.

[0147] Table 5. Properties of various carbon support materials

[0148]

[0149]

[0150] Various silicon-carbon composites were prepared using the CVI method with carbon scaffold samples as described in Table 5 and in a static bed configuration as generally described in Example 1. These silicon-carbon samples were prepared using a range of process conditions: silane concentrations from 1.25% to 100%, dilution gases of nitrogen or hydrogen, and starting carbon scaffold masses from 0.2 g to 700 g.

[0151] 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 comprise 60-90% silicon-carbon composite, 5-20% Na-CMC (as a binder), and 5-20% Super C45 (as a conductivity enhancer), and the electrolyte may comprise a 2:1 ratio of ethylene carbonate:diethyl carbonate, 1M LiPF6, and 10% fluoroethylene carbonate. The half-cell coin cell can be cycled for 5 cycles at C / 5 at 25°C, followed by cycling at C / 10. The voltage can be cycled between 0V and 0.8V, or alternatively, between 0V and 1.5V. Based on the half-cell coin cell data, the maximum capacity and the average coulombic efficiency (CE) over a cycle range of 7 to 20 cycles can be measured. The physicochemical and electrochemical properties of various silicon-carbon composites are shown in Table 6.

[0152] Table 6. Properties of various silicon-carbon materials

[0153]

[0154]

[0155] The graph of the average Coulomb efficiency as a function of Z is shown in... Figure 1 The results show that the average coulombic efficiency increases significantly for silicon-carbon samples with low Z values. In particular, all silicon-carbon samples with Z values ​​below 10.0 exhibit... > An average coulombic efficiency of 0.9941 was observed, and all silicon-carbon samples (silicon-carbon composite sample 12 to silicon-carbon composite sample 16) with Z greater than 10 were found to have < The average coulombic efficiency is 0.9909. Without being bound by theory, the high coulombic efficiency of the silicon-carbon sample with Z < 10 provides excellent cycle stability in full-cell lithium-ion battery packs. Further tests in the table reveal surprising and unexpected findings, including the silicon-carbon composite sample with Z < 10 and also containing… > The combination of carbon scaffolds with a microporosity of 70 provides > Average coulomb efficiency of 0.9950.

[0156] Therefore, in a preferred embodiment, the silicon-carbon composite material contains less than 10 Z, for example less than 5 Z, for example less than 3 Z, for example less than 2 Z, for example less than 1 Z, for example less than 0.5 Z, for example less than 0.1 Z, or 0 Z.

[0157] In some preferred embodiments, the silicon-carbon composite material comprises a carbon scaffold with a Z of less than 10 and a microporosity of >70%, such as a Z of less than 10 and a microporosity of >80%, such as a Z of less than 10 and a microporosity of >90%, such as a Z of less than 10 and a microporosity of >95%, such as a Z of less than 5 and a microporosity of >70%, such as a Z of less than 5 and a microporosity of >80%, such as a Z of less than 5 and a microporosity of >90%, such as a Z of less than 5 and a microporosity of >95%, such as a Z of less than 3 and a microporosity of >70%, such as a Z of less than 3 and a microporosity of >80%, such as a Z of less than 3 and a microporosity of >90%, such as a Z of less than 3 and a microporosity of >95%, such as a Z of less than 2 and a microporosity of >70%, such as a Z of less than 2 and a microporosity of >80%, such as a Z of less than 2 and a microporosity of >90%, such as a Z of less than 2 and a microporosity of >90%. Z and >95% microporosity, e.g., Z <1 and >70% microporosity, e.g., Z <1 and >80% microporosity, e.g., Z <1 and >90% microporosity, e.g., Z <1 and >95% microporosity, e.g., Z <0.5 and >70% microporosity, e.g., Z <0.5 and >80% microporosity, e.g., Z <0.5 and >90% microporosity, e.g., Z <0.5 And >95% microporosity, for example, less than 0.1 Z and >70% microporosity, for example, less than 0.1 Z and >80% microporosity, for example, less than 0.1 Z and >90% microporosity, for example, less than 0.1 Z and >95% microporosity, for example, 0 Z and >70% microporosity, for example, 0 Z and >80% microporosity, for example, 0 Z and >90% microporosity, for example, 0 Z and >95% microporosity.

[0158] In some preferred embodiments, the silicon-carbon composite material comprises a carbon scaffold with a Z of less than 10 and a microporosity of >70%, and wherein the silicon-carbon composite further comprises 15%-85% silicon and has a surface area of ​​less than 100 m². 2 / g; for example, Z less than 10 and microporosity >70%, wherein the silicon-carbon composite also contains 15%-85% silicon and has a surface area less than 50m². 2 / g; for example, Z less than 10 and microporosity >70%, wherein the silicon-carbon composite also contains 15%-85% silicon and has a surface area less than 30m². 2 / g; for example, Z less than 10 and microporosity >70%, wherein the silicon-carbon composite also contains 15%-85% silicon and has a surface area less than 10 m². 2 / g; for example, Z less than 10 and microporosity >70%, wherein the silicon-carbon composite also contains 15%-85% silicon and has a surface area less than 5m². 2 / g; for example, Z less than 10 and microporosity >80%, wherein the silicon-carbon composite also contains 15%-85% silicon and has a surface area less than 50m². 2 / g; for example, Z less than 10 and microporosity >80%, wherein the silicon-carbon composite also contains 15%-85% silicon and has a surface area less than 30m². 2 / g; for example, Z less than 10 and microporosity >80%, wherein the silicon-carbon composite also contains 15%-85% silicon and has a surface area less than 10 m². 2 / g; for example, Z less than 10 and microporosity >80%, wherein the silicon-carbon composite also contains 15%-85% silicon and has a surface area less than 5m². 2 / g; for example, Z less than 10 and microporosity >90%, wherein the silicon-carbon composite also contains 15%-85% silicon and has a surface area less than 50m². 2 / g; for example, Z less than 10 and microporosity >90%, wherein the silicon-carbon composite also contains 15%-85% silicon and has a surface area less than 30m². 2 / g; for example, Z less than 10 and microporosity >90%, wherein the silicon-carbon composite also contains 15%-85% silicon and has a surface area less than 10 m². 2 / g; for example, Z less than 10 and microporosity >90%, wherein the silicon-carbon composite also contains 15%-85% silicon and has a surface area less than 5m². 2 / g; for example, Z less than 10 and microporosity >95%, wherein the silicon-carbon composite also contains 15%-85% silicon and has a surface area less than 50m². 2 / g; for example, Z less than 10 and microporosity >95%, wherein the silicon-carbon composite also contains 15%-85% silicon and has a surface area less than 30m². 2 / g; for example, Z less than 10 and microporosity >95%, wherein the silicon-carbon composite also contains 15%-85% silicon and has a surface area less than 10 m². 2 / g; for example, Z less than 10 and microporosity >95%, wherein the silicon-carbon composite also contains 15%-85% silicon and has a surface area less than 5m². 2 / g.

[0159] In some preferred embodiments, the silicon-carbon composite material comprises a carbon scaffold with a Z of less than 10 and a microporosity of >70%, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 100 m². 2 / g; for example, Z less than 10 and microporosity >70%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 50m². 2 / g; for example, Z less than 10 and microporosity >70%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 30m². 2 / g; for example, Z less than 10 and microporosity >70%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 10 m². 2 / g; for example, Z less than 10 and microporosity >70%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 5m². 2 / g; for example, Z less than 10 and microporosity >80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 50m². 2 / g; for example, Z < 10 and microporosity > 80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g; for example, Z less than 10 and microporosity >80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 10 m². 2 / g; for example, Z less than 10 and microporosity >80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 5m². 2 / g; for example, Z less than 10 and microporosity >90%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 50m². 2 / g; for example, Z less than 10 and microporosity >90%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 30m². 2 / g; for example, Z less than 10 and microporosity >90%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 10 m². 2 / g; for example, Z less than 10 and microporosity >90%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 5m². 2 / g; for example, Z less than 10 and microporosity >95%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 50m². 2 / g; for example, Z less than 10 and microporosity >95%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 30m². 2 / g; for example, Z less than 10 and microporosity >95%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 10 m². 2 / g; for example, Z less than 10 and microporosity >95%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 5m². 2 / g.

[0160] In some preferred embodiments, the silicon-carbon composite material comprises a carbon scaffold with a Z of less than 10 and a microporosity of >80%, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g and an average coulombic efficiency ≥0.9969. For example, silicon-carbon composites contain carbon scaffolds with a Z of less than 10 and a microporosity >80%, and wherein the silicon-carbon composite also contains 30%-60% silicon and a surface area of ​​less than 30m². 2 / g and an average coulombic efficiency ≥0.9970. For example, silicon-carbon composites contain carbon scaffolds with a Z of less than 10 and a microporosity >80%, and wherein the silicon-carbon composite also contains 30%-60% silicon and a surface area of ​​less than 30 m². 2 / g and an average coulombic efficiency ≥0.9975. For example, silicon-carbon composites contain carbon scaffolds with a Z of less than 10 and a microporosity >80%, and wherein the silicon-carbon composite also contains 30%-60% silicon and a surface area of ​​less than 30m². 2 / g and an average coulombic efficiency ≥0.9980. For example, silicon-carbon composites contain carbon scaffolds with a Z of less than 10 and a microporosity >80%, and wherein the silicon-carbon composite also contains 30%-60% silicon and a surface area of ​​less than 30m². 2 / g and an average coulombic efficiency ≥0.9985. For example, silicon-carbon composites contain carbon scaffolds with a Z of less than 10 and a microporosity >80%, and wherein the silicon-carbon composite also contains 30%-60% silicon and a surface area of ​​less than 30m². 2 / g and an average coulombic efficiency ≥0.9990. For example, silicon-carbon composites contain carbon scaffolds with a Z of less than 10 and a microporosity >80%, and wherein the silicon-carbon composite also contains 30%-60% silicon and a surface area of ​​less than 30m². 2 / g and an average coulombic efficiency ≥0.9995. For example, silicon-carbon composites contain carbon scaffolds with a Z of less than 10 and a microporosity >80%, and wherein the silicon-carbon composite also contains 30%-60% silicon and a surface area of ​​less than 30m². 2 / g and average coulombic efficiency ≥0.9999.

[0161] Example 3.

[0162] dV / dQ of various silicon composite materials.

[0163] Differential capacity curves (dQ / dV versus voltage) are commonly used as a non-destructive tool to understand phase transitions as a function of voltage in lithium-ion battery electrodes (MNObrovac et al., Structural Changes in Silicon Anodes during Lithium Insertion / Extraction, Electrochemical and Solid-State Letters, 7(5)A93-A96(2004); Ogata, K. et al., Revealing lithium–silicide phase transformations in nano-structured silicon-based lithium ion batteries via insitu NMR spectroscopy. Nat. Commun. 5:3217). The differential capacity curves presented in this paper were calculated from data obtained by constant current cycling at 0.1C rate from 5mV to 0.8V in half-cell coin cells at 25°C. Typical differential capacity curves of silicon-based materials versus lithium in half-cells can be found in many references (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); MNObrovac et al., Li15Si4 Formation in SiliconThin 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 metalpowder, Journal of Power Sources 347 (2017)170-177). The first-cycle lithiation behavior depends on factors such as the crystallinity of silicon and oxygen content.

[0164] Following the first cycle, previous amorphous silicon materials in the art exhibited two distinct phase transition peaks in the dQ / dV vs. V plots for lithiation, and correspondingly two distinct phase transition peaks in the dQ / dV vs. V plots for delithiation. For lithiation, one peak corresponding to the lithium-poor Li-Si alloy phase appears between 0.2 and 0.4 V, while another peak corresponding to the lithium-rich Li-Si alloy phase appears below 0.15 V. For delithiation, one delithiation peak corresponding to lithium intercalation appears below 0.4 V, while another peak appears between 0.4 V and 0.55 V. If Li 15 The Si4 phase forms during lithiation, and it delithiates at ~0.45V, exhibiting a very narrow, sharp peak.

[0165] Figure 2 Cycle 2 dQ / dV versus voltage curves for the silicon-carbon composite material corresponding to silicon-carbon composite 3 of Example 1 are plotted. Silicon-carbon composite 3 contains a Z of 0.6. For ease of identification, the graph is divided into regions I, II, III, IV, V, and VI. Regions I (0.8V to 0.4V), II (0.4V to 0.15V), and III (0.15V to 0V) constitute the lithiation potential, and regions IV (0V to 0.4V), V (0.4V to 0.55V), and VI (0.55V to 0.8V) include the delithiation potential. As described above, previous amorphous silicon-based materials in the art exhibit phase transition peaks in two regions (regions II and III) of the lithiation potential and two regions (regions IV and V) of the delithiation potential.

[0166] from Figure 2 As can be seen, the dQ / dV voltage curves reveal surprising and unexpected results. The silicon-carbon composite 3 (containing 0.6 Z) exhibits two additional peaks in the dQ / dV voltage curves: region I in the lithiation potential and region VI in the delithiation potential. All six peaks are reversible and were also observed in subsequent cycles, such as... Figure 3 As shown in the image.

[0167] Without being bound by theory, this three-peak behavior of the dQ / dV curve with respect to V is novel and also reflects a novel form of silicon.

[0168] It is noteworthy that the novel peaks observed in regions I and VI are more pronounced in some scaffold matrices, but are not present at all in other samples illustrating the prior art (silicon-carbon composite samples with Z>10, see explanation and table below).

[0169] Figure 4The dQ / dV versus V curves of silicon-carbon composite 3 are shown, where the new peaks in regions I and VI are evident compared to those of silicon-carbon composites 15, 16, and 14 (all three of which contain Z>10 and whose dQ / dV versus V curves have no peaks in regions I and VI).

[0170] Without being bound by theory, these novel peaks observed in Regions I and VI relate to the properties of silicon impregnated into the porous carbon scaffold, specifically the interactions between and within the properties of the porous carbon scaffold, silicon, and lithium impregnated into the porous carbon scaffold via CVI. To provide quantitative analysis, we define parameters in this paper. ("phi"), which is calculated as the normalized peak I relative to peak III:

[0171]

[0172] In this study, dQ / dV was measured in a half-cell coin cell, with region I being 0.8V–0.4V and region III being 0.15V–0V; the half-cell coin cell was manufactured as is known in the art. If the Si-C sample exhibited a graphite-related peak in region III of the differential curve, this was omitted when calculating the D-factor, and the Li-Si-related phase transition peak was used instead. For this example, the half-cell coin cell included an anode comprising 60–90% silicon-carbon composite, 5–20% SBR-Na-CMC, and 5–20% Super C45. Figure 5 The image shows silicon-carbon composite 3. Example of calculation. In this case, the maximum peak height in region I is -2.39 and is found at a voltage of 0.53V. Similarly, the maximum peak height in region III is -9.71 at 0.04V. In this case, the above formula can be used to calculate... get The data were determined from the half-cell coin cell data of various silicon-carbon composites given in Example 2. The values ​​are summarized in Table 7. Table 7 also includes data on the first-cycle efficiency measured for half-cell coin cells cycling from 5mV to 0.8V.

[0173] Table 7. Properties of various silicon-carbon scaffold materials.

[0174]

[0175]

[0176] *These data represent the first cycle efficiency measurements taken over a voltage window from 5mV to 1.5V.

[0177] The data in Table 7 reveal the effects of decreasing Z and increasing Z. An unexpected relationship exists between them. All silicon-carbon complexes with Z < 10 possess... Furthermore, all silicon-carbon composites with Z>10 possess In fact, all silicon-carbon composites with Z>10 have This relationship also Figure 6 This has been proven. Without being bound by theory, it contains... For example For example For example For example For example The silicon material corresponds to a new form of silicon. Alternatively, it contains... The silicon material corresponds to a new form of silicon. This includes... For example For example For example For example For example The silicon-carbon composite material corresponds to a novel silicon-carbon composite material. Alternatively, it contains... The silicon-carbon composite material corresponds to the novel silicon-carbon composite material.

[0178] In some embodiments, the silicon-carbon composite contains or In some implementation schemes, In some implementation schemes, or

[0179] In some embodiments, the silicon-carbon composite comprises a carbon scaffold with a Z of less than 10 and a microporosity of >70%, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 100 m². 2 / g, For example, a Z value less than 10 and a microporosity >70%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 50 m². 2 / g, For example, a Z value less than 10 and a microporosity >70%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 30 m². 2 / g, For example, a Z value less than 10 and a microporosity >70%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 10 m². 2 / g, For example, a Z value less than 10 and a microporosity >70%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 5 m². 2 / g,

[0180] In some embodiments, the silicon-carbon composite comprises a carbon scaffold with a Z of less than 10 and a microporosity of >70%, and wherein the silicon-carbon composite further comprises 40%-60% silicon and has a surface area of ​​less than 100 m². 2 / g, For example, a Z value less than 10 and a microporosity >70%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 50 m². 2 / g, For example, a Z value less than 10 and a microporosity >70%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 30 m². 2 / g, For example, a Z value less than 10 and a microporosity >70%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 10 m². 2 / g, For example, a Z value less than 10 and a microporosity >70%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 5 m². 2 / g,

[0181] In some embodiments, the silicon-carbon composite comprises a carbon scaffold with a Z of less than 10 and a microporosity of >70%, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 100 m². 2 / g, For example, a Z value less than 10 and a microporosity >70%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 50 m². 2 / g, For example, a Z value less than 10 and a microporosity >70%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 30 m². 2 / g, For example, a Z value less than 10 and a microporosity >70%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 10 m². 2 / g, For example, a Z value less than 10 and a microporosity >70%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 5 m². 2 / g,

[0182] In some embodiments, the silicon-carbon composite comprises a carbon scaffold with a Z of less than 10 and a microporosity of >70%, and wherein the silicon-carbon composite further comprises 40%-60% silicon and has a surface area of ​​less than 100 m². 2 / g, For example, a Z value less than 10 and a microporosity >70%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 50 m². 2 / g, For example, a Z value less than 10 and a microporosity >70%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 30 m². 2 / g, For example, a Z value less than 10 and a microporosity >70%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 10 m². 2 / g, For example, a Z value less than 10 and a microporosity >70%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 5 m². 2 / g,

[0183] In some embodiments, the silicon-carbon composite comprises a carbon scaffold with a Z of less than 10 and a microporosity of >80%, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 100 m². 2 / g, For example, a Z value less than 10 and a microporosity >80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 50 m². 2 / g, For example, a Z value less than 10 and a microporosity >80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 30 m². 2 / g, For example, a Z value less than 10 and a microporosity >80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 10 m². 2 / g, For example, a Z value less than 10 and a microporosity >80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 5 m². 2 / g,

[0184] In some embodiments, the silicon-carbon composite comprises a carbon scaffold with a Z of less than 10 and a microporosity of >80%, and wherein the silicon-carbon composite further comprises 40%-60% silicon and has a surface area of ​​less than 100 m². 2 / g, For example, a Z value less than 10 and a microporosity >80%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 50 m². 2 / g, For example, a Z value less than 10 and a microporosity >80%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 30 m². 2 / g, For example, a Z value less than 10 and a microporosity >80%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 10 m². 2 / g, For example, a Z value less than 10 and a microporosity >80%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 5 m². 2 / g,

[0185] In some embodiments, the silicon-carbon composite comprises a carbon scaffold with a Z of less than 10 and a microporosity of >80%, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 100 m². 2 / g, For example, a Z value less than 10 and a microporosity >80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 50 m². 2 / g, For example, a Z value less than 10 and a microporosity >80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 30 m². 2 / g, For example, a Z value less than 10 and a microporosity >80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 10 m². 2 / g, For example, a Z value less than 10 and a microporosity >80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 5 m². 2 / g,

[0186] In some embodiments, the silicon-carbon composite comprises a carbon scaffold with a Z of less than 10 and a microporosity of >80%, and wherein the silicon-carbon composite further comprises 40%-60% silicon and has a surface area of ​​less than 100 m². 2 / g, For example, a Z value less than 10 and a microporosity >80%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 50 m². 2 / g, For example, a Z value less than 10 and a microporosity >80%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 30 m². 2 / g, For example, a Z value less than 10 and a microporosity >80%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 10 m². 2 / g, For example, a Z value less than 10 and a microporosity >80%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 5 m². 2 / g,

[0187] In some embodiments, the silicon-carbon composite comprises a carbon scaffold with a Z of less than 10 and a microporosity of >90%, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 100 m². 2 / g, For example, a Z value less than 10 and a microporosity >90%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 50 m². 2 / g, For example, a Z value less than 10 and a microporosity >90%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 30 m². 2 / g, For example, a Z value less than 10 and a microporosity >90%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 10 m². 2 / g, For example, a Z value less than 10 and a microporosity >90%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 5 m². 2 / g,

[0188] In some embodiments, the silicon-carbon composite comprises a carbon scaffold with a Z of less than 10 and a microporosity of >90%, and wherein the silicon-carbon composite further comprises 40%-60% silicon and has a surface area of ​​less than 100 m². 2 / g, For example, a Z value less than 10 and a microporosity >90%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 50 m². 2 / g, For example, a Z value less than 10 and a microporosity >90%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 30 m². 2 / g, For example, a Z value less than 10 and a microporosity >90%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 10 m². 2 / g, For example, a Z value less than 10 and a microporosity >90%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 5 m². 2 / g,

[0189] In some embodiments, the silicon-carbon composite comprises a carbon scaffold with a Z of less than 10 and a microporosity of >90%, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 100 m². 2 / g, For example, a Z value less than 10 and a microporosity >90%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 50 m². 2 / g, For example, a Z value less than 10 and a microporosity >90%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 30 m². 2 / g, For example, a Z value less than 10 and a microporosity >90%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 10 m². 2 / g, For example, a Z value less than 10 and a microporosity >90%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 5 m². 2 / g,

[0190] In some embodiments, the silicon-carbon composite comprises a carbon scaffold with a Z of less than 10 and a microporosity of >90%, and wherein the silicon-carbon composite further comprises 40%-60% silicon and has a surface area of ​​less than 100 m². 2 / g, For example, a Z value less than 10 and a microporosity >90%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 50 m². 2 / g, For example, a Z value less than 10 and a microporosity >90%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 30 m². 2 / g, For example, a Z value less than 10 and a microporosity >90%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 10 m². 2 / g, For example, a Z value less than 10 and a microporosity >90%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 5 m². 2 / g,

[0191] In some embodiments, the silicon-carbon composite comprises a carbon scaffold with a Z of less than 10 and a microporosity of >95%, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 100 m². 2 / g, For example, a Z value less than 10 and a microporosity >95%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 50 m². 2 / g, For example, a Z value less than 5 and a microporosity >95%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 30 m². 2 / g, For example, a Z value less than 10 and a microporosity >95%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 10 m². 2 / g, For example, a Z value less than 10 and a microporosity >95%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 5 m². 2 / g,

[0192] In some embodiments, the silicon-carbon composite comprises a carbon scaffold with a Z of less than 10 and a microporosity of >95%, and wherein the silicon-carbon composite further comprises 40%-60% silicon and has a surface area of ​​less than 100 m². 2 / g, For example, a Z value less than 10 and a microporosity >95%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 50 m². 2 / g, For example, a Z value less than 10 and a microporosity >95%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 30 m². 2 / g, For example, a Z value less than 10 and a microporosity >95%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 10 m². 2 / g, For example, a Z value less than 10 and a microporosity >95%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 5 m². 2 / g,

[0193] In some embodiments, the silicon-carbon composite comprises a carbon scaffold with a Z of less than 10 and a microporosity of >95%, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 100 m². 2 / g, For example, a Z value less than 10 and a microporosity >95%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 50 m². 2 / g, For example, a Z value less than 10 and a microporosity >95%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 30 m². 2 / g, For example, a Z value less than 10 and a microporosity >95%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 10 m². 2 / g, For example, a Z value less than 10 and a microporosity >95%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 5 m². 2 / g,

[0194] In some embodiments, the silicon-carbon composite comprises a carbon scaffold with a Z of less than 10 and a microporosity of >95%, and wherein the silicon-carbon composite further comprises 40%-60% silicon and has a surface area of ​​less than 100 m². 2 / g, For example, a Z value less than 10 and a microporosity >95%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 50 m². 2 / g, For example, a Z value less than 10 and a microporosity >95%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 30 m². 2 / g, For example, a Z value less than 10 and a microporosity >95%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 10 m². 2 / g, For example, a Z value less than 10 and a microporosity >95%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 5 m². 2 / g,

[0195] In some embodiments, the silicon-carbon composite comprises a carbon scaffold with a Z of less than 10 and a microporosity of >80%, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency ≥0.9969; for example, silicon-carbon composites containing a Z of less than 10 and a carbon scaffold with a microporosity >80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency ≥0.9970; for example, silicon-carbon composites containing a carbon scaffold with a Z of less than 10 and a microporosity >80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency ≥0.9975; for example, silicon-carbon composites containing a carbon scaffold with a Z of less than 10 and a microporosity >80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency ≥0.9980; for example, silicon-carbon composites containing a carbon scaffold with a Z of less than 10 and a microporosity >80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency ≥0.9985; for example, silicon-carbon composites containing a Z of less than 10 and a carbon scaffold with a microporosity >80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency ≥0.9990; for example, silicon-carbon composites containing a Z of less than 10 and a carbon scaffold with a microporosity >80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency ≥0.9995; for example, silicon-carbon composites containing a carbon scaffold with a Z of less than 10 and a microporosity >80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And the average coulomb efficiency is ≥0.9999.

[0196] In some embodiments, the silicon-carbon composite comprises a carbon scaffold with a Z of less than 10 and a microporosity of >80%, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency ≥0.9969; for example, silicon-carbon composites containing a Z of less than 10 and a carbon scaffold with a microporosity >80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency ≥0.9970; for example, silicon-carbon composites containing a carbon scaffold with a Z of less than 10 and a microporosity >80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency ≥0.9975; for example, silicon-carbon composites containing a carbon scaffold with a Z of less than 10 and a microporosity >80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency ≥0.9980; for example, silicon-carbon composites containing a carbon scaffold with a Z of less than 10 and a microporosity >80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency ≥0.9985; for example, silicon-carbon composites containing a Z of less than 10 and a carbon scaffold with a microporosity >80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency ≥0.9990; for example, silicon-carbon composites containing a Z of less than 10 and a carbon scaffold with a microporosity >80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency ≥0.9995; for example, silicon-carbon composites containing a carbon scaffold with a Z of less than 10 and a microporosity >80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And the average coulomb efficiency is ≥0.9999.

[0197] In some embodiments, the silicon-carbon composite comprises a carbon scaffold with a Z of less than 10 and a microporosity of >80%, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency ≥0.9969; for example, silicon-carbon composites containing a Z of less than 10 and a carbon scaffold with a microporosity >80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency ≥0.9970; for example, silicon-carbon composites containing a carbon scaffold with a Z of less than 10 and a microporosity >80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency ≥0.9975; for example, silicon-carbon composites containing a carbon scaffold with a Z of less than 10 and a microporosity >80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency ≥0.9980; for example, silicon-carbon composites containing a carbon scaffold with a Z of less than 10 and a microporosity >80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency ≥0.9985; for example, silicon-carbon composites containing a Z of less than 10 and a carbon scaffold with a microporosity >80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency ≥0.9990; for example, silicon-carbon composites containing a Z of less than 10 and a carbon scaffold with a microporosity >80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency ≥0.9995; for example, silicon-carbon composites containing a carbon scaffold with a Z of less than 10 and a microporosity >80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And the average coulomb efficiency is ≥0.9999.

[0198] In some embodiments, the silicon-carbon composite comprises a carbon scaffold with a Z of less than 10 and a microporosity of >80%, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency ≥0.9969; for example, silicon-carbon composites containing a Z of less than 10 and a carbon scaffold with a microporosity >80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency ≥0.9970; for example, silicon-carbon composites containing a carbon scaffold with a Z of less than 10 and a microporosity >80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency ≥0.9975; for example, silicon-carbon composites containing a carbon scaffold with a Z of less than 10 and a microporosity >80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m².2 / g、 And an average coulombic efficiency ≥0.9980; for example, silicon-carbon composites containing a carbon scaffold with a Z of less than 10 and a microporosity >80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency ≥0.9985; for example, silicon-carbon composites containing a Z of less than 10 and a carbon scaffold with a microporosity >80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency ≥0.9990; for example, silicon-carbon composites containing a Z of less than 10 and a carbon scaffold with a microporosity >80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency ≥0.9995; for example, silicon-carbon composites containing a carbon scaffold with a Z of less than 10 and a microporosity >80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And the average coulomb efficiency is ≥0.9999.

[0199] Example 4. Primary spherical pyrolytic carbon particles are generated in the absence of a preferred exclusion agent.

[0200] Various samples were produced according to Table 8. Sucrose was weighed and added to a Teflon-lined autoclave, followed by deionized water. The solution was stirred until the sucrose was completely dissolved, then the autoclave was sealed and placed in a convection oven at an elevated temperature. The container remained at the temperature. During this time, the reaction proceeded via a hydrothermal condensation mechanism. After the residence period, the container was removed from the oven and allowed to cool completely to room temperature. The lid was slowly opened to allow residual vapor pressure to escape, and brown granular hydrothermal char (HTC) was collected from the container. The HTC was rinsed twice with deionized water on a filter, then dried at 80°C for >2 hours, and subsequently sieved through a 25-micron sieve. The dried HTC was then loaded into an alumina crucible and pyrolyzed in a tube furnace at 900°C under a constant nitrogen flow for 1 hour. The furnace was then cooled to room temperature to obtain the pyrolyzed spherical carbon product.

[0201] Table 8. Various samples of carbon particles produced from primary spherical pyrolysis in the absence of exclusion agents.

[0202]

[0203]

[0204] Various samples of primary spherical pyrolysis carbon particles produced in the absence of a preferred exclusion agent were characterized as outlined in Table 9.

[0205] Table 9. Characterization of various samples of carbon particles from primary spherical pyrolysis in the absence of exclusion agents.

[0206]

[0207] Example 5. Generation of primary spherical pyrolysis carbon particles in the presence of a exclusion agent.

[0208] Various samples were produced according to Table 10. Sucrose was weighed and added to a Teflon-lined autoclave, followed by deionized water containing varying amounts of poly(acrylic acid) (PAA) as a preferred exclusion agent. The solution was stirred until the sucrose was completely dissolved, then the autoclave was sealed and placed in a convection oven at elevated temperatures. The vessel remained at the temperature. During this period, the reaction proceeded via a hydrothermal condensation mechanism. After the residence time, the vessel was removed from the oven and allowed to cool completely to room temperature. The lid was slowly opened to allow residual vapor pressure to escape, and brown granular hydrothermal char (HTC) was collected from the vessel. The HTC was rinsed twice with deionized water on a filter, then dried at 80°C for >2 hours, and subsequently sieved through a 25-micron sieve. The dried HTC was then loaded into an alumina crucible and pyrolyzed in a tube furnace at 900°C under a constant nitrogen flow for 1 hour. The furnace was then cooled to room temperature to obtain the pyrolyzed spherical char product.

[0209] Table 10. Samples of primary spherical pyrolysis carbon particles produced in the presence of exclusion agents.

[0210]

[0211] The data in the table show that the overall yield tends to be higher for samples produced in the presence of a preferred exclusion agent, reaching as high as 7.4% for carbon scaffold 14. The Dv1, Dv50, and Dv99 of carbon scaffold 13 are 1.6 μm, 9.5 μm, and 33.0 μm, respectively, while those of carbon scaffold 14 are 1.6 μm, 8.6 μm, and 40.4 μm, respectively.

[0212] Figure 8 SEM images of various samples according to Example 5 were depicted. The SEM images reveal that the addition of PAA as a preferred exclusion agent controlled the morphology and particle size of the carbon scaffold particles. At the minimum addition amount of PAA (i.e., 1000:1 sucrose:PAA)... Figure 8 In the lower left image, when carbon support 16 is added, the particles show indentation, with most particles appearing in the 6-13 μm size range. As the PAA addition increases to 800:1 sucrose:PAA (…),… Figure 8 In the lower right image (carbon scaffold 13), the particles appear smoother, with most particles appearing in the 2.3-2.9 μm size. With the PAA addition further increased to 400:1 sucrose:PAA (… Figure 8 In the upper right image (carbon scaffold 14), the particles appear smoother, with most particles appearing in the 2.3-2.9 μm size range. Finally, at the highest PAA addition (100:1 sucrose:PAA) (… Figure 8 In the upper left image, under the carbon support 15, the particles are no longer spherical and show a very irregular shape.

[0213] In some embodiments, the polyol:surfactant ratio is greater than 1000:1. In some embodiments, the polyol:surfactant ratio is from 1000:1 to 800:1. In further embodiments, the polyol:surfactant ratio is from 800:1 to 600:1; 600:1 to 500:1; 500:1 to 400:1; 400:1 to 300:1; 300:1 to 200:1; 200:1 to 100:1. In some embodiments, the polyol:surfactant ratio is less than 100:1.

[0214] Example 6. Generation of primary spherical activated carbon particles.

[0215] Carbon scaffolds 13, 14, and 16 were activated by steam to increase the available porosity, resulting in scaffold samples 17, 18, and 19. In a typical experiment, 1 gram of pyrolyzed material was placed in an alumina crucible and then placed in the central hot zone of a horizontal tube furnace. The furnace was purged with a nitrogen stream (~500 sccm) directed through a bubbler (a flask heated to a set point of 200°C) upstream of the furnace containing distilled water. This served as a steam source to activate the carbon via the reaction C + H₂O => CO + H₂. The furnace temperature was ramped up to 900°C at a rate of 10°C / min and held for varying durations. The furnace environment was then cooled, and the samples were removed for analysis. An overview of the samples and their properties is given in Table 11.

[0216] Table 11. Samples that produced primary spherical activated carbon particles in the presence of exclusion agents.

[0217]

[0218] Example 7. Generation of primary spherical group 14 composite particles.

[0219] Silane gas was used to subject the carbon scaffold 13 to CVI to deposit silicon within the carbon porosity. The resulting material is a silicon-carbon composite 21, the properties of which are listed in Table 12. In a typical experiment, 0.2 g of the activating material was placed in an alumina crucible and then placed in the central hot zone of a horizontal tube furnace. The furnace was purged with a nitrogen gas flow (~500 sccm) for 10 min, and then ramped up to 475 °C at a rate of 20 °C / min. The furnace temperature was stabilized at the peak temperature for 30 min, and then the gas flow was switched to a 1.3 mol% SiH4 / N2 mixture at 580 sccm for 1.75 h. After deposition, the gas flow was switched back to pure nitrogen, and the furnace environment was cooled. When the furnace temperature reached <60 °C, the sample was removed for analysis.

[0220] Table 12. Properties of silicon-composite 21

[0221]

[0222] The measured particle size distribution of the silicon-carbon composite 21 is very similar to that of the starting carbon scaffold 13; the latter exhibits Dv1, Dv50, and Dv99 of 0.8 μm, 10.3 μm, and 48.7 μm, respectively. Figure 9 The SEM image of silicon-carbon composite 21 is depicted in the figure.

[0223] Example 8. Primary spherical activated carbon particles were produced in the absence of a preferred exclusion agent.

[0224] Primary spherical activated carbon particles were prepared according to Table 13. Sucrose was weighed and added to a Teflon-lined autoclave, followed by deionized water. Samples were prepared without a preferred exclusion agent. The solution was stirred until the sucrose was completely dissolved, then the autoclave was sealed and placed in a convection oven at an elevated temperature. The container remained at the temperature. During this period, the reaction proceeded via a hydrothermal condensation mechanism. After the residence period, the container was removed from the oven and allowed to cool completely to room temperature. The lid was slowly opened to allow residual vapor pressure to escape, and granular hydrothermal carbon (HTC) was collected from the container. The HTC was rinsed twice with deionized water on a filter and then dried at 80°C for >2 hours. The dried HTC was then loaded into an alumina crucible and pyrolyzed in a tube furnace at 900°C under a constant nitrogen flow for 1 hour. The furnace was then cooled to room temperature to obtain the pyrolyzed spherical carbon product.

[0225] Table 13. Samples of activated carbon granules produced from primary spherical pyrolysis

[0226]

[0227] Following pyrolysis, the particles are activated by steam to increase usable porosity. In a typical experiment, 1 gram of pyrolyzed material is placed in an alumina crucible and then placed in the central hot zone of a horizontal tube furnace. The furnace is purged with a nitrogen stream (~500 sccm) directed through a bubbler (a flask heated to a set point of 200°C) upstream of the furnace containing distilled water. This serves as a steam source to activate the carbon via the reaction C + H₂O => CO + H₂. The furnace temperature is ramped up to 900°C at a rate of 10°C / min and held for varying durations. The furnace environment is then cooled, and the sample is removed for analysis.

[0228] Following steam activation, various silicon-carbon composites were produced using the CVI method with an activated carbon scaffold as described in Table 13 and in a static bed configuration as generally described in Example 1. The physicochemical properties of the resulting silicon-carbon composites are shown in Table 14 and compared with silicon-carbon composites derived from non-polyol precursor materials, which are designated as silicon-carbon composites C1 and C2 in Table 14.

[0229] Table 14. Properties of primary spherical Si-C composite particles.

[0230]

[0231] The resulting silicon-carbon composites are uniform in appearance, without visible particle agglomeration and a soft texture. Without being bound by theory, in some cases, as shown in Table 14, the polyol-based Si-C composites exhibit lower surface areas after silicon CVI compared to contrasting Si-C composites produced from non-polyol precursors. In some cases, the surface area is less than 1.0 m². 2 / g but greater than 0.5m 2 / g.

[0232] Silicon-carbon composites 22 and 23 were also tested according to the methods generally described in Example 2. The physicochemical and electrochemical properties of these silicon-carbon composites are shown in Table 15.

[0233] Table 15. Properties of primary spherical Si-C composite particles

[0234]

[0235] Detailed Implementation Plan

[0236] Implementation Scheme 1. A Group 14 complex comprising a plurality of primary particles containing Group 14 elements silicon and carbon, wherein said particles exhibit a spherical morphology, a Dv50 less than or equal to 10 μm, a Z < 10, and The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0237] Implementation Scheme 2. A Group 14 complex comprising a plurality of primary particles containing Group 14 elements silicon and carbon, wherein said particles exhibit a spherical morphology, a Dv50 less than or equal to 10 μm, a Z < 10, and The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0238] Implementation Scheme 3. A Group 14 complex comprising a plurality of primary particles containing Group 14 elements silicon and carbon, wherein said particles exhibit a spherical morphology, a Dv50 less than or equal to 10 μm, a Z < 10, and The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0239] Implementation Scheme 4. A Group 14 complex comprising: (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) a Dv50 less than or equal to 10 μm; (d) Z < 10; and The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0240] Implementation Scheme 5. The group 14 complex according to Implementation Scheme 4, wherein

[0241] Implementation Scheme 6. The group 14 complex according to Implementation Scheme 4, wherein

[0242] Implementation Scheme 7. The Group 14 complex according to any one of Implementation Schemes 1 to 6, wherein Dv50 is less than or equal to 5 μm.

[0243] Implementation Scheme 8. The Group 14 complex according to any one of Implementation Schemes 1 to 7, wherein the individual particles of the porous carbon primary particles are discrete, non-agglomerated particles.

[0244] Implementation Scheme 9. The Group 14 complex according to any one of Implementation Schemes 1 to 8, wherein Z < 5.

[0245] Implementation Scheme 10. The Group 14 complex according to any one of Implementation Schemes 1 to 9, further comprising <50m 2 / g of surface area.

[0246] Implementation Scheme 11. The group 14 complex according to Implementation Schemes 1 to 10, further comprising: (a) greater than 0.6 cm 3 (a) the total pore volume / g; (b) the volume fraction of micropores in the range of 20-50% and the volume fraction of mesopores in the range of 50-80%; and (c) the fractional pore volume of pores of 10 nm or less, which accounts for at least 75% of the total pore volume from 5 nm to 20 μm.

[0247] Implementation Scheme 12. The Group 14 composite according to any one of Implementation Schemes 1 to 11, wherein the weight percentage of silicon to the porous carbon primary particles is 10% to 80%.

[0248] Implementation Scheme 13. A Group 14 complex comprising a plurality of primary particles containing Group 14 elements silicon and carbon, comprising 30 wt% to 60 wt% silicon, wherein said particles exhibit a spherical morphology, a Dv50 less than or equal to 10 μm, a Z < 10, and The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0249] Implementation Scheme 14. A Group 14 complex comprising a plurality of primary particles containing Group 14 elements silicon and carbon, comprising 30 wt% to 60 wt% silicon, wherein said particles exhibit a spherical morphology, a Dv50 less than or equal to 10 μm, a Z < 10, and The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0250] Implementation Scheme 15. A Group 14 complex comprising a plurality of primary particles containing Group 14 elements silicon and carbon, comprising 30 wt% to 60 wt% silicon, wherein said particles exhibit a spherical morphology, a Dv50 less than or equal to 10 μm, a Z < 10, and The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0251] Implementation Scheme 16. A Group 14 complex comprising: (a) a plurality of primary particles comprising Group 14 elements silicon and carbon, wherein the primary particles have a sphericity of at least 0.5 and wherein each particle comprises a porous carbon scaffold; (b) 30 wt% to 60 wt% silicon; (c) Dv50 less than or equal to 10 μm; (d) Z < 10; and The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0252] Implementation Scheme 17. A group 14 complex comprising carbon and silicon, wherein: (a) the carbon comprises a porous carbon scaffold derived from a polyol, and further comprises: (i) amorphous carbon, (ii) a pore volume wherein greater than 70% of the pore volume consists of pores with a diameter less than 2 nm, and (iii) a Dv90 less than 50 nm; (b) the silicon comprises: (i) amorphous nanoscale silicon embedded within the pore volume of the porous carbon scaffold; and (c) the group 14 complex further comprises: (i) 30 wt% to 60 wt% silicon, (ii) a Dv50 less than or equal to 10 μm, (iii) Z < 10, and The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0253] Implementation Scheme 18. The Group 14 complex according to any one of Implementation Schemes 1 to 10 and Implementation Schemes 12 to 17, further comprising a carbon scaffold containing a pore volume, wherein the pore volume comprises a microporosity of >70%.

[0254] Implementation Scheme 19. The Group 14 complex according to any one of Implementation Schemes 1 to 10 and Implementation Schemes 12 to 17, further comprising a carbon scaffold containing a pore volume, wherein the pore volume comprises a microporosity of >80%.

[0255] Implementation Scheme 20. The Group 14 complex according to any one of Implementation Schemes 1 to 10 and Implementation Schemes 12 to 17, further comprising a carbon scaffold containing a pore volume, wherein the pore volume comprises a microporosity of >90%.

[0256] Implementation Scheme 21. The Group 14 complex according to any one of Implementation Schemes 1 to 20, wherein the Group 14 complex has a capacity greater than 900 mAh / g.

[0257] Implementation Scheme 22. The Group 14 complex according to any one of Implementation Schemes 1 to 20, wherein the Group 14 complex contains a capacity greater than 1300 mAh / g.

[0258] Implementation Scheme 23. The Group 14 complex according to any one of Implementation Schemes 1 to 20, wherein the Group 14 complex has a capacity greater than 1600 mAh / g.

[0259] Implementation Scheme 24. A Group 14 complex according to any one of Implementation Schemes 1 to 23, wherein the Group 14 complex comprises an average coulombic efficiency of ≥0.9970.

[0260] Implementation Scheme 25. A Group 14 complex according to any one of Implementation Schemes 1 to 23, wherein the Group 14 complex comprises an average coulombic efficiency of ≥0.9980.

[0261] Implementation Scheme 26. A Group 14 complex according to any one of Implementation Schemes 1 to 23, wherein the Group 14 complex comprises an average coulombic efficiency of ≥0.9985.

[0262] Implementation Scheme 27. A Group 14 complex according to any one of Implementation Schemes 1 to 23, wherein the Group 14 complex comprises an average coulombic efficiency of ≥0.9990.

[0263] Implementation Scheme 28. A Group 14 complex according to any one of Implementation Schemes 1 to 23, wherein the Group 14 complex comprises an average coulombic efficiency of ≥0.9995.

[0264] Implementation Scheme 29. A Group 14 complex according to any one of Implementation Schemes 1 to 23, wherein the Group 14 complex comprises an average coulombic efficiency of ≥0.9995.

[0265] Implementation Scheme 30. A Group 14 complex according to any one of Implementation Schemes 1 to 23, wherein the Group 14 complex comprises an average coulombic efficiency of ≥0.9999.

[0266] Implementation Scheme 31. The Group 14 complex according to any one of Implementation Schemes 1 to 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.

[0267] Implementation Scheme 32. A Group 14 complex according to any one of Implementation Schemes 1 to 31, wherein the primary particles of the Group 14 complex do not require sieving or grinding in their manufacture.

[0268] Implementation Scheme 33. A Group 14 composite, wherein: (a) the carbon comprises a porous carbon scaffold, the porous carbon scaffold comprising (i) amorphous carbon, (ii) a pore volume, wherein greater than 70% of the pore volume is present in pores with a diameter less than 2 nm, and (iii) a DPv90 less than 50 nm; (b) the silicon comprises (i) amorphous nanoscale silicon embedded within the pore volume of the carbon scaffold; and (c) the composite comprises (i) 30 wt% to 60 wt% silicon, (ii) a Dv50 less than or equal to 10 μm, (iii) Z < 10, and The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0269] Implementation Scheme 34. The group 14 complex according to any one of Implementation Schemes 1 to 33, further comprising less than 30m 2 / g of surface area.

[0270] Implementation Scheme 35. The Group 14 complex according to any one of Implementation Schemes 1 to 21 and Implementation Schemes 24 to 34, further comprising a capacity of 1300 mAh / g.

[0271] Implementation Scheme 36. The Group 14 complex according to any one of Implementation Schemes 1 to 21 and Implementation Schemes 24 to 34, further comprising a maximum capacity of 1300 mAh / g as measured by a half-cell coin cell.

[0272] Implementation Scheme 37. The Group 14 complex according to any one of Implementation Schemes 1 to 6 and Implementation Schemes 8 to 36, wherein Dv50 is less than or equal to 5 μm.

[0273] Implementation Scheme 38. The Group 14 complex according to any one of Implementation Schemes 1 to 8 and Implementation Schemes 10 to 37, wherein Z < 5.

[0274] Implementation Scheme 39. The Group 14 complex according to any one of Implementation Schemes 7 to 13 and Implementation Schemes 16 to 38, wherein Greater than or equal to 0.2.

[0275] Implementation Scheme 40. The Group 14 complex according to any one of Implementation Schemes 7 to 13 and Implementation Schemes 16 to 38, wherein Greater than or equal to 0.3.

[0276] Implementation Scheme 41. The Group 14 composite according to any one of Implementation Schemes 1 to 40, wherein the porous carbon scaffold has an average sphericity of 0.5 to 0.8.

[0277] Implementation Scheme 42. An energy storage device comprising the Group 14 complex described in any one of Implementation Schemes 1 to 41.

[0278] Implementation Scheme 43. A lithium-ion battery pack comprising the Group 14 complex described in any one of Implementation Schemes 1 to 41.

[0279] Implementation Scheme 44. A lithium-silicon battery pack comprising the Group 14 composite described in any one of Implementation Schemes 1 to 41.

[0280] Implementation Scheme 45. A method for preparing Group 14 composite particles, the method comprising: a. providing a polyol and optionally a preferred exclusion agent in an aqueous environment; b. heating the aqueous environment at 150°C to 250°C to produce hydrothermal carbon; c. heating the hydrothermal carbon 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 activating gas to produce primary activated carbon particles comprising a porous carbon framework; and e. heating the primary activated carbon particles to 350°C to 450°C in the presence of a silicon-containing gas to impregnate silicon within the porous carbon framework, wherein individual particles of the Group 14 composite particles have a sphericity greater than 0.5.

[0281] Implementation Scheme 46. A method for preparing Group 14 composite particles, the method comprising: a. providing a polyol and a preferred exclusion agent in an aqueous environment; b. heating the mixture at 150°C to 250°C to produce hydrothermal carbon; c. heating the hydrothermal carbon to 750°C to 1050°C in the presence of an inert gas to produce pyrolytic carbon particles; d. heating the pyrolytic particles to 750°C to 1050°C in the presence of an activating gas to produce primary activated carbon particles containing pore volumes; and e. heating the primary activated carbon particles containing pore volumes to 350°C to 450°C in the presence of a silicon-containing gas to impregnate silicon within the porous carbon framework.

[0282] Implementation Scheme 47. The method according to any one of Implementation Scheme 45 or Implementation Scheme 46, wherein the aqueous environment optionally comprises a co-solvent, the co-solvent comprising one or more of the following: alcohols, alkanes, ethers, THF, DMSO, DMF, N-methylpyrrolidone, ethylene glycol, and ethylene glycol dimethyl ether.

[0283] Implementation Scheme 48. The method according to any one of Implementation Schemes 45 to 47, wherein the aqueous environment is heated to a temperature less than or equal to the decomposition temperature of the preferred exclusion agent.

[0284] Implementation Scheme 49. The method according to any one of Implementation Schemes 45 to 48, wherein the aqueous environment may be stirred or otherwise mixed to promote the formation of spherical domains throughout the aqueous environment.

[0285] Implementation Scheme 50. The method according to any one of Implementation Schemes 45 to 49, wherein the polyol is sucrose.

[0286] Implementation Scheme 51. The method according to any one of Implementation Schemes 45 to 50, wherein the preferred exclusion agent is: Span 80, poly(acrylic acid), Triton X, or a combination thereof.

[0287] Implementation Scheme 52. The method according to any one of Implementation Schemes 45 to 51, wherein the preferred exclusion agent is poly(acrylic acid).

[0288] Implementation Scheme 53. The method according to any one of Implementation Schemes 45 to 52, wherein the ratio of polyol to exclusion agent is 1000:1 or lower.

[0289] Implementation Scheme 54. The method according to any one of Implementation Schemes 45 to 53, wherein the inert gas is nitrogen.

[0290] Implementation Scheme 55. The method according to any one of Implementation Schemes 45 to 54, wherein the activating gas is carbon dioxide, vapor, or a combination thereof.

[0291] Implementation Scheme 56. The method according to any one of Implementation Schemes 45 to 55, wherein the method further comprises stirring the aqueous environment.

[0292] Implementation Scheme 57. The method according to any one of Implementation Schemes 45 to 56, wherein the silicon-containing gas deposits silicon onto at least a portion of the surface of the primary activated carbon particles.

[0293] Implementation Scheme 58. The method according to any one of Implementation Schemes 45 to 57, wherein the fraction of silicon not impregnated in the porous carbon framework, Z, is less than 10 relative to the fraction of silicon impregnated in the porous carbon framework.

[0294] Implementation Scheme 59. The method according to any one of Implementation Schemes 45 to 58, wherein impregnating silicon within the porous carbon framework comprises depositing silicon nanoparticles within the internal framework of the activated carbon particles.

[0295] Implementation Scheme 60. The method according to any one of Implementation Schemes 45 to 59, wherein the pyrolyzed carbon particles are discrete or non-agglomerated particles and do not require sieving.

[0296] Implementation Scheme 61. The method according to any one of Implementation Schemes 45 to 60, wherein the Group 14 composite particles are discrete particles or non-agglomerated particles and do not require sieving.

[0297] Implementation Scheme 62. The method according to any one of Implementation Schemes 45 to 59, wherein both the pyrolyzed particles and the Group 14 composite particles are discrete particles or non-agglomerated particles and do not require sieving.

[0298] Implementation Scheme 63. The method according to any one of Implementation Schemes 45 to 61, wherein the group 14 particles further comprises two or more discrete group 14 particles, and wherein the discrete group 14 particles are non-agglomerated.

[0299] Implementation Scheme 64. The method according to any one of Implementation Schemes 45 to 63, wherein the pore volume of the primary activated carbon is at least 0.6 cm³. 3 / g.

[0300] Implementation Scheme 65. The method according to any one of Implementation Schemes 45 to 64, wherein the silicon-containing gas is introduced via chemical vapor injection (CVI).

[0301] Implementation Scheme 66. The method according to any one of Implementation Schemes 45 to 65, wherein the silicon-containing gas is silane.

[0302] Implementation Scheme 67. The method according to any one of Implementation Schemes 45 to 66 further comprises casting a slurry containing the Group 14 particles to produce an anode electrode.

[0303] As can be understood from the foregoing, although specific embodiments of the invention have been described herein for illustrative purposes, various modifications may be made without departing from the spirit and scope of the invention. Therefore, the invention is not limited except by the appended claims.

[0304] This application claims the benefit of U.S. Provisional Application No. 63 / 218,786, filed July 6, 2021, under 35 U.S.SC §119(e), the entire contents of which are incorporated herein by reference.

Claims

1. A method for preparing group 14 composite particles, the method comprising: a. Providing a polyol and optional size exclusion agent in an aqueous environment, said size exclusion agent being defined as an agent that promotes the formation of spherical micron-sized domains in said aqueous environment, said domains being converted into hydrothermal carbon over time after experiencing elevated temperatures; b. Heating the aqueous environment at 150°C to 250°C to produce hydrothermal carbon; c. The hydrothermal carbon is heated to 750°C to 1050°C in the presence of an inert gas to produce pyrolytic carbon particles; d. Heating the pyrolyzed carbon particles to 750°C to 1050°C in the presence of an activating gas to produce primary activated carbon particles, the primary activated carbon particles comprising a porous carbon framework, and the porous carbon framework comprising pore volumes; and e. The primary activated carbon particles are heated to 350°C to 450°C in the presence of a silicon-containing gas to impregnate the porous carbon framework with silicon. in: The pore volume of the porous carbon framework comprises more than 80% micropores; The silicon content of the group 14 composite particles is 30% to 60% by weight. The surface area of ​​the group 14 composite particles is less than 30 m². 2 / g; The group 14 composite particles contain a Z value less than 5, where Z = 1.875 x [(M1100 [M) / M1100] x100, where M1100 is the mass of the Group 14 composite particle when oxidation is completed at a temperature of 1100°C, and M is the minimum mass of the Group 14 composite particle when it is heated from 800°C to 1100°C, determined by thermogravimetric analysis; The group 14 composite particles contain greater than or equal to 0.12 ,in These are parameters related to the differential capacity curve (dQ / dV versus voltage) of the anode when implemented in a half-cell coin cell, where = (maximum peak height dQ / dV in region I) / (maximum peak height dQ / dV in region III), where region I is 0.8V-0.4V and region III is 0.15V-0V; and The individual particles of the group 14 composite particles have a sphericity greater than 0.

5.

2. The method of claim 1, wherein the aqueous environment comprises a co-solvent, the co-solvent comprising one or more of alcohols, alkanes, ethers, THF, DMSO, DMF, and N-methylpyrrolidone.

3. The method of claim 1, wherein the aqueous environment comprises a co-solvent, the co-solvent comprising ethylene glycol, ethylene glycol dimethyl ether, or a combination thereof.

4. The method of any one of claims 1-3, wherein the aqueous environment is heated to a temperature below or equal to the decomposition temperature of the preferred exclusion agent.

5. The method according to any one of claims 1-4, wherein the polyol is sucrose.

6. The method of any one of claims 1-5, wherein the preferred exclusion agent is: Span 80, poly(acrylic acid), Triton X, or a combination thereof.

7. The method according to any one of claims 1-6, wherein the mass ratio (m:m) of the polyol to the preferred exclusion agent is 1000:1 or lower.

8. The method of any one of claims 1-7, wherein the inert gas is nitrogen.

9. The method of any one of claims 1-8, wherein the activating gas is carbon dioxide, vapor, or a combination thereof.

10. The method of any one of claims 1-9, further comprising stirring the aqueous environment.

11. The method of any one of claims 1-10, wherein the silicon-containing gas deposits silicon onto at least a portion of the surface of the primary activated carbon particles.

12. The method of any one of claims 1-11, wherein Z is less than 4.

13. The method of claim 12, wherein impregnating silicon within the porous carbon framework comprises depositing silicon nanoparticles within the internal framework of the activated carbon particles.

14. The method of any one of claims 1-13, wherein the group 14 composite particles do not agglomerate.

15. The method according to any one of claims 1-14, wherein the pore volume of the primary activated carbon is at least 0.6 cm³. 3 / g.

16. The method of any one of claims 1-15, wherein the silicon-containing gas is introduced by chemical vapor injection (CVI).

17. The method of any one of claims 1-16, wherein the silicon-containing gas is a silane.

18. The method of any one of claims 1-17, further comprising casting a slurry containing the group 14 composite particles to prepare an anode electrode.

19. A group 14 complex comprising: (a) A plurality of porous carbon primary particles derived from polyols, wherein the plurality of porous carbon primary particles exhibit a spherical morphology and the pore volume of the porous carbon primary particles comprises more than 80% micropores. (b) Silicon impregnated within the pores of the porous carbon primary particles, such that the silicon content of the Group 14 composite is 30% to 60% by weight. (c) Dv50 is less than or equal to 10 μm; (d) Z less than 5, where Z = 1.875 x [(M1100 [M) / M1100] x 100, where M1100 is the mass of the Group 14 complex when oxidation is completed at a temperature of 1100°C, and M is the minimum mass of the Group 14 complex when it is heated from 800°C to 1100°C, determined by thermogravimetric analysis; (e) greater than or equal to 0.12 ,in These are parameters related to the differential capacity curve (dQ / dV versus voltage) of a half-cell coin cell containing the group 14 compound, where = (maximum peak height dQ / dV in region I) / (maximum peak height dQ / dV in region III), where region I is 0.8V-0.4V and region III is 0.15V-0V; and (f) Less than 30 m 2 / g of surface area.

20. The group 14 complex of claim 19, wherein Dv50 is less than or equal to 5 μm.

21. The Group 14 composite of claim 19 or 20, wherein the individual particles of the porous carbon primary particles are discrete, non-agglomerated particles.

22. The group 14 complex according to any one of claims 19-21, wherein Z < 4.

23. The group 14 complex according to any one of claims 19-22, wherein > 0.

2.

24. The group 14 complex according to any one of claims 19-22, wherein > 0.

3.

25. A group 14 complex comprising: (a) A plurality of primary particles comprising silicon and carbon, elements of group 14, wherein the primary particles have a sphericity of at least 0.5, each primary particle comprising a porous carbon scaffold comprising a pore volume, and the pore volume comprising more than 80% micropores. (b) 30% to 60% by weight of silicon; (c) Dv50 is less than or equal to 10 μm; (d) Z less than 5, where Z = 1.875 x [(M1100 [M) / M1100] x 100, where M1100 is the mass of the Group 14 complex when oxidation is completed at a temperature of 1100°C, and M is the minimum mass of the Group 14 complex when it is heated from 800°C to 1100°C, determined by thermogravimetric analysis; (e) greater than or equal to 0.12 ,in These are parameters related to the differential capacity curve (dQ / dV versus voltage) of a half-cell coin cell containing the group 14 compound, where = (maximum peak height dQ / dV in region I) / (maximum peak height dQ / dV in region III), where region I is 0.8V-0.4V and region III is 0.15V-0V; and (f) Less than 30 m 2 / g of surface area.

26. A group 14 complex comprising carbon and silicon, wherein: (a) The carbon comprises a porous carbon scaffold derived from a polyol and further comprises: (i) amorphous carbon, (ii) pore volume, wherein more than 80% of the pore volume consists of pores with a diameter of less than 2 nm, and (iii) Dv90 is less than 50 nm; (b) The silicon comprises: (i) amorphous nanoscale silicon embedded within the pore volume of the porous carbon scaffold; and (c) The group 14 complex further comprises: (i) 30% to 60% silicon by weight (ii) Dv50 is less than or equal to 10 μm, (iii) Z less than 5, where Z = 1.875 x [(M1100 [M) / M1100] x 100, where M1100 is the mass of the Group 14 complex when oxidation is completed at 1100°C, and M is the minimum mass of the Group 14 complex when heated from 800°C to 1100°C, determined by thermogravimetric analysis. (iv) Greater than or equal to 0.12 ,in These are parameters related to the differential capacity curve (dQ / dV versus voltage) of a half-cell coin cell containing the group 14 compound, where = (maximum peak height dQ / dV in region I) / (maximum peak height dQ / dV in region III), where region I is 0.8V-0.4V and region III is 0.15V-0V. (v) less than 30 m 2 / g of surface area.

27. The group 14 complex as claimed in claim 25 or 26, further comprising less than 20 m 2 / g of surface area.

28. The Group 14 complex as claimed in any one of claims 25-27, further comprising a maximum capacity greater than 1300 mAh / g as measured by a half-cell coin cell.

29. The group 14 complex according to any one of claims 25-28, wherein Dv50 is less than or equal to 5 μm.

30. The group 14 complex according to any one of claims 25-29, wherein Z < 4.

31. The group 14 complex according to any one of claims 25-30, wherein Greater than or equal to 0.

2.

32. The group 14 complex according to any one of claims 25-30, wherein Greater than or equal to 0.

3.

33. The Group 14 composite according to any one of claims 25-32, wherein the porous carbon scaffold has an average sphericity of 0.5 to 0.

8.

34. An energy storage device comprising the Group 14 complex according to any one of claims 25-33.

35. The energy storage device of claim 34, wherein the energy storage device is a lithium-silicon battery pack or a lithium-ion battery pack.

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