Passivation method for controlling oxygen content and reactivity of silicon-carbon composite material

Abstract

Passivated silicon-carbon composites and related methods are disclosed that overcome the challenge to provide for the entrainment of amorphous nano-sized silicon within porous carbon. The materials and methods disclosed herein have superior utility in various applications, including energy storage devices, such as lithium ion batteries, compared to other poorer materials and methods described in the prior art.

Description

[0001] This application is a divisional application of Chinese patent application No. 202180076456.4, filed on September 30, 2021, with the invention name “Passivation method for controlling the oxygen content and reactivity of silicon-carbon composite materials”. Background Art Technical Field

[0002] Embodiments of the present invention generally relate to passivation methods for controlling the oxygen content and reactivity of silicon-carbon composite materials, and compositions of matter related thereto. The silicon-carbon composite material is produced by chemical vapor infiltration using a silicon-containing gas to impregnate amorphous nano-sized silicon into the pores of a porous support. Suitable porous supports include, but are not limited to, porous carbon supports, such as carbon having a pore volume including micropores (less than 2nm), mesopores (2 to 50nm) and / or macropores (greater than 50nm). Chemical vapor infiltration (CVI) of silicon into the pores of a porous support material is achieved by exposing the porous support to a silicon-containing gas (e.g., silane) at an elevated temperature.

[0003] Passivation can be performed by infiltrating various oxygen-containing gases into the carbon pores until the surface of the silicon impregnated therein. Alternatively, passivation can be performed by infiltrating various non-oxygen-containing gases into the carbon pores until the surface of the silicon impregnated therein. Such passivation is critical to enhancing the performance of silicon-carbon composites and minimizing undesirable reactivity, such as reactivity between silicon and electrolyte components used in lithium-ion batteries.

[0004] Related technical description

[0005] CVI is a method in which a gaseous substrate reacts within a porous support material. The method can be used to produce composite materials, such as silicon-carbon composites, in which a silicon-containing gas decomposes at high temperatures within a porous carbon support. Although the method can be used to make a variety of composite materials, silicon-carbon (Si-C) composites are of particular interest. Such Si-C composites have utility, for example as energy storage materials, such as anode materials within lithium-ion batteries (LIBs). LIBs have the potential to replace devices currently used in many applications. For example, current lead-acid automotive batteries are not suitable for the next generation of all-electric and hybrid electric vehicles due to the formation of irreversible, stable sulfates during discharge. Lithium-ion batteries are a viable alternative to currently used lead-based systems due to their capacity and other considerations.

[0006] To this end, there has been a strong interest in developing new LIB anode materials, especially silicon, which has a gravimetric capacity 10 times higher than conventional graphite. However, silicon exhibits large volume changes during cycling, leading to electrode degradation and solid electrolyte interphase (SEI) instability. The most common improvement approach is to reduce the silicon particle size, such as D V,50 <150nm, such as D V,50 <100nm, such as D V,50 <50nm, for example D V,50 <20nm, for example D V,50 <10nm, for example D V,50 <5nm, for example D V,50 <2nm, as discrete particles or in a matrix. To date, the techniques used to make nanoscale silicon involve high-temperature reduction of silicon oxides, extensive particle refinement, multi-step toxic etching, and / or other costly methods. Likewise, common matrix methods involve expensive materials, such as graphene or nanographite, and / or require complex processing and coating.

[0007] It is known from the scientific literature that non-graphitizable (hard) carbon is beneficial as a LIB anode material (Liu Y, Xue, JS, Zheng T, Dahn, JR. Carbon 1996, 34: 193-200; Wu, YP, Fang, SB, Jiang, YY. 1998, 75: 201-206; Buiel E, Dahn JR. Electrochim Acta 1999 45: 121-130). The reason for this improved performance is the disordered nature of the graphene layers, which allows Li ions to be embedded on either side of the graphene plane, thereby allowing the stoichiometric content of Li ions relative to crystalline graphite to be theoretically doubled. In addition, in contrast to graphite, where lithiation can only proceed parallel to the stacked graphene planes, the disordered structure improves the rate capability of the material by allowing Li ions to be embedded isotropically. Despite these desirable electrochemical properties, amorphous carbon has not been widely adopted in commercial Li-ion batteries primarily due to low FCE and low bulk density (<1 g / cc). Instead, amorphous carbon has been more commonly used as a low-quality additive and coating for other active material components of the battery to improve conductivity and reduce surface side reactions.

[0008] In recent years, amorphous carbon as a LIB battery material has received considerable attention as a coating for silicon anode materials. Such silicon-carbon core-shell structures have the potential to not only improve conductivity, but also buffer the expansion of silicon during lithiation, thereby stabilizing its cycle stability and minimizing problems associated with particle crushing, 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 C 2007 111: 11131–11138). Problems associated with this strategy include the lack of suitable silicon starting materials suitable for coating processes, and the inherent lack of engineered void space in carbon-coated silicon core-shell composite particles to accommodate the expansion of silicon during lithiation. This inevitably leads to failure of cycling stability 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).

[0009] An alternative to the core-shell structure is one in which amorphous nanosized silicon is uniformly distributed within the pores of a porous carbon scaffold. Porous carbon has desirable properties: (i) the carbon porosity provides void volume to accommodate the expansion of silicon during lithiation, thereby reducing the net composite particle expansion at the electrode level; (ii) the disordered graphene network provides increased conductivity for silicon, thereby enabling faster charge / discharge rates, and (iii) the nanoporous structure acts as a template for silicon synthesis, thereby dictating its size, distribution, and morphology.

[0010] To this end, the desired inverse layered structure can be achieved by employing CVI, in which silicon-containing gases can fully penetrate the nanoporous carbon and decompose into nanosized silicon therein. The CVI approach has several advantages in terms of silicon structure. One advantage is that the nanoporous carbon provides nucleation sites for growing silicon while dictating the maximum particle shape and size. Confining the growth of silicon within the nanoporous structure reduces the susceptibility to cracking or crushing and contact loss caused by expansion. In addition, this structure promotes that the nanosized silicon remains in the amorphous phase. This property provides high charge / discharge rates, especially when combined with the silicon vicinity within the conductive carbon scaffold. The system provides a solid-state lithium diffusion path with high rate capabilities to deliver lithium ions directly to the nanoscale silicon interface. Another benefit of providing silicon via CVI within the carbon scaffold is the suppression of undesirable crystallization of Li 15Formation of Si4 phase. Yet another benefit is that the CVI process provides void space within the particles.

[0011] To quantify the percent loading of silicon comprising a silicon-carbon composite, thermogravimetric analysis (TGA) can be used. For this purpose, the silicon composite is heated from 25°C to 1100°C, which, without being bound by theory, dictates that all carbon is burned off and all silicon is oxidized to SiO2. Thus, the % silicon constituting the silicon-carbon composite is calculated to be

[0012] %Si=100x[[M1100 x(28 / (28+(16x 2)))] / M°]

[0013] Wherein M1100 is the mass of the silicon-carbon composite at 1100°C, and M° is the minimum mass of the silicon-carbon composite between 50°C and 200°C when the silicon-carbon composite is heated from about 25°C to about 1100°C in air, as determined by thermogravimetric analysis.

[0014] In order to measure the relative amount of silicon impregnated into the pores of the porous carbon, thermogravimetric analysis TGA can be used. TGA can be used to evaluate the fraction of silicon residing in the pores of the porous carbon relative to the total silicon present (i.e., the sum of silicon in the pores and on the surface of the particles). When the silicon-carbon composite is heated in air, the sample shows a mass increase starting at about 300°C to 500°C, which reflects the beginning of the oxidation of silicon to SiO2; the sample then shows a mass loss due to the burning of carbon; the sample then shows a mass increase, which reflects the continued conversion of silicon to SiO2, increasing to an asymptotic value when the temperature approaches 1100°C, and the oxidation of silicon is complete. For the purpose 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 the 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 the completion of oxidation is SiO2. Therefore, the percentage of unoxidized silicon after the carbon is burned off, expressed as a proportion of the total amount of silicon, can be determined using the following formula:

[0015] Z=1.875x[(M1100-M) / M1100]x 100

[0016] where M1100 is the mass of the sample when oxidation is completed at a temperature of 1100 °C, and M is the minimum mass recorded when the sample is heated from 800 °C to 1100 °C.

[0017] 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 the 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 because of the necessarily thinner coating on these surfaces. In this way, the calculation of Z is used to quantitatively assess the fraction of silicon that is not impregnated within the pores of the porous carbon scaffold. Summary of the invention

[0018] Silicon-carbon composites and related methods (including passivation methods) with enhanced electrochemical properties and performance are disclosed, which overcome the challenges of providing amorphous nano-sized silicon entrapped within porous carbon. The materials and methods disclosed herein are superior to other inferior materials and methods described in the prior art for various applications, including energy storage devices, such as lithium-ion batteries.

[0019] Embodiments provide new anode materials constituting lithium-silicon batteries, comprising a composite comprising a Group 14 element such as silicon and carbon, wherein the composite has new properties that overcome the challenges of providing an anode for a lithium-silicon battery, the composite comprising silicon in a preferred mode: silicon is amorphous, nanosized and entrained in porous carbon. The silicon-carbon composite material is produced by impregnating amorphous nanosized silicon into the pores of a porous support via chemical vapor infiltration (CVI). Suitable porous supports include, but are not limited to, porous carbon supports, such as carbon having a pore volume including micropores (less than 2nm), mesopores (2 to 50nm) and / or macropores (greater than 50nm). Suitable precursors for carbon supports 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 materials. Precursors for silicon include, but are not limited to, silicon-containing gases such as silane, higher order silanes (e.g., disilane, trisilane, and / or tetrasilane) and / or chlorosilanes (e.g., monochlorosilane, dichlorosilane, trichlorosilane, and tetrachlorosilane) and mixtures thereof. CVI of silicon within the pores of the porous support material is achieved by exposing the porous support to a silicon-containing gas (e.g., silane) at elevated temperatures. The porous carbon support may be a granular porous carbon.

[0020] The key achievement in this regard is to obtain silicon in the desired form and shape, i.e. amorphous nano-sized silicon. In addition, another key achievement is to achieve the impregnation of silicon into the pores of porous carbon. Such materials, such as silicon-carbon composites, can be used as anode materials for energy storage devices (e.g., lithium-silicon batteries). BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 .Relationship between Z and average Coulombic efficiency of various silicon-carbon composites.

[0022] Figure 2. Differential capacity versus voltage plot for the second cycle of silicon-carbon composite 3 using a half cell.

[0023] Figure 3 . Differential capacity versus voltage plots from the 2nd to the 5th cycle of the silicon-carbon composite 3 using a half cell.

[0024] Figure 4 .dQ / dV vs. V plots for various silicon-carbon composites.

[0025] Figure 5 .Silicon-carbon composite 3 Calculation example.

[0026] Figure 6 .Z pairs of various silicon-carbon composites picture. DETAILED DESCRIPTION

[0027] In the following description, certain specific details are set forth in order to provide a thorough understanding of the various embodiments. However, it will be appreciated by those skilled in the art that the present invention may be practiced without these details. In other cases, generally known structures 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 the appended claims, the words "comprise" and their variants (e.g., "comprises" and "comprising") shall be interpreted in an open, inclusive sense, i.e., as "including but not limited to". In addition, the titles provided herein are for convenience only and do not explain the scope or meaning of the claimed invention.

[0028] "One embodiment" or "embodiment" mentioned throughout this specification means that in at least one embodiment, specific features, structures or characteristics related to the embodiment are included. Therefore, the phrases "in one embodiment" or "in an embodiment" appearing in various places throughout this specification do not necessarily all refer to the same embodiment. In addition, specific features, structures or characteristics can be combined in any suitable manner in one or more embodiments. In addition, as used in this specification and the appended claims, the singular forms "a", "an" and "the" include plural indicators unless the context clearly stipulates otherwise. It should also be noted that the term "or" is generally used in its meaning including "and / or" unless the context clearly stipulates otherwise.

[0029] A. Porous Scaffold Materials

[0030] For the purpose of embodiments of the present invention, a porous support into which silicon is to be impregnated can be used. In this article, the porous support can include various materials. In some embodiments, the porous support material mainly includes carbon, such as hard carbon. Other allotropes of carbon are also envisioned in other embodiments, such as graphite, amorphous carbon, diamond, C60, carbon nanotubes (e.g., single-walled and / or multi-walled), graphene and / or carbon fiber. The introduction of pores into the carbon material can be achieved in various ways. For example, the pores in the carbon material can be achieved by adjusting the polymer precursor and / or processing conditions to produce the porous carbon material, and described in detail in the subsequent section.

[0031] In other embodiments, the porous support comprises a polymer material. For this reason, it is envisioned in various embodiments to use various polymers, including but not limited to inorganic polymers, organic polymers and addition polymers. The example of inorganic polymers in this article includes but is not limited to the homogeneous chain polymers of silicon-silicon, such as polysilane, silicon carbide, polygermane and polystannane. Other examples of inorganic polymers include but are not limited to heterochain polymers, for example, polyborane (polyborazylene), polysiloxane (such as polydimethylsiloxane (PDMS), polymethylhydrogensiloxane (PMHS) and polydiphenylsiloxane), polysilazane (such as perhydropolysilazane (PHPS)), polyphosphazene and poly (dichlorophosphazene), polyphosphoric acid (salt), polysulfur nitride (polythiazyl) and polysulfide. Examples of organic polymers include, but are not limited to, low density polyethylene (LDPE), high density polyethylene (HDPE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), nylon, nylon 6, nylon 6,6, Teflon (polytetrafluoroethylene), thermoplastic polyurethane (TPU), polyurea, poly (lactide), poly (glycolide) and combinations thereof, phenolic resins, polyamides, polyaramids, polyethylene terephthalate, polychloroprene, polyacrylonitrile, polyaniline, polyimide, poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PDOT:PSS) and other substances known in the art. The organic polymer may be of synthetic or natural origin. In some embodiments, the polymer is a polysaccharide, such as starch, cellulose, cellobiose, amylose, amylopectin, gum arabic, lignin, and the like. In some embodiments, the polysaccharide is derived from the caramelization of monosaccharides or oligosaccharides (e.g., fructose, glucose, sucrose, maltose, raffinose, and the like).

[0032] In certain embodiments, the porous scaffold polymer material includes a coordination polymer. Coordination polymers herein include, but are not limited to, metal organic frameworks (MOFs). Techniques for producing MOFs and exemplary materials of MOFs are known and described in the art ("The Chemistry and Applications of Metal-Organic Frameworks", Hiroyasu Furukawa et al., Science 341, (2013); DOI: 10.1126 / science.1230444). Examples of MOFs herein include, but are not limited to, Basolite TM Materials and zeolitic imidazolate frameworks (ZIFs).

[0033] Along with the various polymers envisioned to have the potential to provide porous substrates, various processing approaches are envisioned in various embodiments to achieve the porosity. In this article, as known in the art, the general methods for generating porosity in various materials are various, including but certainly not limited to the following methods: including emulsification, micelle generation, gasification, dissolution and then removal of solvent (e.g., freeze drying), axial compaction and sintering, gravity sintering, powder rolling and sintering, isostatic compaction and sintering, metal spraying, metal coating and sintering, metal injection molding and sintering, etc. Other approaches to generating porous polymer materials are also envisioned, including the generation of porous gels, such as freeze-dried gels, aerogels, etc.

[0034] In certain embodiments, the porous scaffold material comprises a porous ceramic material. In certain embodiments, the porous scaffold material comprises a porous ceramic foam. In this article, as known in the art, the general methods for generating porosity in ceramic materials are various, including but certainly not limited to generating porous. In this article, the general methods and materials suitable for forming porous ceramics include but are not limited to porous alumina, porous zirconia toughened alumina, porous partially stabilized zirconia, porous alumina, porous sintered silicon carbide, sintered silicon nitride, porous cordierite, porous zirconia, clay-bonded silicon carbide, etc.

[0035] In certain embodiments, the porous support comprises porous silica or other oxygen-containing silicon materials.The production of silica gels (including sol-gels) and other porous silicas is known in the art.

[0036] In certain embodiments, porous material includes porous metal. In this regard, suitable metals include but are not limited to porous aluminum, porous steel, porous nickel, porous Inconel (Inconcel), porous Hastelloy (Hasteloy), porous titanium, porous copper, porous brass, porous gold, porous silver, porous germanium and other metals capable of forming porous structures, as known in the art. In certain embodiments, porous support material includes porous metal foam. The type of metal and its manufacture method are known in the art. Such methods include but are not limited to casting (including foaming, infiltration and low foam casting), deposition (chemical and physical), gas eutectic formation and powder metallurgy technology (for example, powder sintering, compaction and fiber metallurgy technology in the presence of foaming agent).

[0037] B. Porous Carbon Scaffold

[0038] 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. Pat. 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 in its entirety for all purposes.

[0039] Therefore, in one embodiment, the present disclosure provides a method for preparing any of the above-mentioned carbon materials or polymer gels. Carbon materials can be synthesized by pyrolysis of a single precursor, such as a carbohydrate material, such as sucrose, fructose, glucose, dextrin, maltodextrin, starch, amylopectin, amylose, lignin, gum arabic, and other carbohydrates known in the art, and combinations thereof. Alternatively, carbon materials can be synthesized by pyrolysis of a composite resin, such as using a polymer precursor (e.g., phenol, resorcinol, bisphenol A, urea, melamine, and other suitable compounds known in the art, and combinations thereof) with a crosslinking agent (e.g., formaldehyde, hexamethylenetetramine, furfural, and other crosslinking agents known in the art, and combinations thereof) in a suitable solvent (e.g., water, ethanol, methanol, and other solvents known in the art, and combinations thereof) using a sol-gel method to form. The resin can be an acid or a base and can contain a catalyst. The catalyst can be volatile or non-volatile. The pyrolysis temperature and residence time can be varied as known in the art.

[0040] In some embodiments, the method comprises a sol-gel method, a condensation method, or a cross-linking method involving a monomer precursor and a cross-linking agent, two existing polymers and a cross-linking agent, or a single polymer and a cross-linking agent to prepare a polymer gel, followed by pyrolysis of the polymer gel. The polymer gel can be dried (e.g., freeze-dried) prior to pyrolysis; however, drying is not necessarily required.

[0041] The target carbon properties can be derived from a variety of polymer chemistries, as long as the polymerization reaction produces a resin / polymer with the desired carbon backbone. Different polymer families include novolacs, resols, acrylates, styrenics, urethanes, rubbers (chloroprene, styrene-butadiene, etc.), nylons, etc. Any of these polymer resins can be prepared via a number of different methods, including sol-gel, emulsion / suspension, solid state, molten state, etc. for polymerization and crosslinking processes.

[0042] In some embodiments, the electrochemical modifier is incorporated into the material as a polymer. For example, an organic or carbon-containing polymer, such as RF, is copolymerized with a polymer containing an electrochemical modifier. In one embodiment, the polymer containing the electrochemical modifier contains silicon. In one embodiment, the polymer is tetraethyl orthosilicate (TEOS). In one embodiment, a TEOS solution is added to an RF solution before or during polymerization. In another embodiment, the polymer is a polysilane with an organic side group. In some cases, these side groups are methyl groups, in other cases, these groups are phenyl groups, and in other cases, side chains include phenyl, pyrrolidone, acetate, vinyl, siloxane fragments. In some cases, the side chain includes a 14th group element (silicon, germanium, tin or lead). In other cases, the side chain includes a 13th group element (boron, aluminum, boron, gallium, indium). In other cases, the side chain includes a 15th group element (nitrogen, phosphorus, arsenic). In other cases, the side chain includes a 16th group element (oxygen, sulfur, selenium).

[0043] In another embodiment, the electrochemical modifier includes silole. In some cases, it is phenol-silole or silanol. In other cases, it is polysilole or polysilanol. In some cases, silicon is replaced with germanium (germanyl heterocyclopentadiene or germanyl heterofluorene), tin (tin heterocyclopentadiene or tin heterofluorene), nitrogen (carbazole) or phosphorus (phosphorus heteropentadiene or phosphorus heterofluorene). In all cases, the material containing heteroatoms can be small molecules, oligomers or polymers. The phosphorus atom can also be bonded to oxygen or may not be bonded to oxygen.

[0044] In some embodiments, the reactant comprises phosphorus. In certain other embodiments, phosphorus is in the form of phosphoric acid. In certain other embodiments, phosphorus can be in the form of a salt, wherein the anion of the salt comprises one or more phosphates, phosphites, phosphonium ions, hydrogen phosphates, dihydrogen phosphates, hexafluorophosphates, hypophosphites, polyphosphates or pyrophosphate ions, or combinations thereof. In certain other embodiments, phosphorus can be in the form of a salt, wherein the cation of the salt comprises one or more phosphonium ions. Any of the above embodiments can be selected to contain non-phosphate anions or cation pairs for those known and described in the art. In this case, exemplary cations paired with phosphate-containing anions include but are not limited to ammonium ions, tetraethylammonium ions and tetramethylammonium ions. In this case, exemplary anions paired with phosphate-containing cations include but are not limited to carbonate ions, bicarbonate ions and acetate ions.

[0045] In some embodiments, the catalyst comprises a basic volatile catalyst. For example, in one embodiment, the basic volatile catalyst comprises ammonium carbonate, ammonium bicarbonate, ammonium acetate, ammonium hydroxide, or a combination thereof. In other embodiments, the basic volatile catalyst is ammonium carbonate. In yet another other embodiment, the basic volatile catalyst is ammonium acetate.

[0046] In other embodiments, the method includes mixing the acid. In certain embodiments, the acid is solid at room temperature and pressure. In some embodiments, the acid is liquid at room temperature and pressure. In some embodiments, the acid is liquid at room temperature and pressure that does not provide dissolution of one or more other polymer precursors.

[0047] Acid can be selected from many acids that are suitable for polymerization process. For example, in some embodiments, acid is acetic acid, and in other embodiments, acid is oxalic acid. In other embodiments, acid is mixed with the first solvent or the second solvent in the ratio of 99:1, 90:10, 75:25, 50:50, 25:75, 20:80, 10:90 or 1:90 acid and solvent. In other embodiments, acid is acetic acid, and the first solvent or the second solvent is water. In other embodiments, acidity is provided by adding solid acid.

[0048] The total content of the acid in the mixture can be varied to change the properties of the final product. In some embodiments, the acid is present in about 1% to about 50% of the mixture by weight. In other embodiments, the acid is present in about 5% to about 25%. In other embodiments, the acid is present in about 10% to about 20%, for example, about 10%, about 15%, or about 20%.

[0049] In certain embodiments, the polymer precursor components are blended together and subsequently maintained at a time and temperature sufficient to achieve polymerization. One or more of the polymer precursor components may have a particle size less than about 20 mm, such as less than 10 mm, such as less than 7 mm, such as less than 5 mm, such as less than 2 mm, such as less than 1 mm, such as less than 100 microns, such as less than 10 microns. In some embodiments, during the blending process, the particle size of one or more polymer precursor components is reduced.

[0050] The mixing of one or more polymer precursor components without solvent can be achieved by methods described in the art, such as ball milling, jet milling, Fritsch milling, planetary mixing, and other mixing methods for mixing or blending solid particles, while controlling process conditions (e.g., temperature). The mixing or blending process can be achieved before, during, and / or after (or a combination thereof) incubation at the reaction temperature.

[0051] Reaction parameters include aging the blended mixture at a temperature and time sufficient to react one or more polymer precursors with each other and form a polymer. In this regard, a suitable aging temperature is a temperature from about room temperature to a temperature that is or is close to the melting point of one or more polymer precursors. In some embodiments, a suitable aging temperature is a temperature from about room temperature to a temperature that is or is close to the glass transition temperature of one or more polymer precursors. For example, in some embodiments, the solvent-free mixture is aged at a temperature of about 20°C to about 600°C, for example, from about 20°C to about 500°C, for example, from about 20°C to about 400°C, for example, from about 20°C to about 300°C, for example, from about 20°C to about 200°C. In certain embodiments, the solvent-free mixture is aged at a temperature of about 50°C to about 250°C.

[0052] The reaction duration is usually sufficient to react the polymer precursor and form a polymer, for example, the mixture can be aged for any time from 1 hour to 48 hours, more or less depending on the desired result. Typical embodiments include aging for a period of about 2 hours to about 48 hours, for example in some embodiments, aging for about 12 hours, and in other embodiments, aging for about 4-8 hours (e.g., about 6 hours).

[0053] In certain embodiments, the electrochemical modifier is incorporated during the polymerization process described above. For example, in some embodiments, an electrochemical modifier in the form of metal particles, metal slurry, metal salt, metal oxide, or molten metal can be dissolved or suspended in the mixture that produces the gel resin.

[0054] Exemplary electrochemical modifiers for producing composite materials can fall into one or more than one chemical class. 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.

[0055] In certain embodiments, the electrochemical modifier comprises a metal, and exemplary materials include, but are not limited to, aluminum isopropoxide, manganese acetate, nickel acetate, ferric acetate, tin chloride, silicon chloride, and combinations thereof. In certain embodiments, the electrochemical modifier is a phosphoric acid (salt) compound, including but not limited to phytic acid, phosphoric acid, ammonium dihydrogen phosphate, and combinations thereof. In certain embodiments, the electrochemical modifier comprises silicon, and exemplary materials include, but are not limited to, silicon powder, silicon nanotubes, polycrystalline silicon, nanocrystalline silicon, amorphous silicon, porous silicon, nano-sized silicon, nano-featured silicon, nano-sized and nano-featured silicon, silicyne, and black silicon, and combinations thereof.

[0056] Electrochemical modifiers can be combined with various polymer systems with potential (or secondary) polymer functional groups by physical mixing or chemical reaction. Examples of potential polymer functional groups include but are not limited to epoxy groups, unsaturated groups (double bonds and triple bonds), acid groups, alcohol groups, amine groups, basic groups. Crosslinking with potential functional groups can occur via heteroatoms (for example, with sulfur vulcanization, acid / base / with phosphoric acid ring-opening reaction), with organic acid or base (described above) reaction, with transition metal (including but not limited to Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ag, Au) coordination, ring-opening or ring-closure reaction (rotaxane, spiro compounds, etc.).

[0057] Electrochemical modifiers can also be added to the polymer system by physical blending. Physical blending can include, but is not limited to, melt blending of polymers and / or copolymers, addition of discrete particles, chemical vapor deposition of electrochemical modifiers, and co-precipitation of electrochemical modifiers and primary polymer materials.

[0058] In some cases, electrochemical modifiers can be added via metal salt solids, solutions or suspensions. Metal salt solids, solutions or suspensions can include acids and / or alcohols to improve the solubility of metal salts. In another variation, the polymer gel (before or after an optional drying step) is contacted with a slurry comprising an electrochemical modifier. In another variation, the polymer gel (before or after an optional drying step) is contacted with a metal or metal oxide sol comprising a desired electrochemical modifier.

[0059] In addition to the electrochemical modifiers exemplified above, the composite material may include one or more other forms (i.e., allotropes) of carbon. In this regard, it has been found that the inclusion of different allotropes of carbon (e.g., graphite, amorphous carbon, conductive carbon, carbon black, diamond, C60, carbon nanotubes (e.g., single-walled and / or multi-walled), graphene and / or carbon fiber) in the composite material is effective for optimizing the electrochemical properties of the composite material. Various allotropes of carbon can be incorporated into the carbon material during any stage of the preparation method described herein. For example, during the solution stage, during the gelation stage, during the curing stage, during the pyrolysis stage, during the grinding stage or after grinding. In some embodiments, the second carbon form is incorporated into the composite material by adding the second carbon form before or during the polymerization of the polymer gel as described in more detail herein. The polymer gel containing the polymerization of the second carbon form is then processed according to the general techniques described herein to obtain a carbon material containing the second allotrope of carbon.

[0060] In a preferred embodiment, the carbon is produced from a precursor with little or no solvent required for processing (solvent-free). The structure of the polymer precursor suitable for use in a low solvent or substantially solvent-free reaction mixture is not particularly limited, as long as the polymer precursor is capable of reacting with another polymer precursor or with a second polymer precursor to form a polymer. Polymer precursors include amine-containing compounds, alcohol-containing compounds, and carbonyl-containing compounds, for example, in some embodiments, the polymer precursor is selected from alcohols, phenols, polyols, sugars, alkylamines, aromatic amines, aldehydes, ketones, carboxylic acids, esters, ureas, acyl halides, and isocyanates.

[0061] In one embodiment of a reaction mixture with low solvent or substantially no solvent, the method includes using a first polymer precursor and a second polymer precursor, and in some embodiments, the first polymer precursor or the second polymer precursor is a carbonyl-containing compound and the remaining first polymer precursor or the second polymer precursor is an alcohol-containing compound. In some embodiments, the first polymer precursor is a phenolic compound and the second polymer precursor is an aldehyde compound (e.g., formaldehyde). In one embodiment of the method, the phenolic compound is phenol, resorcinol, catechol, hydroquinone, phloroglucinol, or a combination thereof; and the aldehyde compound is formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, benzaldehyde, cinnamaldehyde, or a combination thereof. In other embodiments, the phenolic compound is resorcinol, phenol, or a combination thereof, and the aldehyde compound is formaldehyde. In other embodiments, the phenolic compound is resorcinol and the aldehyde compound is formaldehyde. In some embodiments, the polymer precursors are alcohols and carbonyl compounds (e.g., resorcinol and acetaldehyde), and they are present in a ratio of about 0.5:1.0, respectively.

[0062] Polymer precursor materials suitable for low solvent or substantially solvent-free reaction mixtures as disclosed herein include (a) alcohol compounds, phenolic compounds and other monohydroxy or polyhydroxy compounds and (b) aldehydes, ketones and combinations thereof. In this article, representative alcohols include linear and branched, saturated and unsaturated alcohols. Suitable phenolic compounds include polyhydroxybenzenes, such as dihydroxybenzenes or trihydroxybenzenes. Representative polyhydroxybenzenes include meta-diphenol (i.e., 1,3-dihydroxybenzene), catechol, hydroquinone and phloroglucinol. In this regard, other suitable compounds are bisphenols, such as bisphenol A. Mixtures of two or more polyhydroxybenzenes can also be used. Phenol (monohydroxybenzene) can also be used. Representative polyhydroxy compounds include sugars, such as glucose, sucrose, fructose, chitin and other polyols, such as mannitol. In this article, aldehydes include: straight-chain saturated aldehydes, such as formaldehyde (methanal / formaldehyde), acetaldehyde (ethanal / acetaldehyde), propanal / propionaldehyde, butanal / butyraldehyde, etc.; straight-chain unsaturated aldehydes, such as vinyl ketone and other ketones, 2-propenal (propenal / acrylaldehyde), 2-butenal (crotonaldehyde), 3-butenal, etc.; branched saturated and unsaturated aldehydes; and aromatic aldehydes, such as benzaldehyde, salicylaldehyde, hydrocinnamaldehyde, etc. Suitable ketones include: straight-chain saturated ketones, such as acetone and 2-butanone, etc.; straight-chain unsaturated ketones, such as propenone, 2-butenone and 3-butenone (methyl vinyl ketone), etc.; branched saturated and unsaturated ketones; and aromatic ketones, such as methyl benzyl ketone (phenylacetone), ethyl benzyl ketone, etc. The polymer precursor material can also be a combination of the above-mentioned precursors.

[0063] In some embodiments, a polymer precursor in a low solvent or substantially solvent-free reaction mixture is an alcohol-containing substance, and another polymer precursor is a carbonyl-containing substance. The relative amount of the alcohol-containing substance (for example, alcohol, phenolic compound and monohydroxy or polyhydroxy compound or its combination) reacted with a carbonyl-containing substance (for example, aldehyde, ketone or its combination) can vary significantly. In some embodiments, the ratio of alcohol-containing substance and aldehyde substance is selected to make the total mole number of the reactive alcohol group in the alcohol-containing substance roughly the same as the total mole number of the reactive carbonyl group in the aldehyde substance. Similarly, the ratio of alcohol-containing substance and ketone substance can be selected to make the total mole number of the reactive alcohol group in the alcohol-containing substance roughly the same as the total mole number of the reactive carbonyl group in the ketone substance. When the carbonyl-containing substance comprises a combination of aldehyde substance and ketone substance, the same approximately 1:1 mol ratio is equally applicable.

[0064] In other embodiments, the polymer precursor in the low solvent or substantially solvent-free reaction mixture is a urea-containing or amine-containing compound. For example, in some embodiments, the polymer precursor is urea, melamine, hexamethylenetetramine (HMT) or a combination thereof. Other embodiments include polymer precursors selected from isocyanates or other reactive carbonyl compounds (e.g., acyl halides, etc.).

[0065] Some embodiments of the disclosed method include preparing a low solvent or solvent-free polymer gel (and carbon material) comprising an electrochemical modifier. Such electrochemical modifiers include, but are not limited to, nitrogen, silicon, and sulfur. In other embodiments, the electrochemical modifier includes fluorine, iron, tin, silicon, nickel, aluminum, zinc, or manganese. The electrochemical modifier may be included in any step of the preparation process. For example, in some cases, the electrochemical modifier is mixed with a mixture, a polymer phase, or a continuous phase.

[0066] The mixing of one or more polymer precursor components without solvent can be achieved by methods described in the art, such as ball milling, jet milling, Fritsch milling, planetary mixing, and other mixing methods for mixing or blending solid particles, while controlling process conditions (e.g., temperature). The mixing or blending process can be achieved before, during, and / or after (or a combination thereof) incubation at the reaction temperature.

[0067] Reaction parameters include aging the blended mixture at a temperature and time sufficient to react one or more polymer precursors with each other and form a polymer. In this regard, a suitable aging temperature is a temperature from about room temperature to a temperature that is or is close to the melting point of one or more polymer precursors. In some embodiments, a suitable aging temperature is a temperature from about room temperature to a temperature that is or is close to the glass transition temperature of one or more polymer precursors. For example, in some embodiments, the solvent-free mixture is aged at a temperature of about 20°C to about 600°C, for example, from about 20°C to about 500°C, for example, from about 20°C to about 400°C, for example, from about 20°C to about 300°C, for example, from about 20°C to about 200°C. In certain embodiments, the solvent-free mixture is aged at a temperature of about 50°C to about 250°C.

[0068] The porous carbon material may be achieved via pyrolysis of a polymer produced from a precursor material as described above. In some embodiments, the porous carbon material comprises an amorphous activated carbon produced by pyrolysis, physical or chemical activation, or a combination thereof in a single process step or sequential process steps.

[0069] The temperature and residence time of pyrolysis can be varied, for example, the residence time can be varied from 1 minute to 10 minutes, from 10 minutes to 30 minutes, from 30 minutes to 1 hour, from 1 hour to 2 hours, from 2 hours to 4 hours, from 4 hours to 24 hours. The temperature can be varied, for example, the pyrolysis temperature can be varied from 200°C to 300°C, from 250 to 350°C, from 350°C to 450°C, from 450°C to 550°C, from 540°C to 650°C, from 650°C to 750°C, from 750°C to 850°C, from 850°C to 950°C, from 950°C to 1050°C, from 1050°C to 1150°C, from 1150°C to 1250°C. In some embodiments, the pyrolysis temperature is varied from 650°C to 1100°C. Pyrolysis can be completed in an inert gas such as nitrogen or argon.

[0070] In some embodiments, alternative gases are used to further realize carbon activation. In certain embodiments, pyrolysis and activation are combined. Suitable gases for realizing carbon activation include but are not limited to carbon dioxide, carbon monoxide, water (steam), air, oxygen and other combinations thereof. The temperature and residence time of activation can be varied, for example, the residence time can be varied from 1 minute to 10 minutes, from 10 minutes to 30 minutes, from 30 minutes to 1 hour, from 1 hour to 2 hours, from 2 hours to 4 hours, from 4 hours to 24 hours. The temperature can be varied, for example, the pyrolysis temperature can be varied from 200°C to 300°C, from 250 to 350°C, from 350°C to 450°C, from 450°C to 550°C, from 540°C to 650°C, from 650°C to 750°C, from 750°C to 850°C, from 850°C to 950°C, from 950°C to 1050°C, from 1050°C to 1150°C, from 1150°C to 1250°C. In some embodiments, the temperature of the combined pyrolysis and activation varies from 650°C to 1100°C.

[0071] In some embodiments, a combined pyrolysis and activation is performed to prepare the porous carbon scaffold. In such embodiments, the process gas can remain the same during the process, or the composition of the process gas can be changed during the process. In some embodiments, the addition of an activation gas such as CO2, steam, or a combination thereof is added to the process gas after the hottest temperature and time to allow pyrolysis of the solid carbon precursor.

[0072] Suitable gases for realizing carbon activation include but are not limited to carbon dioxide, carbon monoxide, water (steam), air, oxygen and other combinations thereof. The temperature and residence time of activation can vary, for example, the residence time can vary from 1 minute to 10 minutes, from 10 minutes to 30 minutes, from 30 minutes to 1 hour, from 1 hour to 2 hours, from 2 hours to 4 hours, from 4 hours to 24 hours. The temperature can vary, for example, the pyrolysis temperature can vary from 200°C to 300°C, from 250 to 350°C, from 350°C to 450°C, from 450°C to 550°C, from 540°C to 650°C, from 650°C to 750°C, from 750°C to 850°C, from 850°C to 950°C, from 950°C to 1050°C, from 1050°C to 1150°C, from 1150°C to 1250°C. In some embodiments, the temperature of activation varies from 650°C to 1100°C.

[0073] The carbon may be subjected to particle size reduction prior to pyrolysis, and / or after pyrolysis, and / or after activation. Particle size reduction may be achieved by various techniques known in the art, such as by jet milling in the presence of various gases, including air, nitrogen, argon, helium, supercritical steam, 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.

[0074] The porous carbon support can be in the form of particles. The particle size and particle size distribution can be measured by various techniques known in the art and can be described based on fractional volume. In this regard, the Dv,50 of the carbon support can be 10nm to 10mm, for example, 100nm to 1mm, for example, 1um to 100um, for example, 2um to 50um, for example, 3um to 30um, for example, 4um to 20um, for example, 5um to 10um. In certain embodiments, Dv,50 is less than 1mm, for example, less than 100um, for example, less than 50um, for example, less than 30um, for example, less than 20um, for example, less than 10um, for example, less than 8um, for example, less than 5um, for example, less than 3um, for example, less than 1um. In certain embodiments, Dv,100 is less than 1mm, for example, less than 100um, for example, less than 50um, for example, less than 30um, for example, less than 20um, for example, less than 10um, for example, less than 8um, for example, less than 5um, for example, less than 3um, for example, less than 1um. In certain embodiments, Dv,99 is less than 1 mm, for example, less than 100 um, for example, less than 50 um, for example, less than 30 um, for example, less than 20 um, for example, less than 10 um, for example, less than 8 um, for example, less than 5 um, for example, less than 3 um, for example, less than 1 um. In certain embodiments, Dv,90 is less than 1 mm, for example, less than 100 um, for example, less than 50 um, for example, less than 30 um, for example, less than 20 um, for example, less than 10 um, for example, less than 8 um, for example, less than 5 um, for example, less than 3 um, for example, less than 1 um. In certain embodiments, Dv,0 is greater than 10 nm, for example, greater than 100 nm, for example, greater than 500 nm, for example, greater than 1 um, for example, greater than 2 um, for example, greater than 5 um, for example, greater than 10 um. In certain embodiments, Dv,1 is greater than 10 nm, for example, greater than 100 nm, for example, greater than 500 nm, for example, greater than 1 um, for example, greater than 2 um, for example, greater than 5 um, for example, greater than 10 um. In certain embodiments, Dv,10 is greater than 10 nm, such as greater than 100 nm, such as greater than 500 nm, such as greater than 1 um, such as greater than 2 um, such as greater than 5 um, such as greater than 10 um.

[0075] In some embodiments, the surface area of ​​the porous carbon support may include greater than 400 m 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 2000m2 / g, for example, greater than 2500m 2 / g, for example, greater than 3000m 2 In other embodiments, the surface area of ​​the porous carbon support may be less than 500 m 2 In some embodiments, the surface area of ​​the porous carbon support is 200 to 500 m 2 In some embodiments, the surface area of ​​the porous carbon support is 100 to 200 m 2 In some embodiments, the surface area of ​​the porous carbon support is 50 to 100 m 2 In some embodiments, the surface area of ​​the porous carbon support is 10 to 50 m 2 In some embodiments, the surface area of ​​the porous carbon support can be less than 10 m 2 / g.

[0076] In some embodiments, the pore volume of the porous carbon scaffold is greater than 0.4 cm 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 1.0 cm 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 In other embodiments, the pore volume of the porous carbon scaffold is less than 0.5 cm3, for example 0.1 cm 3 / g to 0.5cm 3 In certain other embodiments, the pore volume of the porous carbon scaffold is 0.01 cm 3 / g to 0.1cm 3 / g.

[0077] In some other embodiments, the porous carbon scaffold has a pore volume of 0.2 to 2.0 cm 3 / g of amorphous activated carbon. In certain embodiments, the carbon has a pore volume of 0.4 to 1.5 cm 3 / g of amorphous activated carbon. In certain embodiments, the carbon has a pore volume of 0.5 to 1.2 cm 3 / g of amorphous activated carbon. In certain embodiments, the carbon has a pore volume of 0.6 to 1.0 cm 3 / g of amorphous activated carbon.

[0078] In some other embodiments, the porous carbon scaffold comprises less than 1.0 g / cm 3 The tap density is less than 0.8 g / cm 3 , for example, less than 0.6 g / cm 3 , for example, less than 0.5 g / cm 3 , for example, less than 0.4 g / cm 3 , for example, less than 0.3 g / cm 3 , for example, less than 0.2 g / cm 3 , for example, less than 0.1 g / cm 3 .

[0079] The surface functionality of the porous carbon scaffold can vary. One property that can predict the surface functionality is the pH of the porous carbon scaffold. The porous carbon scaffold disclosed herein comprises a pH value of less than 1 to about 14, such as less than 5, 5 to 8, or greater than 8. In some embodiments, the pH of the porous carbon 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.

[0080] The pore volume distribution of the porous carbon scaffold can vary. For example, the % micropores can account for less than 30%, such as less than 20%, such as less than 10%, such as less than 5%, such as less than 4%, such as less than 3%, such as less than 2%, such as less than 1%, such as less than 0.5%, such as less than 0.2%, such as less than 0.1%. In some embodiments, there is no detectable micropore volume in the porous carbon scaffold.

[0081] The mesopores that make up the porous carbon scaffold can vary. For example, the % mesopores can account for less than 30%, such as less than 20%, such as less than 10%, such as less than 5%, such as less than 4%, such as less than 3%, such as less than 2%, such as less than 1%, such as less than 0.5%, such as less than 0.2%, such as less than 0.1%. In some embodiments, there is no detectable mesopore volume in the porous carbon scaffold.

[0082] In some embodiments, the pore volume distribution of the porous carbon scaffold includes greater than 50% macropores, such as greater than 60% macropores, such as greater than 70% macropores, such as greater than 80% macropores, such as greater than 90% macropores, such as greater than 95% macropores, such as greater than 98% macropores, such as greater than 99% macropores, such as greater than 99.5% macropores, such as greater than 99.9% macropores.

[0083] In certain preferred embodiments, the pore volume of the porous carbon scaffold comprises a blend of micropores, mesopores, and macropores. Thus, in certain embodiments, the porous carbon scaffold comprises 0-20% micropores, 30-70% mesopores, and less than 10% macropores. In certain other embodiments, the porous carbon scaffold comprises 0-20% micropores, 0-20% mesopores, and 70-95% macropores. In certain other embodiments, the porous carbon scaffold comprises 20-50% micropores, 50-80% mesopores, and 0-10% macropores. In certain other embodiments, the porous carbon scaffold comprises 40-60% micropores, 40-60% mesopores, and 0-10% macropores. In certain other embodiments, the porous carbon scaffold comprises 80-95% micropores, 0-10% mesopores, and 0-10% macropores. In certain other embodiments, the porous carbon scaffold comprises 0-10% micropores, 30-50% mesopores, and 50-70% macropores. In certain other embodiments, the porous carbon scaffold comprises 0-10% micropores, 70-80% mesopores, and 0-20% macropores. In certain other embodiments, the porous carbon scaffold comprises 0-20% micropores, 70-95% mesopores, and 0-10% macropores. In certain other embodiments, the porous carbon scaffold comprises 0-10% micropores, 70-95% mesopores, and 0-20% macropores.

[0084] In certain embodiments, the pore volume percentage of the porous carbon scaffold representing pores ranging from 100 to 1000 Å (10 to 100 nm) accounts for greater than 30% of the total pore volume, such as greater than 40% of the total pore volume, such as greater than 50% of the total pore volume, such as greater than 60% of the total pore volume, such as greater than 70% of the total pore volume, such as greater than 80% of the total pore volume, such as greater than 90% of the total pore volume, such as greater than 95% of the total pore volume, such as greater than 98% of the total pore volume, such as greater than 99% of the total pore volume, such as greater than 99.5% of the total pore volume, such as greater than 99.9% of the total pore volume.

[0085] In certain embodiments, the porous carbon scaffold has a gravimetric density of about 1 g / cc to about 3 g / cc, such as about 1.5 g / cc to about 2.3 g / cc. In other embodiments, the skeletal density is about 1.5 cc / g to about 1.6 cc / g, about 1.6 cc / g to about 1.7 cc / g, about 1.7 cc / g to about 1.8 cc / g, about 1.8 cc / g to about 1.9 cc / g, about 1.9 cc / g to about 2.0 cc / g, about 2.0 cc / g to about 2.1 cc / g, about 2.1 cc / g to about 2.2 cc / g, or about 2.2 cc / g to about 2.3 cc / g, about 2.3 cc to about 2.4 cc / g, such as about 2.4 cc / g to about 2.5 cc / g.

[0086] C. Silicon production by chemical vapor infiltration (CVI)

[0087] 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 a Si-C composite material in which 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 into the pores of the porous scaffold material (into the pores) to provide a second component of the composite.

[0088] In embodiments, silicon is produced within the pores of the porous carbon support by subjecting the porous carbon particles to a silicon-containing precursor gas at elevated temperature and in the presence of a silicon-containing gas, preferably a silane, to decompose the gas into silicon. In some embodiments, the silicon-containing gas may include higher-order silanes (e.g., disilane, trisilane, and / or tetrasilane), chlorosilanes (e.g., monochlorosilane, dichlorosilane, trichlorosilane, and tetrachlorosilane), or mixtures thereof.

[0089] The silicon-containing precursor gas may be mixed with other inert gases, such as nitrogen, hydrogen, argon, helium or a combination thereof. The temperature and time of the process may 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.

[0090] 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.

[0091] The pressure of the CVI process can vary. In some embodiments, the pressure is atmospheric pressure. In some embodiments, the pressure is below atmospheric pressure. In some embodiments, the pressure is above atmospheric pressure.

[0092] D. Physical and electrochemical properties of silicon-carbon composites

[0093] While not wishing to be bound by theory, it is believed that the nano-sized silicon (e.g., silicon filling pores of 5 to 1000 nm or other ranges as disclosed elsewhere herein) achieved due to filling certain desired pore volume structures of the porous carbon scaffold, along with the favorable properties of the other components of the composite (including low surface area, low gravimetric density), results in a composite material having different and advantageous properties (e.g., electrochemical performance when the composite constitutes an anode of a lithium-ion energy storage device).

[0094] In certain embodiments, the embedded silicon particles embedded in the composite include nano-sized features. The nano-sized features may have a characteristic length scale that is preferably less than 1 um, preferably less than 300 nm, preferably less than 150 nm, preferably less than 100 um, preferably less than 50 nm, preferably less than 30 nm, preferably less than 15 nm, preferably less than 10 nm, preferably less than 5 nm.

[0095] In certain embodiments, the shape of the silicon embedded in the composite is spherical. In certain other embodiments, the porous silicon particles are non-spherical, such as rod-shaped or fibrous structures. In some embodiments, silicon exists as a layer inside the hole in the porous carbon support. The depth of the silicon layer can vary, such as a depth of 5nm to 10nm, such as 5nm to 20nm, such as 5nm to 30nm, such as 5nm to 33nm, such as 10nm to 30nm, such as 10nm to 50nm, such as 10nm to 100nm, such as 10 to 150nm, such as 50nm to 150nm, such as 100 to 300nm, such as 300 to 1000nm.

[0096] In some embodiments, the silicon embedded in the composite is nano-sized and resides in the pores of the porous carbon support. For example, the embedded silicon can be impregnated, deposited by CVI, or other suitable methods into the pores in the porous carbon particles, the pore size of the porous carbon particles is 5 to 1000nm, such as 10 to 500nm, such as 10 to 200nm, such as 10 to 100nm, such as 33 to 150nm, such as 20 to 100nm. Other ranges of carbon pore sizes with respect to fractional pore volume are also contemplated, whether microporous, mesoporous or macroporous.

[0097] In some embodiments, the carbon support pore volume distribution can be described as the number or volume distribution of pores determined based on gas adsorption analysis (e.g., nitrogen adsorption analysis) as known in the art. In some embodiments, the pore size distribution can be expressed as a pore size at or below which a certain portion of the total pore volume is located. For example, a pore size at or below which 10% of the pores are located can be expressed as DPv10.

[0098] The DPv10 of the porous carbon scaffold can vary, for example, the DPv10 can be 0.01 nm to 100 nm, for example 0.1 nm to 100 nm, for example 1 nm to 100 nm, for example 1 nm to 50 nm, for example 1 nm to 40 nm, for example 1 nm to 30 nm, for example 1 nm to 10 nm, for example 1 nm to 5 nm.

[0099] The DPv50 of the porous carbon scaffold can vary, for example, the DPv50 can be 0.01 nm to 100 nm, for example, 0.1 nm to 100 nm, for example, 1 nm to 100 nm, for example, 1 nm to 50 nm, for example, 1 nm to 40 nm, for example, 1 nm to 30 nm, for example, 1 nm to 10 nm, for example, 1 nm to 5 nm. In other embodiments, the DPv50 is 2 to 100, for example, 2 to 50, for example, 2 to 30, for example, 2 to 20, for example, 2 to 15, for example, 2 to 10.

[0100] The DPv90 of the porous carbon scaffold can vary, for example, the DPv90 can be 0.01 nm to 100 nm, for example, 0.1 nm to 100 nm, for example, 1 nm to 100 nm, for example, 1 nm to 50 nm, for example, 1 nm to 50 nm, for example, 1 nm to 40 nm, for example, 1 nm to 30 nm, for example, 1 nm to 10 nm, for example, 1 nm to 5 nm. In other embodiments, the DPv50 is 2 nm to 100 nm, for example, 2 nm to 50 nm, for example, 2 nm to 30 nm, for example, 2 nm to 20 nm, for example, 2 nm to 15 nm, for example, 2 nm to 10 nm.

[0101] In some embodiments, DPv90 is less than 100 nm, such as less than 50 nm, such as less than 40 nm, such as less than 30 nm, such as less than 20 nm, such as less than 15 nm, such as less than 10 nm. In some embodiments, the carbon scaffold comprises a pore volume that is greater than 70% micropores (and a DPv90 of less than 100 nm, such as a DPv90 of less than 50 nm, such as a DPv90 of less than 40 nm, such as a DPv90 of less than 30 nm, such as a DPv90 of less than 20 nm, such as a DPv90 of less than 15 nm, such as a DPv90 of less than 10 nm, such as a DPv90 of less than 5 nm, such as a DPv90 of less than 4 nm, such as a DPv90 of less than 3 nm. In other embodiments, the carbon scaffold comprises a pore volume that is greater than 80% micropores and a DPv90 of less than 100 nm, such as a DPv90 of less than 50 nm, such as a DPv90 of less than 40 nm, such as a DPv90 of less than 30 nm, such as a DPv90 of less than 20 nm, such as a DPv90 of less than 15 nm, such as a DPv90 of less than 10 nm, such as a DPv90 of less than 5 nm, such as a DPv90 of less than 4 nm, such as a DPv90 of less than 3 nm.

[0102] The DPv99 of the porous carbon scaffold can vary, for example, the DPv99 can be 0.01 nm to 1000 nm, for example, 0.1 nm to 1000 nm, for example, 1 nm to 500 nm, for example, 1 nm to 200 nm, for example, 1 nm to 150 nm, for example, 1 nm to 100 nm, for example, 1 nm to 50 nm, for example, 1 nm to 20 nm. In other embodiments, the DPv99 is 2 nm to 500 nm, for example, 2 nm to 200 nm, for example, 2 nm to 150 nm, for example, 2 nm to 100 nm, for example, 2 nm to 50 nm, for example, 2 nm to 20 nm, for example, 2 nm to 15 nm, for example, 2 nm to 10 nm.

[0103] Embodiments of the composites disclosed herein with extremely durable lithium intercalation improve the properties of any number of electrical energy storage devices (e.g., lithium ion batteries). In some embodiments, the silicon-carbon composites disclosed herein exhibit a Z of less than 10, such as a Z of less than 5, such as a Z of less than 4, such as a Z of less than 3, such as a Z of less than 2, such as a Z of less than 1, such as a Z of less than 0.1, such as a Z of less than 0.01, such as a Z of less than 0.001. In certain embodiments, Z is 0.

[0104] In certain preferred embodiments, the silicon-carbon composite comprises a desired low Z 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 certain embodiments of the combination of properties (including reversible capacity) of the silicon-carbon composite. The surface area can be measured as known in the art, for example, by nitrogen adsorption analysis. The silicon content can be measured as known in the art, for example, by TGA. The property Z can be measured by TGA according to the present disclosure. The first cycle efficiency can be measured as known in the art, for example, based on the first cycle charge and discharge capacity in a full cell or half cell. For example, the first cycle efficiency can be measured in a half cell for a voltage window of 5mV to 0.8V, or alternatively, 5mV to 1.5V. The reversible capacity can be described as the maximum reversible capacity or maximum capacity, and can be measured as known in the art, for example, in a half cell for a voltage window of 5mV to 0.8V, or alternatively, 5mV to 1.5V.

[0105] Table 1. Embodiments of silicon-carbon composites with achieved properties.

[0106]

[0107] According to Table 1, the silicon-carbon composite can contain various combinations of properties. For example, the silicon-carbon composite can contain Z less than 10, 2 / g surface area, greater than 80% first cycle efficiency and at least 1300 mAh / g reversible capacity. For example, the silicon-carbon composite can contain less than 10 Z, less than 100 m 2 / g surface area, greater than 80% first cycle efficiency and at least 1600 mAh / g reversible capacity. For example, the silicon-carbon composite can contain less than 10 Z, less than 20 m 2 / g surface area, greater than 85% first cycle efficiency and at least 1600 mAh / g reversible capacity. For example, the silicon-carbon composite can contain less than 10 Z, less than 10m 2 / g surface area, greater than 85% first cycle efficiency and at least 1600 mAh / g reversible capacity. For example, the silicon-carbon composite can contain less than 10 Z, less than 10m 2 / g surface area, greater than 90% first cycle efficiency and at least 1600 mAh / g reversible capacity. For example, the silicon-carbon composite can contain less than 10 Z, less than 10m 2 / g surface area, greater than 90% first cycle efficiency and at least 1800 mAh / g reversible capacity.

[0108] In addition to also comprising a carbon scaffold having the properties also described in this embodiment, the silicon-carbon composite may also comprise a combination of the above properties. Accordingly, Table 2 provides a description of certain embodiments of combinations of properties of the silicon-carbon composite.

[0109] Table 2. Embodiments of silicon-carbon composites with achieved properties.

[0110]

[0111] As used herein, "micropores", "mesopores" and "macroporous" percentages refer to the percentage of total pore volume of micropores, mesopores and macropores, respectively. For example, a carbon scaffold having 90% micropores is a carbon scaffold in which 90% of the total pore volume of the carbon scaffold is formed by micropores.

[0112] According to Table 2, the silicon-carbon composite can include a combination of various properties. For example, the silicon-carbon composite can include: D / I G ≤0.7, Z less than 10, surface area less than 100m 2 / g, the first cycle efficiency is greater than 80%, the reversible capacity is at least 1600 mAh / g, the silicon content is 15%-85%, and the total pore volume of the carbon scaffold is 0.2-1.2 cm 3 / g, wherein the scaffold pore volume comprises >80% micropores, <20% mesopores, and <10% macropores. For example, the silicon-carbon composite may include I D / I G ≤0.7, Z less than 10, surface area less than 20m 2 / g, the first cycle efficiency is greater than 85%, the reversible capacity is at least 1600 mAh / g, the silicon content is 15%-85%, and the total pore volume of the carbon scaffold is 0.2-1.2 cm 3 / g, wherein the scaffold pore volume comprises >80% micropores, <20% mesopores, and <10% macropores. For example, the silicon-carbon composite may include I D / I G ≤0.7, Z less than 10, surface area less than 10m 2 / g, the first cycle efficiency is greater than 85%, the reversible capacity is at least 1600 mAh / g, the silicon content is 15%-85%, and the total pore volume of the carbon scaffold is 0.2-1.2 cm 3 / g, wherein the scaffold pore volume comprises >80% micropores, <20% mesopores, and <10% macropores. For example, the silicon-carbon composite may include I D / I G ≤0.7, Z less than 10, surface area less than 10m 2 / g, the first cycle efficiency is greater than 90%, the reversible capacity is at least 1600 mAh / g, the silicon content is 15%-85%, and the total pore volume of the carbon scaffold is 0.2-1.2 cm 3 / g, wherein the scaffold pore volume comprises >80% micropores, <20% mesopores, and <10% macropores. For example, the silicon-carbon composite may include I D / I G ≤0.7, Z less than 10, surface area less than 10m 2 / g, the first cycle efficiency is greater than 90%, the reversible capacity is at least 1800mAh / g, the silicon content is 15%-85%, and the total pore volume of the carbon scaffold is 0.2-1.2cm 3 / g, where the scaffold pore volume contains >80% micropores, <20% mesopores and <10% macropores.

[0113] Also according to Table 2, the silicon-carbon composite may include a carbon scaffold having micropores>80%, a silicon content of 30-60%, an average coulombic efficiency of ≥0.9969, and Z<10. For example, the silicon-carbon composite may include a carbon scaffold having micropores>80%, a silicon content of 30-60%, an average coulombic efficiency of ≥0.9970, and Z<10. For example, the silicon-carbon composite may include a carbon scaffold having micropores>80%, a silicon content of 30-60%, an average coulombic efficiency of ≥0.9975, and Z<10. For example, the silicon-carbon composite may include a carbon scaffold having micropores>80%, a silicon content of 30-60%, an average coulombic efficiency of ≥0.9980, and Z<10. For example, the silicon-carbon composite may include a carbon scaffold having micropores>80%, a silicon content of 30-60%, an average coulombic efficiency of ≥0.9985, and Z<10. For example, a silicon-carbon composite may include a carbon scaffold having >80% micropores, a silicon content of 30-60%, an average coulombic efficiency of ≥0.9990, and Z<10. For example, a silicon-carbon composite may include a carbon scaffold having >80% micropores, a silicon content of 30-60%, an average coulombic efficiency of ≥0.9995, and Z<10. For example, a silicon-carbon composite may include a carbon scaffold having >80% micropores, a silicon content of 30-60%, an average coulombic efficiency of ≥0.9970, and Z<10. For example, a silicon-carbon composite may include a carbon scaffold having >80% micropores, a silicon content of 30-60%, an average coulombic efficiency of ≥0.9999, and Z<10.

[0114] Without being bound by theory, the packing of silicon within the pores of the porous carbon entraps the pores within the porous carbon scaffold particles, creating an inaccessible volume, such as a volume inaccessible to nitrogen. Thus, the silicon-carbon composite material may exhibit a gravimetric density of less than 2.1 g / cm 3 , for example, less than 2.0 g / cm 3, for example, less than 1.9 g / cm 3 , for example, less than 1.8 g / cm 3 , for example, less than 1.7 g / cm 3 , for example, less than 1.6 g / cm 3 , for example, less than 1.4 g / cm 3 , for example, less than 1.2 g / cm 3 , for example, less than 1.0 g / cm 3 .

[0115] In some embodiments, the silicon-carbon composite material may exhibit a gravimetric density of 1.7 g / cm3 to 2.1 g / cm 3 , for example 1.7g.cm3 to 1.8g / cm 3 , 1.8g.cm3 to 1.9g / cm 3 , for example 1.9 g.cm3 to 2.0 g / cm 3 , for example 2.0g.cm3 to 2.1g / cm 3 In some embodiments, the silicon-carbon composite material may exhibit a gravimetric density of 1.8 g.cm3 to 2.1 g / cm 3 In some embodiments, the silicon-carbon composite material may exhibit a gravimetric density of 1.8 g.cm3 to 2.0 g / cm 3 In some embodiments, the silicon-carbon composite material may exhibit a gravimetric density of 1.9 g.cm3 to 2.1 g / cm 3 .

[0116] The pore volume of the composite material showing extremely durable lithium intercalation can be 0.01 cm 3 / g to 0.2cm 3 In certain embodiments, the pore volume of the composite material may be 0.01 cm 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.

[0117] The particle size distribution of the composite material showing extremely durable lithium embedding is important for determining power performance and volume capacity. As the stacking improves, the volume capacity can be increased. In one embodiment, the distribution is a Gaussian distribution with a shape of unimodal, bimodal or multimodal (>2 different peaks, such as trimodal). The properties of the particle size of the composite can be described by D0 (the smallest particle in the distribution), Dv50 (average particle size) and Dv100 (the maximum size of the largest particle). The best combination of particle stacking and performance will be some combinations of the following size ranges. The particle size reduction in such embodiments can be carried out as known in the art, for example, by jet milling in the presence of various gases, including air, nitrogen, argon, helium, supercritical steam and other gases known in the art.

[0118] In one embodiment, the Dv0 of the composite material can be 1 nm to 5 microns. In another embodiment, the Dv0 of the composite is 5 nm to 1 micron, such as 5-500 nm, such as 5-100 nm, such as 10-50 nm. In other embodiments, the Dv0 of the composite is 500 nm to 2 microns, or 750 nm to 1 um, or 1-2 um. micron to 2 microns. In other embodiments, the Dv0 of the composite is 2-5 um, or > 5 um.

[0119] In one embodiment, the Dv1 of the composite material can be 1 nm to 5 microns. In another embodiment, the Dv1 of the composite is 5 nm to 1 micron, such as 5-500 nm, such as 5-100 nm, such as 10-50 nm. In another embodiment, the Dv1 of the composite is 100 nm to 10 microns, 200 nm to 5 microns, 500 nm to 2 microns, or 750 nm to 1 um, or 1-2 um. micron to 2 microns. In other embodiments, the Dv1 of the composite is 2-5 um, or> 5 um.

[0120] In one embodiment, the Dv10 of the composite material can be 1 nm to 10 microns. In another embodiment, the Dv10 of the composite is 5 nm to 1 micron, such as 5-500 nm, such as 5-100 nm, such as 10-50 nm. In another embodiment, the Dv10 of the composite is 100 nm to 10 microns, 500 nm to 10 microns, 500 nm to 5 microns, or 750 nm to 1 um, or 1-2 um. In other embodiments, the Dv10 of the composite is 2-5 um, or> 5 um.

[0121] In some embodiments, the Dv50 of the composite material is 5nm to 20um. In other embodiments, the Dv50 of the composite is 5nm to 1um, such as 5-500nm, such as 5-100nm, such as 10-50nm. In other embodiments, the Dv50 of the composite is 500nm to 2um, 750nm to 1um, 1-2um. In some further embodiments, the Dv50 of the composite is 1 to 1000um, such as 1-100um, such as 1-10um, such as 2-20um, such as 3-15um, such as 4-8um. In certain embodiments, Dv50>20um, such as>50um, such as>100um.

[0122] The span (Dv50) / (Dv90-Dv10) (where Dv10, Dv50, and Dv90 represent the particle sizes at 10%, 50%, and 90% of the volume distribution) can vary, for example, from 100 to 10, 10 to 5, 5 to 2, 2 to 1; in some embodiments, the span can be less than 1. In certain embodiments, the composite comprising carbon and porous silicon material particle size distribution can be multimodal, for example, bimodal or trimodal.

[0123] The surface functionality of the composite materials disclosed herein that exhibit extremely durable lithium intercalation can be varied to obtain desired electrochemical properties. One property that can predict surface functionality is the pH of the composite material. The composite materials disclosed herein comprise a pH value of 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.

[0124] 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 carbon content of the composite is 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%, such as 20-80%, such as 30-70%, such as 40-60%.

[0125] In some embodiments, the nitrogen content of the silicon-carbon composite is 0-90%, such as 0.1-1%, such as 1-3%, such as 1-5%, such as 1-10%, such as 10-20%, such as 20-30%, such as 30-90%.

[0126] In some embodiments, the oxygen content is 0-90%, such as 0.1-1%, such as 1-3%, such as 1-5%, such as 1-10%, such as 10-20%, such as 20-30%, such as 30-90%.

[0127] Silicon-carbon composites can also incorporate electrochemical modifiers, which are selected to optimize the electrochemical properties of unmodified composites. Electrochemical modifiers can be incorporated into the pore structure and / or surface of porous carbon scaffolds, in embedded silicon, or in the final carbon layer, or in a conductive polymer, in a coating, or in any other manner. For example, in some embodiments, the composite material includes a coating of an electrochemical modifier (e.g., silicon or Al2O3) on the surface of the carbon material. In some embodiments, the composite material includes an electrochemical modifier greater than about 100ppm. In certain embodiments, the electrochemical modifier is selected from iron, tin, silicon, nickel, aluminum and manganese.

[0128] In certain embodiments, the electrochemical modifier comprises an element having the ability to be lithiated at 3 to 0V relative to lithium metal (e.g., silicon, tin, sulfur). In other embodiments, the electrochemical modifier comprises a metal oxide having the ability to be lithiated at 3 to 0V relative to lithium metal (e.g., iron oxide, molybdenum oxide, titanium oxide). In other embodiments, the electrochemical modifier comprises an element that will not be lithiated at 3 to 0V relative to lithium metal (e.g., aluminum, manganese, nickel, metal phosphate). In other embodiments, the electrochemical modifier comprises a non-metallic element (e.g., fluorine, nitrogen, hydrogen). In other embodiments, the electrochemical modifier includes any one of the aforementioned electrochemical modifiers or any combination thereof (e.g., tin-silicon, nickel-titanium oxide).

[0129] The electrochemical modifier can be provided in a variety of 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.

[0130] The electrochemical properties of the composite material can be modified at least in part by the amount of electrochemical modifier in the material, wherein the electrochemical modifier is an alloy material, such as silicon, tin, indium, aluminum, germanium, gallium. Thus, in some embodiments, the composite material comprises 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.

[0131] The particle size of the composite material can expand upon lithiation compared to the non-lithiation state. For example, the expansion factor is defined as the ratio of the average particle size of the particles of the composite material comprising the porous silicon material upon lithiation divided by the average particle size under non-lithiation conditions. As described in the art, the expansion factor of previously known non-optimal silicon-containing materials can be relatively large, such as about 4X (corresponding to a 400% volume expansion upon lithiation). The inventors have discovered that composite materials comprising porous silicon materials 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, 1.0 to 1.5.

[0132] It is contemplated that in certain embodiments, the composite material will contain a portion of trapped pore volume, i.e., void volume that is inaccessible to nitrogen as detected by nitrogen adsorption measurements. Without being bound by theory, this trapped pore volume is important because it provides volume into which silicon can expand upon lithiation.

[0133] In certain embodiments, the ratio of the trapped void volume to the volume of silicon comprising the composite particle is from 0.1: 1 to 10: 1. For example, the ratio of the trapped void volume to the volume of silicon comprising the composite particle is from 1: 1 to 5: 1 or from 5: 1 to 10: 1. In embodiments, to effectively accommodate the maximum expansion of silicon upon lithiation, the ratio of the trapped void volume to the volume of silicon comprising the composite particle is from 2: 1 to 5: 1, or about 3: 1.

[0134] In certain embodiments, the electrochemical performance of the composite disclosed herein is tested in a half-cell; alternatively, the performance of the composite with extremely durable lithium intercalation disclosed herein is tested in a full cell (e.g., a full cell button cell, a full cell pouch cell, a square cell, or other battery structures known in the art). As known in the art, the anode composition comprising the composite with extremely durable lithium intercalation disclosed herein may further comprise various 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., adhesives, such as styrene-butadiene rubber sodium carboxymethyl cellulose (SBR-Na-CMC), polyvinylidene fluoride (PVDF), polyimide (PI), polyacrylic acid (PAA), etc., and combinations thereof. In certain embodiments, the adhesive may include lithium ions as counter ions.

[0135] Other substances constituting the electrode are known in the art. The percentage by weight of the active material in the electrode 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 accounts for 80 to 95% of the electrode. In certain embodiments, the amount of the 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 the active material in the electrode is 5 to 25%. In certain embodiments, the amount of the binder can vary, for example, 1 to 5%, 5 to 15%, for example, 15 to 25%, for example, 25 to 35%. In certain embodiments, the amount of the conductive additive in the electrode is 5 to 25%.

[0136] As known in the art, silicon-carbon composite materials can be pre-lithiated. In certain embodiments, before the lithiated anode comprising a porous silicon material is assembled into a full-cell lithium-ion battery, pre-lithiation is electrochemically achieved, for example, in a half-cell. In certain embodiments, pre-lithiation is achieved by doping the cathode with a lithium-containing compound, for example, a lithium-containing salt. In this article, examples of suitable lithium salts include, but are not limited to, dilithium tetrabromonickelate (II), dilithium tetrachlorocuprate (II), lithium azide, lithium benzoate, lithium bromide, lithium carbonate, lithium chloride, lithium cyclohexanebutyrate, lithium fluoride, lithium formate, lithium hexafluoroarsenate (V) acid, 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.

[0137] Anodes comprising silicon-carbon composites can be paired with various cathode materials to obtain full-cell lithium-ion batteries. Examples of suitable cathode materials are known in the art. Examples of such cathode materials include, but are not limited to, LiCoO2 (LCO), LiNi 0.8 Co 0.15 Al 0.05 O2(NCA), LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (NMC), LiMn2O4 and variants (LMO), and LiFePO4 (LFP).

[0138] For a full-cell lithium-ion battery including an anode that also includes a silicon-carbon composite material, the pairing of the cathode and the anode can be changed. For example, the ratio of the cathode to the anode capacity can be changed to 0.7 to 1.3. In certain embodiments, the ratio of the cathode to the anode capacity can be changed to 0.7 to 1.0, such as 0.8 to 1.0, such as 0.85 to 1.0, such as 0.9 to 1.0, such as 0.95 to 1.0. In other embodiments, the ratio of the cathode to the anode capacity can be changed to 1.0 to 1.3, such as 1.0 to 1.2, such as 1.0 to 1.15, such as 1.0 to 1.1, such as 1.0 to 1.05. In other embodiments, the ratio of the cathode to the anode capacity can be changed to 0.8 to 1.2, such as 0.9 to 1.1, such as 0.95 to 1.05.

[0139] For a full-cell lithium-ion battery including an anode that also includes a silicon-carbon composite material, the voltage window for charging and discharging can be changed. In this regard, the voltage window can vary as known in the art, depending on the various properties of the lithium-ion battery. For example, the choice of cathode works in the selected voltage window, as known in the art. For example, an example of a voltage window varies from 2.0V to 5.0V, such as 2.5V to 4.5V, such as 2.5V to 4.2V, depending on the potential relative to Li / Li+.

[0140] For a full-cell lithium-ion battery including an anode that also includes a silicon-carbon composite material, the strategy for conditioning the battery can vary as known in the art. For example, conditioning can be accomplished by one or more charge and discharge cycles at various rates (e.g., at a rate slower than the desired cycle rate). As known in the art, the conditioning process can also include the steps of unsealing the lithium-ion battery, evacuating any gas generated therein during the conditioning process, and then resealing the lithium-ion battery.

[0141] For a full-cell lithium-ion battery including an anode that also includes a silicon-carbon composite material, the cycle rate can vary as 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 certain embodiments, the cycle rate is C / 10. In certain embodiments, the cycle rate is C / 5. In certain embodiments, the cycle rate is C / 2. In certain embodiments, the cycle rate is 1C. In certain embodiments, the cycle rate is 1C, wherein the rate is periodically reduced to a slower rate, such as cycling at 1C, wherein every 20th cycle adopts a C / 10 rate. In certain embodiments, the cycle rate is 2C. In certain embodiments, the cycle rate is 4C. In certain embodiments, the cycle rate is 5C. In certain embodiments, the cycle rate is 10C. In certain embodiments, the cycle rate is 20C.

[0142] The first cycle efficiency of the composites disclosed herein with extremely durable lithium intercalation is determined by comparing the lithium intercalated into the anode during the first cycle with the lithium deintercalated from the anode in the first cycle (before pre-lithiation modification). When the intercalation and deintercalation are equal, the efficiency is 100%. As is known in the art, the anode material can be tested in a half-cell where the counter electrode is lithium metal and the electrolyte is 1M LiPF6 1:1 ethylene carbonate: diethyl carbonate (EC:DEC), using a commercially available polypropylene separator. In certain embodiments, the electrolyte may include various additives known to provide improved performance, such as fluoroethylene carbonate (FEC) or other related fluorinated carbonate compounds, or ester co-solvents such as methyl butyrate, vinylene carbonate, and other electrolyte additives known to improve the electrochemical performance of silicon-containing anode materials.

[0143] In certain embodiments, the first cycle efficiency of the half-cell can be determined within a voltage window of 5 mV to 0.8 V. In another embodiment, the first cycle efficiency in the half-cell can be determined within a voltage window of 5 mV to 1.0 V. In another embodiment, the first cycle efficiency in the half-cell can be determined within a voltage window of 5 mV to 1.5 V. In another embodiment, the first cycle efficiency in the half-cell can be determined within a voltage window of 5 mV to 2.0 V. In other embodiments, the first cycle efficiency is determined in a full cell, for example, within a voltage window of 2.0 V to 4.5 V, or 2.3 V to 4.5 V, or 2.5 V to 4.2 V, or 3.0 V to 4.2 V.

[0144] The coulombic efficiency can be averaged, for example, from cycle 7 to cycle 25 when tested in a half cell. The coulombic efficiency can be averaged, for example, from cycle 7 to cycle 20 when tested in a half cell. In certain embodiments, the average efficiency of the composite with extremely durable lithium intercalation is greater than 0.9 or 90%. In certain embodiments, the average efficiency is greater than 0.95 or 95%. In certain other embodiments, the average efficiency is 0.99 or greater, e.g., 0.991 or greater, e.g., 0.992 or greater, e.g., 0.993 or greater, e.g., 0.994 or greater, e.g., 0.995 or greater, e.g., 0.996 or greater, e.g., 0.997 or greater, e.g., 0.998 or greater, e.g., 0.999 or greater, e.g., 0.9991 or greater, e.g., 0.9992 or greater, e.g., 0.9993 or greater, e.g., 0.9994 or greater, e.g., 0.9995 or greater, e.g., 0.9996 or greater, e.g., 0.9997 or greater, e.g., 0.9998 or greater, e.g., 0.9999 or greater.

[0145] In other embodiments, the present disclosure provides a composite material that exhibits extremely durable lithium intercalation, wherein when the composite material is incorporated into an electrode of a lithium-based energy storage device, the volumetric capacity of the composite material is at least 10% greater than when the lithium-based energy storage device includes a graphite electrode. In some embodiments, the lithium-based energy storage device is a lithium-ion battery. In other embodiments, the volumetric capacity of the composite material in a lithium-based energy storage device is at least 5%, at least 10%, at least 15% greater than the volumetric capacity of the same energy storage device with a graphite electrode. In other embodiments, the volumetric capacity of the composite material in a 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 with a graphite electrode.

[0146] As is known in the art, the composite material may 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 may be calculated by techniques known to those skilled in the art:

[0147] #Li=Q x 3.6 x MM / (C% x F)

[0148] Where Q is the lithium deintercalation capacity measured in mAh / g at voltages between 5 mV and 2.0 V relative to lithium metal, MM is the molecular weight of 72 or 6 carbons, F is the Faraday constant of 96500, and C% is the mass percent of carbon present in the structure as measured by CHNO or XPS.

[0149] The composite material may be characterized by a ratio of lithium atoms to carbon atoms (Li:C), which may vary from about 0:6 to 2:6. In some embodiments, the Li:C ratio is about 0.05:6 to about 1.9:6. In other embodiments, the maximum Li:C ratio in which lithium is in ionic form rather than metallic form is 2.2:6. In certain other embodiments, the Li:C ratio 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 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 specific embodiments, the Li:C ratio is about 1.78:6.

[0150] In certain 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 has a lithium absorption capacity (i.e., the ability to absorb a certain amount of lithium), such as when the material is cycled between two voltage conditions (in the case of a lithium ion half-cell, an exemplary voltage window is between 0 and 3V, such as 0.005 to 2.7V, such as 0.005 to 1V, such as 0.005 to 0.8V). Although not wishing to be bound by theory, it is believed that the lithium absorption capacity of the composite material contributes to their excellent performance in lithium-based energy storage devices. The lithium absorption capacity is expressed as the ratio of lithium atoms absorbed by the composite material. In certain other embodiments, the lithium absorption capacity of the composite material that exhibits 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.

[0151] In certain 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 specific embodiments, the Li:C ratio is about 1.78:6.

[0152] E. Passivation method to control oxygen content and reactivity of silicon-carbon materials using silane as silicon precursor

[0153] The properties of low temperature chemical vapor deposition of elemental silicon produced by silane gas produce an amorphous structure that is prone to rapid oxidation (spontaneous combustion) when not properly passivated. The current prior art for passivating the synthesized silicon requires simply introducing air to react while still in the furnace without worrying about flammability issues. The problem is that the degree of oxidation can vary significantly depending on the final surface area of ​​the composite. For example, a composite with a high surface area will react more easily with oxygen, exponentially heat up, and therefore further oxidize. And a composite with a lower surface area will passivate more slowly and produce very little heat. The latter situation seems to be the most ideal, however, in order to better understand and utilize composites with higher surface areas (smaller size silicon) that may improve electrochemical cycling stability, an alternative passivation method is needed to have a low oxygen content and maintain the deposited silicon morphology. The invention described herein outlines several methods that passivate the surface of the deposited silicon material by exposing the deposited silicon material to a benign (non-oxygen) gaseous substance so as to maintain a low exothermic temperature, and thus provide the lowest achievable oxygen content and the highest capacity.

[0154] The prior art describes methods for passivating silicon surfaces where silicon films and particles including nanocrystals are present (e.g., Sun et al., 2016, “Heterogeneous reduction of carbon dioxide by hydride-terminated silicon nanocrystals” Nature Communications, 7:1–9; Cicero et al., 2000, “Photoreactivity of Unsaturated Compounds with Hydrogen-Terminated Silicon (111),” Langmuir 16:5688-5695; Cai et al., 2004, “Direct electrical detection of DNA Hybridization at DNA-modified silicon surfaces,” Biosensors and Bioelectronics 19:1013-1019 (2004)). This prior art does not address the very different and more challenging task of passivating the surfaces of amorphous nanosized silicon present within the pores of a porous carbon scaffold. In other words, the prior art does not address how to passivate silicon surfaces of silicon prepared via CVI, i.e., silicon impregnated into the pores of a porous carbon scaffold via CVI.

[0155] The invention functions to mitigate over-oxidation of silicon obtained from the silane CVI reaction, wherein a Si-C composite of high surface area and low oxygen content can be obtained. By controlling time, temperature, and gas species and concentrations, it will be possible to influence the passivation characteristics of silicon so as to maintain the deposited amorphous structure and increase the Li-ion capacity. Furthermore, without being bound by theory, such passivation of silicon prepared via CVI produces improved Li-ion rate performance by minimizing the thickness of the oxide barrier.

[0156] When high surface area silane-derivatized silicon is suddenly exposed to air, a strongly exothermic oxidation occurs, which may be exacerbated by thermal destabilization, potentially completely oxidizing the silicon present (i.e., rendering it inert / unusable) and creating safety issues of flammability. The present invention addresses this problem when deposited on high surface areas (particularly >500 m2) by allowing for a stepwise controlled passivation of the material. 2 / g) on ​​substrates with pyrophoric silane-derived silicon.

[0157] In some embodiments, silicon prepared via CVI can be passivated by cooling the freshly prepared silicon-carbon material to a temperature below the CVI reaction temperature, for example to <400°C, or <350°C, or <300°C, or <250°C, or <200°C, or <150°C, or <100°C, or <50°C, under a nitrogen flow, followed by the introduction of air, or alternatively, oxygen (in pure form, or blended with various percentages of nitrogen, for example, the passivating gas stream can contain 1% oxygen and 99% nitrogen, or 5% oxygen and 95% nitrogen, or 10% oxygen and 90% nitrogen, or 15% oxygen and 85% nitrogen, or 20% oxygen and 80% nitrogen, or the passivating gas stream can contain >20% oxygen in a nitrogen mixture).

[0158] Typical low temperature chemical vapor deposition (CVD) reactions involving hydride-based (e.g., silane) gaseous precursors to produce highly disordered nanofilms / particles generally exhibit an inherent tendency to oxidize or passivate when exposed to atmospheric conditions. The extent to which this occurs and the exothermic nature depend greatly on the size and crystallinity of the deposited material. In the case of polycrystalline growth such as that performed in the photovoltaic industry, deposition conditions are typically carried out at much higher temperatures (>600°C) and thick films or particles are formed. These materials not only exhibit high crystallinity, but also very low surface areas, resulting in very slow and benign reactivity when exposed to air, so controlling the degree of passivation is highly unnecessary.

[0159] Compared to the prior art, the present invention discloses a passivation method for silicon prepared via CVI (e.g., silicon prepared via CVI within the pores of a porous carbon support). When very tortuous porous high surface area materials with irregular morphology and high surface area (e.g., containing a surface area >500 m 2 / g and total pore volume>0.4cm 3 When low temperature elemental silicon CVI is performed on granular porous carbon (granular porous carbon of 1000 g / cm2), the silicon structure is more disordered (amorphous), contains a high percentage of surface-terminated reactive hydrogen bonds, and is very small in size (e.g., <200 nm, or <100 nm, or <50 nm, or <30 nm, or <20 nm, or <10 nm, or <5 nm, or <3 nm, or <2 nm, or <1 nm). These material properties result in a significant reduction in the activation energy required for silicon oxidation to occur under atmospheric conditions, resulting in uncontrolled and generally unsafe reactivity (spontaneous combustion) to oxygen when exposed to air. The material may experience thermal instability, burn, and may therefore be completely oxidized to silicon dioxide. Thermal instability is numerically defined herein as the removal of the silicon-carbon composite after silane CVI processing from a reactor at a temperature of <50°C and continued heating to a temperature of >50°C after exposure to air. In order to control the degree of oxidation of the deposited nano-silicon, the passivation method must be carefully controlled to meet the thermodynamic sensitivity but limit the kinetic reactivity as described in the present invention.

[0160] In the case of using air as a passivating agent, it is important to limit the reactant (oxygen) concentration initially exposed to the deposited amorphous silicon in order to minimize thermal destabilization. In one embodiment, after the porous carbon support is subjected to silicon CVI, the material is cooled to <100°C under an inert gas, and then air is slowly introduced into the reaction chamber at a total diluted oxygen content of 1 vol%. Sufficient time is allowed to pass to ensure complete purge of the chamber volume and stoichiometric excess of O:Si. At this point, the oxygen concentration is gradually increased (e.g., ~5, 10, 15, and finally 20 vol% oxygen) by reducing the inert gas flow through the chamber, allowing sufficient purge time and stoichiometric excess of O:Si. Once the oxygen concentration reaches the oxygen concentration of ambient air, passivation is considered complete and the sample can then be safely removed from the reaction chamber.

[0161] In another embodiment, after silicon CVI is performed on the porous carbon support, the material is cooled to <100°C under an inert gas, and the pressure is then reduced, for example to a pressure of <700 Torr, or <600 Torr, or <500 Torr, or <300 Torr, or <100 Torr, or <50 Torr, or <30 Torr, or <20 Torr, or <10 Torr, or <5 Torr, or <3 Torr, or <2 Torr, or <1 Torr. Subsequently, air is gradually introduced until a specific pressure is reached (e.g., 50 Torr, 100 Torr, 200 Torr, 300 Torr, 500 Torr, 600 Torr, 760 Torr) and allowed to dwell for a specific increment of time (e.g., 1 minute, or 5 minutes, or 10 minutes, or 20 minutes, or 30 minutes, or 60 minutes). This method does not require controlled dilution of the air with an inert gas flow, but rather uses a vacuum as a "diluent". The advantage of this method is that the convective heat flux is reduced due to the partial vacuum conditions, thereby mitigating thermal instability before initiation. Without being bound by theory, the pressure reduction prior to passivation is important for passivating silicon that is within the carbon pores and therefore relatively inaccessible to the gas phase (e.g., silicon prepared via CVI), which presents a very different situation compared to prior art techniques for passivating silicon that is relatively accessible to the gas phase and is present on the surface.

[0162] In addition to controlling the concentration and distribution of the oxygen reactant, silicon passivation can also be achieved by exploiting the reactivity of surface terminated hydrogen (Si-H) bonds using chemical reactions known in the art. In one such embodiment, after silicon deposition on a porous substrate, the material is cooled / heated to about 400° C. under an inert gas. At this point, carbon dioxide is introduced into the furnace, where it undergoes a self-terminating hydride exchange reaction with Si-H surface groups (Si-H + CO2 → Si-OH + CO), thereby producing hydroxyl termini that are no longer susceptible to further oxidation upon final exposure to air.

[0163] In another embodiment, after silicon deposition on the porous substrate, the material is cooled / heated to 100 to 200° C. under an inert gas. At this point, an olefin or alkyne gas (e.g., ethylene, propylene, acetylene, etc.) is introduced into the furnace and allowed to reside for a period of time (e.g., 1-24 hours), wherein the olefin or alkyne gas undergoes a self-terminating hydrosilylation reaction with the Si-H surface groups 2,3 (Si-H+R1=R2→Si-R1H-R2), thereby producing alkyl ends that are no longer susceptible to further oxidation upon final exposure to air. This particular passivation reaction is advantageous because it does not release byproducts and does not impart oxygen content, thereby potentially improving electrochemical anode performance by mitigating the formation of irreversible Li-O byproducts in Li-ion batteries.

[0164] An alternative to air passivation to those described above would be to, after silicon deposition on a porous substrate, cool the material to <100°C, evacuate the chamber and backfill with just enough oxygen to react stoichiometrically with the surface monolayer of silicon. The chamber is maintained under these conditions for a nominal amount of time (e.g., several hours) to ensure sufficient time for passivation and heat loss to occur. This approach would ensure the creation of the minimum amount of oxygen required to prevent any further oxidation of the oxide film.

[0165] In the case of passivation using a hydrosilylation reaction, specific olefins can be tailored to impart certain advantageous properties, including but not limited to hydrophobicity, covalent crosslinking with common Li-ion anode binders, or an artificial SEI.

[0166] In the case of passivation using carbon dioxide or hydrosilylation, UV light can be used instead of heat to initiate the reaction. This will have the advantage of limiting further CO2 diffusion into the silicon bulk by keeping the material at cooler (ambient) temperatures.

[0167] In some embodiments, the passivating gas includes an oxygen species, and the passivating gas is a liquid at room temperature. In such embodiments, the reaction between the passivating gas and silicon not only achieves the desired passivation of the silicon surface, but also, without being bound by theory, produces a chemical modification of the surface to improve the electrochemical properties and / or stability of the silicon material. In some embodiments, passivation at this point results in the formation of a silyl ether species, which provides improved performance for the silicon-carbon composite material when used as an anode of a lithium ion battery, for example, providing a more stable SEI, improved storage period, increased cycle life and / or improved performance at elevated temperatures (such as 45° C. or 60° C.).

[0168] Examples of passivating gases for passivating silicon prepared via CVI include, but are not limited to, oxygen, carbon dioxide, water, methanol, ethanol, propanol, butanol, dimethyl carbonate, ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, vinylene carbonate, fluoroethylene carbonate, and mixtures thereof.

[0169] In certain embodiments, the present invention includes methods for passivating the surface of hydrogen terminated silicon-carbon composites using olefin and / or alkyne chemicals to improve the atmospheric temperature (shelf life) and electrochemical stability of anodes in lithium ion batteries. For such composites prepared via CVI using silicon-containing gases (such as silane) as silicon precursors, the resulting silicon in the silicon-carbon composite is amorphous and this structure is prone to rapid oxidation (thermal instability) unless thoroughly passivated.

[0170] Prior to the present invention, prior art passivation of synthesized silicon involved simply introducing air after the CVI process was completed on a newly synthesized silicon-carbon composite while still in a CVI furnace, or in a cooling chamber downstream of the CVI furnace. However, this prior art method is problematic because the degree of oxidation required can vary significantly depending on the final surface area of ​​the composite. The higher the surface area of ​​a newly synthesized silicon-carbon composite, the more readily the material reacts with oxygen, rapidly heating up, thereby further promoting the reaction, with an undesirable potential for thermal instability events. Conversely, the lower the surface area of ​​a newly synthesized silicon-carbon composite, the slower the material reacts with oxygen, thus generating considerably less heat. Therefore, current prior art methods for passivating newly synthesized silicon-carbon composites are very difficult to control outside of a laboratory under relevant commercial manufacturing scales.

[0171] Therefore, the present invention can be used to passivate newly synthesized silicon-carbon composite materials having a surface area greater than 2 m 2 / g, for example, greater than 5m 2 / g, for example, greater than 10m 2 / g, for example, greater than 15m 2 / g, for example, greater than 20m 2 / g, for example, greater than 25m 2 / g, for example, greater than 30m 2 / g, for example, greater than 40m 2 / g, for example, greater than 50m 2 / g, for example, greater than 100m 2 / g.

[0172] In certain embodiments, the surface of the hydrogen-terminated silicon material is passivated by exposure to benign (non-oxygen) organic species via a gas phase reaction (including but not limited to a hydrosilylation reaction), which not only mitigates exothermic behavior and promotes stable commercial manufacturing, but also provides the lowest achievable oxygen content in the silicon-carbon composite. This content can be expressed as a molar ratio of oxygen to silicon in the silicon-carbon composite. In certain embodiments, after passivating the surface of the hydrogen-terminated silicon material by exposure to an organic substance through a gas phase hydrosilylation reaction, the molar ratio of oxygen to silicon is less than 0.5 mol / mol, such as less than 0.4 mol / mol, such as less than 0.3 mol / mol, such as less than 0.2 mol / mol, such as less than 0.1 mol / mol, such as less than 0.09 mol / mol, such as less than 0.08 mol / mol, such as less than 0.07 mol / mol, such as less than 0.06 mol / mol, such as less than 0.05 mol / mol, such as less than 0.04 mol / mol, such as less than 0.03 mol / mol, such as less than 0.02 mol / mol, such as less than 0.01 mol / mol, such as less than 0.005 mol / mol, such as less than 0.001 mol / mol.

[0173] In certain embodiments, passivation of the surface of the hydrogen-terminated silicon material via a vapor phase hydrosilylation reaction by exposure to benign (non-oxygen) organic species not only mitigates exothermic behavior, facilitates stable commercial manufacturing, and provides the lowest achievable oxygen content in the silicon-carbon composite, but also provides an oxygen content that is highly stable when the silicon-carbon composite powder is exposed to atmospheric conditions (i.e., room temperature of ˜25° C. and atmospheric oxygen). In certain embodiments, the oxygen to silicon ratio in the silicon-carbon composite powder increases by less than 0.01 mol / mol / day, such as less than 0.009 mol / mol / day, such as less than 0.008 mol / mol / day, such as less than 0.007 mol / mol / day, such as less than 0.006 mol / mol / day, such as less than 0.005 mol / mol / day, such as less than 0.004 mol / mol / day, such as less than 0.003 mol / mol / day, such as less than 0.002 mol / mol / day, such as less than 0.001 mol / mol / day when exposed to atmospheric conditions. day, for example less than 0.0009 mol / mol / day, for example less than 0.008 mol / mol / day, for example less than 0.0007 mol / mol / day, for example less than 0.0006 mol / mol / day, for example less than 0.0005 mol / mol / day, for example less than 0.0004 mol / mol / day, for example less than 0.0003 mol / mol / day, for example less than 0.0002 mol / mol / day, for example less than 0.0001 mol / mol / day, for example less than 0.00005 mol / mol / day, for example less than 0.00001 mol / mol / day.

[0174] In turn, the low ratio of oxygen to silicon in the silicon-carbon composite of the above embodiment imparts to the silicon-carbon composite lower reactivity and a more stable molar ratio of oxygen to silicon, thereby improving and maintaining excellent cycle life and shelf life when used as an anode in a lithium ion battery.

[0175] In certain embodiments, passivation of the surface of the hydrogen-terminated silicon material within the silicon-carbon composite material is achieved via a hydrosilylation reaction. In some embodiments, the hydrosilylation reaction is a gas-solid reaction, i.e., a reaction between a passivating agent that exists primarily as a gas under the passivation reaction conditions and a solid silicon-carbon composite. In other embodiments, the hydrosilylation reaction is a liquid-solid reaction, i.e., a reaction between a passivating agent that exists primarily as a liquid under the passivation reaction conditions and a solid silicon-carbon composite.

[0176] The passivating agent selected can be varied, and its properties impart the desired properties of the resulting passivated silicon-carbon composite material. For example, a passivating agent with an ether functional group, when used as a reagent for the surface of a hydrogen-terminated silicon material in a passivating silicon-carbon composite material, provides a passivated silicon-carbon composite material with increased ionic conductivity. As another example, a passivating agent with a carbonate group, when used as a reagent for the surface of a hydrogen-terminated silicon material in a passivating silicon-carbon composite material, provides a passivated silicon-carbon composite material, which, when used as an anode active material circulated in a lithium ion battery, forms a more stable SEI layer. As another example, a passivating agent with an epoxy group, when used as a reagent for the surface of a hydrogen-terminated silicon material in a passivating silicon-carbon composite material, provides a passivated silicon-carbon composite material, which forms a bond with a binder (e.g., polyacrylic acid) in an anode formulation, and when the silicon-carbon composite material is circulated as an anode active material in a lithium ion battery, an improved performance is produced. As yet another example, a passivating agent comprising a fluoride, when used as an agent for passivating the surface of a hydrogen-terminated silicon material within a silicon-carbon composite, provides a passivated silicon-carbon composite that forms a more stable SEI layer when used as an anode active material cycled in a lithium-ion battery. As yet another example, a passivating agent comprising a nitrogen-containing functional group (e.g., amine, amide, etc.), when used as an agent for passivating the surface of a hydrogen-terminated silicon material within a silicon-carbon composite, provides a passivated silicon-carbon composite having mixed properties of the above examples, including increased ionic conductivity and adhesion properties.

[0177] Example

[0178] Example 1.

[0179] Preparation of silicon-carbon composites by CVI.

[0180] The properties of the carbon support (carbon support 1) used to prepare the silicon-carbon composite are shown in Table 3. Using carbon support 1, a silicon-carbon composite (silicon-carbon composite 1) was prepared by CVI as follows. A 0.2 gram mass of amorphous porous carbon was placed in a 2 inch × 2 inch ceramic crucible, which was then placed in the center of a horizontal tube furnace. The furnace was sealed and purged continuously with nitrogen at 500 cubic centimeters per minute (ccm). The furnace temperature was raised to a peak temperature of 450°C at 20°C / min, and it was balanced at this peak temperature for 30 minutes. At this point, the nitrogen was turned off, and silane and hydrogen were then introduced at flow rates of 50ccm and 450ccm, respectively, for a total residence time of 30 minutes. After the residence time, the silane and hydrogen were turned off, and nitrogen was introduced into the furnace again to purge the internal atmosphere. At the same time, the furnace heat was turned off and allowed to cool to ambient temperature. The completed Si-C material was then taken out of the furnace.

[0181] Table 3. Description of the carbon scaffolds used in Example 1.

[0182]

[0183] Example 2.

[0184] Analysis of various silicon composite materials.

[0185] A variety of carbon scaffold materials were used and characterized by nitrogen adsorption gas analysis to determine the 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 4, i.e., data of carbon scaffold surface area, pore volume, and pore volume distribution (% micropores, % mesopores, and % macropores), all determined by nitrogen adsorption analysis.

[0186] Table 4. Properties of various carbon scaffold materials.

[0187]

[0188] Various silicon-carbon composites were prepared using the CVI method using the carbon scaffold samples described in Table 4 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%, diluent gases of nitrogen or hydrogen, and carbon scaffold starting masses from 0.2 g to 700 g.

[0189] 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 button cell. The anode of the half-cell button cell may include 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 include 2:1 ethylene carbonate: diethylene carbonate, 1M LiPF6 and 10% fluoroethylene carbonate. The half-cell button cell can be cycled for 5 cycles at a rate of C / 5 at 25°C and then cycled at a rate of C / 10. The voltage can be cycled between 0V and 0.8V, alternatively, the voltage can be cycled between 0V and 1.5V. From the half-cell button cell data, the maximum capacity can be measured, as well as the average coulombic efficiency (CE) over a cycle range of cycle 7 to cycle 20. The physicochemical and electrochemical properties of various silicon-carbon composites are shown in Table 5.

[0190] The oxygen, nitrogen and hydrogen content of silicon-carbon composites are determined using an inert gas fusion instrument (LECO ONH 836) known in the art. The silicon-carbon composite sample is rapidly heated to ~3000°C in a graphite arc furnace under flowing helium. The oxygen carbon in the sample is thermally reduced to CO2 and / or CO entrained in the helium gas stream, and quantified using an IR spectrometer downstream. Hydrogen is released from the sample in the form of H2, which is catalytically converted into H2O in the gas phase, and is also quantified using an IR spectrometer. Finally, nitrogen is released from the sample in the form of N2, and is quantified using a thermal conductivity detector. The results are expressed as element weight fractions relative to the total mass of the sample.

[0191] Table 5. Properties of various silicon-carbon materials.

[0192]

[0193] ND = Not Determined

[0194] The plot of the average Coulombic efficiency as a function of Z is shown in Figure 1 In. It can be seen that for low Z silicon-carbon samples, the average Coulombic efficiency increases significantly. In particular, all silicon-carbon samples with Z below 10.0 exhibit an average Coulombic efficiency of ≥0.9941, and all silicon-carbon samples with Z above 10 (silicon-carbon composite sample 12 to silicon-carbon composite sample 16) are observed to have an average Coulombic efficiency of ≤0.9909. Without being bound by theory, the higher Coulombic efficiency of silicon-carbon samples with Z<10 provides excellent cycle stability in full-cell lithium-ion batteries. Other inspections of the table reveal surprising and unexpected findings that the combination of Z<10 of the silicon-carbon composite sample and the carbon scaffold also comprising>70 micropores provides an average Coulombic efficiency of ≥0.995.

[0195] Therefore, in preferred embodiments, the silicon-carbon composite material comprises Z less than 10, such as Z less than 5, such as Z less than 3, such as Z less than 2, such as Z less than 1, such as Z less than 0.5, such as Z less than 0.1, or Z of 0.

[0196] In certain preferred embodiments, the silicon-carbon composite material comprises a carbon scaffold having a Z of less than 10 and >70% micropores, such as a Z of less than 10 and >80% micropores, such as a Z of less than 10 and >90% micropores, such as a Z of less than 10 and >95% micropores, such as a Z of less than 5 and >70% micropores, such as a Z of less than 5 and >80% micropores, such as a Z of less than 5 and >90% micropores, such as a Z of less than 5 and >95% micropores, such as a Z of less than 3 and >70% micropores, such as a Z of less than 3 and >80% micropores, such as a Z of less than 3 and >90% micropores, such as a Z of less than 3 and >95% micropores, such as a Z of less than 2 and >70% micropores, such as a Z of less than 2 and >80% micropores, such as a Z of less than 2 and >90% micropores, such as a Z of less than 2 and >95% micropores. and >95% micropores, such as less than 1 Z and >70% micropores, such as less than 1 Z and >80% micropores, such as less than 1 Z and >90% micropores, such as less than 1 Z and >95% micropores, such as less than 0.5 Z and >70% micropores, such as less than 0.5 Z and >80% micropores, such as less than 0.5 Z and >90% micropores, such as less than 0.5 Z and >95% micropores, such as less than 0.1 Z and >70% micropores, such as less than 0.1 Z and >80% micropores, such as less than 0.1 Z and >90% micropores, such as less than 0.1 Z and >95% micropores, such as 0 Z and >70% micropores, such as 0 Z and >80% micropores, such as 0 Z and >90% micropores, such as 0 Z and >95% micropores.

[0197] In certain preferred embodiments, the silicon-carbon composite comprises a Z of less than 10 and a carbon scaffold with >70% micropores, and wherein the silicon-carbon composite further comprises 15%-85% silicon and has a surface area of ​​less than 100 m 2 / g; such as less than 10 Z and> 70% micropores, and wherein the silicon-carbon composite further comprises 15%-85% silicon and has a surface area of ​​less than 50m 2 / g; such as less than 10 Z and> 70% micropores, and wherein the silicon-carbon composite further comprises 15%-85% silicon and has a surface area of ​​less than 30m 2 / g; such as less than 10 Z and> 70% micropores, and wherein the silicon-carbon composite further comprises 15%-85% silicon and has a surface area of ​​less than 10m 2 / g; such as less than 10 Z and> 70% micropores, and wherein the silicon-carbon composite also contains 15%-85% silicon and has a surface area of ​​less than 5m 2 / g; such as less than 10 Z and> 80% micropores, and wherein the silicon-carbon composite further comprises 15%-85% silicon and has a surface area of ​​less than 50m 2 / g; such as less than 10 Z and> 80% micropores, and wherein the silicon-carbon composite further comprises 15%-85% silicon and has a surface area of ​​less than 30m 2 / g; such as less than 10 Z and> 80% micropores, and wherein the silicon-carbon composite further comprises 15%-85% silicon and has a surface area of ​​less than 10m 2 / g; such as less than 10 Z and> 80% micropores, and wherein the silicon-carbon composite further comprises 15%-85% silicon and has a surface area of ​​less than 5m 2 / g; such as less than 10 Z and> 90% micropores, and wherein the silicon-carbon composite further comprises 15%-85% silicon and has a surface area of ​​less than 50m 2 / g; such as less than 10 Z and> 90% micropores, and wherein the silicon-carbon composite further comprises 15%-85% silicon and has a surface area of ​​less than 30m 2 / g; such as less than 10 Z and> 90% micropores, and wherein the silicon-carbon composite further comprises 15%-85% silicon and has a surface area of ​​less than 10m 2 / g; such as less than 10 Z and> 90% micropores, and wherein the silicon-carbon composite further comprises 15%-85% silicon and has a surface area of ​​less than 5m 2 / g; such as less than 10 Z and> 95% micropores, and wherein the silicon-carbon composite further comprises 15%-85% silicon and has a surface area of ​​less than 50m 2 / g; such as less than 10 Z and> 95% micropores, and wherein the silicon-carbon composite further comprises 15%-85% silicon and has a surface area of ​​less than 30m 2 / g; such as less than 10 Z and> 95% micropores, and wherein the silicon-carbon composite further comprises 15%-85% silicon and has a surface area of ​​less than 10m 2 / g; such as less than 10 Z and> 95% micropores, and wherein the silicon-carbon composite further comprises 15%-85% silicon and has a surface area of ​​less than 5m 2 / g.

[0198] In certain preferred embodiments, the silicon-carbon composite comprises a Z of less than 10 and a carbon scaffold with >70% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 100 m 2 / g; such as less than 10 Z and> 70% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 50m 2 / g; such as less than 10 Z and> 70% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30m 2 / g; such as less than 10 Z and> 70% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 10m 2 / g; such as less than 10 Z and> 70% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 5m 2 / g; such as less than 10 Z and> 80% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 50m 2 / g; such as less than 10 Z and> 80% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30m 2 / g; such as less than 10 Z and> 80% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 10m 2 / g; such as less than 10 Z and> 80% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 5m 2 / g; such as less than 10 Z and> 90% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 50m 2 / g; such as less than 10 Z and> 90% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30m 2 / g; such as less than 10 Z and> 90% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 10m 2 / g; such as less than 10 Z and> 90% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 5m 2 / g; such as less than 10 Z and> 95% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 50m 2 / g; such as less than 10 Z and> 95% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30m 2 / g; such as less than 10 Z and> 95% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 10m 2 / g; such as less than 10 Z and> 95% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 5m 2 / g.

[0199] In certain preferred embodiments, the silicon-carbon composite comprises a Z of less than 10 and a carbon scaffold with >80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon, a surface area of ​​less than 30 m 2 / g and the average coulombic efficiency > 0.9969. For example, a silicon-carbon composite material comprises a Z of less than 10 and a carbon scaffold with >80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon, a surface area of ​​less than 30 m 2 / g and an average coulombic efficiency of ≥0.9970. For example, the silicon-carbon composite material comprises a Z of less than 10 and a carbon scaffold with >80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon, a surface area of ​​less than 30m 2 / g and an average coulombic efficiency of ≥0.9975. For example, the silicon-carbon composite material comprises a Z of less than 10 and a carbon scaffold with >80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon, a surface area of ​​less than 30m 2 / g and an average coulombic efficiency of ≥0.9980. For example, the silicon-carbon composite material comprises a Z of less than 10 and a carbon scaffold with >80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon, a surface area of ​​less than 30m 2 / g and an average coulombic efficiency of ≥0.9985. For example, the silicon-carbon composite material comprises a Z of less than 10 and a carbon scaffold with >80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon, a surface area of ​​less than 30m 2 / g and an average coulombic efficiency of ≥0.9990. For example, the silicon-carbon composite material comprises a Z of less than 10 and a carbon scaffold with >80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon, a surface area of ​​less than 30m 2 / g and an average coulombic efficiency of ≥0.9995. For example, the silicon-carbon composite material comprises a Z of less than 10 and a carbon scaffold with >80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon, a surface area of ​​less than 30m 2 / g and the average coulombic efficiency is ≥0.9999.

[0200] Example 3.

[0201] dV / dQ of various silicon composite materials.

[0202] Differential capacity curves (dQ / dV versus voltage) are commonly used as a non-destructive tool to understand phase changes as a function of voltage in lithium 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 in situ NMR spectroscopy. Nat. Commun. 5:3217). As an alternative to plotting dQ / dV versus voltage, a strategy to produce a similar analysis is to plot dQ versus V. For this example, differential capacity plots (dQ / dV versus voltage) capacity plots (dQ / dV versus voltage) were calculated from data obtained using constant current cycling from 5 mV to 0.8 V at 0.1 C rate in half-cell coin cells at 25°C. Typical differential capacity curves of silicon-based materials with 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 LiFePO4Cathodes. Sci. Rep. 6, 37787; doi: 10.1038 / srep37787 (2016); MN Obrovac et al., Li15Si4Formation in Silicon Thin Film Negative Electrodes, Journal of The Electrochemical Society, 163(2)A255-A261 (2016); Q. Pan et al., Improved electrochemical performance of micro-sizedSiO2-based composite anode by prelithiation of stabilized lithium metal powder, Journal of Power Sources 347 (2017)170-177).The first cycle lithiation behavior depends on factors such as the crystallinity and oxygen content of silicon.

[0203] After the first cycle, previous amorphous silicon materials in the art showed two specific phase transition peaks in the dQ / dV vs. V diagram of lithiation, and correspondingly showed two specific phase transition peaks in the dQ / dV vs. V diagram of delithiation. For lithiation, one peak corresponding to the lithium-poor Li-Si alloy phase appears at 0.2 to 0.4V, while another peak corresponding to the lithium-rich Li-Si alloy phase appears below 0.15V. For delithiation, one delithiation peak corresponding to lithium intercalation appears below 0.4V, while the other peak appears at 0.4V to 0.55V. If the Li15Si4 phase is formed during lithiation, it is delithiated at ~0.45V and presents a very narrow sharp peak.

[0204] Figure 2 The dQ / dV versus voltage curve for cycle 2 of the silicon-carbon composite material corresponding to the silicon-carbon composite 3 of Example 1 is depicted. The silicon-carbon composite 3 contains a Z of 0.6. For ease of identification, the figure is divided into regions I, II, II, IV, V, and VI. Regions I (0.8V to 0.4V), II (0.4V to 0.15V), III (0.15V to 0V) constitute the lithiation potential, and regions IV (0V to 0.4V), V (0.4V to 0.55V), VI (0.55V to 0.8V) include the delithiation potential. As described above, previous amorphous silicon-based materials in the art exhibit phase change peaks in two regions (region II and region III) in the lithiation potential and in two regions (region IV and region V) in the delithiation potential.

[0205] from Figure 2 As can be seen in the dQ / dV versus voltage curves, the surprising and unexpected result is that the silicon-carbon composite 3 (which contains a Z of 0.6) includes two additional peaks in the dQ / dV versus voltage curve, namely, region I in the lithiation potential and region VI in the delithiation potential. All six peaks are reversible and are also observed in subsequent cycles, such as Figure 3 as shown in .

[0206] Without being bound by theory, this triple peak behavior of the dQ / dV vs. V curve is novel and also reflects a novel form of silicon.

[0207] It is noteworthy that the new peaks observed in regions I and VI are more prominent in certain scaffold matrices and are completely absent in other samples exemplifying the prior art (silicon-carbon composite samples with Z>10, see explanation and table below).

[0208] Figure 4The dQ / dV vs. V curve of silicon-carbon composite 3 is shown, wherein new peaks in regions I and VI are apparent compared to silicon-carbon composites 15, 16, and 14 (all three of which contain Z>10 and whose dQ / dV vs. V curves do not have any peaks in regions I and VI).

[0209] Without being bound by theory, these new peaks observed in Regions I and VI are related to the properties of silicon impregnated into the porous carbon scaffold, i.e., to the interactions between and among the properties of the porous carbon scaffold, silicon impregnated into the porous carbon scaffold via CVI, and lithium. To provide a quantitative analysis, we define the parameter It is calculated as normalized Peak I relative to Peak III:

[0210]

[0211] Where dQ / dV is measured in a half-cell coin cell and region I is 0.8V-0.4V and region III is 0.15V-0V; the half-cell coin cell is produced as known in the art. If the Si-C sample shows a graphite-related peak in region III of the differential curve, it is omitted when calculating the D factor and the Li-Si-related phase change peak is used. For this example, the half-cell coin cell includes an anode comprising 60-90% silicon-carbon composite, 5-20% SBR-Na-CMC and 5-20% Super C45. Figure 5 The silicon-carbon composite 3 is shown in 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 Determined from the half-cell coin cell data for various silicon-carbon composites given in Example 2 These data are summarized in Table 6. Table 6 also includes data on the first cycle efficiency measured on half-cell coin cells cycled from 5 mV to 0.8 V.

[0212] Table 6. Properties of various silicon-carbon materials.

[0213]

[0214]

[0215] *These data for the first cycle efficiency in parentheses were measured for a voltage window of 5mV to 1.5V.

[0216] The data in Table 6 reveal that decreasing Z and increasing All silicon-carbon composites with Z < 10 have And all silicon-carbon composites with Z>10 have Virtually all silicon-carbon composites with Z>10 have This relationship is also Figure 6 Without being bound by theory, For example For example For example For example For example The silicon material corresponds to a new form of silicon. Alternatively, The silicon material corresponds to a new form of silicon. Without being bound by theory, The silicon material is characterized by a silicon material in which the silicon is amorphous, nanometer-sized silicon, confined within pores, such as the pores of a porous carbon scaffold. For example For example For example For example For example The silicon-carbon composite material of silicon corresponds to a novel silicon-carbon composite material. The silicon-carbon composite material corresponds to a new silicon-carbon composite material.

[0217] In certain embodiments, the silicon-carbon composite comprises

[0218] or In some embodiments, In one embodiment, or

[0219] In certain embodiments, the silicon-carbon composite comprises a Z of less than 10 and a carbon scaffold with >70% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 100 m 2 / g, For example, Z less than 10 and >70% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 50 m 2 / g, For example, Z less than 10 and >70% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 30 m 2 / g, For example, Z less than 10 and >70% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 10m 2 / g, For example, Z less than 10 and >70% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 5 m 2 / g,

[0220] In certain embodiments, the silicon-carbon composite comprises a Z of less than 10 and a carbon scaffold with >70% micropores, and wherein the silicon-carbon composite further comprises 40%-60% silicon and has a surface area of ​​less than 100 m 2 / g, For example, Z less than 10 and >70% micropores, and wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 50 m 2 / g, For example, Z less than 10 and >70% micropores, and wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 30 m 2 / g, For example, Z less than 10 and >70% micropores, and wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 10m 2 / g, For example, Z less than 10 and >70% micropores, and wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 5 m 2 / g,

[0221] In certain embodiments, the silicon-carbon composite comprises a Z of less than 10 and a carbon scaffold with >70% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 100 m 2 / g, For example, Z less than 10 and >70% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 50 m 2 / g, For example, Z less than 10 and >70% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 30 m 2 / g, For example, Z less than 10 and >70% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 10m 2 / g, For example, Z less than 10 and >70% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 5 m2 / g,

[0222] In certain embodiments, the silicon-carbon composite comprises a Z of less than 10 and a carbon scaffold with >70% micropores, and wherein the silicon-carbon composite further comprises 40%-60% silicon and has a surface area of ​​less than 100 m 2 / g, For example, Z less than 10 and >70% micropores, and wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 50 m 2 / g, For example, Z less than 10 and >70% micropores, and wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 30 m 2 / g, For example, Z less than 10 and >70% micropores, and wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 10m 2 / g, For example, Z less than 10 and >70% micropores, and wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 5 m 2 / g,

[0223] In certain embodiments, the silicon-carbon composite comprises a Z of less than 10 and a carbon scaffold with >80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 100 m 2 / g, For example, Z less than 10 and >80% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 50 m 2 / g, For example, Z less than 10 and >80% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 30 m 2 / g, For example, Z less than 10 and >80% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 10m 2 / g, For example, Z less than 10 and >80% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 5m 2 / g,

[0224] In certain embodiments, the silicon-carbon composite comprises a Z of less than 10 and a carbon scaffold with >80% micropores, and wherein the silicon-carbon composite further comprises 40%-60% silicon and has a surface area of ​​less than 100 m2 / g, For example, Z less than 10 and >80% micropores, and wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 50 m 2 / g, For example, Z less than 10 and >80% micropores, and wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 30 m 2 / g, For example, Z less than 10 and >80% micropores, and wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 10m 2 / g, For example, Z less than 10 and >80% micropores, and wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 5 m 2 / g,

[0225] In certain embodiments, the silicon-carbon composite comprises a Z of less than 10 and a carbon scaffold with >80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 100 m 2 / g, For example, Z less than 10 and >80% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 50 m 2 / g, For example, Z less than 10 and >80% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 30 m 2 / g, For example, Z less than 10 and >80% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 10m 2 / g, For example, Z less than 10 and >80% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 5m 2 / g,

[0226] In certain embodiments, the silicon-carbon composite comprises a Z of less than 10 and a carbon scaffold with >80% micropores, and wherein the silicon-carbon composite further comprises 40%-60% silicon and has a surface area of ​​less than 100 m 2 / g, For example, Z less than 10 and >80% micropores, and wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 50 m 2 / g, For example, Z less than 10 and >80% micropores, and wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 30 m 2 / g, For example, Z less than 10 and >80% micropores, and wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 10m 2 / g, For example, Z less than 10 and >80% micropores, and wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 5 m 2 / g,

[0227] In certain embodiments, the silicon-carbon composite comprises a Z of less than 10 and a carbon scaffold of >90% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 100 m 2 / g, For example, Z less than 10 and >90% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 50 m 2 / g, For example, Z less than 10 and >90% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 30 m 2 / g, For example, Z less than 10 and >90% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 10m 2 / g, For example, Z less than 10 and >90% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 5 m 2 / g,

[0228] In certain embodiments, the silicon-carbon composite comprises a Z of less than 10 and a carbon scaffold of >90% micropores, and wherein the silicon-carbon composite further comprises 40%-60% silicon and has a surface area of ​​less than 100 m 2 / g, For example, Z less than 10 and >90% micropores, and wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 50 m 2 / g, For example, Z less than 10 and >90% micropores, and wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 30 m 2 / g, For example, Z less than 10 and >90% micropores, and wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 10m2 / g, For example, Z less than 10 and >90% micropores, and wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 5 m 2 / g,

[0229] In certain embodiments, the silicon-carbon composite comprises a Z of less than 10 and a carbon scaffold of >90% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 100 m 2 / g, For example, Z less than 10 and >90% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 50 m 2 / g, For example, Z less than 10 and >90% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 30 m 2 / g, For example, Z less than 10 and >90% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 10m 2 / g, For example, Z less than 10 and >90% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 5 m 2 / g,

[0230] In certain embodiments, the silicon-carbon composite comprises a Z of less than 10 and a carbon scaffold of >90% micropores, and wherein the silicon-carbon composite further comprises 40%-60% silicon and has a surface area of ​​less than 100 m 2 / g, For example, Z less than 10 and >90% micropores, and wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 50 m 2 / g, For example, Z less than 10 and >90% micropores, and wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 30 m 2 / g, For example, Z less than 10 and >90% micropores, and wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 10m 2 / g, For example, Z less than 10 and >90% micropores, and wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 5 m 2 / g,

[0231] In certain embodiments, the silicon-carbon composite comprises a Z of less than 10 and a carbon scaffold of >95% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 100 m 2 / g, For example, Z less than 10 and >95% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 50 m 2 / g, For example, Z less than 5 and >95% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 30 m 2 / g, For example, Z less than 10 and >95% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 10m 2 / g, For example, Z less than 10 and >95% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 5 m 2 / g,

[0232] In certain embodiments, the silicon-carbon composite comprises a Z of less than 10 and a carbon scaffold of >95% micropores, and wherein the silicon-carbon composite further comprises 40%-60% silicon and has a surface area of ​​less than 100 m 2 / g, For example, Z less than 10 and >95% micropores, and wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 50 m 2 / g, For example, Z less than 10 and >95% micropores, and wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 30 m 2 / g, For example, Z less than 10 and >95% micropores, and wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 10m 2 / g, For example, Z less than 10 and >95% micropores, and wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 5 m 2 / g,

[0233] In certain embodiments, the silicon-carbon composite comprises a Z of less than 10 and a carbon scaffold of >95% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 100 m 2 / g, For example, Z less than 10 and >95% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 50 m 2 / g, For example, Z less than 10 and >95% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 30 m 2 / g, For example, Z less than 10 and >95% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 10m 2 / g, For example, Z less than 10 and >95% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 5 m 2 / g,

[0234] In certain embodiments, the silicon-carbon composite comprises a Z of less than 10 and a carbon scaffold of >95% micropores, and wherein the silicon-carbon composite further comprises 40%-60% silicon and has a surface area of ​​less than 100 m 2 / g, For example, Z less than 10 and >95% micropores, and wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 50 m 2 / g, For example, Z less than 10 and >95% micropores, and wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 30 m 2 / g, For example, Z less than 10 and >95% micropores, and wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 10m 2 / g, For example, Z less than 10 and >95% micropores, and wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 5 m 2 / g,

[0235] In certain embodiments, the silicon-carbon composite comprises a Z of less than 10 and a carbon scaffold with >80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 30 m 2 / g, and an average coulombic efficiency of ≥ 0.9969; such as a silicon-carbon composite material comprising a Z of less than 10 and a carbon scaffold of > 80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 30m 2 / g, and an average coulombic efficiency of ≥ 0.9970; such as a silicon-carbon composite material comprising a Z of less than 10 and a carbon scaffold of > 80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 30m 2 / g, and an average coulombic efficiency of ≥ 0.9975; such as a silicon-carbon composite material comprising a Z of less than 10 and a carbon scaffold of > 80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 30m 2 / g, and an average coulombic efficiency of ≥ 0.9980; such as a silicon-carbon composite material comprising a Z of less than 10 and a carbon scaffold of > 80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 30m 2 / g, and an average coulombic efficiency of ≥ 0.9985; such as a silicon-carbon composite material comprising a Z of less than 10 and a carbon scaffold of > 80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 30m 2 / g, and an average coulombic efficiency of ≥ 0.9990; such as a silicon-carbon composite material comprising a Z of less than 10 and a carbon scaffold of > 80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 30m 2 / g, and an average coulombic efficiency of ≥ 0.9995; such as a silicon-carbon composite material comprising a Z of less than 10 and a carbon scaffold of > 80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 30m 2 / g, and the average Coulombic efficiency ≥ 0.9999.

[0236] In certain embodiments, the silicon-carbon composite comprises a Z of less than 10 and a carbon scaffold with >80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 30 m 2 / g, and an average coulombic efficiency of ≥ 0.9969; such as a silicon-carbon composite material comprising a Z of less than 10 and a carbon scaffold of > 80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 30m 2 / g, and an average coulombic efficiency of ≥ 0.9970; such as a silicon-carbon composite material comprising a Z of less than 10 and a carbon scaffold of > 80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 30m 2 / g, and an average coulombic efficiency of ≥ 0.9975; such as a silicon-carbon composite material comprising a Z of less than 10 and a carbon scaffold of > 80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 30m 2 / g, and an average coulombic efficiency of ≥ 0.9980; such as a silicon-carbon composite material comprising a Z of less than 10 and a carbon scaffold of > 80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 30m 2 / g, and an average coulombic efficiency of ≥ 0.9985; such as a silicon-carbon composite material comprising a Z of less than 10 and a carbon scaffold of > 80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 30m 2 / g, and an average coulombic efficiency of ≥ 0.9990; such as a silicon-carbon composite material comprising a Z of less than 10 and a carbon scaffold of > 80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 30m 2 / g, and an average coulombic efficiency of ≥ 0.9995; such as a silicon-carbon composite material comprising a Z of less than 10 and a carbon scaffold of > 80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 30m 2 / g, and the average Coulombic efficiency ≥ 0.9999.

[0237] In certain embodiments, the silicon-carbon composite comprises a Z of less than 10 and a carbon scaffold with >80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 30 m 2 / g, and an average coulombic efficiency of ≥ 0.9969; such as a silicon-carbon composite material comprising a Z of less than 10 and a carbon scaffold of > 80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 30m 2 / g, and an average coulombic efficiency of ≥ 0.9970; such as a silicon-carbon composite material comprising a Z of less than 10 and a carbon scaffold of > 80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 30m 2 / g, and an average coulombic efficiency of ≥ 0.9975; such as a silicon-carbon composite material comprising a Z of less than 10 and a carbon scaffold of > 80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 30m 2 / g, and an average coulombic efficiency of ≥ 0.9980; such as a silicon-carbon composite material comprising a Z of less than 10 and a carbon scaffold of > 80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 30m 2 / g, and an average coulombic efficiency of ≥ 0.9985; such as a silicon-carbon composite material comprising a Z of less than 10 and a carbon scaffold of > 80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 30m 2 / g, and an average coulombic efficiency of ≥ 0.9990; such as a silicon-carbon composite material comprising a Z of less than 10 and a carbon scaffold of > 80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 30m 2 / g, and an average coulombic efficiency of ≥ 0.9995; such as a silicon-carbon composite material comprising a Z of less than 10 and a carbon scaffold of > 80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 30m 2 / g, and the average Coulombic efficiency ≥ 0.9999.

[0238] In certain embodiments, the silicon-carbon composite comprises a Z of less than 10 and a carbon scaffold with >80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 30 m 2 / g, and an average coulombic efficiency of ≥ 0.9969; such as a silicon-carbon composite material comprising a Z of less than 10 and a carbon scaffold of > 80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 30m 2 / g, and an average coulombic efficiency of ≥ 0.9970; such as a silicon-carbon composite material comprising a Z of less than 10 and a carbon scaffold of > 80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 30m 2 / g, and an average coulombic efficiency of ≥ 0.9975; such as a silicon-carbon composite material comprising a Z of less than 10 and a carbon scaffold of > 80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 30m 2 / g, and an average coulombic efficiency of ≥ 0.9980; such as a silicon-carbon composite material comprising a Z of less than 10 and a carbon scaffold of > 80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 30m 2 / g, and an average coulombic efficiency of ≥ 0.9985; such as a silicon-carbon composite material comprising a Z of less than 10 and a carbon scaffold of > 80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 30m 2 / g, and an average coulombic efficiency of ≥ 0.9990; such as a silicon-carbon composite material comprising a Z of less than 10 and a carbon scaffold of > 80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 30m 2 / g, and an average coulombic efficiency of ≥ 0.9995; such as a silicon-carbon composite material comprising a Z of less than 10 and a carbon scaffold of > 80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 30m 2 / g, and the average Coulombic efficiency ≥ 0.9999.

[0239] Example 4.

[0240] Particle size distribution of various carbon scaffold materials.

[0241] The particle size distribution of various carbon scaffold materials was determined by using a laser diffraction particle size analyzer known in the art. Table 7 gives the data, specifically Dv,1, Dv10, Dv50, Dv,90 and Dv,100.

[0242] Table 7. Properties of various carbon scaffold materials.

[0243]

[0244]

[0245] Example 5.

[0246] A lithium-silicon battery includes an anode comprising a composite comprising Group 14 element silicon and carbon.

[0247] The new composite containing Group 14 elements silicon and carbon can be used to significantly improve the performance of lithium silicon batteries. As is known in the art, lithium silicon batteries include various other properties as described in this embodiment.

[0248] The lithium silicon battery includes an anode including a composite comprising silicon and carbon of Group 14 elements. The concentration of the composite comprising silicon and carbon of Group 14 elements in the anode on a dry weight basis can vary, for example, 1% to 90%, for example, 5% to 95%, for example, 10% to 70%. In certain embodiments, the concentration of the composite comprising silicon and carbon of Group 14 elements in the anode on a dry weight basis is 5% to 25% or 25% to 35%, or 35% to 50%, or 50% to 70%, or greater than 70%.

[0249] The anode may also include other components. These other components include graphite, conductive carbon additives and binders, and combinations thereof.

[0250] In some embodiments, the lithium-silicon battery includes an anode comprising graphite or a combination thereof. In this regard, exemplary graphites include, but are not limited to, natural graphite, synthetic graphite, nanographite, or a combination thereof. The concentration of graphite in the anode on a dry weight basis can vary, for example, 5% to 95%, for example, 10% to 70%, for example, 20% to 60%, for example, 30% to 50%. In certain embodiments, the lithium-silicon battery includes an anode that does not contain graphite.

[0251] In a preferred embodiment, the lithium-silicon battery includes an anode comprising a conductive carbon additive or a combination thereof. Exemplary conductive carbon additives include, but are not limited to, carbon black, conductive carbon black, superconducting carbon black, external conductive carbon black, high conductive carbon black, Super C, SuperP, Super [C45 or C65], Ketjenblack carbon, acetylene black, fullerene, graphene, carbon fiber, carbon nanofiber, carbon nanotube, or a combination thereof. The concentration of the conductive carbon additive in the anode on a dry weight basis can vary, for example, 0.1% to 20%, for example, 1% to 10%, for example, 2% to 8%, for example, 3% to 6%. In certain embodiments, for example, where the anode does not contain graphite, the concentration of the conductive carbon additive on a dry weight basis can be 5% to 20%, for example, 10% to 20%, for example, 14% to 16%.

[0252] In a preferred embodiment, the lithium-silicon battery includes an anode comprising a binder or a combination thereof. Exemplary binders include, but are not limited to, polyvinylidene fluoride (PVDF), styrene-butadiene rubber (SBR), sodium carboxymethyl cellulose (Na-CMC), polyacrylonitrile (PAN), polyacrylic latex, polyacrylic acid (PAA), polyvinyl alcohol (PVA), polyethylene glycol (PEG), polyamide-imide (PAI), polyimide (PI) and combinations thereof. In certain embodiments, the binder may include lithium ions as counterions. The concentration of the binder in the anode may vary, for example, from 0.1% to 20%, for example, from 1% to 10%, for example, from 2% to 8%, for example, from 3% to 6%, by dry weight. In certain embodiments, for example, where the anode does not contain graphite, the concentration of the binder may be from 5% to 20%, for example, from 10% to 20%, for example, from 14% to 16%, by dry weight.

[0253] The anode of the lithium-silicon battery includes a composite comprising Group 14 element silicon and carbon, wherein the anode also includes porosity in a dry state. The porosity of the dry anode can vary, for example, 10% to 90%, for example, 20% to 80%, for example, 30% to 70%, for example, 40% to 60%. In certain preferred embodiments, the porosity of the dry anode is 30% to 50%. In certain preferred embodiments, the porosity of the dry anode is 10% to 50%.

[0254] The lithium-silicon battery includes an anode including a composite including Group 14 element silicon and carbon, wherein the lithium-silicon battery also includes a cathode. Exemplary cathodes include, but are not limited to, lithium cobalt oxide (LiCoO2) (LCO), lithium manganese oxide (LiMn2O4) (LMO), lithium iron phosphate (LiFePO4) (LFP), lithium nickel cobalt aluminum oxide (LiNiCoAlO2) (NCA), lithium titanate (Li2TiO3) (LTO), lithium nickel manganese cobalt oxide (LiNi x Mn y Co z O2) (NMC, wherein x+y+z=1, x:y:z=3:3:3 (NMC333), 4:3:3 (NMC433), 5:3:2 (NMC532), 6:1:1 (NMC611), 6:2:2 (NMC622), 8:1:1 (NMC811)). In certain preferred embodiments, the anode is NMC811.

[0255] Lithium-silicon batteries include a ratio known as the N / P ratio, which describes the capacity ratio between the anode and cathode in the battery. N / P is important in determining the energy density of lithium-silicon batteries. Without being bound by theory, a lower N / P ratio provides less excess anode, and therefore a higher energy density for lithium-silicon batteries. The average discharge potential of silicon-carbon anodes is higher than that of graphite anodes. Without being bound by theory, the N / P ratio in the anode is greater than that in the graphite anode. The presence of enables to reduce the excess anode required in the battery to avoid precipitation. Therefore, without being bound by theory, the new anode material described herein comprises For example For example For example For example Thus allowing for a lower N / P ratio, and a higher energy density lithium-silicon battery. In certain embodiments, the N / P ratio>1.1, such as N / P ratio>1.2, such as N / P ratio>1.3, such as N / P ratio>1.4, such as N / P ratio>1.5, such as N / P ratio>2.0. In certain preferred embodiments, the N / P ratio≤2.0, such as N / P ratio≤1.5, such as N / P ratio≤1.4, such as N / P ratio≤1.3, such as N / P ratio≤1.2, such as N / P ratio≤1.1, such as N / P ratio≤1.0, such as N / P ratio≤0.9, such as N / P ratio≤0.8.

[0256] The lithium-silicon battery includes an electrolyte, wherein the electrolyte includes various components, including solvents, solvent additives, and electrolyte ions. Exemplary electrolyte components include, but are not limited to, ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), ethyl propyl ether (EPE), fluorinated cyclic carbonate (F-AEC), fluorinated linear carbonate (F-EMC), dimethyl acrylamide (DMAA), succinic anhydride (SA), tris(trimethylsilyl) borate (TTMB), tris(trimethylsilyl) phosphate (TTSP), 1,3-propane sultone (PS), fluorinated ether (F-EPE), fluoroethylene carbonate (FEC), performance-enhanced organosilicon electrolyte materials such as OS3, vinylene carbonate (VC), LiPF6, LiBF4, LiBOB, LiTFSI, LiFSI, LiClO4, and combinations thereof. In some embodiments, the electrolyte salt concentration is >1.0 M, such as salt concentration >1.2, such as salt concentration >1.3, such as salt concentration >1.4, such as salt concentration >1.5, such as salt concentration >2.0. In some preferred embodiments, the electrolyte salt concentration is <2.0, such as electrolyte salt concentration <1.5, such as electrolyte salt concentration <1.4, such as electrolyte salt concentration <1.3, such as electrolyte salt concentration <1.2, such as electrolyte salt concentration <1.1, such as electrolyte salt concentration <1.0, such as electrolyte salt concentration <0.9.

[0257] The lithium-silicon battery including a composite containing Group 14 elements silicon and carbon also includes a separator to keep the anode and cathode separated. The separator can be made of one or more layers of polymer material, or coated with aromatic polyamide, ceramic or fluoride material. Exemplary separator materials include, but are not limited to, non-woven fibers (cotton, nylon, polyester, glass), polymer films (polyethylene, polypropylene, polytetrafluoroethylene, polyvinyl chloride), ceramics, and naturally occurring substances (rubber, asbestos, wood). In certain preferred embodiments, the separator comprises a polymer, wherein exemplary polymers include, but are not limited to, polyolefin-based materials with a semi-crystalline structure, polyethylene, polypropylene, grafted polymers including micropores, poly(methyl methacrylate) grafted and siloxane grafted polyethylene, polyvinylidene fluoride (PVDF) nanofiber mesh, and polytriphenylamine (PTPA).

[0258] A lithium-silicon battery comprising a composite comprising Group 14 elements silicon and carbon cycles between the lower and upper limits of the lithium-silicon battery operating voltage window during battery use. Without being bound by theory, lowering the lower limit of the operating voltage window provides a lithium-silicon battery with a higher energy density. Thus, without being bound by theory, the new anode material described herein comprises For example For example For example For example Thus allowing a lower limit of the voltage window, and therefore a higher energy density lithium-silicon battery. In certain embodiments, the lower limit of the voltage window is ≤3.0V, such as ≤2.9V, such as ≤2.8V, such as ≤2.7V, such as ≤2.6V, such as ≤2.5V, such as ≤2.4V, such as ≤2.3V. The upper limit of the voltage window for cycling lithium-silicon batteries can vary. For example, the upper limit of the voltage window can vary, such as ≥4.0V, such as 4.0V, or 4.1V, or 4.2V, or 4.3V, or 4.4V, or 4.5V, or 4.6V, or 4.7V, or 4.8, or 4.9V, or 5.0V.

[0259] Example 6.

[0260] The silicon-carbon composites prepared by CVI were passivated using various oxygen-containing gases.

[0261] A silicon-carbon composite material was prepared using carbon support 10 as a porous carbon support, and the CVI process as described in Example 1 was performed, but for this example, various samples were passivated by various methods for the final step of preparing the silicon-carbon composite. In each case, after the CVI process was completed, the process gas was switched to nitrogen until the desired passivation temperature was reached, at which time the temperature was maintained at the desired passivation temperature and the process gas was switched to the passivation gas. After passivation, the temperature was reduced to <100°C and the material was removed for characterization. An overview of the passivation methods and properties of the resulting silicon-carbon composites is shown in Table 8.

[0262] Table 8. Passivation of silicon-carbon composites according to Example 6.

[0263]

[0264] The use of air as the passivating agent (Silicon-Carbon Composite Sample #22) resulted in satisfactory conditions. No excessive sample heating was observed (no thermal destabilization), and therefore, this condition represents a safe and industrially relevant and scalable method for preparing Silicon-Carbon Composites. In contrast, a Silicon-Carbon Composite Comparative Sample was prepared using the same carbon scaffold, where the CVI reaction was carried out to a lower mass gain (29%) and a lower measured silicon content (25%), and passivated with air at a relatively low temperature (26°C), yielding 730 m 2 It is noteworthy that for this sample, thermal instability was observed.

[0265] It can also be seen from the table that various alternative oxygen-containing gases (such as water vapor, ethanol vapor or carbon dioxide) can also be successfully used as passivation gases at the temperatures described in the table. The silicon-carbon composites were also analyzed by TGA to determine the silicon content and Z, and the values ​​are shown in Table 8. The silicon-carbon composites were also tested in half-cell button cells, and these data are shown in Table 9.

[0266] Table 9. Electrochemical evaluation of various silicon-carbon composite samples prepared according to Example 5.

[0267]

[0268] For any of the various passivation methods used as per Table 9, no excessive heating was observed. As can be seen, the conditions of 200°C and water vapor were found to be suitable passivating gases for the silicon-carbon composite samples prepared by CVI. Similarly, the conditions of 200°C and ethanol vapor were also found to be suitable passivating gases for the silicon-carbon composite samples prepared by CVI. Without being bound by theory, it is expected that the increased diffusion restriction provided by the silicon prepared by CVI makes the passivation of oxygen-containing gases with molecular sizes greater than oxygen less prone. Therefore, it is surprising and unexpected that such alcohols, such as denatured alcohols, are suitable for passivating silicon prepared via CVI, i.e., silicon located within the pores of the porous carbon support. In additional embodiments, the oxygen-containing passivating gas can be an alcohol, including but not limited to methanol, ethanol, denatured alcohol, propanol, butanol, isopropanol, dimethyl carbonate, ethylene carbonate, and mixtures thereof.

[0269] In addition, it was found that the conditions of 400°C and carbon dioxide were also suitable passivation gases for silicon-carbon composite samples prepared by CVI. In this way, passivation was performed in a temperature range similar to that of the CVI process. In some embodiments, passivation can be performed alternately with CVI processing, thereby stratifying the oxygen content within the silicon impregnated into the porous carbon. In this way, the characteristic silicon size is further reduced compared to the case where passivation is performed when the CVI processing is completed. Without being bound by theory, the stratification of oxygen within the silicon located within the carbon pores prepared by CVI provides benefits when the material is used as an anode of a lithium-ion battery, such as increased cycle stability and reduced expansion during lithiation.

[0270] To this end, a silicon-carbon composite sample was prepared in a similar manner to silicon-carbon composite #25, but the reaction temperature was maintained at 440°C and the gas entering the reactor was alternated between silane (to complete CVI) and CO2 (to complete passivation) at three intervals (i.e., three separate and equal time courses for each of the CVI process and passivation), thereby providing a three-layer silicon and oxygen passivated surface on the silicon. This is represented in Tables 8 and 9 as silicon-carbon composite #26. This sample shows a significantly lower silicon content as determined by TGA compared to the total mass increase after the three intermittent CVI and passivation processes. This difference is due to the increased oxygen content in the sample compared to the other samples shown in Table 8. Importantly, the average coulombic efficiency of this sample is higher than that of the other comparative samples in Table 9, at 0.9983.

[0271] In some embodiments, the silicon-carbon composite material is prepared by maintaining the porous carbon support at a temperature of 350° C. to 550° C. and alternating the process gas between the silicon-containing gas and the oxygen-containing gas (two time courses in total). In some embodiments, the process of alternating the introduction between the silicon-containing gas and the oxygen-containing gas can be carried out for a total of three time courses, or four time courses, or five time courses, or five to ten time courses, or more than ten time courses.

[0272] Example 7.

[0273] Silicon-carbon composites prepared by CVI were passivated using a non-oxygen-containing gas.

[0274] Carbon support 10 was used as a porous carbon support to prepare silicon-carbon composites, and the CVI process as described in Example 1 was performed, but for this example, various samples were passivated by a non-oxygen-containing gas for the final step of preparing the silicon-carbon composite. For this example, the non-oxygen-containing gas was a hydrocarbon, i.e., propylene gas. For this example, the CVI reaction temperature was 440°C, and the passivation with propylene was performed by introducing propylene after the CVI process was completed, and the process temperature was initially 440°C and allowed to cool for about 60 minutes for passivation, so the passivation temperature was <440°C. Details about the sample are shown in Table 10, and the electrochemical properties are shown in Table 11.

[0275] Table 10. Passivation of silicon-carbon composites.

[0276]

[0277] ND = Not Determined

[0278] Table 11. Electrochemical evaluation of various silicon-carbon composite samples prepared according to Example 6.

[0279]

[0280] Without being bound by theory, the use of propylene as a passivating agent provides not only passivation of the silicon surface, but also provides the addition of a terminal carbon coating on the silicon-carbon composite. Without being bound by theory, this also provides additional benefits, such as improved conductivity, and increased stability provided by reducing the reactivity of the terminal carbon coating. In turn, the silicon-carbon composite thus prepared has additional benefits when used as an anode material in a lithium-ion battery, such as, but not limited to, increased rate performance, increased cycle life at room temperature, increased cycle life at elevated temperatures (e.g., 45° C. or 60° C.), and / or increased shelf life.

[0281] In some embodiments, refinement is performed after the CVI process and before passivation to reduce the size of the silicon-carbon composite particles. In alternative embodiments, refinement is performed after passivation to reduce the size of the silicon-carbon composite particles.

[0282] Example 8.

[0283] Silicon-carbon composites prepared by CVI were passivated by hydrosilylation using acetylene.

[0284] After the silicon-carbon composite is prepared via CVI, passivation can be achieved by hydrosilylation passivation. The temperature can be varied from 100 to 500°C, for example 120°C, for example 150°C, for example 170°C, for example 180°C, for example 200°C, for example 250°C, for example 300°C, for example 350°C, for example 400°C, for example 450°C. In a preferred embodiment, the temperature is 170°C or 190°C. The pressure can be atmospheric pressure. In some embodiments, the pressure can be lower than atmospheric pressure. In some embodiments, the pressure can be higher than atmospheric pressure. Without being bound by theory, acetylene undergoes a self-terminating hydrosilylation reaction with Si-H surface groups (Si-H+R1=R2→Si-R1H-R2), thereby producing an alkyl (ethyl) end that is not easily further oxidized when finally exposed to air, wherein R1 and R2 correspond to alkanes, alkenes or alkynes, as known in the art. This specific hydrosilylation passivation reaction is advantageous because it does not release byproducts and does not impart oxygen content, thereby potentially improving electrochemical anode performance by mitigating the formation of irreversible Li-O byproducts in Li-ion batteries or other accompanying side reactions with the electrolyte.

[0285] Without being bound by theory, hydrosilylation passivation of the silicon-carbon composite produces a material comprising a carbon scaffold, nanometer-sized silicon domains within the pores of the porous carbon, wherein the silicon surface comprises Si-R bonds (wherein R represents an organic functional group comprising a combination of carbon, oxygen, nitrogen, or hydrogen; exemplary R species are alkanes, alkenes, or alkynes). In some embodiments, R comprises a halogen element, such as bromine, fluorine, chlorine, or iodine.

[0286] Table 12 shows various samples prepared using hydrosilylation passivation according to Example 8. Carbon scaffold 10 was used to prepare these samples.

[0287] Table 12. Hydrosilylation passivation of silicon-carbon composites according to Example 8.

[0288]

[0289]

[0290] ND = Not Determined; Silicon-Carbon Composite #27 represents a control that was not passivated by hydrosilylation but air passivated.

[0291] The electrochemical characterization of selected samples was analyzed (Table 13). The trends and ranges for the chemical vapor passivated samples and the samples passivated with air follow similar behavior as shown in the above examples (eg, Examples 1-3).

[0292] Table 13. Electrochemical characterization of hydrosilylation passivation of silicon-carbon composites according to Example 8.

[0293]

[0294] Example 9.

[0295] Silicon-carbon composites prepared by CVI were passivated using vaporized liquids.

[0296] In certain embodiments, olefin and / or alkyne passivating agent is liquid under standard temperature and pressure conditions. After silicon deposition by silane on porous substrate, the material is cooled and maintained at 100 to 500 ℃, for example 120 ℃, for example 150 ℃, for example 170 ℃, for example 180 ℃, for example 200 ℃, for example 250 ℃, for example 300 ℃, for example 350 ℃, for example 400 ℃, for example 450 ℃. In a preferred embodiment, the temperature is 170 ℃. Allow to achieve temperature equilibrium (about 30 minutes) over a period of time. At this point, stop the gas flow, and evacuate the reactor. Then the reactor is backfilled to the desired pressure (for example, allyl glycidyl ether, bp=154 ℃) from the bubbler / Dewar flask containing liquid olefins, which has a boiling point lower than the reactor temperature so as to remain in the gas phase during the reaction conditions. The reactor is sealed and allowed to stay at this temperature for 1-24 hours to promote the hydrosilylation passivation reaction. In another embodiment, the vacuum step may be omitted and, instead, the inert gas stream may be routed through a bubbler / Dewar containing the olefin / alkyne liquid material, allowing the vapor to be entrained in the gas stream and introduced into the reactor for the time period specified above, thereby maintaining atmospheric pressure throughout the reaction.

[0297] In another embodiment, the hydrosilylation reaction is carried out in a liquid suspension. Herein, the silicon-carbon complex is transferred from a reactor to an inert gas (e.g., argon, nitrogen, helium) environment, and then dispersed in an aprotic solvent (e.g., THF or toluene) with or without stirring. An olefin / alkyne (e.g., allyl glycidyl ether) substance is added to the suspension, followed by a catalyst (e.g., platinum (0) -1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex). The suspension is moderately heated (e.g., 30-50 ° C) and allowed to react for a period of time (e.g., 1-24 hours). The passivated silicon-carbon complex is then recovered from the suspension using conventional methods (e.g., centrifugation, filtration, spray drying, etc.).

[0298] Example 10.

[0299] The silicon-carbon composites prepared by CVI were passivated by employing a combination of passivating agents.

[0300] In another embodiment, the combination of different olefin / alkyne materials is used for passivation simultaneously to realize the combination of physical properties and / or performance characteristics.After silicon deposition is carried out by silane on porous substrate, material is cooled and maintained at 170 ℃ under inert gas.Allow to realize temperature equilibrium (about 30 minutes) through a period of time.At this moment, stop airflow, and evacuate reactor.Then reactor is backfilled to required pressure from the bubbler / Dewar flask containing the mixture of two or more liquid olefins (for example, allyl glycidyl ether and allyloxy (polyethylene oxide)), it has a boiling point lower than reactor temperature so that during reaction conditions, it remains in gas phase.Reactor is sealed and it is stopped 3 hours at this temperature to promote hydrosilylation passivation reaction.

[0301] In a preferred embodiment, the temperature of the hydrosilylation passivation is 100°C to 220°C, preferably 160 to 190°C. In a preferred embodiment, the pressure of the hydrosilylation passivation is 0.001 torr to 800 torr, preferably 500-760 torr. Exemplary substances used as hydrosilylation passivating agents include acetylene, propylene, ethylene, butylene, allyloxyethanol, diallyl carbonate, allyl methyl carbonate, allyl ethyl carbonate, allyl glycidyl ether, allyloxy (polyethylene oxide) methyl ether and allyloxytrimethylsilane (preferred substances: acetylene, allyl glycidyl ether, allyl ethyl carbonate and allyloxy (polyethylene oxide)). The preferred duration of the hydrosilylation passivation is 0.5 to 12 hours, preferably 1 to 6 hours. In certain embodiments, a catalyst can be used to reduce the temperature and / or time of the hydrosilylation passivation reaction. With respect to such embodiments, exemplary catalysts include platinum (Karstedt's catalyst), ultraviolet light (-365 nm wavelength), free radical initiators (eg, 2,2-azobisisobutyronitrile, benzoyl peroxide, or borane), and combinations thereof.

[0302] Example 11.

[0303] Chemical Vapor Passivation (CVP) of Silicon-Carbon Composites

[0304] This embodiment describes a novel method for in-situ passivation of silicon-carbon composites, referred to herein as chemical vapor passivation (CVP). According to the CVP process, a silicon-carbon composite (e.g., a silicon-carbon composite prepared via CVI to produce nano-sized amorphous silicon within a porous carbon scaffold material) is then passivated in the presence of a hydrocarbon gas at elevated temperatures. The CVP temperature may vary, for example, from 400 to 1000°C, such as from 400 to 500°C, such as from 500 to 600°C, such as from 600 to 700°C, such as from 700 to 800°C, such as from 800 to 900°C, such as from 900 to 1000°C, such as from 400 to 450°C, such as from 450 to 500°C, such as from 500 to 550°C, such as from 550 to 600°C, such as from 600 to 650°C, such as from 650 to 700°C, such as from 700 to 750°C, such as from 750 to 800°C, such as from 800 to 850°C, such as from 850 to 900°C, such as from 900 to 950°C, such as from 950 to 1000°C. In some embodiments, the CVP temperature is 400 to 600°C, or 500 to 700°C, or 600 to 800°C, or 700 to 900°C, or 800 to 1000°C. In some preferred embodiments, the temperature is 300 to 700°C. The gas used in the CVP process can be a hydrocarbon (e.g., acetylene, ethylene, propylene, propane, ethane, methane, butane, butene, etc., or a combination thereof). In some preferred embodiments, acetylene is used. The pressure can be atmospheric pressure. In some embodiments, the pressure can be lower than atmospheric pressure. In some embodiments, the pressure can be higher than atmospheric pressure. During the CVP process, the hydrocarbon gas decomposes on the surface of the material to produce an amorphous carbon coating (thus CxHy=>C+H2). This particular passivation reaction is advantageous because the thickness of the carbon layer can be controlled by adjusting the temperature and / or residence time, and the carbon layer itself can contribute to the conductivity of the host silicon-carbon composite material.

[0305] Without being bound by theory, CVP of silicon-carbon composites produces a material comprising a carbon scaffold, nanometer-sized silicon domains within the pores of the porous carbon (wherein the silicon surface comprises Si-H bonds), and a carbonaceous layer at least partially covering the silicon domains.

[0306] According to this embodiment, various silicon-carbon composite samples were prepared generally according to the methods described herein, and their passivation was achieved by CVP. These samples are shown in Table 14. The carbon support used was Carbon Support 10 or had similar porous properties. The CVP temperature was in the range of 300 to 700°C. Alternatively, the CVP temperature can be in the range of 700°C to 1000°C. The oxygen content of the selected samples was measured; the oxygen content was in the range of 0.6 to 2.9%. With respect to Z and The trends and ranges for the hydrosilylation passivated samples and the samples passivated with air follow similar behavior as shown in the above examples (eg, Examples 1-3).

[0307] Table 14. CVP of the silicon-carbon composite according to Example 11.

[0308]

[0309] Specific implementation plan

[0310] Embodiment 1. A method for preparing passivated silicon-carbon composite particles, the method comprising:

[0311] a. Providing a carbon scaffold comprising a pore volume, wherein the pore volume comprises greater than 70% micropores;

[0312] b. heating the porous carbon support particles to a temperature of 350°C to 550°C in the presence of silane gas;

[0313] c. reducing the temperature to ≤ 200°C in the presence of nitrogen; and

[0314] d. Add oxygen-containing gas.

[0315] Embodiment 2. A method for preparing passivated silicon-carbon composite particles, the method comprising:

[0316] a. Providing a carbon scaffold comprising a pore volume, wherein the pore volume comprises greater than 70% micropores;

[0317] b. heating the porous carbon support particles to a temperature of 350°C to 550°C in the presence of silane gas;

[0318] c. lowering the temperature to ≤200°C in the presence of nitrogen;

[0319] d. adding oxygen-containing gas; and

[0320] e. wherein the passivated silicon-carbon composite comprises:

[0321] i. Z less than 10, where Z = 1.875x[(M1100-M) / M1100]x

[0322] 100%, wherein M1100 is the mass of the silicon-carbon composite at 1100°C, and M is the minimum mass of the silicon-carbon composite between 800°C and 1100°C when the silicon-carbon composite is heated from about 25°C to about 1100°C in air, as determined by thermogravimetric analysis.

[0323] Embodiment 3. A method for preparing passivated silicon-carbon composite particles, the method comprising:

[0324] a. Providing a carbon scaffold comprising a pore volume, wherein the pore volume comprises greater than 70% micropores;

[0325] b. heating the porous carbon support particles to a temperature of 350°C to 550°C in the presence of silane gas;

[0326] c. lowering the temperature to ≤200°C in the presence of nitrogen;

[0327] d. adding oxygen-containing gas; and

[0328] e. wherein the passivated silicon-carbon composite comprises:

[0329] i. Z less than 10, where Z = 1.875x[(M1100-M) / M1100]x

[0330] 100%, wherein M1100 is the mass of the silicon-carbon composite at 1100°C, and M is the minimum mass of the silicon-carbon composite between 800°C and 1100°C when the silicon-carbon composite is heated from about 25°C to about 1100°C in air, as determined by thermogravimetric analysis; and

[0331] ii. Greater than or equal to 0.1 in Where dQ / dV is measured in a half-cell coin cell and region I is 0.8V-0.4V and region III is 0.15V-0V.

[0332] Embodiment 4. A method for preparing passivated silicon-carbon composite particles, the method comprising:

[0333] a. Providing a carbon scaffold comprising a pore volume, wherein the pore volume comprises greater than 70% micropores;

[0334] b. heating the porous carbon support particles to a temperature of 350°C to 550°C in the presence of silane gas;

[0335] c. lowering the temperature to ≤200°C in the presence of nitrogen;

[0336] d. adding oxygen-containing gas; and

[0337] e. wherein the passivated silicon-carbon composite comprises:

[0338] i. a silicon content of 30% to 60% by weight;

[0339] ii. Less than 30m 2 Surface area / g;

[0340] iii. Z less than 10, where Z = 1.875x[(M1100-M) / M1100]x

[0341] 100%, wherein M1100 is the mass of the silicon-carbon composite at 1100°C, and M is the minimum mass of the silicon-carbon composite between 800°C and 1100°C when the silicon-carbon composite is heated from about 25°C to about 1100°C in air, as determined by thermogravimetric analysis; and

[0342] iv. Greater than or equal to 0.1 in Where dQ / dV is measured in a half-cell coin cell and region I is 0.8V-0.4V and region III is 0.15V-0V.

[0343] Embodiment 5. A method for preparing passivated silicon-carbon composite particles, the method comprising:

[0344] a. Providing a carbon scaffold comprising a pore volume, wherein the pore volume comprises greater than 70% micropores;

[0345] b. heating the porous carbon support particles to a temperature of 350°C to 550°C in the presence of silane gas;

[0346] c. adjusting the temperature to ≤400°C in the presence of nitrogen; and

[0347] d. Add oxygen-containing gas.

[0348] Embodiment 6. A method for preparing passivated silicon-carbon composite particles, the method comprising:

[0349] a. Providing a carbon scaffold comprising a pore volume, wherein the pore volume comprises greater than 70% micropores;

[0350] b. heating the porous carbon support particles to a temperature of 350°C to 550°C in the presence of silane gas;

[0351] c. adjusting the temperature to ≤400°C in the presence of nitrogen;

[0352] d. adding oxygen-containing gas; and

[0353] e. wherein the passivated silicon-carbon composite comprises:

[0354] i. Z less than 10, where Z = 1.875x[(M1100-M) / M1100]x

[0355] 100%, wherein M1100 is the mass of the silicon-carbon composite at 1100°C, and M is the minimum mass of the silicon-carbon composite between 800°C and 1100°C when the silicon-carbon composite is heated from about 25°C to about 1100°C in air, as determined by thermogravimetric analysis.

[0356] Embodiment 7. A method for preparing passivated silicon-carbon composite particles, the method comprising:

[0357] a. Providing a carbon scaffold comprising a pore volume, wherein the pore volume comprises greater than 70% micropores;

[0358] b. heating the porous carbon support particles to a temperature of 350°C to 550°C in the presence of silane gas;

[0359] c. adjusting the temperature to <400°C in the presence of nitrogen;

[0360] d. adding oxygen-containing gas; and

[0361] e. wherein the passivated silicon-carbon composite comprises:

[0362] i. Z less than 10, where Z = 1.875x[(M1100-M) / M1100]x

[0363] 100%, wherein M1100 is the mass of the silicon-carbon composite at 1100°C, and M is the minimum mass of the silicon-carbon composite between 800°C and 1100°C when the silicon-carbon composite is heated from about 25°C to about 1100°C in air, as determined by thermogravimetric analysis; and

[0364] ii. Greater than or equal to 0.1 in Where dQ / dV is measured in a half-cell coin cell and region I is 0.8V-0.4V and region III is 0.15V-0V.

[0365] Embodiment 8. A method for preparing passivated silicon-carbon composite particles, the method comprising:

[0366] a. Providing a carbon scaffold comprising a pore volume, wherein the pore volume comprises greater than 70% micropores;

[0367] b. heating the porous carbon support particles to a temperature of 350°C to 550°C in the presence of silane gas;

[0368] c. adjusting the temperature to ≤400°C in the presence of nitrogen;

[0369] d. adding oxygen-containing gas; and

[0370] e. wherein the passivated silicon-carbon composite comprises:

[0371] i. a silicon content of 30% to 60% by weight;

[0372] ii. Less than 30m 2 Surface area / g;

[0373] iii. Z less than 10, where Z = 1.875x[(M1100-M) / M1100]x

[0374] 100%, wherein M1100 is the mass of the silicon-carbon composite at 1100°C, and M is the minimum mass of the silicon-carbon composite between 800°C and 1100°C when the silicon-carbon composite is heated from about 25°C to about 1100°C in air, as determined by thermogravimetric analysis; and

[0375] iv. Greater than or equal to 0.1 in Where dQ / dV is measured in a half-cell coin cell and region I is 0.8V-0.4V and region III is 0.15V-0V.

[0376] Embodiment 9. The method for preparing passivated silicon-carbon composite particles according to any one of Embodiments 1 to 8, wherein the pore volume comprises greater than 80% micropores.

[0377] Embodiment 10. The method for preparing passivated silicon-carbon composite particles according to any one of Embodiments 1 to 9, wherein the pore volume comprises greater than 90% micropores.

[0378] Embodiment 11. The method of preparing passivated silicon-carbon composite particles according to any one of Embodiments 1 to 10, wherein the pore volume comprises greater than 95% micropores.

[0379] Embodiment 12. A method for preparing passivated silicon-carbon composite particles according to any one of Embodiments 1 to 11, wherein the porous carbon scaffold particles are heated to a temperature of 400°C to 525°C in the presence of silane gas.

[0380] Embodiment 13. The method for preparing passivated silicon-carbon composite particles according to any one of Embodiments 1 to 12, wherein the silicon-carbon composite comprises a silicon content of 40-60%.

[0381] Embodiment 14. The method for preparing passivated silicon-carbon composite particles according to any one of Embodiments 1 to 13, wherein the silicon-carbon composite comprises Z less than 5.

[0382] Embodiment 15. A method for preparing passivated silicon-carbon composite particles according to any one of Embodiments 1 to 14, wherein the silicon-carbon composite comprises less than 10 m 2 / g of surface area.

[0383] Embodiment 16. A method for preparing passivated silicon-carbon composite particles according to any one of Embodiments 1 to 15, wherein the silicon-carbon composite comprises greater than or equal to 0.2 in Where dQ / dV is measured in a half-cell coin cell and region I is 0.8V-0.4V and region III is 0.15V-0V.

[0384] Embodiment 17. A method for preparing passivated silicon-carbon composite particles according to any one of Embodiments 1 to 16, wherein the silicon-carbon composite comprises greater than or equal to 0.3 in Where dQ / dV is measured in a half-cell coin cell and region I is 0.8V-0.4V and region III is 0.15V-0V.

[0385] Embodiment 18. The method for preparing passivated silicon-carbon composite particles according to any one of Embodiments 1 to 17, wherein the silicon-carbon composite comprises a Dv50 of 5 nm to 20 microns.

[0386] Embodiment 19. The method for preparing passivated silicon-carbon composite particles according to any one of Embodiments 1 to 18, wherein the silicon-carbon composite comprises a capacity greater than 900 mA / g.

[0387] Embodiment 20. The method for preparing passivated silicon-carbon composite particles according to any one of embodiments 1 to 19, wherein the silicon-carbon composite comprises a capacity greater than 1300 mA / g.

[0388] Embodiment 21. The method for preparing passivated silicon-carbon composite particles according to any one of Embodiments 1 to 20, wherein the silicon-carbon composite comprises a capacity greater than 1600 mA / g.

[0389] Embodiment 22. The method for preparing passivated silicon-carbon composite particles according to any one of Embodiments 1 to 21, wherein the oxygen-containing gas comprises carbon dioxide.

[0390] Embodiment 23. The method for preparing passivated silicon-carbon composite particles according to any one of Embodiments 1 to 21, wherein the oxygen-containing gas comprises ethanol.

[0391] Embodiment 24. A method for preparing passivated silicon-carbon composite particles according to any one of Embodiments 1 to 21, wherein the oxygen-containing gas comprises dimethyl carbonate, ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate or vinylene carbonate, or a mixture thereof.

[0392] Embodiment 25. A method of preparing passivated silicon-carbon composite particles, the method comprising:

[0393] a. Providing a carbon scaffold comprising a pore volume, wherein the pore volume comprises greater than 70% micropores;

[0394] b. heating the porous carbon support particles to a temperature of 350°C to 550°C in the presence of silane gas; and

[0395] c. Alternate the process gas between silane gas and carbon dioxide gas.

[0396] Embodiment 26. A method of preparing passivated silicon-carbon composite particles, the method comprising:

[0397] a. Providing a carbon scaffold comprising a pore volume, wherein the pore volume comprises greater than 70% micropores;

[0398] b. heating the porous carbon support particles to a temperature of 350°C to 550°C in the presence of silane gas;

[0399] c. alternating the process gas between silane gas and carbon dioxide gas; and

[0400] d. wherein the passivated silicon-carbon composite comprises:

[0401] i. Z less than 10, where Z = 1.875x[(M1100-M) / M1100]x

[0402] 100%, wherein M1100 is the mass of the silicon-carbon composite at 1100°C, and M is the minimum mass of the silicon-carbon composite between 800°C and 1100°C when the silicon-carbon composite is heated from about 25°C to about 1100°C in air, as determined by thermogravimetric analysis.

[0403] Embodiment 27. A method of preparing passivated silicon-carbon composite particles, the method comprising:

[0404] a. Providing a carbon scaffold comprising a pore volume, wherein the pore volume comprises greater than 70% micropores;

[0405] b. heating the porous carbon support particles to a temperature of 350°C to 550°C in the presence of silane gas;

[0406] c. alternating the process gas between silane gas and carbon dioxide gas; and

[0407] d. wherein the passivated silicon-carbon composite comprises:

[0408] i. Z less than 10, where Z = 1.875x[(M1100-M) / M1100]x

[0409] 100%, wherein M1100 is the mass of the silicon-carbon composite at 1100°C, and M is the minimum mass of the silicon-carbon composite between 800°C and 1100°C when the silicon-carbon composite is heated from about 25°C to about 1100°C in air, as determined by thermogravimetric analysis; and

[0410] ii. Greater than or equal to 0.1 in Where dQ / dV is measured in a half-cell coin cell and region I is 0.8V-0.4V and region III is 0.15V-0V.

[0411] Embodiment 28. A method of preparing passivated silicon-carbon composite particles, the method comprising:

[0412] a. Providing a carbon scaffold comprising a pore volume, wherein the pore volume comprises greater than 70% micropores;

[0413] b. heating the porous carbon support particles to a temperature of 350°C to 550°C in the presence of silane gas;

[0414] c. alternating the process gas between silane gas and carbon dioxide gas; and

[0415] d. wherein the passivated silicon-carbon composite comprises:

[0416] i. a silicon content of 30% to 60% by weight;

[0417] ii. Less than 30m 2 Surface area / g;

[0418] iii. Z less than 10, where Z = 1.875x[(M1100-M) / M1100]x

[0419] 100%, wherein M1100 is the mass of the silicon-carbon composite at 1100°C, and M is the minimum mass of the silicon-carbon composite between 800°C and 1100°C when the silicon-carbon composite is heated from about 25°C to about 1100°C in air, as determined by thermogravimetric analysis; and

[0420] iv. Greater than or equal to 0.1 in Where dQ / dV is measured in a half-cell coin cell and region I is 0.8V-0.4V and region III is 0.15V-0V.

[0421] Embodiment 29. The method for preparing passivated silicon-carbon composite particles according to any one of Embodiments 25 to 28, wherein the pore volume comprises greater than 80% micropores.

[0422] Embodiment 30. The method for preparing passivated silicon-carbon composite particles according to any one of Embodiments 25 to 28, wherein the pore volume comprises greater than 90% micropores.

[0423] Embodiment 31. The method of preparing passivated silicon-carbon composite particles according to any one of Embodiments 25 to 28, wherein the pore volume comprises greater than 95% micropores.

[0424] Embodiment 32. The method for preparing passivated silicon-carbon composite particles according to any one of Embodiments 25 to 28, wherein the silicon-carbon composite comprises a silicon content of 40-60%.

[0425] Embodiment 33. A method for preparing passivated silicon-carbon composite particles according to any one of Embodiments 25 to 28, wherein the silicon-carbon composite comprises Z less than 5.

[0426] Embodiment 34. A method for preparing passivated silicon-carbon composite particles according to any one of Embodiments 25 to 28, wherein the silicon-carbon composite comprises less than 10 m 2 / g of surface area.

[0427] Embodiment 35. A method for preparing passivated silicon-carbon composite particles according to any one of Embodiments 25 to 28, wherein the silicon-carbon composite comprises greater than or equal to 0.2 in Where dQ / dV is measured in a half-cell coin cell and region I is 0.8V-0.4V and region III is 0.15V-0V.

[0428] Embodiment 36. A method for preparing passivated silicon-carbon composite particles according to any one of Embodiments 25 to 28, wherein the silicon-carbon composite comprises greater than or equal to 0.3 in Where dQ / dV is measured in a half-cell coin cell and region I is 0.8V-0.4V and region III is 0.15V-0V.

[0429] Embodiment 37. The method for preparing passivated silicon-carbon composite particles according to any one of Embodiments 25 to 28, wherein the silicon-carbon composite comprises a Dv50 of 5 nm to 20 microns.

[0430] Embodiment 38. The method for preparing passivated silicon-carbon composite particles according to any one of Embodiments 25 to 28, wherein the silicon-carbon composite comprises a capacity greater than 900 mA / g.

[0431] Embodiment 39. The method for preparing passivated silicon-carbon composite particles according to any one of Embodiments 25 to 28, wherein the silicon-carbon composite comprises a capacity greater than 1300 mA / g.

[0432] Embodiment 40. The method for preparing passivated silicon-carbon composite particles according to any one of Embodiments 25 to 28, wherein the silicon-carbon composite comprises a capacity greater than 1600 mA / g.

[0433] Embodiment 41. A method of preparing passivated silicon-carbon composite particles, the method comprising:

[0434] a. Providing a carbon scaffold comprising a pore volume, wherein the pore volume comprises greater than 70% micropores;

[0435] b. heating the porous carbon support particles to a temperature of 350°C to 550°C in the presence of silane gas; and

[0436] c. Cooling the silicon-carbon composite in the presence of propylene gas.

[0437] Embodiment 42. A method of preparing passivated silicon-carbon composite particles, the method comprising:

[0438] a. Providing a carbon scaffold comprising a pore volume, wherein the pore volume comprises greater than 70% micropores;

[0439] b. heating the porous carbon support particles to a temperature of 350°C to 550°C in the presence of silane gas;

[0440] c. cooling the silicon-carbon composite in the presence of propylene gas; and

[0441] d. wherein the passivated silicon-carbon composite comprises:

[0442] i. Z less than 10, where Z = 1.875x[(M1100-M) / M1100]x

[0443] 100%, wherein M1100 is the mass of the silicon-carbon composite at 1100°C, and M is the minimum mass of the silicon-carbon composite between 800°C and 1100°C when the silicon-carbon composite is heated from about 25°C to about 1100°C in air, as determined by thermogravimetric analysis.

[0444] Embodiment 43. A method of preparing passivated silicon-carbon composite particles, the method comprising:

[0445] a. Providing a carbon scaffold comprising a pore volume, wherein the pore volume comprises greater than 70% micropores;

[0446] b. heating the porous carbon support particles to a temperature of 350°C to 550°C in the presence of silane gas;

[0447] c. cooling the silicon-carbon composite in the presence of propylene gas; and

[0448] d. wherein the passivated silicon-carbon composite comprises:

[0449] i. Z less than 10, where Z = 1.875x[(M1100-M) / M1100]x

[0450] 100%, wherein M1100 is the mass of the silicon-carbon composite at 1100°C, and M is the minimum mass of the silicon-carbon composite between 800°C and 1100°C when the silicon-carbon composite is heated from about 25°C to about 1100°C in air, as determined by thermogravimetric analysis; and

[0451] ii. Greater than or equal to 0.1 in Where dQ / dV is measured in a half-cell coin cell and region I is 0.8V-0.4V and region III is 0.15V-0V.

[0452] Embodiment 44. A method of preparing passivated silicon-carbon composite particles, the method comprising:

[0453] a. Providing a carbon scaffold comprising a pore volume, wherein the pore volume comprises greater than 70% micropores;

[0454] b. heating the porous carbon support particles to a temperature of 350°C to 550°C in the presence of silane gas;

[0455] c. cooling the silicon-carbon composite in the presence of propylene gas; and

[0456] d. wherein the passivated silicon-carbon composite comprises:

[0457] i. a silicon content of 30% to 60% by weight;

[0458] ii. Less than 30m 2 Surface area / g;

[0459] iii. Z less than 10, where Z = 1.875x[(M1100-M) / M1100]x

[0460] 100%, wherein M1100 is the mass of the silicon-carbon composite at 1100°C, and M is the minimum mass of the silicon-carbon composite between 800°C and 1100°C when the silicon-carbon composite is heated from about 25°C to about 1100°C in air, as determined by thermogravimetric analysis; and

[0461] iv. Greater than or equal to 0.1 in Where dQ / dV is measured in a half-cell coin cell and region I is 0.8V-0.4V and region III is 0.15V-0V.

[0462] Embodiment 45. A method of preparing passivated silicon-carbon composite particles, the method comprising:

[0463] a. Providing a carbon scaffold comprising a pore volume, wherein the pore volume comprises greater than 70% micropores;

[0464] b. heating the porous carbon support particles to a temperature of 350°C to 550°C in the presence of silane gas; and

[0465] c. Cooling the silicon-carbon composite to a temperature of 100° C. to 300° C. in the presence of acetylene gas.

[0466] Embodiment 46. A method of preparing passivated silicon-carbon composite particles, the method comprising:

[0467] a. Providing a carbon scaffold comprising a pore volume, wherein the pore volume comprises greater than 70% micropores;

[0468] b. heating the porous carbon support particles to a temperature of 350°C to 550°C in the presence of silane gas;

[0469] c. cooling the silicon-carbon composite to a temperature of 100°C to 300°C in the presence of acetylene gas; and

[0470] d. wherein the passivated silicon-carbon composite comprises:

[0471] ii. Z less than 10, where Z = 1.875x[(M1100-M) / M1100]x

[0472] 100%, wherein M1100 is the mass of the silicon-carbon composite at 1100°C, and M is the minimum mass of the silicon-carbon composite between 800°C and 1100°C when the silicon-carbon composite is heated from about 25°C to about 1100°C in air, as determined by thermogravimetric analysis.

[0473] Embodiment 47. A method of preparing passivated silicon-carbon composite particles, the method comprising:

[0474] a. Providing a carbon scaffold comprising a pore volume, wherein the pore volume comprises greater than 70% micropores;

[0475] b. heating the porous carbon support particles to a temperature of 350°C to 550°C in the presence of silane gas;

[0476] c. cooling the silicon-carbon composite to a temperature of 100°C to 300°C in the presence of acetylene gas; and

[0477] d. wherein the passivated silicon-carbon composite comprises:

[0478] i. Z less than 10, where Z = 1.875x[(M1100-M) / M1100]x

[0479] 100%, wherein M1100 is the mass of the silicon-carbon composite at 1100°C, and M is the minimum mass of the silicon-carbon composite between 800°C and 1100°C when the silicon-carbon composite is heated from about 25°C to about 1100°C in air, as determined by thermogravimetric analysis; and

[0480] ii. Greater than or equal to 0.1 in Where dQ / dV is measured in a half-cell coin cell and region I is 0.8V-0.4V and region III is 0.15V-0V.

[0481] Embodiment 48. A method of preparing passivated silicon-carbon composite particles, the method comprising:

[0482] a. Providing a carbon scaffold comprising a pore volume, wherein the pore volume comprises greater than 70% micropores;

[0483] b. heating the porous carbon support particles to a temperature of 350°C to 550°C in the presence of silane gas;

[0484] c. cooling the silicon-carbon composite to a temperature of 100°C to 300°C in the presence of acetylene gas; and

[0485] d. wherein the passivated silicon-carbon composite comprises:

[0486] i. a silicon content of 30% to 60% by weight;

[0487] ii. Less than 30m 2 Surface area / g;

[0488] iii. Z less than 10, where Z = 1.875x[(M1100-M) / M1100]x

[0489] 100%, wherein M1100 is the mass of the silicon-carbon composite at 1100°C, and M is the minimum mass of the silicon-carbon composite between 800°C and 1100°C when the silicon-carbon composite is heated from about 25°C to about 1100°C in air, as determined by thermogravimetric analysis; and

[0490] iv. Greater than or equal to 0.1 in Where dQ / dV is measured in a half-cell coin cell and region I is 0.8V-0.4V and region III is 0.15V-0V.

[0491] Embodiment 49. The method for preparing silicon-carbon composite particles by passivation according to any one of Embodiments 41 to 48, wherein the pore volume comprises greater than 80% micropores.

[0492] Embodiment 50. The method for preparing passivated silicon-carbon composite particles according to any one of Embodiments 41 to 48, wherein the pore volume comprises greater than 90% micropores.

[0493] Embodiment 51. The method of preparing passivated silicon-carbon composite particles according to any one of Embodiments 41 to 48, wherein the pore volume comprises greater than 95% micropores.

[0494] Embodiment 52. The method for preparing passivated silicon-carbon composite particles according to any one of Embodiments 41 to 48, wherein the silicon-carbon composite comprises a silicon content of 40-60%.

[0495] Embodiment 53. A method for preparing passivated silicon-carbon composite particles according to any one of Embodiments 41 to 48, wherein the silicon-carbon composite comprises Z less than 5.

[0496] Embodiment 54. A method for preparing passivated silicon-carbon composite particles according to any one of Embodiments 41 to 48, wherein the silicon-carbon composite comprises less than 10 m2 / g of surface area.

[0497] Embodiment 55. A method for preparing passivated silicon-carbon composite particles according to any one of Embodiments 41 to 48, wherein the silicon-carbon composite comprises greater than or equal to 0.2 in Where dQ / dV is measured in a half-cell coin cell and region I is 0.8V-0.4V and region III is 0.15V-0V.

[0498] Embodiment 56. A method for preparing passivated silicon-carbon composite particles according to any one of Embodiments 41 to 48, wherein the silicon-carbon composite comprises greater than or equal to 0.3 in Where dQ / dV is measured in a half-cell coin cell and region I is 0.8V-0.4V and region III is 0.15V-0V.

[0499] Embodiment 57. The method for preparing passivated silicon-carbon composite particles according to any one of Embodiments 41 to 48, wherein the silicon-carbon composite comprises a Dv50 of 5 nm to 20 microns.

[0500] Embodiment 58. The method for preparing passivated silicon-carbon composite particles according to any one of Embodiments 41 to 48, wherein the silicon-carbon composite comprises a capacity greater than 900 mA / g.

[0501] Embodiment 60. The method for preparing passivated silicon-carbon composite particles according to any one of Embodiments 41 to 48, wherein the silicon-carbon composite comprises a capacity greater than 1300 mA / g.

[0502] Embodiment 61. The method for preparing passivated silicon-carbon composite particles according to any one of Embodiments 41 to 48, wherein the silicon-carbon composite comprises a capacity greater than 1600 mA / g.

[0503] Embodiment 62. A silicon-carbon composite comprising:

[0504] a. a carbon scaffold comprising a pore volume, wherein the pore volume comprises greater than 70% micropores;

[0505] b. Z less than 10, wherein Z = 1.875 x [(M1100 - M) / M1100] x 100%, wherein M1100 is the mass of the silicon-carbon composite at 1100 ° C, and M is the minimum mass of the silicon-carbon composite between 800 ° C and 1100 ° C when the silicon-carbon composite is heated from about 25 ° C to about 1100 ° C in air, as determined by thermogravimetric analysis; and

[0506] c. One or more passivating silicon layers beneath the terminal passivated silicon surface.

[0507] Embodiment 63. The silicon-carbon composite of Embodiment 62, wherein the silicon-carbon composite further comprises a silicon content of 30% to 60% by weight.

[0508] Embodiment 64. The silicon-carbon composite of any one of Embodiments 62 to 63, wherein the silicon-carbon composite comprises particles comprising a Dv50 of 5 nm to 20 microns.

[0509] Embodiment 65. A silicon-carbon composite according to any one of Embodiments 62 to 64, wherein the silicon-carbon composite comprises greater than or equal to 0.1 in Where dQ / dV is measured in a half-cell coin cell and region I is 0.8V-0.4V and region III is 0.15V-0V.

[0510] Embodiment 66. The silicon-carbon composite of any one of Embodiments 62 to 65, wherein the passivating silicon layer is a silicon oxide layer.

[0511] Embodiment 67. A method of preparing hydrosilylation passivated silicon-carbon composite particles, the method comprising:

[0512] a. Providing a carbon scaffold particle comprising a pore volume, wherein the pore volume comprises greater than 70% micropores;

[0513] b. contacting the porous carbon support particles with silane gas at a temperature of 350°C to 550°C to produce silicon-carbon composite particles;

[0514] c. contacting the silicon-carbon composite particles with an olefin gas at a temperature of 100° C. to 500° C. to produce hydrosilylation passivated silicon-carbon composite particles.

[0515] Embodiment 68. A method of preparing hydrosilylation passivated silicon-carbon composite particles, the method comprising:

[0516] a. Providing a carbon scaffold particle comprising a pore volume, wherein the pore volume comprises greater than 70% micropores;

[0517] b. contacting the porous carbon support particles with silane gas at a temperature of 350°C to 550°C to produce silicon-carbon composite particles;

[0518] c. contacting the silicon-carbon composite particles with an alkyne gas at a temperature of 100° C. to 500° C. to produce hydrosilylated silicon-carbon composite particles.

[0519] Embodiment 69. A method of preparing hydrosilylation passivated silicon-carbon composite particles, the method comprising:

[0520] a. Providing a carbon scaffold particle comprising a pore volume, wherein the pore volume comprises greater than 70% micropores;

[0521] b. contacting the porous carbon support particles with silane gas at a temperature of 350°C to 550°C to produce silicon-carbon composite particles;

[0522] c. contacting the silicon-carbon composite particles with acetylene gas at a temperature of 100° C. to 500° C. to produce hydrosilylation passivated silicon-carbon composite particles.

[0523] Embodiment 70. A method of preparing hydrosilylation passivated silicon-carbon composite particles, the method comprising:

[0524] a. Providing a carbon scaffold particle comprising a pore volume, wherein the pore volume comprises greater than 70% micropores;

[0525] b. contacting the porous carbon support particles with silane gas at a temperature of 350°C to 550°C to produce silicon-carbon composite particles;

[0526] c. contacting the silicon-carbon composite particles with propylene gas at a temperature of 100° C. to 500° C. to produce hydrosilylation passivated silicon-carbon composite particles.

[0527] Embodiment 71. A method of preparing hydrosilylation passivated silicon-carbon composite particles, the method comprising:

[0528] a. Providing a carbon scaffold particle comprising a pore volume, wherein the pore volume comprises greater than 70% micropores;

[0529] b. contacting the porous carbon support particles with silane gas at a temperature of 350°C to 550°C to produce silicon-carbon composite particles;

[0530] c. contacting the silicon-carbon composite particles with ethylene gas at a temperature of 100° C. to 500° C. to produce hydrosilylation passivated silicon-carbon composite particles.

[0531] Embodiment 72. A method of preparing hydrosilylation passivated silicon-carbon composite particles, the method comprising:

[0532] a. Providing a carbon scaffold particle comprising a pore volume, wherein the pore volume comprises greater than 70% micropores;

[0533] b. contacting the porous carbon support particles with silane gas at a temperature of 350°C to 550°C to produce silicon-carbon composite particles;

[0534] c. contacting the silicon-carbon composite particles with acetylene gas at a temperature of 100° C. to 500° C. to produce hydrosilylation passivated silicon-carbon composite particles; and

[0535] d. wherein the hydrosilylation passivated silicon-carbon composite comprises:

[0536] i. a silicon content of 30% to 60% by weight;

[0537] ii. Less than 30m 2 Surface area / g;

[0538] iii. Z less than 10, where Z = 1.875x[(M1100-M) / M1100]x

[0539] 100%, wherein M1100 is the mass of the silicon-carbon composite at 1100°C, and M is the minimum mass of the silicon-carbon composite between 800°C and 1100°C when the silicon-carbon composite is heated from about 25°C to about 1100°C in air, as determined by thermogravimetric analysis; and

[0540] iv. Greater than or equal to 0.1 in Where dQ / dV is measured in a half-cell coin cell and region I is 0.8V-0.4V and region III is 0.15V-0V.

[0541] Embodiment 73. A method of preparing hydrosilylation passivated silicon-carbon composite particles, the method comprising:

[0542] a. Providing a carbon scaffold particle comprising a pore volume, wherein the pore volume comprises greater than 70% micropores;

[0543] b. contacting the porous carbon support particles with silane gas at a temperature of 350°C to 550°C to produce silicon-carbon composite particles;

[0544] c. contacting the silicon-carbon composite particles with propylene gas at a temperature of 100° C. to 500° C. to produce hydrosilylation passivated silicon-carbon composite particles; and

[0545] d. wherein the hydrosilylation passivated silicon-carbon composite comprises:

[0546] i. a silicon content of 30% to 60% by weight;

[0547] ii. Less than 30m 2 Surface area / g;

[0548] iii. Z less than 10, where Z = 1.875x[(M1100-M) / M1100]x

[0549] 100%, wherein M1100 is the mass of the silicon-carbon composite at 1100°C, and M is the minimum mass of the silicon-carbon composite between 800°C and 1100°C when the silicon-carbon composite is heated from about 25°C to about 1100°C in air, as determined by thermogravimetric analysis; and

[0550] iv. Greater than or equal to 0.1 in Where dQ / dV is measured in a half-cell coin cell and region I is 0.8V-0.4V and region III is 0.15V-0V.

[0551] Embodiment 74. A method of preparing hydrosilylation passivated silicon-carbon composite particles, the method comprising:

[0552] a. Providing a carbon scaffold particle comprising a pore volume, wherein the pore volume comprises greater than 70% micropores;

[0553] b. contacting the porous carbon support particles with silane gas at a temperature of 350°C to 550°C to produce silicon-carbon composite particles;

[0554] c. contacting the silicon-carbon composite particles with ethylene gas at a temperature of 100° C. to 500° C. to produce hydrosilylation passivated silicon-carbon composite particles; and

[0555] d. wherein the hydrosilylation passivated silicon-carbon composite comprises:

[0556] i. a silicon content of 30% to 60% by weight;

[0557] ii. Less than 30m 2 Surface area / g;

[0558] iii. Z less than 10, where Z = 1.875x[(M1100-M) / M1100]x

[0559] 100%, wherein M1100 is the mass of the silicon-carbon composite at 1100°C, and M is the minimum mass of the silicon-carbon composite between 800°C and 1100°C when the silicon-carbon composite is heated from about 25°C to about 1100°C in air, as determined by thermogravimetric analysis; and

[0560] iv. Greater than or equal to 0.1 in Where dQ / dV is measured in a half-cell coin cell and region I is 0.8V-0.4V and region III is 0.15V-0V.

[0561] Embodiment 75. A hydrosilylation passivated silicon-carbon composite material comprising:

[0562] a. a carbon scaffold comprising a pore volume, wherein the pore volume comprises greater than 70% micropores;

[0563] b. Nano-sized silicon domains within the pores of porous carbon, wherein the silicon surface contains Si-R bonds;

[0564] c. Where R includes:

[0565] a. organic functional groups comprising a combination of carbon, oxygen, nitrogen or hydrogen;

[0566] b. and one or more optional halogen elements, such as bromine, fluorine, chlorine or iodine;

[0567] as well as

[0568] d. wherein the hydrosilylation passivated silicon-carbon composite comprises:

[0569] i. a silicon content of 30% to 60% by weight;

[0570] ii. Less than 30m 2 Surface area / g;

[0571] iii. Z less than 10, wherein Z = 1.875 x [(M1100 - M) / M1100] x 100%, wherein M1100 is the mass of the silicon-carbon composite at 1100 ° C, and M is the minimum mass of the silicon-carbon composite between 800 ° C and 1100 ° C when the silicon-carbon composite is heated from about 25 ° C to about 1100 ° C in air, as determined by thermogravimetric analysis; and

[0572] iv. Greater than or equal to 0.1 in Where dQ / dV is measured in a half-cell coin cell and region I is 0.8V-0.4V and region III is 0.15V-0V.

[0573] Embodiment 76. A method of preparing chemical vapor passivated silicon-carbon composite particles, the method comprising:

[0574] a. Providing a carbon scaffold particle comprising a pore volume, wherein the pore volume comprises greater than 70% micropores;

[0575] b. contacting the porous carbon support particles with silane gas at a temperature of 350°C to 550°C to produce silicon-carbon composite particles;

[0576] c. contacting the silicon-carbon composite particles with an alkane gas at a temperature of 300° C. to 700° C. to produce chemical vapor passivated silicon-carbon composite particles.

[0577] Embodiment 77. A method of preparing chemical vapor passivated silicon-carbon composite particles, the method comprising:

[0578] a. Providing a carbon scaffold particle comprising a pore volume, wherein the pore volume comprises greater than 70% micropores;

[0579] b. contacting the porous carbon support particles with silane gas at a temperature of 350°C to 550°C to produce silicon-carbon composite particles;

[0580] c. contacting the silicon-carbon composite particles with an olefin gas at a temperature of 300° C. to 700° C. to produce chemical vapor passivated silicon-carbon composite particles.

[0581] Embodiment 78. A method of preparing chemical vapor passivated silicon-carbon composite particles, the method comprising:

[0582] a. Providing a carbon scaffold particle comprising a pore volume, wherein the pore volume comprises greater than 70% micropores;

[0583] b. contacting the porous carbon support particles with silane gas at a temperature of 350°C to 550°C to produce silicon-carbon composite particles;

[0584] c. contacting the silicon-carbon composite particles with acetylene gas at a temperature of 300° C. to 700° C. to produce chemical vapor passivated silicon-carbon composite particles.

[0585] Embodiment 79. A method of preparing chemical vapor passivated silicon-carbon composite particles, the method comprising:

[0586] a. Providing a carbon scaffold particle comprising a pore volume, wherein the pore volume comprises greater than 70% micropores;

[0587] b. contacting the porous carbon support particles with silane gas at a temperature of 350°C to 550°C to produce silicon-carbon composite particles;

[0588] c. contacting the silicon-carbon composite particles with propylene gas at a temperature of 300° C. to 700° C. to produce chemical vapor passivated silicon-carbon composite particles.

[0589] Embodiment 80. A method of preparing chemical vapor passivated silicon-carbon composite particles, the method comprising:

[0590] a. Providing a carbon scaffold particle comprising a pore volume, wherein the pore volume comprises greater than 70% micropores;

[0591] b. contacting the porous carbon support particles with silane gas at a temperature of 350°C to 550°C to produce silicon-carbon composite particles;

[0592] c. contacting the silicon-carbon composite particles with ethylene gas at a temperature of 300° C. to 700° C. to produce chemical vapor passivated silicon-carbon composite particles.

[0593] Embodiment 81. A method of preparing chemical vapor passivated silicon-carbon composite particles, the method comprising:

[0594] a. Providing a carbon scaffold particle comprising a pore volume, wherein the pore volume comprises greater than 70% micropores;

[0595] b. contacting the porous carbon support particles with silane gas at a temperature of 350°C to 550°C to produce silicon-carbon composite particles;

[0596] c. contacting the silicon-carbon composite particles with acetylene gas at a temperature of 300° C. to 700° C. to produce chemical vapor passivated silicon-carbon composite particles; and

[0597] d. wherein the chemical vapor passivated silicon-carbon composite comprises:

[0598] i. a silicon content of 30% to 60% by weight;

[0599] ii. Less than 30m 2 Surface area / g;

[0600] iii. Z less than 10, where Z = 1.875x[(M1100-M) / M1100]x

[0601] 100%, wherein M1100 is the mass of the silicon-carbon composite at 1100°C, and M is the minimum mass of the silicon-carbon composite between 800°C and 1100°C when the silicon-carbon composite is heated from about 25°C to about 1100°C in air, as determined by thermogravimetric analysis; and

[0602] iv. Greater than or equal to 0.1 in Where dQ / dV is measured in a half-cell coin cell and region I is 0.8V-0.4V and region III is 0.15V-0V.

[0603] Embodiment 82. A method of preparing chemical vapor passivated silicon-carbon composite particles, the method comprising:

[0604] a. Providing a carbon scaffold particle comprising a pore volume, wherein the pore volume comprises greater than 70% micropores;

[0605] b. contacting the porous carbon support particles with silane gas at a temperature of 350°C to 550°C to produce silicon-carbon composite particles;

[0606] c. contacting the silicon-carbon composite particles with propylene gas at a temperature of 300° C. to 700° C. to produce chemical vapor passivated silicon-carbon composite particles; and

[0607] d. wherein the chemical vapor passivated silicon-carbon composite comprises:

[0608] i. a silicon content of 30% to 60% by weight;

[0609] ii. Less than 30m 2 Surface area / g;

[0610] iii. Z less than 10, where Z = 1.875x[(M1100-M) / M1100]x

[0611] 100%, wherein M1100 is the mass of the silicon-carbon composite at 1100°C, and M is the minimum mass of the silicon-carbon composite between 800°C and 1100°C when the silicon-carbon composite is heated from about 25°C to about 1100°C in air, as determined by thermogravimetric analysis; and

[0612] iv. Greater than or equal to 0.1 in Where dQ / dV is measured in a half-cell coin cell and region I is 0.8V-0.4V and region III is 0.15V-0V.

[0613] Embodiment 83. A method of preparing chemical vapor passivated silicon-carbon composite particles, the method comprising:

[0614] a. Providing a carbon scaffold particle comprising a pore volume, wherein the pore volume comprises greater than 70% micropores;

[0615] b. contacting the porous carbon support particles with silane gas at a temperature of 350°C to 550°C to produce silicon-carbon composite particles;

[0616] c. contacting the silicon-carbon composite particles with ethylene gas at a temperature of 300° C. to 700° C. to produce chemical vapor passivated silicon-carbon composite particles; and

[0617] d. wherein the chemical vapor passivated silicon-carbon composite comprises:

[0618] i. a silicon content of 30% to 60% by weight;

[0619] ii. Less than 30m 2 Surface area / g;

[0620] iii. Z less than 10, where Z = 1.875x[(M1100-M) / M1100]x

[0621] 100%, wherein M1100 is the mass of the silicon-carbon composite at 1100°C, and M is the minimum mass of the silicon-carbon composite between 800°C and 1100°C when the silicon-carbon composite is heated from about 25°C to about 1100°C in air, as determined by thermogravimetric analysis; and

[0622] iv. Greater than or equal to 0.1 in Where dQ / dV is measured in a half-cell coin cell and region I is 0.8V-0.4V and region III is 0.15V-0V.

[0623] Embodiment 84. A chemical vapor passivated silicon-carbon composite material comprising:

[0624] a. a carbon scaffold comprising a pore volume, wherein the pore volume comprises greater than 70% micropores;

[0625] b. nanometer-sized silicon domains within the pores of the porous carbon, wherein the silicon surface comprises Si-H bonds; and

[0626] c. a carbonaceous layer at least partially covering the silicon domain; and

[0627] d. wherein the chemical vapor passivated silicon-carbon composite comprises:

[0628] i. a silicon content of 30% to 60% by weight;

[0629] ii. Less than 30m 2 Surface area / g;

[0630] iii. Z less than 10, where Z = 1.875x[(M1100-M) / M1100]x

[0631] 100%, wherein M1100 is the mass of the silicon-carbon composite at 1100°C, and M is the minimum mass of the silicon-carbon composite between 800°C and 1100°C when the silicon-carbon composite is heated from about 25°C to about 1100°C in air, as determined by thermogravimetric analysis; and

[0632] iv. Greater than or equal to 0.1 in

[0633] Where dQ / dV is measured in a half-cell coin cell and region I is 0.8V-0.4V and region III is 0.15V-0V.

[0634] From the foregoing it will be appreciated that although specific embodiments of the invention have been described herein for purposes of illustration, various modifications may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except by the appended claims.

[0635] U.S. Provisional Patent Application No. 63 / 085,788, filed on September 30, 2020, and U.S. Provisional Patent Application No. 63 / 129,363, filed on December 22, 2020, to which this application claims priority, are incorporated herein by reference in their entirety.

Claims

1. A method for preparing passivated silicon-carbon composite particles, the method comprising: a. providing a porous carbon scaffold comprising a pore volume, wherein the pore volume comprises greater than 70% micropores; b. in the presence of silane gas, heating the porous carbon support particles to a temperature of 350°C to 550°C to produce silicon-carbon composite particles; c. adjusting the temperature to ≤400°C in the presence of nitrogen; d. adding an oxygen-containing passivating gas to produce passivated silicon-carbon composite particles; and e. wherein the passivated silicon-carbon composite comprises: i. Z less than 10, wherein Z = 1.875 x [(M1100 - M) / M1100] x 100%, wherein M1100 is the mass of the silicon-carbon composite at 1100°C, and M is the minimum mass of the silicon-carbon composite between 800°C and 1100°C when the silicon-carbon composite is heated from about 25°C to about 1100°C in air, as determined by thermogravimetric analysis.

2. The method for preparing passivated silicon-carbon composite particles according to claim 1, wherein the silicon-carbon composite comprises a silicon content of 30 to 60% by weight.

3. The method for preparing passivated silicon-carbon composite particles of claim 1, wherein the silicon-carbon composite comprises a Dv50 of 5 nm to 20 microns.

4. The method for preparing passivated silicon-carbon composite particles according to claim 1, wherein the silicon-carbon composite comprises greater than or equal to 0.1 in Where dQ / dV is measured in a half-cell coin cell, and region I is 0.8V-0.4V and region III is 0.15V-0V.

5. The method for preparing passivated silicon-carbon composite particles of claim 1, wherein the oxygen-containing passivating gas comprises ethanol.

6. The method for preparing passivated silicon-carbon composite particles according to claim 1, wherein the oxygen-containing passivating gas is selected from dimethyl carbonate, ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate or vinylene carbonate, or a mixture thereof.

7. The method for preparing passivated silicon-carbon composite particles according to claim 1, wherein the silicon-carbon composite comprises less than 30 m 2 / g of surface area.

8. The method for preparing passivated silicon-carbon composite particles according to claim 7, wherein the silicon-carbon composite comprises less than 10 m 2 / g of surface area.

9. A method for preparing passivated silicon-carbon composite particles, the method comprising: a. providing a porous carbon scaffold comprising a pore volume, wherein the pore volume comprises greater than 70% micropores; b. in the presence of silane gas, heating the porous carbon support particles to a temperature of 350°C to 550°C to produce silicon-carbon composite particles; c. alternating the process gas between silane gas and carbon dioxide gas to produce multi-layer passivated silicon-carbon composite particles; and d. wherein the passivated silicon-carbon composite comprises: i. Z less than 10, wherein Z = 1.875 x [(M1100 - M) / M1100] x 100%, wherein M1100 is the mass of the silicon-carbon composite at 1100°C, and M is the minimum mass of the silicon-carbon composite between 800°C and 1100°C when the silicon-carbon composite is heated from about 25°C to about 1100°C in air, as determined by thermogravimetric analysis.

10. The method for preparing passivated silicon-carbon composite particles according to claim 9, wherein the silicon-carbon composite comprises a silicon content of 30 to 60% by weight.

11. The method of preparing passivated silicon-carbon composite particles of claim 9, wherein the silicon-carbon composite comprises a Dv50 of 5 nm to 20 microns.

12. The method for preparing passivated silicon-carbon composite particles according to claim 9, wherein the silicon-carbon composite comprises greater than or equal to 0.1 in Where dQ / dV is measured in a half-cell coin cell, and region I is 0.8V-0.4V and region III is 0.15V-0V.

13. The method for preparing passivated silicon-carbon composite particles according to claim 9, wherein the silicon-carbon composite comprises less than 30 m 2 / g of surface area.

14. The method for preparing passivated silicon-carbon composite particles according to claim 13, wherein the silicon-carbon composite comprises less than 10 m 2 / g of surface area.

15. A method for preparing passivated silicon-carbon composite particles, the method comprising: a. providing a porous carbon scaffold comprising a pore volume, wherein the pore volume comprises greater than 70% micropores; b. in the presence of silane gas, heating the porous carbon support particles to a temperature of 350°C to 550°C to produce silicon-carbon composite particles; c. cooling the silicon-carbon composite particles in the presence of propylene gas to produce passivated silicon-carbon composite particles; and d. wherein the passivated silicon-carbon composite comprises: i. Z less than 10, wherein Z = 1.875 x [(M1100 - M) / M1100] x 100%, wherein M1100 is the mass of the silicon-carbon composite at 1100°C, and M is the minimum mass of the silicon-carbon composite between 800°C and 1100°C when the silicon-carbon composite is heated from about 25°C to about 1100°C in air, as determined by thermogravimetric analysis.

16. The method for preparing passivated silicon-carbon composite particles according to claim 15, wherein the silicon-carbon composite comprises a silicon content of 30 to 60% by weight.

17. The method of preparing passivated silicon-carbon composite particles of claim 15, wherein the silicon-carbon composite comprises a Dv50 of 5 nm to 20 microns.

18. The method for preparing passivated silicon-carbon composite particles according to claim 15, wherein the silicon-carbon composite comprises greater than or equal to 0.1 in Where dQ / dV is measured in a half-cell coin cell, and region I is 0.8V-0.4V and region III is 0.15V-0V.

19. The method for preparing passivated silicon-carbon composite particles according to claim 15, wherein the silicon-carbon composite comprises less than 30 m 2 / g of surface area.

20. The method for preparing passivated silicon-carbon composite particles according to claim 19, wherein the silicon-carbon composite comprises less than 10 m 2 / g of surface area.

21. A method for preparing passivated silicon-carbon composite particles, the method comprising: a. providing a porous carbon scaffold comprising a pore volume, wherein the pore volume comprises greater than 70% micropores; b. in the presence of silane gas, heating the porous carbon support particles to a temperature of 350°C to 550°C to produce silicon-carbon composite particles; c. in the presence of acetylene gas, cooling the silicon-carbon composite particles to a temperature of 100° C. to 300° C. to produce passivated silicon-carbon composite particles; as well as d. wherein the passivated silicon-carbon composite comprises: i. Z less than 10, wherein Z = 1.875 x [(M1100 - M) / M1100] x 100%, wherein M1100 is the mass of the silicon-carbon composite at 1100°C, and M is the minimum mass of the silicon-carbon composite between 800°C and 1100°C when the silicon-carbon composite is heated from about 25°C to about 1100°C in air, as determined by thermogravimetric analysis.

22. The method for preparing passivated silicon-carbon composite particles of claim 21, wherein the silicon-carbon composite comprises a silicon content of 30% to 60% by weight.

23. The method of preparing passivated silicon-carbon composite particles of claim 21, wherein the silicon-carbon composite comprises a Dv50 of 5 nm to 20 microns.

24. The method for preparing passivated silicon-carbon composite particles according to claim 21, wherein the silicon-carbon composite comprises greater than or equal to 0.1 in Where dQ / dV is measured in a half-cell coin cell, and region I is 0.8V-0.4V and region III is 0.15V-0V.

25. The method for preparing passivated silicon-carbon composite particles according to claim 21, wherein the silicon-carbon composite comprises less than 30 m 2 / g of surface area.

26. The method for preparing passivated silicon-carbon composite particles according to claim 25, wherein the silicon-carbon composite comprises less than 10 m 2 / g of surface area.

27. A method for preparing hydrosilylation passivated silicon-carbon composite particles, the method comprising: a. Providing a carbon scaffold particle comprising a pore volume, wherein the pore volume comprises greater than 70% micropores; b. contacting the porous carbon support particles with silane gas at a temperature of 350°C to 550°C to produce silicon-carbon composite particles; c. contacting the silicon-carbon composite particles with an olefin gas at a temperature of 100° C. to 500° C. to produce hydrosilylation passivated silicon-carbon composite particles.

28. A method for preparing hydrosilylation passivated silicon-carbon composite particles, the method comprising: a. Providing a carbon scaffold particle comprising a pore volume, wherein the pore volume comprises greater than 70% micropores; b. contacting the porous carbon support particles with silane gas at a temperature of 350°C to 550°C to produce silicon-carbon composite particles; c. contacting the silicon-carbon composite particles with an alkyne gas at a temperature of 100° C. to 500° C. to produce hydrosilylated silicon-carbon composite particles.

29. A method for preparing hydrosilylation passivated silicon-carbon composite particles, the method comprising: a. Providing a carbon scaffold particle comprising a pore volume, wherein the pore volume comprises greater than 70% micropores; b. contacting the porous carbon support particles with silane gas at a temperature of 350°C to 550°C to produce silicon-carbon composite particles; c. contacting the silicon-carbon composite particles with acetylene gas at a temperature of 100° C. to 500° C. to produce hydrosilylation passivated silicon-carbon composite particles.

30. A hydrosilylation passivated silicon-carbon composite material comprising: a. a carbon scaffold comprising a pore volume, wherein the pore volume comprises greater than 70% micropores; b. Nano-sized silicon domains within the pores of porous carbon, wherein the silicon surface contains Si-R bonds; c. Where R includes: i. organic functional groups comprising a combination of carbon, oxygen, nitrogen or hydrogen; ii. and one or more optional halogen elements, such as bromine, fluorine, chlorine or iodine, d. wherein the hydrosilylation passivated silicon-carbon composite comprises: i. a silicon content of 30% to 60% by weight; ii. Less than 30m 2 Surface area / g; iii. Z less than 10, wherein Z = 1.875 x [(M1100 - M) / M1100] x 100%, wherein M1100 is the mass of the silicon-carbon composite at 1100 ° C, and M is the minimum mass of the silicon-carbon composite between 800 ° C and 1100 ° C when the silicon-carbon composite is heated from about 25 ° C to about 1100 ° C in air, as determined by thermogravimetric analysis; and iv. Greater than or equal to 0.1 in Where dQ / dV is measured in a half-cell coin cell, and region I is 0.8V-0.4V and region III is 0.15V-0V.

31. A method for preparing chemical vapor passivated silicon-carbon composite particles, the method comprising: d. providing a carbon scaffold particle comprising a pore volume, wherein the pore volume comprises greater than 70% micropores; e. contacting the porous carbon support particles with silane gas at a temperature of 350°C to 550°C to produce silicon-carbon composite particles; f. contacting the silicon-carbon composite particles with an alkyne gas at a temperature of 300° C. to 700° C. to produce chemical vapor passivated silicon-carbon composite particles.

32. Chemical vapor passivated silicon-carbon composite material, comprising: a. a carbon scaffold comprising a pore volume, wherein the pore volume comprises greater than 70% micropores; b. nanometer-sized silicon domains within the pores of the porous carbon, wherein the silicon surface comprises Si-H bonds; and c. a carbonaceous layer at least partially covering the silicon domain; and d. wherein the chemical vapor passivated silicon-carbon composite comprises: i. a silicon content of 30% to 60% by weight; ii. Less than 30m 2 Surface area / g; iii. Z less than 10, wherein Z = 1.875 x [(M1100 - M) / M1100] x 100%, wherein M1100 is the mass of the silicon-carbon composite at 1100 ° C, and M is the minimum mass of the silicon-carbon composite between 800 ° C and 1100 ° C when the silicon-carbon composite is heated from about 25 ° C to about 1100 ° C in air, as determined by thermogravimetric analysis; and iv. Greater than or equal to 0.1 in Where dQ / dV is measured in a half-cell coin cell, and region I is 0.8V-0.4V and region III is 0.15V-0V.

33. A method for preparing chemical vapor passivated silicon-carbon composite particles, the method comprising: d. providing a carbon scaffold particle comprising a pore volume, wherein the pore volume comprises greater than 70% micropores; e. contacting the porous carbon support particles with silane gas at a temperature of 350°C to 550°C to produce silicon-carbon composite particles; f. contacting the silicon-carbon composite particles with acetylene at a temperature of 300° C. to 700° C. to produce chemical vapor passivated silicon-carbon composite particles.

34. Chemical vapor passivated silicon-carbon composite material, comprising: a. a carbon scaffold comprising a pore volume, wherein the pore volume comprises greater than 70% micropores; b. nanometer-sized silicon domains within the pores of the porous carbon, wherein the silicon surface comprises Si-H bonds; and c. a carbonaceous layer at least partially covering the silicon domain; and d. wherein the chemical vapor passivated silicon-carbon composite comprises: i. a silicon content of 30% to 60% by weight; ii. Less than 30m 2 Surface area / g; iii. Z less than 10, wherein Z = 1.875 x [(M1100 - M) / M1100] x 100%, wherein M1100 is the mass of the silicon-carbon composite at 1100 ° C, and M is the minimum mass of the silicon-carbon composite between 800 ° C and 1100 ° C when the silicon-carbon composite is heated from about 25 ° C to about 1100 ° C in air, as determined by thermogravimetric analysis; and iv. Greater than or equal to 0.1 in Where dQ / dV is measured in a half-cell coin cell, and region I is 0.8V-0.4V and region III is 0.15V-0V.

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