Silicon-carbon composites

Abstract

Silicon-carbon composites and related methods are disclosed that overcome the challenge of providing amorphous nanometer-sized silicon entrained within a porous carbon. The materials and methods disclosed herein are better for various applications, including energy storage devices, such as lithium ion batteries, than other inferior materials and methods described in the prior art.

Description

Background Technology Technical Field

[0002] Embodiments of the present invention generally relate to silicon-carbon composite materials having properties that overcome the challenge of providing amorphous nanoscale silicon encased within porous carbon. The silicon-carbon composite materials are produced by chemical vapor infiltration (CVI) to impregnate amorphous nanoscale silicon into the pores of a porous scaffold. Suitable porous scaffolds include, but are not limited to, porous carbon scaffolds, such as carbon having pore volumes including micropores (less than 2 nm), mesopores (2 to 50 nm), and / or macropores (greater than 50 nm). Suitable precursors for carbon scaffolds include, but are not limited to, sugars and polyols, organic acids, phenolic compounds, crosslinking agents, and amine compounds. Suitable composite materials include, but are not limited to, silicon materials. Silicon precursors include, but are not limited to, silicon-containing gases, such as silanes, higher silanes (e.g., disilane, trisilane, and / or tetrasilane) and / or chlorosilanes (e.g., monochlorosilane, dichlorosilane, trichlorosilane, and tetrachlorosilane) and mixtures thereof. Silicon chemical vapor infiltration (CVI) into the pores of the porous scaffold material is achieved by exposing the porous scaffold to a silicon-containing gas (e.g., silane) at elevated temperatures. The porous carbon scaffold can be particulate porous carbon.

[0003] A key achievement in this area is obtaining silicon in the desired form and shape, namely amorphous nanoscale silicon. Furthermore, another key achievement is realizing the impregnation of silicon into the pores of porous carbon. Such materials, such as silicon-carbon composites, have practical applications as anode materials for energy storage devices (e.g., lithium-ion batteries).

[0004] Related technical descriptions

[0005] CVI is a method in which a gaseous substrate is reacted within a porous support material. This method can be used to produce composite materials, such as silicon-carbon composites, where silicon-containing gases decompose within a porous carbon support at high temperatures. While this method can be used to manufacture a variety of composite materials, particular attention is paid to silicon-carbon (Si-C) composites. Such Si-C composites have practical applications, such as as energy storage materials, for example, as anode materials in lithium-ion batteries (LIBs). LIBs have the potential to replace devices currently used in many applications. For example, current lead-acid automotive batteries are unsuitable for next-generation 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] Therefore, there has been considerable interest in developing new LIB anode materials, particularly silicon, which has a 10-fold higher gravimetric capacity than conventional graphite. However, silicon exhibits large volumetric changes during cycling, leading to electrode degradation and instability in the solid electrolyte interphase (SEI). The most common approach to improvement is to reduce the silicon particle size, for example, by using D... V,50 <150nm, for example, D V,50 <100nm, for example, 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 within a matrix. To date, techniques for fabricating nanoscale silicon have involved high-temperature reduction of silicon oxide, coarse-grained particle refinement, multi-step toxic etching, and / or other costly methods. Similarly, common matrix methods involve expensive materials such as graphene or nanographite, and / or require complex processing and coating.

[0007] It is known from scientific literature that non-graphitizable (hard) carbon is advantageous as an anode material for LIBs (Liu Y, Xue, JS, Zheng T, Dahn, JR. Carbon 1996, 34: 193–200; Wu, YP, Fang, SB, Jiang, YY. 1998, 75: 201–206; Buiel E, Dahn JR. Electrochim Acta 1999 45: 121-130). This improved performance is due to the disordered nature of the graphene layers, which allows Li ions to embed on either side of the graphene plane, thus theoretically allowing for a doubling of the stoichiometric content of Li ions relative to crystalline graphite. Furthermore, unlike graphite, where lithiation can only occur parallel to the stacked graphene planes, the disordered structure improves the rate capability of the material by allowing isotropic embedding of Li ions. Despite possessing these desirable electrochemical properties, amorphous carbon has not yet been widely adopted in commercial Li-ion batteries, primarily due to its low free charge efficiency (FCE) and low bulk density (<1 g / cc). Instead, amorphous carbon has been more commonly used as a low-mass additive and coating for other active material components in batteries to improve conductivity and reduce surface side reactions.

[0008] In recent years, amorphous carbon, as a material for LIB batteries, has attracted considerable attention as a coating for silicon anode materials. Such silicon-carbon core-shell structures not only have the potential to improve conductivity but also to buffer the expansion of silicon during lithiation, thereby stabilizing its cycle stability and minimizing problems related to particle fragmentation, insulation, and SEI integrity (Jung, Y, Lee K, Oh, S. Electrochim Acta 2007 52:7061–7067; Zuo P, Yin G, Ma Y. Electrochim Acta 2007 52:4878–4883; Ng SH, Wang J, Wexler D, Chew SY, Liu HK. J Phys Chem C 2007 111:11131–11138). Problems associated with this strategy include the lack of suitable silicon starting materials for coating processes and the inherent lack of engineered void spaces within carbon-coated silicon core-shell composite particles to accommodate silicon expansion during lithiation. This inevitably leads to cyclic stability failure due to the destruction of the core-shell structure and the SEI layer (Beattie SD, Larcher D, Morcrette M, Simon B, Tarascon, JM. J Electrochem Soc 2008 155: A158-A163).

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

[0010] To this end, the desired reverse hierarchical structure can be achieved using CVI, where silicon-containing gas can completely permeate nanoporous carbon and decompose into nanoscale silicon within it. The CVI method offers several advantages in terms of silicon structure. One advantage is that nanoporous carbon provides nucleation sites for silicon growth, while also defining the maximum particle shape and size. Confining silicon growth within the nanoporous structure reduces susceptibility to breakage or fragmentation and contact losses due to expansion. Furthermore, this structure promotes the nanoscale silicon to remain in an amorphous phase. This property provides high charge / discharge rates, especially when combined with the silicon-peripheral region within the conductive carbon scaffold. This system provides a high-rate solid-state lithium diffusion pathway capable of directly delivering lithium ions to the nanoscale silicon interface. Another benefit of providing silicon within the carbon scaffold via CVI is the suppression of undesirable Li crystallization. 15The formation of the Si4 phase. Another benefit is that the CVI method provides void space within the particles.

[0011] To measure the relative amount of silicon impregnated into the pores of porous carbon, thermogravimetric analysis (TGA) can be used. TGA can be used to assess the fraction of silicon residing within the pores of porous carbon relative to the total silicon present (i.e., the sum of silicon within the pores and on the particle surface). When the silicon-carbon composite is heated in air, the sample shows a mass increase starting at approximately 300°C to 500°C, reflecting the initial oxidation of silicon to SiO2; the sample then shows a mass loss as carbon is burned off; then the sample shows a mass increase, reflecting the continued conversion of silicon to SiO2, increasing to an asymptotic value near 1100°C, where silicon oxidation is complete. For the purposes of this analysis, it is assumed that the minimum mass recorded when the sample is heated from 800°C to 1100°C represents the point at which carbon is completely burned off. Any other mass increase beyond this point corresponds to the oxidation of silicon to SiO2, and the total mass at which oxidation is complete is SiO2. Therefore, the percentage of partially or unoxidized silicon after carbon burn-off, expressed as a proportion of the total silicon, can be determined using the following formula:

[0012] Z=1.875x[(M1100-M) / M1100]x 100

[0013] Where M1100 is the mass of the sample when oxidation is completed at 1100℃, and M is the minimum mass recorded when the sample is heated from 800℃ to 1100℃.

[0014] Without being bound by theory, the temperature at which silicon is oxidized under TGA conditions is related to the length scale of the oxide coating on silicon due to the diffusion of oxygen atoms through the oxide layer. Therefore, silicon residing within the carbon pores will oxidize at a lower temperature than silicon deposits on the particle surfaces, where a thinner coating is necessarily present. In this way, the calculation of Z is used to quantitatively assess the fraction of silicon not impregnated within the pores of the porous carbon scaffold. Summary of the Invention

[0015] Silicon-carbon composite materials and related methods are disclosed, overcoming the challenge of providing amorphous nanoscale silicon encased within porous carbon. The materials and methods disclosed herein are superior for a variety of applications, including energy storage devices such as lithium-ion batteries, compared to other inferior materials and methods described in the prior art.

[0016] The implementation provides a novel anode material constituting a lithium-silicon battery, comprising a composite containing a Group 14 element such as silicon and carbon, wherein the composite possesses novel properties that overcome the challenges of providing anodes for lithium-silicon batteries, the composite comprising silicon in a preferred mode: the silicon is amorphous, nanoscale, and embedded within porous carbon. The silicon-carbon composite is prepared by chemical vapor infiltration (CVI) to impregnate the amorphous nanoscale silicon into the pores of a porous scaffold. Suitable porous scaffolds include, but are not limited to, porous carbon scaffolds, such as carbon having pore volumes including micropores (less than 2 nm), mesopores (2 to 50 nm), and / or macropores (greater than 50 nm). Suitable precursors for carbon scaffolds include, but are not limited to, sugars and polyols, organic acids, phenolic compounds, crosslinking agents, and amine compounds. Suitable composites include, but are not limited to, silicon materials. Silicon precursors include, but are not limited to, silicon-containing gases such as silanes, higher silanes (e.g., disilane, trisilane, and / or tetrasilane) and / or chlorosilanes (e.g., monochlorosilane, dichlorosilane, trichlorosilane, and tetrachlorosilane) and mixtures thereof. CVI of silicon within the pores of the porous scaffold material is achieved by exposing the porous scaffold to a silicon-containing gas (e.g., silane) at elevated temperatures. The porous carbon scaffold may be particulate porous carbon.

[0017] A key achievement in this area is obtaining silicon in the desired form and shape, namely amorphous nanoscale silicon. Furthermore, another key achievement is realizing the impregnation of silicon into the pores of porous carbon. Such materials, such as silicon-carbon composites, have practical applications as anode materials for energy storage devices (e.g., lithium-ion batteries). Attached Figure Description

[0018] Figure 1 The relationship between Z and average coulombic efficiency for various silicon-carbon composite materials.

[0019] Figure 2 Differential capacity versus voltage plot of silicon-carbon composite 3 using half-cells in the second cycle.

[0020] Figure 3 Differential capacity versus voltage plot for silicon-carbon composite 3 using half-cells from the 2nd to the 5th cycle.

[0021] Figure 4 dQ / dV versus V diagrams for various silicon-carbon composite materials.

[0022] Figure 5 Silicon-carbon composite 3 Calculation examples.

[0023] Figure 6 Z-pairs of various silicon-carbon composite materials picture. Detailed Implementation

[0024] In the following description, certain specific details are set forth to provide a thorough understanding of various embodiments. However, those skilled in the art will understand that the invention can be practiced without these details. In other instances, structures generally known are not shown or described in detail to avoid unnecessarily obscuring the description of the embodiments. Unless the context otherwise requires, throughout the specification and appended claims, the word “comprise” and its variations (e.g., “comprises” and “comprising”) should be interpreted in an open-ended, inclusive sense, i.e., as meaning “including but not limited to”. Furthermore, the headings provided herein are for convenience only and do not constitute an explanation of the scope or meaning of the claimed invention.

[0025] Throughout this specification, the phrase "an embodiment" or "implementation" means that at least one embodiment includes a specific feature, structure, or characteristic relating to that embodiment. Therefore, the phrases "in one embodiment" or "in an embodiment" appearing throughout this specification do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. Additionally, as used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural indicators unless the context clearly specifies otherwise. It should also be noted that the term "or" is generally used to include the meaning of "and / or" unless the context clearly specifies otherwise.

[0026] A. Porous support material

[0027] For the purposes of embodiments of the present invention, porous scaffolds into which silicon is to be impregnated can be used. Throughout this document, the porous scaffold can comprise a variety of materials. In some embodiments, the porous scaffold material primarily comprises carbon, such as hard carbon. Other allotropes of carbon are also contemplated in other embodiments, such as graphite, amorphous carbon, diamond, C60, carbon nanotubes (e.g., single-walled and / or multi-walled), graphene, and / or carbon fibers. Porosity can be introduced into carbon materials in various ways. For example, porosity in the carbon material can be achieved by adjusting the polymer precursor and / or processing conditions to produce the porous carbon material, which is described in detail in subsequent sections.

[0028] In other embodiments, the porous scaffold comprises a polymeric material. For this purpose, various polymers are contemplated for use in the various embodiments, including but not limited to inorganic polymers, organic polymers, and addition polymers. Examples of inorganic polymers herein include, but are not limited to, homo-chain polymers of silicon-silicon, such as polysilanes, silicon carbide, polygermanane, and polystanane. Other examples of inorganic polymers include, but are not limited to, hetero-chain polymers, such as polyborazylene, polysiloxanes (e.g., polydimethylsiloxane (PDMS), polymethylhydrosiloxane (PMHS), and polydiphenylsiloxane), polysilazanes (e.g., perhydropolysilazane (PHPS)), polyphosphazenes and poly(dichlorophosphazene), polyphosphates (salts), polythiazyl nitrides, and polysulfides. 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(glycolic acid) and combinations thereof, phenolic resins, polyamides, polyarylamides, polyethylene terephthalate, polychloroprene, polyacrylonitrile, polyaniline, polyimide, poly(3,4-ethylenedioxythiophene)polystyrene sulfonate (PDOT:PSS), and other substances known in the art. Organic polymers can be synthetic or of natural origin. In some embodiments, the polymer is a polysaccharide, such as starch, cellulose, cellobiose, amylose, amylopectin, gum arabic, lignin, etc. In some embodiments, the polysaccharide is derived from the caramelization of monosaccharides or oligosaccharides (e.g., fructose, glucose, sucrose, maltose, raffinose, etc.).

[0029] In some embodiments, the porous scaffold polymer material comprises a coordination polymer. Coordination polymers as used herein include, but are not limited to, metal-organic frameworks (MOFs). Techniques for generating MOFs and exemplary materials for 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 as used herein include, but are not limited to, those mentioned above. Materials and zeolite imidazole ester skeleton (ZIF).

[0030] With the envisioning of various polymers possessing the potential to provide porous substrates, various processing methods are envisioned in various embodiments to achieve the aforementioned porosity. In this regard, as is known in the art, there are many general methods for generating porosity in various materials, including, but not limited to, methods such as emulsification, micelle generation, vaporization, dissolution followed by solvent removal (e.g., freeze-drying), axial compaction and sintering, gravity sintering, powder rolling and sintering, isobaric compaction and sintering, metal sputtering, metal coating and sintering, metal injection molding and sintering, etc. Other methods for generating porous polymer materials are also envisioned, including the generation of porous gels, such as freeze-dried gels, aerogels, etc.

[0031] In some embodiments, the porous scaffold material comprises a porous ceramic material. In some embodiments, the porous scaffold material comprises a porous ceramic foam. As is known herein, general methods for generating porosity within ceramic materials are diverse, including, but not limited to, generating pores. General methods and materials suitable for constituting 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.

[0032] In some embodiments, the porous scaffold comprises porous silica or other oxygen-containing silicon materials. The production of silica gels (including sol-gels) and other porous silica materials is known in the art.

[0033] In some embodiments, the porous material comprises a porous metal. Suitable metals in this regard include, but are not limited to, porous aluminum, porous steel, porous nickel, porous inconcel, porous 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 some embodiments, the porous support material comprises a porous metal foam. The types of metals and methods of their manufacture are known in the art. Such methods include, but are not limited to, casting (including foaming, infiltration, and low-foaming casting), deposition (chemical and physical), gas eutectic formation, and powder metallurgy techniques (e.g., powder sintering, compaction in the presence of a foaming agent, and fiber metallurgy).

[0034] B. Porous carbon scaffold

[0035] 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. Patents Nos. 7,723,262, 8,293,818, 8,404,384, 8,654,507, 8,916,296, 9,269,502, and 10,590,277, and U.S. Patent Application No. 16 / 745,197, the entire disclosure of which is incorporated herein by reference for all purposes.

[0036] Therefore, in one embodiment, this disclosure provides a method for preparing any of the above-described carbon materials or polymer gels. Carbon materials can be synthesized by the pyrolysis of a single precursor, such as saccharides, including sucrose, fructose, glucose, dextrin, maltodextrin, starch, amylopectin, amylose, lignin, gum arabic, and other sugars known in the art, and combinations thereof. Alternatively, carbon materials can be synthesized by the pyrolysis of a composite resin, for example, 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. The resin can be acidic or basic 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.

[0037] In some embodiments, the method includes preparing a polymer gel involving a monomer precursor and a crosslinking agent, two existing polymers and a crosslinking agent, or a single polymer and a crosslinking agent, a condensation method, or a crosslinking method, followed by pyrolysis of the polymer gel. The polymer gel may be dried (e.g., freeze-dried) prior to pyrolysis; however, drying is not necessarily required.

[0038] The desired carbon properties can be derived from various polymer chemistry principles, as long as the polymerization reaction produces a resin / polymer with the desired carbon backbone. Different polymer families include linear phenolic resins, soluble phenolic resins, acrylates, styrene-based resins, urethanes, rubbers (chloroprene rubber, styrene-butadiene, etc.), nylon, etc. Any of these polymer resins can be prepared by a variety of methods, including sol-gel, emulsion / suspension, solid, and molten states, for the polymerization and crosslinking processes.

[0039] In some embodiments, an electrochemical modifier is incorporated into the polymer material. For example, an organic or carbon-containing polymer, such as RF, is copolymerized with the polymer containing the 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 the RF solution before or during polymerization. In another embodiment, the polymer is a polysilane having organic side groups. In some cases, these side groups are methyl groups; in others, they are phenyl groups; and in still others, the side chains include phenyl, pyrrolidone, acetate, vinyl, or siloxane segments. In some cases, the side chains include Group 14 elements (silicon, germanium, tin, or lead). In still others, the side chains include Group 13 elements (boron, aluminum, boron, gallium, indium). In still others, the side chains include Group 15 elements (nitrogen, phosphorus, arsenic). In still others, the side chains include Group 16 elements (oxygen, sulfur, selenium).

[0040] In another embodiment, the electrochemical modifier includes thiophene. In some cases, it is phenol-thiophene or silane-fluorene. In others, it is polythiophene or polysilane-fluorene. In some cases, silicon is replaced by germanium (germanium heterocyclopentadiene or germanium heterofluorene), tin (tin heterocyclopentadiene or tin heterofluorene), nitrogen (carbazole), or phosphorus (phosphapentadiene or phosphaphenene). In all cases, the heteroatom-containing material can be a small molecule, oligomer, or polymer. The phosphorus atom may or may not be bonded to oxygen.

[0041] In some embodiments, the reactants comprise phosphorus. In some other embodiments, phosphorus is in the form of phosphoric acid. In some other embodiments, phosphorus may be in the form of a salt, wherein the anion of the salt comprises one or more phosphate, phosphite, phosphine, hydrogen phosphate, dihydrogen phosphate, hexafluorophosphate, hypophosphite, polyphosphate, or pyrophosphate ions, or combinations thereof. In some other embodiments, phosphorus may be in the form of a salt, wherein the cation of the salt comprises one or more phosphonium ions. Any of the non-phosphate-containing anion or cation pairs from the above embodiments may be selected for use with 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.

[0042] 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 combinations thereof. In other embodiments, the basic volatile catalyst is ammonium carbonate. In yet another embodiment, the basic volatile catalyst is ammonium acetate.

[0043] In other embodiments, the method includes mixing acids. In some embodiments, the acid is a solid at room temperature and pressure. In some embodiments, the acid is a liquid at room temperature and pressure. In some embodiments, the acid is a liquid at room temperature and pressure that does not provide dissolution of one or more other polymer precursors.

[0044] The acid can be selected from many acids suitable for use in the polymerization process. For example, in some embodiments, the acid is acetic acid, and in other embodiments, the acid is oxalic acid. In other embodiments, the acid is mixed with a first solvent or a second solvent in an acid-to-solvent ratio of 99:1, 90:10, 75:25, 50:50, 25:75, 20:80, 10:90, or 1:90. In other embodiments, the acid is acetic acid, and the first solvent or the second solvent is water. In other embodiments, acidity is provided by adding a solid acid.

[0045] The total acid content in the mixture can vary to alter the properties of the final product. In some embodiments, the acid is present at about 1% to about 50% by weight of the mixture. In other embodiments, the acid is present at about 5% to about 25%. In still other embodiments, the acid is present at about 10% to about 20%, for example, about 10%, about 15%, or about 20%.

[0046] In some embodiments, the polymer precursor components are blended together and subsequently held 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, for example less than 10 mm, for example less than 7 mm, for example less than 5 mm, for example less than 2 mm, for example less than 1 mm, for example less than 100 micrometers, for example less than 10 micrometers. In some embodiments, the particle size of one or more polymer precursor components is reduced during the blending process.

[0047] The blending of one or more polymer precursor components without solvents can be achieved by methods in the art, while simultaneously controlling process conditions (e.g., temperature). These methods include ball milling, jet milling, Fritsch milling, planetary mixing, and other mixing methods for mixing or blending solid particles. The mixing or blending process can be carried out before, during, and / or after incubation at the reaction temperature (or a combination thereof).

[0048] The reaction parameters include aging the blended mixture at temperatures and times sufficient to cause one or more polymer precursors to react with each other and form a polymer. In this regard, suitable aging temperatures are from about room temperature to or near the melting points of one or more polymer precursors. In some embodiments, suitable aging temperatures are from about room temperature to or near the glass transition temperatures of one or more polymer precursors. For example, in some embodiments, the solvent-free mixture is aged at temperatures from about 20°C to about 600°C, such as from about 20°C to about 500°C, such as from about 20°C to about 400°C, such as from about 20°C to about 300°C, such as from about 20°C to about 200°C. In some embodiments, the solvent-free mixture is aged at temperatures from about 50°C to about 250°C.

[0049] The reaction duration is typically sufficient for the polymer precursor to react 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 outcome. Typical embodiments include aging periods of approximately 2 hours to approximately 48 hours, for example, in some embodiments, aging for approximately 12 hours, and in other embodiments, aging for approximately 4-8 hours (e.g., approximately 6 hours).

[0050] In some embodiments, an electrochemical modifier is incorporated during the polymerization process described above. For example, in some embodiments, the electrochemical modifier, in the form of metal particles, metal slurry, metal salt, metal oxide, or molten metal, may be dissolved or suspended in the mixture that produces the gel resin.

[0051] Exemplary electrochemical modifiers used to generate composite materials may fall into one or more chemical categories. 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.

[0052] In some embodiments, the electrochemical modifier comprises a metal, and exemplary substances include, but are not limited to, aluminum isopropoxide, manganese acetate, nickel acetate, ferric acetate, tin chloride, silicon chloride, and combinations thereof. In some embodiments, the electrochemical modifier is a phosphate (salt) compound, including but not limited to phytic acid, phosphoric acid, ammonium dihydrogen phosphate, and combinations thereof. In some embodiments, the electrochemical modifier comprises silicon, and exemplary substances include, but are not limited to, silicon powder, silicon nanotubes, polycrystalline silicon, nanocrystalline silicon, amorphous silicon, porous silicon, nanoscale silicon, silicon with nano-features, silicon with both nanoscale and nano-features, silicyne, and black silicon, and combinations thereof.

[0053] Electrochemical modifiers can be combined with various polymer systems using latent (or secondary) polymeric functional groups through physical mixing or chemical reactions. Examples of latent polymeric functional groups include, but are not limited to, epoxy groups, unsaturated groups (double and triple bonds), acid groups, alcohol groups, amine groups, and basic groups. Crosslinking with latent functional groups can occur via heteroatoms (e.g., sulfidation with sulfur, acid / base / ring-opening reactions with phosphoric acid), reactions with organic acids or bases (as described above), coordination with transition metals (including but not limited to Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ag, Au), ring-opening or ring-closing reactions (rotaxanes, spirocyclic compounds, etc.).

[0054] Electrochemical modifiers can also be added to polymer systems through 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 main polymer materials.

[0055] In some cases, electrochemical modifiers can be added via metal salt solids, solutions, or suspensions. The metal salt solids, solutions, or suspensions may contain acids and / or alcohols to improve the solubility of the metal salt. In another variation, the polymer gel (before or after an optional drying step) is contacted with a slurry containing the electrochemical modifier. In yet another variation, the polymer gel (before or after an optional drying step) is contacted with a metal or metal oxide sol containing the desired electrochemical modifier.

[0056] In addition to the electrochemical modifiers exemplified above, composite materials may contain one or more other forms of carbon (i.e., allotropes). In this regard, it has been found that incorporating 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 fibers) into the composite material is effective for optimizing the electrochemical properties of the composite. Various allotropes of carbon can be incorporated into the carbon material during any stage of the preparation methods described herein. For example, during the solution stage, during the gelation stage, during the curing stage, during the pyrolysis stage, during the milling stage, or after milling. In some embodiments, a second carbon form is incorporated into the composite material by adding a second carbon form before or during polymer gel polymerization as described in more detail herein. The polymer gel containing the second carbon form is then treated according to the general techniques described herein to obtain a carbon material containing a second allotropy of carbon.

[0057] In a preferred embodiment, carbon is generated from a precursor having little or no solvent required for processing (solvent-free). The structure of polymer precursors suitable for use in low-solvent or substantially solvent-free reaction mixtures is not particularly limited, as long as the polymer precursor can react 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.

[0058] In one embodiment employing a low-solvent or substantially solvent-free reaction mixture, the method includes using a first polymer precursor and a second polymer precursor, and in some embodiments, the first or second polymer precursor is a carbonyl-containing compound and the remainder of the first or 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 precursor is an alcohol and a carbonyl compound (e.g., resorcinol and acetaldehyde), and they are present in a ratio of about 0.5:1.0, respectively.

[0059] Polymer precursor materials suitable for reaction mixtures with low or substantially no solvents as disclosed herein include (a) alcohols, phenols, and other monohydroxy or polyhydroxy compounds, and (b) aldehydes, ketones, and combinations thereof. Representative alcohols herein include straight-chain and branched, saturated and unsaturated alcohols. Suitable phenols include polyhydroxybenzenes, such as dihydroxybenzenes or trihydroxybenzenes. Representative polyhydroxybenzenes include resorcinol (i.e., 1,3-dihydroxybenzene), catechol, hydroquinone, and phloroglucinol. Other suitable compounds in this regard are bisphenols, such as bisphenol A. Mixtures of two or more polyhydroxybenzenes may also be used. Phenols (monohydroxybenzenes) may also be used. Representative polyhydroxy compounds include sugars such as glucose, sucrose, fructose, chitin, and other polyols such as mannitol. In this paper, aldehydes include: straight-chain saturated aldehydes, such as formaldehyde, acetaldehyde, propanal, and butanal; straight-chain unsaturated aldehydes, such as ketene and other ketones, propenal, crotonal, and 3-butenal; branched-chain saturated and unsaturated aldehydes; and aromatic aldehydes, such as benzaldehyde, salicylaldehyde, and hydrogenated cinnamaldehyde. Suitable ketones include: straight-chain saturated ketones, such as acetone and 2-butanone; straight-chain unsaturated ketones, such as acrylone, 2-butenone, and 3-butenone; branched-chain saturated and unsaturated ketones; and aromatic ketones, such as methyl benzyl ketone and ethyl benzyl ketone. Polymer precursor materials can also be combinations of the precursors described above.

[0060] In some embodiments, in a low-solvent or substantially solvent-free reaction mixture, one polymer precursor is an alcohol-containing substance, and the other polymer precursor is a carbonyl-containing substance. The relative amounts of the alcohol-containing substance (e.g., alcohols, phenolic compounds, and monohydroxy or polyhydroxy compounds, or combinations thereof) reacting with the carbonyl-containing substance (e.g., aldehydes, ketones, or combinations thereof) can vary significantly. In some embodiments, the ratio of the alcohol-containing substance to the aldehyde-containing substance is chosen such that the total number of moles of reactive alcohol groups in the alcohol-containing substance is approximately the same as the total number of moles of reactive carbonyl groups in the aldehyde-containing substance. Similarly, the ratio of the alcohol-containing substance to the ketone-containing substance can be chosen such that the total number of moles of reactive alcohol groups in the alcohol-containing substance is approximately the same as the total number of moles of reactive carbonyl groups in the ketone-containing substance. The same approximately 1:1 molar ratio also applies when the carbonyl-containing substance comprises a combination of aldehydes and ketones.

[0061] In other embodiments, the polymer precursor in the low-solvent or substantially solvent-free reaction mixture is a urea- or amine-containing compound. For example, in some embodiments, the polymer precursor is urea, melamine, hexamethylenetetramine (HMT), or combinations thereof. Other embodiments include polymer precursors selected from isocyanates or other reactive carbonyl compounds (e.g., acyl halides).

[0062] Some embodiments of the disclosed method involve preparing low-solvent or solvent-free polymer gels (and carbon materials) containing electrochemical modifiers. Such electrochemical modifiers include, but are not limited to, nitrogen, silicon, and sulfur. In other embodiments, the electrochemical modifiers include 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.

[0063] The blending of one or more polymer precursor components without solvents can be achieved by methods described in the art, while simultaneously controlling process conditions (e.g., temperature). These methods include ball milling, jet milling, Fritsch milling, planetary mixing, and other mixing methods for mixing or blending solid particles. The mixing or blending process can be carried out before, during, and / or after incubation at the reaction temperature (or a combination thereof).

[0064] The reaction parameters include aging the blended mixture at temperatures and times sufficient to cause one or more polymer precursors to react with each other and form a polymer. In this regard, suitable aging temperatures are from about room temperature to or near the melting points of one or more polymer precursors. In some embodiments, suitable aging temperatures are from about room temperature to or near the glass transition temperatures of one or more polymer precursors. For example, in some embodiments, the solvent-free mixture is aged at temperatures from about 20°C to about 600°C, such as from about 20°C to about 500°C, such as from about 20°C to about 400°C, such as from about 20°C to about 300°C, such as from about 20°C to about 200°C. In some embodiments, the solvent-free mixture is aged at temperatures from about 50°C to about 250°C.

[0065] Porous carbon materials can be achieved via the pyrolysis of polymers from which the precursor materials described above are produced. In some embodiments, the porous carbon material comprises amorphous activated carbon produced by pyrolysis, physical or chemical activation, or a combination thereof, in a single or sequential process step.

[0066] The pyrolysis temperature and residence time can be varied; for example, the residence time can be varied from 1 min to 10 min, 10 min to 30 min, 30 min to 1 hour, 1 hour to 2 hours, 2 hours to 4 hours, and 4 hours to 24 hours. The temperature can also be varied; for example, the pyrolysis temperature can be varied from 200℃ to 300℃, 250℃ to 350℃, 350℃ to 450℃, 450℃ to 550℃, 540℃ to 650℃, 650℃ to 750℃, 750℃ to 850℃, 850℃ to 950℃, 950℃ to 1050℃, 1050℃ to 1150℃, and 1150℃ to 1250℃. Pyrolysis can be carried out in an inert gas (such as nitrogen or argon).

[0067] In some embodiments, alternative gases are used to further achieve carbon activation. In some embodiments, pyrolysis and activation are combined. Suitable gases for achieving carbon activation include, but are not limited to, carbon dioxide, carbon monoxide, water (steam), air, oxygen, and other combinations thereof. The activation temperature and residence time can be varied, for example, the residence time can be varied from 1 min to 10 min, 10 min to 30 min, 30 min to 1 hour, 1 hour to 2 hours, 2 hours to 4 hours, and 4 hours to 24 hours. The temperature can be varied, for example, the pyrolysis temperature can be varied from 200°C to 300°C, 250°C to 350°C, 350°C to 450°C, 450°C to 550°C, 540°C to 650°C, 650°C to 750°C, 750°C to 850°C, 850°C to 950°C, 950°C to 1050°C, 1050°C to 1150°C, and 1150°C to 1250°C.

[0068] Carbon particle size reduction can be performed before pyrolysis and / or after pyrolysis and / or after activation. Particle size reduction can be achieved by various techniques known in the art, such as jet milling in the presence of various gases, including air, nitrogen, argon, helium, supercritical vapor, and other gases known in the art. Other particle size reduction methods are also envisioned, such as milling, ball milling, jet milling, water jet milling, and other methods known in the art.

[0069] Porous carbon scaffolds can be in the form of particles. Particle size and particle size distribution can be measured using various techniques known in the art and can be described based on fractional volume. In this respect, the Dv,50 of the carbon scaffold can be from 10 nm to 10 mm, for example, from 100 nm to 1 mm, for example, from 1 μm to 100 μm, for example, from 2 μm to 50 μm, for example, from 3 μm to 30 μm, for example, from 4 μm to 20 μm, for example, from 5 μm to 10 μm. In some embodiments, Dv,50 is less than 1 mm, for example, less than 100 μm, for example, less than 50 μm, for example, less than 30 μm, for example, less than 20 μm, for example, less than 10 μm, for example, less than 8 μm, for example, less than 5 μm, for example, less than 3 μm, for example, less than 1 μm. In some embodiments, Dv,100 is less than 1 mm, for example, less than 100 μm, for example, less than 50 μm, for example, less than 30 μm, for example, less than 20 μm, for example, less than 10 μm, for example, less than 8 μm, for example, less than 5 μm, for example, less than 3 μm, for example, less than 1 μm. In some embodiments, Dv,99 is less than 1 mm, for example, less than 100 μm, for example, less than 50 μm, for example, less than 30 μm, for example, less than 20 μm, for example, less than 10 μm, for example, less than 8 μm, for example, less than 5 μm, for example, less than 3 μm, for example, less than 1 μm. In some embodiments, Dv,90 is less than 1 mm, for example, less than 100 μm, for example, less than 50 μm, for example, less than 30 μm, for example, less than 20 μm, for example, less than 10 μm, for example, less than 8 μm, for example, less than 5 μm, for example, less than 3 μm, for example, less than 1 μm. In some embodiments, Dv,0 is greater than 10 nm, for example, greater than 100 nm, for example, greater than 500 nm, for example, greater than 1 μm, for example, greater than 2 μm, for example, greater than 5 μm, for example, greater than 10 μm. In some embodiments, Dv,1 is greater than 10 nm, for example, greater than 100 nm, for example, greater than 500 nm, for example, greater than 1 μm, for example, greater than 2 μm, for example, greater than 5 μm, for example, greater than 10 μm. In some embodiments, Dv,10 is greater than 10 nm, for example, greater than 100 nm, for example, greater than 500 nm, for example, greater than 1 μm, for example, greater than 2 μm, for example, greater than 5 μm, for example, greater than 10 μm.

[0070] In some implementations, the surface area of ​​the porous carbon scaffold may include greater than 400 m². 2 / g surface area, for example, greater than 500m 2 / g, for example, greater than 750m 2 / g, for example, greater than 1000m 2 / g, for example, greater than 1250m 2 / g, for example, greater than 1500m 2 / g, for example, greater than 1750m 2 / g, for example, greater than 2000m2 / g, for example, greater than 2500m 2 / g, for example, greater than 3000m 2 / g. In other embodiments, the surface area of ​​the porous carbon scaffold can be less than 500m². 2 / g. In some embodiments, the surface area of ​​the porous carbon scaffold is 200 to 500 m². 2 / g. In some embodiments, the surface area of ​​the porous carbon scaffold is 100 to 200 m². 2 / g. In some embodiments, the surface area of ​​the porous carbon scaffold is 50 to 100 m². 2 / g. In some embodiments, the surface area of ​​the porous carbon scaffold is 10 to 50 m². 2 / g. In some embodiments, the surface area of ​​the porous carbon scaffold can be less than 10m². 2 / g.

[0071] In some implementations, the pore volume of the porous carbon scaffold is greater than 0.4 cm³. 3 / g, for example, greater than 0.5cm 3 / g, for example, greater than 0.6cm 3 / g, for example, greater than 0.7cm 3 / g, for example, greater than 0.8cm 3 / g, for example, greater than 0.9cm 3 / g, for example, greater than 1.0cm 3 / g, for example, greater than 1.1cm 3 / g, for example, greater than 1.2cm 3 / g, for example, greater than 1.4cm 3 / g, for example, greater than 1.6cm 3 / g, for example, greater than 1.8cm 3 / g, for example, greater than 2.0cm 3 / g. In other embodiments, the pore volume of the porous carbon scaffold is less than 0.5 cm³, for example, 0.1 cm³. 3 / g to 0.5cm 3 / g. In some other embodiments, the pore volume of the porous carbon scaffold is 0.01 cm³. 3 / g to 0.1cm 3 / g.

[0072] In some other embodiments, the porous carbon scaffold has a pore volume of 0.2 to 2.0 cm³. 3 / g of amorphous activated carbon. In some embodiments, the carbon has a pore volume of 0.4 to 1.5 cm³. 3 / g of amorphous activated carbon. In some embodiments, the carbon has a pore volume of 0.5 to 1.2 cm³. 3 / g of amorphous activated carbon. In some embodiments, the carbon has a pore volume of 0.6 to 1.0 cm³. 3 / g of amorphous activated carbon.

[0073] In some other embodiments, the porous carbon scaffold comprises less than 1.0 g / cm³. 3 The tap density, for example, is less than 0.8 g / cm³. 3 For example, less than 0.6 g / cm³ 3 For example, less than 0.5 g / cm³ 3 For example, less than 0.4 g / cm³ 3 For example, less than 0.3 g / cm³ 3 For example, less than 0.2 g / cm³ 3 For example, less than 0.1 g / cm³ 3 .

[0074] The surface functionality of porous carbon scaffolds can vary. One property that can predict surface functionality is the pH of the porous carbon scaffold. The porous carbon scaffolds disclosed in this invention contain pH values ​​from less than 1 to about 14, for example, less than 5, 5 to 8, or greater than 8. In some embodiments, the pH of the porous carbon is less than 4, less than 3, less than 2, or even less than 1. In other embodiments, the pH of the porous carbon is about 5 to 6, about 6 to 7, about 7 to 8, or 8 to 9, or 9 to 10. In other embodiments, the pH is high and the pH range of the porous carbon is greater than 8, greater than 9, greater than 10, greater than 11, greater than 12, or even greater than 13.

[0075] The pore volume distribution of the porous carbon scaffold can vary. For example, the percentage of micropores can be less than 30%, such as less than 20%, less than 10%, less than 5%, less than 4%, less than 3%, less than 2%, less than 1%, less than 0.5%, less than 0.2%, or less than 0.1%. In some embodiments, there is no detectable micropore volume in the porous carbon scaffold.

[0076] The mesopores constituting the porous carbon scaffold can vary. For example, the percentage of mesopores can be less than 30%, such as less than 20%, less than 10%, less than 5%, less than 4%, less than 3%, less than 2%, less than 1%, less than 0.5%, less than 0.2%, or less than 0.1%. In some embodiments, there is no detectable mesopore volume in the porous carbon scaffold.

[0077] In some embodiments, the pore volume distribution of the porous carbon scaffold includes more than 50% macropores, such as more than 60% macropores, more than 70% macropores, more than 80% macropores, more than 90% macropores, more than 95% macropores, more than 98% macropores, more than 99% macropores, more than 99.5% macropores, and more than 99.9% macropores.

[0078] In some preferred embodiments, the pore volume of the porous carbon scaffold comprises a mixture of micropores, mesopores, and macropores. Therefore, in some embodiments, the porous carbon scaffold comprises 0-20% micropores, 30-70% mesopores, and less than 10% macropores. In some other embodiments, the porous carbon scaffold comprises 0-20% micropores, 0-20% mesopores, and 70-95% macropores. In some other embodiments, the porous carbon scaffold comprises 20-50% micropores, 50-80% mesopores, and 0-10% macropores. In some other embodiments, the porous carbon scaffold comprises 40-60% micropores, 40-60% mesopores, and 0-10% macropores. In some other embodiments, the porous carbon scaffold comprises 80-95% micropores, 0-10% mesopores, and 0-10% macropores. In some other embodiments, the porous carbon scaffold comprises 0-10% micropores, 30-50% mesopores, and 50-70% macropores. In some other embodiments, the porous carbon scaffold comprises 0-10% micropores, 70-80% mesopores, and 0-20% macropores. In some other embodiments, the porous carbon scaffold comprises 0-20% micropores, 70-95% mesopores, and 0-10% macropores. In some other embodiments, the porous carbon scaffold comprises 0-10% micropores, 70-95% mesopores, and 0-20% macropores.

[0079] In some embodiments, the pore volume percentage representing pores of 100 to 1000 Å (10 to 100 nm) in the porous carbon scaffold is greater than 30% of the total pore volume, for example, greater than 40% of the total pore volume, for example, greater than 50% of the total pore volume, for example, greater than 60% of the total pore volume, for example, greater than 70% of the total pore volume, for example, greater than 80% of the total pore volume, for example, greater than 90% of the total pore volume, for example, greater than 95% of the total pore volume, for example, greater than 98% of the total pore volume, for example, greater than 99% of the total pore volume, for example, greater than 99.5% of the total pore volume, for example, greater than 99.9% of the total pore volume.

[0080] In some embodiments, the specific gravity density of the porous carbon scaffold is from about 1 g / cc to about 3 g / cc, for example, from about 1.5 g / cc to about 2.3 g / cc. In other embodiments, the scaffold density is from about 1.5 cc / g to about 1.6 cc / g, from about 1.6 cc / g to about 1.7 cc / g, from about 1.7 cc / g to about 1.8 cc / g, from about 1.8 cc / g to about 1.9 cc / g, from about 1.9 cc / g to about 2.0 cc / g, from about 2.0 cc / g to about 2.1 cc / g, from about 2.1 cc / g to about 2.2 cc / g, or from about 2.2 cc / g to about 2.3 cc / g, from about 2.3 cc to about 2.4 cc / g, for example, from about 2.4 cc / g to about 2.5 cc / g.

[0081] C. Silicon production via chemical vapor infiltration (CVI)

[0082] Chemical vapor deposition (CVD) is a method in which a substrate provides a solid surface comprising a first component of a composite, and a gas is thermally decomposed on the solid surface to provide a second component of the composite. For example, this CVD method can be used to produce Si-C composites, where silicon is coated on the outer surface of silicon particles. Alternatively, chemical vapor infiltration (CVI) is a method in which a substrate provides a porous scaffold comprising a first component of a composite, and a gas is thermally decomposed to enter the pores of the porous scaffold material (entering the pores) to provide the second component of the composite.

[0083] In one embodiment, silicon is generated within the pores of the porous carbon scaffold by subjecting porous carbon particles to a silicon-containing precursor gas at elevated temperatures and in the presence of a silicon-containing gas (preferably silane) to decompose the gas into silicon. The silicon-containing precursor gas may be mixed with other inert gases such as nitrogen. The process temperature and time can vary, for example, the temperature may be 200 to 900°C, such as 200 to 250°C, such as 250 to 300°C, such as 300 to 350°C, such as 300 to 400°C, such as 350 to 450°C, such as 350 to 400°C, such as 400 to 500°C, such as 500 to 600°C, such as 600 to 700°C, such as 700 to 800°C, such as 800 to 900°C, such as 600 to 1100°C.

[0084] 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.

[0085] The pressure in the CVI method can vary. In some implementations, the pressure is atmospheric pressure. In some implementations, the pressure is below atmospheric pressure. In some implementations, the pressure is above atmospheric pressure.

[0086] D. Physical and electrochemical properties of silicon-carbon composites

[0087] While not wishing to be bound by theory, it is believed that the realization of nanoscale silicon (e.g., silicon with pores filled to 5 to 1000 nm or other ranges as disclosed elsewhere herein) due to certain desired pore volume structures of porous carbon scaffolds, along with the advantageous properties of other components of the composite (including low surface area and low specific gravity), results in composite materials with different and advantageous properties (e.g., electrochemical performance when the composite constitutes the anode of a lithium-ion energy storage device).

[0088] In some embodiments, the embedded silicon particles within the composite include nanoscale features. These nanoscale features may preferably have a feature length scale of less than 1 μm, less than 300 nm, less than 150 nm, less than 100 μm, less than 50 nm, less than 30 nm, less than 15 nm, less than 10 nm, or less than 5 nm.

[0089] In some embodiments, the silicon embedded within the composite is spherical. In other embodiments, the porous silicon particles are non-spherical, such as rod-shaped or fibrous structures. In some embodiments, silicon exists as a layer encapsulating the interior of the pores within a porous carbon scaffold. The depth of this silicon layer can vary, for example, it can be 5 nm to 10 nm, such as 5 nm to 20 nm, such as 5 nm to 30 nm, such as 5 nm to 33 nm, such as 10 nm to 30 nm, such as 10 nm to 50 nm, such as 10 nm to 100 nm, such as 10 nm to 150 nm, such as 50 nm to 150 nm, such as 100 nm to 300 nm, such as 300 nm to 1000 nm.

[0090] In some embodiments, the silicon embedded within the composite is nanoscale and resides within the pores of the porous carbon scaffold. For example, the embedded silicon can be impregnated, deposited via CVI, or otherwise suitably introduced into the pores within the porous carbon particles, the pore sizes of which are 5 to 1000 nm, for example 10 to 500 nm, 10 to 200 nm, 10 to 100 nm, 33 to 150 nm, or 20 to 100 nm. Other ranges of carbon pore sizes with respect to fractional pore volumes are also envisioned, whether micropores, mesopores, or macropores.

[0091] In some embodiments, the pore volume distribution of the carbon scaffold can be described as the number or volume distribution of pores as known in the art based on gas adsorption analysis (e.g., nitrogen adsorption analysis). In some embodiments, the pore size distribution can be represented by the pore size at or below a certain percentage of the total pore volume. For example, 10% of the pores at or below a certain size can be represented as DPv10.

[0092] The DPv10 of the porous carbon scaffold can vary, for example, DPv10 can be 0.01nm to 100nm, for example 0.1nm to 100nm, for example 1nm to 100nm, for example 1nm to 50nm, for example 1nm to 40nm, for example 1nm to 30nm, for example 1nm to 10nm, for example 1nm to 5nm.

[0093] The DPv50 of the porous carbon scaffold can vary; for example, DPv50 can be from 0.01 nm to 100 nm, such as 0.1 nm to 100 nm, 1 nm to 100 nm, 1 nm to 50 nm, 1 nm to 40 nm, 1 nm to 30 nm, 1 nm to 10 nm, or 1 nm to 5 nm. In other embodiments, DPv50 is 2 to 100, such as 2 to 50, 2 to 30, 2 to 20, 2 to 15, or 2 to 10.

[0094] The DPv90 of the porous carbon scaffold can vary; for example, DPv90 can be 0.01 nm to 100 nm, such as 0.1 nm to 100 nm, 1 nm to 100 nm, 1 nm to 50 nm, 1 nm to 50 nm, 1 nm to 40 nm, 1 nm to 30 nm, 1 nm to 10 nm, or 1 nm to 5 nm. In other embodiments, DPv50 is 2 nm to 100 nm, such as 2 nm to 50 nm, 2 nm to 30 nm, 2 nm to 20 nm, 2 nm to 15 nm, or 2 nm to 10 nm.

[0095] In some implementations, DPv90 is less than 100nm, for example less than 50nm, for example less than 40nm, for example less than 30nm, for example less than 20nm, for example less than 15nm, for example less than 10nm. In some embodiments, the carbon scaffold comprises a pore volume greater than 70% of the micropores (and DPv90 is less than 100 nm, for example, DPv90 less than 50 nm, DPv90 less than 40 nm, DPv90 less than 30 nm, DPv90 less than 20 nm, DPv90 less than 15 nm, DPv90 less than 10 nm, DPv90 less than 5 nm, DPv90 less than 4 nm, or DPv90 less than 3 nm). In other embodiments, the carbon scaffold comprises a pore volume greater than 80% of the micropores and DPv90 is less than 100 nm, for example, DPv90 less than 50 nm, DPv90 less than 40 nm, DPv90 less than 30 nm, DPv90 less than 20 nm, DPv90 less than 15 nm, DPv90 less than 10 nm, DPv90 less than 5 nm, DPv90 less than 4 nm, or DPv90 less than 3 nm.

[0096] The DPv99 of the porous carbon scaffold can vary; for example, DPv99 can be 0.01 nm to 1000 nm, such as 0.1 nm to 1000 nm, such as 1 nm to 500 nm, such as 1 nm to 200 nm, such as 1 nm to 150 nm, such as 1 nm to 100 nm, such as 1 nm to 50 nm, such as 1 nm to 20 nm. In other embodiments, DPv99 is 2 nm to 500 nm, such as 2 nm to 200 nm, such as 2 nm to 150 nm, such as 2 nm to 100 nm, such as 2 nm to 50 nm, such as 2 nm to 20 nm, such as 2 nm to 15 nm, such as 2 nm to 10 nm.

[0097] The embodiments of the composites with extremely durable lithium intercalation disclosed herein improve the properties of any number of energy storage devices (e.g., lithium-ion batteries). In some embodiments, the silicon-carbon composites disclosed herein exhibit a Z value less than 10, such as less than 5, less than 4, less than 3, less than 2, less than 1, less than 0.1, less than 0.01, or less than 0.001. In some embodiments, Z is 0.

[0098] In some preferred embodiments, the silicon-carbon composite comprises a desired low Z-value and a combination with another desired physicochemical and / or electrochemical property, or a combination with more than one other desired physicochemical and / or electrochemical property. Table 1 provides a description of certain embodiments of the combination of properties of the silicon-carbon composite (including reversible capacity). Surface area can be determined as known in the art, for example by nitrogen adsorption analysis. Silicon content can be determined as known in the art, for example by TGA. Property Z can be determined by TGA according to this disclosure. First cycle efficiency can be determined as known in the art, for example, based on the first cycle charge and discharge capacity in a full cell or half cell. For example, the first cycle efficiency can be determined in a half cell for a voltage window of 5 mV to 0.8 V, or alternatively, 5 mV to 1.5 V. Reversible capacity can be described as maximum reversible capacity or maximum capacity and can be determined as known in the art, for example, in a half cell for a voltage window of 5 mV to 0.8 V, or alternatively, 5 mV to 1.5 V.

[0099] Table 1. Implementation schemes of silicon-carbon composites with realized properties.

[0100]

[0101] According to Table 1, silicon-carbon composites may contain...

[0102] Combinations of various properties. For example, silicon-carbon composites can contain Z values ​​less than 10 and m values ​​less than 100. 2 A surface area of ​​ / g, a first-cycle efficiency greater than 80%, and a reversible capacity of at least 1300 mAh / g. For example, silicon-carbon composites can contain less than 10 Z and less than 100 m. 2 A surface area of ​​ / g, a first-cycle efficiency greater than 80%, and a reversible capacity of at least 1600 mAh / g. For example, silicon-carbon composites can contain less than 10 Z and less than 20 m. 2 A surface area of ​​ / g, a first-cycle efficiency greater than 85%, and a reversible capacity of at least 1600 mAh / g. For example, silicon-carbon composites can contain less than 10 Z and less than 10 m. 2 A surface area of ​​ / g, a first-cycle efficiency greater than 85%, and a reversible capacity of at least 1600 mAh / g. For example, silicon-carbon composites can contain less than 10 Z and less than 10 m. 2 A surface area of ​​ / g, a first-cycle efficiency greater than 90%, and a reversible capacity of at least 1600 mAh / g. For example, silicon-carbon composites can contain less than 10 Z and less than 10 m. 2 / g surface area, greater than 90% first cycle efficiency and at least 1800mAh / g reversible capacity.

[0103] In addition to including a carbon scaffold with properties also described in this scheme, silicon-carbon composites may also include combinations of the aforementioned properties. Therefore, Table 2 provides descriptions of certain embodiments of combinations of properties in silicon-carbon composites.

[0104] Table 2. Implementation schemes of silicon-carbon composites with realized properties.

[0105]

[0106]

[0107] As used in this article, the percentages of "micropores," "mesopores," and "macropores" refer to the percentages of micropores, mesopores, and macropores in the total pore volume, respectively. For example, a carbon scaffold with 90% micropores is a carbon scaffold in which 90% of the total pore volume of the carbon scaffold is formed by micropores.

[0108] According to Table 2, silicon-carbon composites may contain...

[0109] Combinations of various properties. For example, silicon-carbon composites may include Z values ​​less than 10 and surface areas less than 100 m². 2 / g, first cycle efficiency greater than 80%, reversible capacity of at least 1600mAh / g, silicon content of 15%-85%, and total pore volume of carbon scaffold of 0.2-1.2cm³. 3 / g, wherein the pore volume of the support comprises >80% micropores, <20% mesopores, and <10% macropores. For example, silicon-carbon composites may include a Z of less than 10 and a surface area of ​​less than 20 m². 2 / g, first cycle efficiency greater than 85%, reversible capacity of at least 1600mAh / g, silicon content of 15%-85%, and total pore volume of carbon scaffold of 0.2-1.2cm³. 3 / g, wherein the pore volume of the support comprises >80% micropores, <20% mesopores, and <10% macropores. For example, silicon-carbon composites may include a Z of less than 10 and a surface area of ​​less than 10 m². 2 / g, first cycle efficiency greater than 85%, reversible capacity of at least 1600mAh / g, silicon content of 15%-85%, and total pore volume of carbon scaffold of 0.2-1.2cm³. 3 / g, wherein the pore volume of the support comprises >80% micropores, <20% mesopores, and <10% macropores. For example, silicon-carbon composites may include a Z of less than 10 and a surface area of ​​less than 10 m². 2 / g, first cycle efficiency greater than 90%, reversible capacity of at least 1600mAh / g, silicon content of 15%-85%, and total pore volume of carbon scaffold of 0.2-1.2cm³. 3 / g, wherein the pore volume of the support comprises >80% micropores, <20% mesopores, and <10% macropores. For example, silicon-carbon composites may include a Z of less than 10 and a surface area of ​​less than 10 m². 2 / g, first cycle efficiency greater than 90%, reversible capacity of at least 1800mAh / g, silicon content of 15%-85%, and total pore volume of carbon scaffold of 0.2-1.2cm³. 3 / g, wherein the pore volume of the support comprises >80% micropores, <20% mesopores and <10% macropores.

[0110] Also according to Table 2, silicon-carbon composites can contain carbon scaffolds with >80% microporosity, 30-60% silicon content, >0.9969 average coulombic efficiency, and Z<10. For example, silicon-carbon composites can contain carbon scaffolds with >80% microporosity, 30-60% silicon content, >0.9970 average coulombic efficiency, and Z<10. For example, silicon-carbon composites can contain carbon scaffolds with >80% microporosity, 30-60% silicon content, >0.9975 average coulombic efficiency, and Z<10. For example, silicon-carbon composites can contain carbon scaffolds with >80% microporosity, 30-60% silicon content, >0.9980 average coulombic efficiency, and Z<10. For example, silicon-carbon composites can contain carbon scaffolds with >80% microporosity, 30-60% silicon content, >0.9985 average coulombic efficiency, and Z<10. For example, a silicon-carbon composite may comprise a carbon scaffold having >80% micropores, 30-60% silicon content, >0.9990 average coulombic efficiency, and Z<10. For example, a silicon-carbon composite may comprise a carbon scaffold having >80% micropores, 30-60% silicon content, >0.9995 average coulombic efficiency, and Z<10. For example, a silicon-carbon composite may comprise a carbon scaffold having >80% micropores, 30-60% silicon content, >0.9970 average coulombic efficiency, and Z<10. For example, a silicon-carbon composite may comprise a carbon scaffold having >80% micropores, 30-60% silicon content, >0.9999 average coulombic efficiency, and Z<10.

[0111] Without being bound by theory, the silicon filling within the pores of porous carbon traps the pores within the porous carbon scaffold particles, creating inaccessible volumes, such as those inaccessible to nitrogen. Therefore, silicon-carbon composites can exhibit a specific gravity density of less than 2.1 g / cm³. 3 For example, less than 2.0 g / cm³ 3 For example, less than 1.9 g / cm³ 3 For example, less than 1.8 g / cm³ 3 For example, less than 1.7 g / cm³ 3 For example, less than 1.6 g / cm³ 3For example, less than 1.4 g / cm³ 3 For example, less than 1.2 g / cm³ 3 For example, less than 1.0 g / cm³ 3 .

[0112] In some implementations, the specific gravity density exhibited by the silicon-carbon composite material can range from 1.7 g·cm³ to 2.1 g / cm³. 3 For example, 1.7 g / cm³ to 1.8 g / cm³. 3 1.8 g / cm³ to 1.9 g / cm³ 3 For example, 1.9 g / cm³ to 2.0 g / cm³. 3 For example, 2.0 g / cm³ to 2.1 g / cm³ 3 In some implementations, the specific gravity density exhibited by the silicon-carbon composite material can range from 1.8 g / cm³ to 2.1 g / cm³. 3 In some implementations, the specific gravity density exhibited by the silicon-carbon composite material can range from 1.8 g / cm³ to 2.0 g / cm³. 3 In some implementations, the specific gravity density exhibited by the silicon-carbon composite material can range from 1.9 g / cm³ to 2.1 g / cm³. 3 .

[0113] The pore volume of lithium-intercalated composite materials exhibiting extremely high durability can be as low as 0.01 cm³. 3 / g to 0.2cm 3 / g. In some embodiments, the pore volume of the composite material can be 0.01 cm³. 3 / g to 0.15cm 3 / g, for example, 0.01cm 3 / g to 0.1cm 3 / g, for example 0.01cm 3 / g to 0.05cm2 / g.

[0114] The particle size distribution of lithium-intercalated composites exhibiting extreme durability is important for determining both power performance and volumetric capacity. Volumetric capacity can increase with improved packing. In one embodiment, this distribution is a Gaussian distribution with a single-peak, bimodal, or multimodal (>2 distinct peaks, e.g., trimodal) shape. The particle size properties of the composite can be described by D0 (smallest particle in the distribution), Dv50 (average particle size), and Dv100 (largest particle size). The optimal combination of particle packing and performance will be a combination of some of the following size ranges. Particle size reduction in such embodiments can be performed as is known in the art, for example by jet milling in the presence of various gases, including air, nitrogen, argon, helium, supercritical vapor, and other gases known in the art.

[0115] In one embodiment, the Dv0 of the composite material can be from 1 nm to 5 micrometers. In another embodiment, the Dv0 of the composite material is from 5 nm to 1 micrometer, for example, 5-500 nm, 5-100 nm, or 10-50 nm. In yet another embodiment, the Dv0 of the composite material is from 500 nm to 2 micrometers, 750 nm to 1 μm, or 1-2 μm. In other embodiments, the Dv0 of the composite material is 2-5 μm or >5 μm.

[0116] In one embodiment, the Dv1 of the composite material can be from 1 nm to 5 μm. In another embodiment, the Dv1 of the composite material is from 5 nm to 1 μm, for example, 5-500 nm, 5-100 nm, or 10-50 nm. In yet another embodiment, the Dv1 of the composite material is from 100 nm to 10 μm, 200 nm to 5 μm, 500 nm to 2 μm, or 750 nm to 1 μm, or 1-2 μm. In other embodiments, the Dv1 of the composite material is 2-5 μm, or >5 μm.

[0117] In one embodiment, the Dv10 of the composite material can be from 1 nm to 10 micrometers. In another embodiment, the Dv10 of the composite material is from 5 nm to 1 micrometer, for example, 5-500 nm, 5-100 nm, or 10-50 nm. In yet another embodiment, the Dv10 of the composite material is from 100 nm to 10 micrometers, 500 nm to 10 micrometers, 500 nm to 5 micrometers, or 750 nm to 1 μm, or 1-2 μm. In other embodiments, the Dv10 of the composite material is 2-5 μm, or >5 μm.

[0118] In some embodiments, the composite material has a Dv50 of 5 nm to 20 μm. In other embodiments, the composite material has a Dv50 of 5 nm to 1 μm, for example, 5-500 nm, 5-100 nm, or 10-50 nm. In other embodiments, the composite material has a Dv50 of 500 nm to 2 μm, 750 nm to 1 μm, or 1-2 μm. In still other embodiments, the composite material has a Dv50 of 1 to 1000 μm, for example, 1-100 μm, 1-10 μm, 2-20 μm, 3-15 μm, or 4-8 μm. In some embodiments, Dv50 > 20 μm, for example, > 50 μm or > 100 μm.

[0119] The span (Dv50) / (Dv90-Dv10) (where Dv10, Dv50, and Dv90 represent the particle size at 10%, 50%, and 90% of the volumetric distribution) can vary, for example, from 100 to 10, from 10 to 5, from 5 to 2, and from 2 to 1; in some embodiments, the span can be less than 1. In some embodiments, the composite comprising the particle size distribution of carbon and porous silicon materials can be multimodal, such as bimodal or trimodal.

[0120] The surface functionality of the composite materials disclosed in this invention, exhibiting extremely durable lithium intercalation, can be modified to obtain the desired electrochemical properties. One property that can predict surface functionality is the pH of the composite material. The composite materials disclosed in this invention contain pH values ​​from less than 1 to about 14, for example, less than 5, 5 to 8, or greater than 8. In some embodiments, the pH of the composite material is less than 4, less than 3, less than 2, or even less than 1. In other embodiments, the pH of the composite material is about 5 to 6, about 6 to 7, about 7 to 8, or 8 to 9, or 9 to 10. In other embodiments, the pH is high and the pH range of the composite material is greater than 8, greater than 9, greater than 10, greater than 11, greater than 12, or even greater than 13.

[0121] The silicon-carbon composite material may contain varying amounts of carbon, oxygen, hydrogen, and nitrogen as measured by gas chromatography-CHNO analysis. In one embodiment, the composite has a carbon content greater than 98 wt.% or even greater than 99.9 wt%, as measured by CHNO analysis. In another embodiment, the carbon content of the silicon-carbon composite is about 10-90%, for example 20-80%, for example 30-70%, for example 40-60%.

[0122] In some embodiments, the nitrogen content of the silicon-carbon composite material is 0-90%, for example 0.1-1%, for example 1-3%, for example 1-5%, for example 1-10%, for example 10-20%, for example 20-30%, for example 30-90%.

[0123] In some embodiments, the oxygen content is 0-90%, for example 0.1-1%, for example 1-3%, for example 1-5%, for example 1-10%, for example 10-20%, for example 20-30%, for example 30-90%.

[0124] Silicon-carbon composites can also be incorporated with electrochemical modifiers, selected to optimize the electrochemical properties of the unmodified composite. The electrochemical modifiers can be incorporated within the pore structure and / or surface of the porous carbon scaffold, within embedded silicon, or within the final carbon layer, or within the conductive polymer, within a coating, or in any other manner. For example, in some embodiments, the composite includes a coating of an electrochemical modifier (e.g., silicon or Al₂O₃) on the surface of the carbon material. In some embodiments, the composite contains more than about 100 ppm of the electrochemical modifier. In some embodiments, the electrochemical modifier is selected from iron, tin, silicon, nickel, aluminum, and manganese.

[0125] In some embodiments, the electrochemical modifier comprises an element (e.g., silicon, tin, sulfur) capable of lithiation at 3 to 0 V relative to lithium metal. In other embodiments, the electrochemical modifier comprises a metal oxide (e.g., iron oxide, molybdenum oxide, titanium oxide) capable of lithiation at 3 to 0 V relative to lithium metal. In other embodiments, the electrochemical modifier comprises an element that does not lithilate at 3 to 0 V relative to lithium metal (e.g., aluminum, manganese, nickel, metal phosphates). In other embodiments, the electrochemical modifier comprises a nonmetallic element (e.g., fluorine, nitrogen, hydrogen, boron, phosphorus). In other embodiments, the electrochemical modifier comprises any one or any combination of the aforementioned electrochemical modifiers (e.g., tin-silicon, nickel-titanium oxide).

[0126] Electrochemical modifiers can be provided in various forms. For example, in some embodiments, the electrochemical modifier comprises a salt. In other embodiments, the electrochemical modifier comprises one or more elements in elemental form, such as elemental iron, tin, silicon, nickel, or manganese. In other embodiments, the electrochemical modifier comprises one or more elements in oxidized form, such as iron oxide, tin oxide, silicon oxide, nickel oxide, aluminum oxide, or manganese oxide.

[0127] The electrochemical properties of a composite material can be modified, at least in part, by the amount of an electrochemical modifier in the material, wherein the electrochemical modifier is an alloying material, such as silicon, tin, indium, aluminum, germanium, or gallium. Therefore, in some embodiments, the composite material contains at least 0.10%, at least 0.25%, at least 0.50%, at least 1.0%, at least 5.0%, at least 10%, at least 25%, at least 50%, at least 75%, at least 90%, at least 95%, at least 99%, or at least 99.5% of the electrochemical modifier.

[0128] Compared to the non-lithiated state, the particle size of the composite material can expand during lithiation. For example, the expansion factor is defined as the ratio of the average particle size of the composite material containing porous silicon material during lithiation to the average particle size under non-lithiation conditions. As described in the art, this expansion factor can be relatively large for previously known suboptimal silicon-containing materials, for example, about 4X (corresponding to 400% volume expansion during lithiation). The inventors have discovered that composite materials containing porous silicon material can exhibit a lower degree of expansion, for example, the expansion factor can vary from 3.5 to 4, 3.0 to 3.5, 2.5 to 3.0, 2.0 to 2.5, 1.5 to 2.0, and 1.0 to 1.5.

[0129] It is conceivable that, in some embodiments, the composite material will contain a portion of the pore volume, i.e., the volume of voids inaccessible to nitrogen as detected by nitrogen adsorption measurements. Without being bound by theory, this pore volume is important because it provides the volume into which silicon can expand during lithiation.

[0130] In some embodiments, the ratio of the void volume to the silicon volume constituting the composite particles is from 0.1:1 to 10:1. For example, the ratio is from 1:1 to 5:1 or from 5:1 to 10:1. In some embodiments, to effectively accommodate the maximum expansion of silicon during lithiation, the ratio is from 2:1 to 5:1, or about 3:1.

[0131] In some embodiments, the electrochemical performance of the disclosed composites is tested in a half-cell; alternatively, the performance of the disclosed composites with extremely durable lithium intercalation is tested in a full cell (e.g., a full-cell button cell, a full-cell pouch cell, a prismatic cell, or other battery structures known in the art). As known in the art, anode compositions comprising the disclosed composites with extremely durable lithium intercalation may further comprise a variety of substances. Additional formulation components include, but are not limited to, conductive additives such as conductive carbon (e.g., Super C45, Super P, Ketjenblack carbon, etc.), conductive polymers, etc., binders such as styrene-butadiene rubber sodium carboxymethyl cellulose (SBR-Na-CMC), polyvinylidene fluoride (PVDF), polyimide (PI), polyacrylic acid (PAA), polyacrylonitrile (PAN), polyamide-imide (PAI), etc., and combinations thereof. In some embodiments, the binder may contain lithium ions as counterions.

[0132] Other substances constituting the electrode are known in the art. The percentage of active material in the electrode by weight can vary, for example, 1 to 5%, for example, 5 to 15%, for example, 15 to 25%, for example, 25 to 35%, for example, 35 to 45%, for example, 45 to 55%, for example, 55 to 65%, for example, 65 to 75%, for example, 75 to 85%, for example, 85 to 95%. In some embodiments, the active material constitutes 80 to 95% of the electrode. In some embodiments, the amount of conductive additive in the electrode can vary, for example, 1 to 5%, 5 to 15%, for example, 15 to 25%, for example, 25 to 35%. In some embodiments, the amount of active material in the electrode is 5 to 25%. In some embodiments, the amount of binder can vary, for example, 1 to 5%, 5 to 15%, for example, 15 to 25%, for example, 25 to 35%. In some embodiments, the amount of conductive additive in the electrode is 5 to 25%.

[0133] As is known in the art, silicon-carbon composite materials can be pre-lithiated. In some embodiments, pre-lithiation is electrochemically achieved, for example, in a half-cell, before assembling a lithium-ion anode containing porous silicon material into a full-cell lithium-ion battery. In some embodiments, pre-lithiation is achieved by doping a cathode with a lithium-containing compound, such as a lithium salt. Examples of suitable lithium salts herein include, but are not limited to, lithium(II) tetrabromonickel oxide, lithium(II) tetrachlorocopper oxide, lithium azide, lithium benzoate, lithium bromide, lithium carbonate, lithium chloride, lithium cyclohexanebutyrate, lithium fluoride, lithium formate, lithium hexafluoroarsenic(V) oxide, lithium hexafluorophosphate, lithium hydroxide, lithium iodate, lithium iodide, lithium metaborate, lithium perchlorate, lithium phosphate, lithium sulfate, lithium tetraborate, lithium tetrachloroaluminate, lithium tetrafluoroborate, lithium thiocyanate, lithium trifluoromethanesulfonate, lithium trifluoromethanesulfonate, and combinations thereof.

[0134] Anodes incorporating silicon-carbon composite materials can be paired with a variety of 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) and LiNi. 0.8 Co 0.15 Al 0.05 O2(NCA), LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (NMC), LiMn2O4 and its variants (LMO), and LiFePO4 (LFP).

[0135] For full-cell lithium-ion batteries that include an anode also comprising a silicon-carbon composite material, the cathode-anode pairing can be varied. For example, the cathode-to-anode capacity ratio can be varied from 0.7 to 1.3. In some embodiments, the cathode-to-anode capacity ratio can be varied from 0.7 to 1.0, such as 0.8 to 1.0, 0.85 to 1.0, 0.9 to 1.0, or 0.95 to 1.0. In other embodiments, the cathode-to-anode capacity ratio can be varied from 1.0 to 1.3, such as 1.0 to 1.2, 1.0 to 1.15, 1.0 to 1.1, or 1.0 to 1.05. In other embodiments, the cathode-to-anode capacity ratio can be varied from 0.8 to 1.2, such as 0.9 to 1.1 or 0.95 to 1.05.

[0136] For full-cell lithium-ion batteries, including anodes that also contain silicon-carbon composite materials, the voltage windows for charging and discharging can be varied. In this respect, the voltage window can be varied as is known in the art, depending on various properties of the lithium-ion battery. For example, the choice of cathode plays a role in the selected voltage window, as is known in the art. Examples of voltage windows, for example, vary from 2.0V to 5.0V, such as 2.5V to 4.5V, or 2.5V to 4.2V, depending on the potential variation relative to Li / Li+.

[0137] For a full-cell lithium-ion battery that also includes an anode comprising a silicon-carbon composite material, the battery conditioning strategy can vary as is known in the art. For example, conditioning can be accomplished by one or more charge and discharge cycles at various rates (e.g., at rates slower than the desired cycle rate). As is known in the art, the conditioning process can also include the steps of unsealing the lithium-ion battery, evacuating any gases generated therein during the conditioning process, and then resealing the lithium-ion battery.

[0138] For a full-cell lithium-ion battery including an anode that also comprises a silicon-carbon composite material, the cycle rate can vary as known in the art, for example, it can be C / 20 to 20C, such as C10 to 10C, such as C / 5 to 5C. In some embodiments, the cycle rate is C / 10. In some embodiments, the cycle rate is C / 5. In some embodiments, the cycle rate is C / 2. In some embodiments, the cycle rate is 1C. In some embodiments, the cycle rate is 1C, wherein the rate is periodically reduced to a slower rate, such as cycling at 1C, wherein every 20th cycle uses a C / 10 rate. In some embodiments, the cycle rate is 2C. In some embodiments, the cycle rate is 4C. In some embodiments, the cycle rate is 5C. In some embodiments, the cycle rate is 10C. In some embodiments, the cycle rate is 20C.

[0139] The first cycle efficiency of the lithium-intercalated composite disclosed herein is determined by comparing the lithium intercalated into the anode during the first cycle with the lithium deintercalated from the anode during the first cycle (before pre-lithiation modification). The efficiency is 100% when intercalation and deintercalation are equal. As is known in the art, the anode material can be tested in a half-cell where the counter electrode is lithium metal, the electrolyte is 1M LiPF6 1:1 ethylene carbonate:diethyl carbonate (EC:DEC), and a commercially available polypropylene separator is used. In some embodiments, the electrolyte may contain various additives known to provide improved performance, such as fluoroethylene carbonate (FEC) or other related fluorinated carbonate compounds, or ester cosolvents such as methyl butyrate, vinylene carbonate, and other electrolyte additives known to improve the electrochemical performance of silicon-containing anode materials. In some embodiments, the first cycle efficiency in 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 a half-cell can be determined within a voltage window of 5mV to 1.5V. In another embodiment, the first cycle efficiency in a half-cell can be determined within a voltage window of 5mV to 2.0V. In other embodiments, the first cycle efficiency is determined in a full cell, for example, within a voltage window of 2.0V to 4.5V, or 2.3V to 4.5V, or 2.5V to 4.2V, or 3.0V to 4.2V.

[0140] Coulombic efficiency can be averaged, for example, by averaging from cycle 7 to cycle 25 when tested in a half-cell. In some embodiments, the average efficiency of the complex with extremely durable lithium intercalation is greater than 0.9 or 90%. In some embodiments, the average efficiency is greater than 0.95 or 95%. In some other embodiments, the average efficiency is 0.99 or greater, such as 0.991 or greater, such as 0.992 or greater, such as 0.993 or greater, such as 0.994 or greater, such as 0.995 or greater, such as 0.996 or greater, such as 0.997 or greater, such as 0.998 or greater, such as 0.999 or greater, such as 0.9991 or greater, such as 0.9992 or greater, such as 0.9993 or greater, such as 0.9994 or greater, such as 0.9995 or greater, such as 0.9996 or greater, such as 0.9997 or greater, such as 0.9998 or greater, such as 0.9999 or greater.

[0141] In other embodiments, this disclosure provides a composite material exhibiting extremely durable lithium intercalation, wherein when the composite material is incorporated into the electrode of a lithium-based energy storage device, the volumetric capacity of the composite material is at least 10% greater than that of a lithium-based energy storage device including a graphite electrode. In some embodiments, the lithium-based energy storage device is a lithium-ion battery. In other embodiments, the volumetric capacity of the composite material in the lithium-based energy storage device is at least 5%, at least 10%, or at least 15% greater than the volumetric capacity of the same energy storage device having a graphite electrode. In other embodiments, the volumetric capacity of the composite material in the lithium-based energy storage device is at least 20%, at least 30%, at least 40%, at least 50%, at least 200%, at least 100%, at least 150%, or at least 200% greater than the volumetric capacity of the same energy storage device having a graphite electrode.

[0142] As is known in the art, the composite material can be pre-lithiated. These lithium atoms may or may not be separated from the carbon. The number of lithium atoms relative to six carbon atoms can be calculated using techniques known to those skilled in the art:

[0143] #Li=Q x 3.6x MM / (C%x F)

[0144] Where Q is the lithium intercalation / deintercalation capacity relative to lithium metal at voltages between 5 mV and 2.0 V, measured in mAh / g; MM is the molecular weight of 72 or 6 carbons; F is the Faraday constant of 96,500; and C% is the mass percentage of carbon present in the structure as measured by CHNO or XPS.

[0145] The composite material can be characterized by a lithium to carbon atom ratio (Li:C), which can vary from about 0:6 to 2:6. In some embodiments, the Li:C ratio is from about 0.05:6 to about 1.9:6. In other embodiments, the maximum Li:C ratio in which lithium is in ionic rather than metallic form is 2.2:6. In some other embodiments, the Li:C ratio is from about 1.2:6 to about 2:6, from about 1.3:6 to about 1.9:6, from about 1.4:6 to about 1.9:6, from about 1.6:6 to about 1.8:6, or from about 1.7:6 to about 1.8:6. In other embodiments, the Li:C ratio is greater than 1:6, greater than 1.2:6, greater than 1.4:6, greater than 1.6:6, or even greater than 1.8:6. In even other embodiments, the Li:C ratio is about 1.4:6, about 1.5:6, about 1.6:6, about 1.6:6, about 1.7:6, about 1.8:6, or about 2:6. In a specific embodiment, the Li:C ratio is about 1.78:6.

[0146] In some other embodiments, the Li:C ratio of the composite material is about 1:6 to about 2.5:6, about 1.4:6 to about 2.2:6, or about 1.4:6 to about 2:6. In other embodiments, the composite material may not necessarily contain lithium, but rather possess lithium absorption capacity (i.e., the ability to absorb a certain amount of lithium), for example, when cycling the material between two voltage conditions (in the case of a lithium-ion half-cell, exemplary voltage windows are located between 0 and 3V, such as 0.005 to 2.7V, such as 0.005 to 1V, such as 0.005 to 0.8V). While not wishing to be bound by theory, it is believed that the lithium absorption capacity of composite materials contributes to their excellent performance in lithium-based energy storage devices. Lithium absorption capacity is expressed as the ratio of lithium atoms absorbed by the composite material. In some other embodiments, the lithium absorption capacity of the composite material exhibiting extremely durable lithium intercalation is about 1:6 to about 2.5:6, about 1.4:6 to about 2.2:6, or about 1.4:6 to about 2:6.

[0147] In some other embodiments, the lithium absorption capacity is about 1.2:6 to about 2:6, about 1.3:6 to about 1.9:6, about 1.4:6 to about 1.9:6, about 1.6:6 to about 1.8:6, or about 1.7:6 to about 1.8:6. In other embodiments, the lithium absorption capacity is greater than 1:6, greater than 1.2:6, greater than 1.4:6, greater than 1.6:6, or even greater than 1.8:6. In even other embodiments, the Li:C ratio is about 1.4:6, about 1.5:6, about 1.6:6, about 1.6:6, about 1.7:6, about 1.8:6, or about 2:6. In a specific embodiment, the Li:C ratio is about 1.78:6.

[0148] Example

[0149] Example 1. Preparation of silicon-carbon composite material by CVI. The properties of the carbon scaffold (carbon scaffold 1) used to prepare the silicon-carbon composite are shown in Table 3. Using carbon scaffold 1, the silicon-carbon composite (silicon-carbon composite 1) was prepared by CVI as follows: 0.2 g of amorphous porous carbon was placed in a 2 inch × 2 inch ceramic crucible and then placed in the center of a horizontal tube furnace. The furnace was sealed and continuously purged with nitrogen at 500 cubic centimeters per minute (ccm). The furnace temperature was increased to a peak temperature of 450 °C at 20 °C / min and allowed to equilibrate at this peak temperature for 30 minutes. At this point, the nitrogen was turned off, and silane and hydrogen were introduced at flow rates of 50 ccm and 450 ccm, respectively, for a total residence time of 30 minutes. After this residence time, the silane and hydrogen were turned off, and nitrogen was introduced into the furnace again to purge the internal atmosphere. Simultaneously, the furnace heat was turned off and allowed to cool to ambient temperature. The completed Si-C material was then removed from the furnace.

[0150] Table 3. Description of the carbon support used in Example 1.

[0151]

[0152] Example 2. Analysis of various silicon composite materials. Various carbon scaffold materials were used, and the carbon scaffold materials were characterized by nitrogen adsorption gas analysis to determine specific surface area, total pore volume, and the fraction of pore volume including micropores, mesopores, and macropores. The characterization data of the carbon scaffold materials are shown in Table 4, namely, the data on carbon scaffold surface area, pore volume, and pore volume distribution (% micropores, % mesopores, and % macropores), all determined by nitrogen adsorption analysis.

[0153] Table 4. Properties of various carbon support materials.

[0154]

[0155] Various silicon-carbon composites were prepared using the CVI method with carbon scaffold samples as described in Table 4 and in a static bed configuration as generally described in Example 1. These silicon-carbon samples were prepared using a range of process conditions: silane concentrations from 1.25% to 100%, dilution gases of nitrogen or hydrogen, and starting carbon scaffold masses from 0.2 g to 700 g.

[0156] The surface area of ​​the silicon-carbon composite was determined. The silicon-carbon composite was also analyzed by TGA to determine the silicon content and Z. The silicon-carbon composite was also tested in a half-cell coin cell. The anode of the half-cell coin cell may comprise 60-90% silicon-carbon composite, 5-20% Na-CMC (as a binder), and 5-20% Super C45 (as a conductivity enhancer), and the electrolyte may comprise a 2:1 ratio of ethylene carbonate:diethyl carbonate, 1M LiPF6, and 10% fluoroethylene carbonate. The half-cell coin cell can be cycled for 5 cycles at C / 5 at 25°C, followed by cycling at C / 10. The voltage can be cycled between 0V and 0.8V, or alternatively, between 0V and 1.5V. Based on the half-cell coin cell data, the maximum capacity and the average coulombic efficiency (CE) over a cycle range of 7 to 20 cycles can be measured. The physicochemical and electrochemical properties of various silicon-carbon composites are shown in Table 5.

[0157] Table 5. Properties of various silicon-carbon composite materials.

[0158]

[0159]

[0160] The graph of the average Coulomb efficiency as a function of Z is shown in... Figure 1As can be seen, the average coulombic efficiency increases significantly for silicon-carbon samples with low Z. Specifically, all silicon-carbon samples with Z below 10.0 exhibit an average coulombic efficiency >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 <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. Further tests in the table reveal a surprising and unexpected finding: the combination of silicon-carbon composite samples with Z <10 and a carbon scaffold containing >70 micropores provides an average coulombic efficiency >0.9950.

[0161] Therefore, in a preferred embodiment, the silicon-carbon composite material contains less than 10 Z, for example less than 5 Z, for example less than 3 Z, for example less than 2 Z, for example less than 1 Z, for example less than 0.5 Z, for example less than 0.1 Z, or 0 Z.

[0162] In some preferred embodiments, the silicon-carbon composite material comprises a carbon scaffold with 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... Z and >95% micropores, e.g., less than 1 Z and >70% micropores, e.g., less than 1 Z and >80% micropores, e.g., less than 1 Z and >90% micropores, e.g., less than 1 Z and >95% micropores, e.g., less than 0.5 Z and >70% micropores, e.g., less than 0.5 Z and >80% micropores, e.g., less than 0.5 Z and >90% micropores, e.g., less than 0.5 Z and >95% micropores, e.g., less than 0.1 Z and >70% micropores, e.g., less than 0.1 Z and >80% micropores, e.g., less than 0.1 Z and >90% micropores, e.g., less than 0.1 Z and >95% micropores, e.g., 0 Z and >70% micropores, e.g., 0 Z and >80% micropores, e.g., 0 Z and >90% micropores, e.g., 0 Z and >95% micropores.

[0163] In some preferred embodiments, the silicon-carbon composite comprises a carbon scaffold with a Z-axis of less than 10 and >70% micropores, and wherein the silicon-carbon composite further comprises 15%-85% silicon and has a surface area of ​​less than 100 m².2 / g; for example, less than 10 Z and >70% micropores, wherein the silicon-carbon composite also contains 15%-85% silicon and has a surface area of ​​less than 50 m². 2 / g; for example, less than 10 Z and >70% micropores, wherein the silicon-carbon composite also contains 15%-85% silicon and has a surface area of ​​less than 30m². 2 / g; for example, less than 10 Z and >70% micropores, wherein the silicon-carbon composite also contains 15%-85% silicon and has a surface area of ​​less than 10 m². 2 / g; for example, less than 10 Z and >70% micropores, wherein the silicon-carbon composite also contains 15%-85% silicon and has a surface area of ​​less than 5m². 2 / g; for example, less than 10 Z and >80% micropores, wherein the silicon-carbon composite also contains 15%-85% silicon and has a surface area of ​​less than 50 m². 2 / g; for example, less than 10 Z and >80% micropores, wherein the silicon-carbon composite also contains 15%-85% silicon and has a surface area of ​​less than 30m². 2 / g; for example, less than 10 Z and >80% micropores, wherein the silicon-carbon composite also contains 15%-85% silicon and has a surface area of ​​less than 10 m². 2 / g; for example, less than 10 Z and >80% micropores, wherein the silicon-carbon composite also contains 15%-85% silicon and has a surface area of ​​less than 5m². 2 / g; for example, less than 10 Z and >90% micropores, wherein the silicon-carbon composite also contains 15%-85% silicon and has a surface area of ​​less than 50 m². 2 / g; for example, Z < 10 and > 90% micropores, wherein the silicon-carbon composite also contains 15%–85% silicon and has a surface area of ​​less than 30 m². 2 / g; for example, Z less than 10 and >90% micropores, wherein the silicon-carbon composite also contains 15%-85% silicon and has a surface area of ​​less than 10 m². 2 / g; for example, less than 10 Z and >90% micropores, wherein the silicon-carbon composite also contains 15%-85% silicon and has a surface area of ​​less than 5m². 2 / g; for example, less than 10 Z and >95% micropores, wherein the silicon-carbon composite also contains 15%-85% silicon and has a surface area of ​​less than 50 m². 2 / g; for example, less than 10 Z and >95% micropores, wherein the silicon-carbon composite also contains 15%-85% silicon and has a surface area of ​​less than 30m². 2 / g; for example, Z less than 10 and >95% micropores, wherein the silicon-carbon composite also contains 15%-85% silicon and has a surface area of ​​less than 10m². 2 / g; for example, Z less than 10 and >95% micropores, wherein the silicon-carbon composite also contains 15%-85% silicon and has a surface area of ​​less than 5m². 2 / g.

[0164] In some preferred embodiments, the silicon-carbon composite material comprises a carbon scaffold with a Z-axis of less than 10 and >70% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 100 m². 2 / g; for example, less than 10 Z and >70% micropores, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 50 m². 2 / g; for example, less than 10 Z and >70% micropores, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30m². 2 / g; for example, less than 10 Z and >70% micropores, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 10 m². 2 / g; for example, less than 10 Z and >70% micropores, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 5m². 2 / g; for example, less than 10 Z and >80% micropores, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 50 m². 2 / g; for example, less than 10 Z and >80% micropores, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30m². 2 / g; for example, less than 10 Z and >80% micropores, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 10 m². 2 / g; for example, less than 10 Z and >80% micropores, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 5m². 2 / g; for example, Z < 10 and > 90% micropores, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 50 m². 2 / g; for example, Z less than 10 and >90% micropores, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30m². 2 / g; for example, Z less than 10 and >90% micropores, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 10 m². 2 / g; for example, Z less than 10 and >90% micropores, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 5m². 2 / g; for example, Z < 10 and > 95% micropores, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 50 m². 2 / g; for example, Z less than 10 and >95% micropores, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30m². 2 / g; for example, Z < 10 and > 95% micropores, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 10 m². 2 / g; for example, Z less than 10 and >95% micropores, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 5m². 2 / g.

[0165] In some preferred embodiments, the silicon-carbon composite material comprises a carbon scaffold with a Z-shape of less than 10 and a micropore content of >80%, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g and an average coulombic efficiency ≥0.9969. For example, silicon-carbon composites contain a Z of less than 10 and a carbon scaffold with >80% micropores, and the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30m². 2 / g and an average coulombic efficiency ≥0.9970. For example, silicon-carbon composites contain a Z of less than 10 and a carbon scaffold with >80% micropores, and the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30m². 2 / g and an average coulombic efficiency ≥0.9975. For example, silicon-carbon composites contain a Z of less than 10 and a carbon scaffold with >80% micropores, and the silicon-carbon composite also contains 30%-60% silicon and a surface area of ​​less than 30m². 2 / g and an average coulombic efficiency ≥0.9980. For example, silicon-carbon composites contain a Z of less than 10 and a carbon scaffold with >80% micropores, and the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30m². 2 / g and an average coulombic efficiency ≥0.9985. For example, silicon-carbon composites contain a Z of less than 10 and a carbon scaffold with >80% micropores, and the silicon-carbon composite also contains 30%-60% silicon and a surface area of ​​less than 30m². 2 / g and an average coulombic efficiency ≥0.9990. For example, silicon-carbon composites contain a Z of less than 10 and a carbon scaffold with >80% micropores, and the silicon-carbon composite also contains 30%-60% silicon and a surface area of ​​less than 30m². 2 / g and an average coulombic efficiency ≥0.9995. For example, silicon-carbon composites contain a Z of less than 10 and a carbon scaffold with >80% micropores, and the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30m².2 / g and average coulombic efficiency ≥0.9999.

[0166] Example 3. dV / dQ of various silicon composite materials. Differential capacity curves (dQ / dV versus voltage) are commonly used as a non-destructive tool to understand phase transitions as a function of voltage in lithium-ion battery electrodes (MNObrovac et al., Structural Changes in Silicon Anodes during Lithium Insertion / Extraction, Electrochemical and Solid-State Letters, 7(5)A93-A96(2004); Ogata, K. et al., Revealing lithium-silicide phase transformations in nano-structured silicon-based lithium ion batteries via in situ NMR spectroscopy. Nat. Commun. 5:3217). As an alternative to plotting dQ / dV versus voltage, a strategy to obtain similar analyses is plotting dQ versus V. For this example, the differential capacity plot (dQ / dV versus voltage) is calculated from data obtained by constant current cycling at 0.1C rate from 5mV to 0.8V in a half-cell coin cell at 25°C.Typical differential capacity curves of silicon-based materials and lithium in half-cells can be found in many references (Loveridge, MJ et al., Towards High Capacity Li-Ion Batteries Based on Silicon-Graphene Composite Anodes and Sub-micron V-doped LiFePO4 Cathodes. Sci. Rep. 6, 37787; doi:10.1038 / srep37787 (2016); MNObrovac et al., Li15Si4 Formation in Silicon Thin Film Negative Electrodes, Journal of The Electrochemical Society, 163(2)A255-A261 (2016); Q. Pan et al., Improved electrochemical performance of micro-sized SiO-based composite anode by prelithiation of stabilized lithium metal powder, Journal of Power Sources 347 (2017)170-177). The first-cycle lithiation behavior depends on factors such as the crystallinity of silicon and oxygen content.

[0167] Following the first cycle, previous amorphous silicon materials in the art exhibited two distinct phase transition peaks in the dQ / dV vs. V plots for lithiation, and correspondingly two distinct phase transition peaks in the dQ / dV vs. V plots for delithiation. For lithiation, one peak corresponding to the lithium-poor Li-Si alloy phase appears between 0.2 and 0.4 V, while another peak corresponding to the lithium-rich Li-Si alloy phase appears below 0.15 V. For delithiation, one delithiation peak corresponding to lithium intercalation appears below 0.4 V, while another peak appears between 0.4 V and 0.55 V. If the Li15Si4 phase forms during lithiation, it delithiates at ~0.45 V and exhibits a very narrow, sharp peak.

[0168] Figure 2Cycle 2 dQ / dV versus voltage curves for the silicon-carbon composite material corresponding to silicon-carbon composite 3 of Example 1 are plotted. Silicon-carbon composite 3 contains a Z of 0.6. For ease of identification, the graph is divided into regions I, II, III, IV, V, and VI. Regions I (0.8V to 0.4V), II (0.4V to 0.15V), and III (0.15V to 0V) constitute the lithiation potential, and regions IV (0V to 0.4V), V (0.4V to 0.55V), and VI (0.55V to 0.8V) include the delithiation potential. As described above, previous amorphous silicon-based materials in the art exhibit phase transition peaks in two regions (regions II and III) of the lithiation potential and two regions (regions IV and V) of the delithiation potential.

[0169] from Figure 2 As can be seen, the dQ / dV voltage curves reveal surprising and unexpected results. The silicon-carbon composite 3 (containing 0.6 Z) exhibits two additional peaks in the dQ / dV voltage curves: region I in the lithiation potential and region VI in the delithiation potential. All six peaks are reversible and were also observed in subsequent cycles, such as... Figure 3 As shown in the image.

[0170] Without being bound by theory, this three-peak behavior of the dQ / dV curve with respect to V is novel and also reflects a novel form of silicon.

[0171] It is noteworthy that the novel peaks observed in regions I and VI are more pronounced in some scaffold matrices, but are not present at all in other samples illustrating the prior art (silicon-carbon composite samples with Z>10, see explanation and table below).

[0172] Figure 4 The dQ / dV versus V curves of silicon-carbon composite 3 are shown, where the new peaks in regions I and VI are evident compared to those of silicon-carbon composites 15, 16, and 14 (all three of which contain Z>10 and whose dQ / dV versus V curves have no peaks in regions I and VI).

[0173] Without being bound by theory, these novel peaks observed in Regions I and VI relate to the properties of silicon impregnated into the porous carbon scaffold, specifically the interactions between and within the properties of the porous carbon scaffold, silicon, and lithium impregnated into the porous carbon scaffold via CVI. To provide quantitative analysis, we define parameters in this paper. Its calculation is the normalized peak I relative to peak III:

[0174]

[0175] In this study, dQ / dV was measured in a half-cell coin cell, with region I being 0.8V–0.4V and region III being 0.15V–0V; the half-cell coin cell was manufactured as is known in the art. If the Si-C sample exhibited a graphite-related peak in region III of the differential curve, this was omitted when calculating the D-factor, and the Li-Si-related phase transition peak was used instead. For this example, the half-cell coin cell included an anode comprising 60–90% silicon-carbon composite, 5–20% SBR-Na-CMC, and 5–20% Super C45. Figure 5 The image shows silicon-carbon composite 3. Example of calculation. In this case, the maximum peak height in region I is -2.39 and is found at a voltage of 0.53V. Similarly, the maximum peak height in region III is -9.71 at 0.04V. In this case, the above formula can be used to calculate... get The data were determined from the half-cell coin cell data of various silicon-carbon composites given in Example 2. The values ​​are summarized in Table 6. Table 6 also includes data on the first cycle efficiency, measured in half-cell coin cells cycling from 5mV to 0.8V.

[0176] Table 6. Properties of various silicon-carbon composite materials.

[0177]

[0178] These data, representing the first cycle efficiency (in parentheses), were measured over a voltage window from 5mV to 1.5V.

[0179] The data in Table 6 reveal the effects of decreasing Z and increasing Z. An unexpected relationship exists between them. All silicon-carbon complexes with Z < 10 possess... Furthermore, all silicon-carbon composites with Z>10 possess In fact, all silicon-carbon composites with Z>10 have This relationship also Figure 6 This has been proven. Without being bound by theory, it contains... For example For example For example For example For example The silicon material corresponds to a new form of silicon. Alternatively, it contains... The silicon material corresponds to a new form of silicon. This includes... For example For example For example For example For example The silicon-carbon composite material corresponds to the new silicon-carbon composite material. Alternatively, it contains... The silicon-carbon composite material corresponds to the novel silicon-carbon composite material.

[0180] In some embodiments, the silicon-carbon composite contains or In some implementation schemes, In some implementation schemes, or

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

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

[0183] In some embodiments, the silicon-carbon composite comprises a carbon scaffold with a Z-axis of less than 10 and a micropore content of >70%, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 100 m². 2 / g, For example, a Z value less than 10 and a micropore content greater than 70%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 50 m². 2 / g, For example, a Z value less than 10 and a micropore content greater than 70%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 30 m². 2 / g, For example, a Z value less than 10 and a micropore content greater than 70%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 10 m². 2 / g, For example, a Z value less than 10 and a micropore content greater than 70%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 5 m². 2 / g,

[0184] In some embodiments, the silicon-carbon composite comprises a carbon scaffold with a Z-axis of less than 10 and >70% micropores, and wherein the silicon-carbon composite further comprises 40%-60% silicon and has a surface area of ​​less than 100 m². 2 / g, For example, a Z value less than 10 and a micropore content greater than 70%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 50 m². 2 / g, For example, a Z value less than 10 and a micropore content greater than 70%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 30 m². 2 / g, For example, a Z value less than 10 and a micropore content greater than 70%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 10 m². 2 / g, For example, a Z value less than 10 and a micropore content greater than 70%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 5 m².2 / g,

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

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

[0187] In some embodiments, the silicon-carbon composite comprises a carbon scaffold with a Z-axis of less than 10 and >80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 100 m².2 / g, For example, a Z value less than 10 and a micropore content greater than 80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 50 m². 2 / g, For example, a Z value less than 10 and a micropore content greater than 80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 30 m². 2 / g, For example, a Z value less than 10 and a micropore content greater than 80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 10 m². 2 / g, For example, a Z value less than 10 and a micropore content greater than 80%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 5 m². 2 / g,

[0188] In some embodiments, the silicon-carbon composite comprises a carbon scaffold with a Z-shape of less than 10 and a micropore content of >80%, and wherein the silicon-carbon composite further comprises 40%-60% silicon and has a surface area of ​​less than 100 m². 2 / g, For example, a Z value less than 10 and a micropore content greater than 80%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 50 m². 2 / g, For example, a Z value less than 10 and a micropore content greater than 80%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 30 m². 2 / g, For example, a Z value less than 10 and a micropore content greater than 80%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 10 m². 2 / g, For example, a Z value less than 10 and a micropore content greater than 80%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 5 m². 2 / g,

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

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

[0191] In some embodiments, the silicon-carbon composite comprises a carbon scaffold with a Z-axis of less than 10 and >90% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 100 m². 2 / g, For example, a Z value less than 10 and a micropore content >90%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 50 m². 2 / g, For example, a Z value less than 10 and a micropore content greater than 90%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 30 m². 2 / g, For example, a Z value less than 10 and a micropore content >90%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 10 m².2 / g, For example, a Z value less than 10 and a micropore content greater than 90%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 5 m². 2 / g,

[0192] In some embodiments, the silicon-carbon composite comprises a carbon scaffold with a Z-axis of less than 10 and >90% micropores, and wherein the silicon-carbon composite further comprises 40%-60% silicon and has a surface area of ​​less than 100 m². 2 / g, For example, a Z value less than 10 and a micropore content greater than 90%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 50 m². 2 / g, For example, a Z value less than 10 and a micropore content greater than 90%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 30 m². 2 / g, For example, a Z value less than 10 and a micropore content >90%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 10 m². 2 / g, For example, a Z value less than 10 and a micropore content greater than 90%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 5 m². 2 / g,

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

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

[0195] In some embodiments, the silicon-carbon composite comprises a carbon scaffold with a Z-axis of less than 10 and >95% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 100 m². 2 / g, For example, a Z value less than 10 and a micropore content >95%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 50 m². 2 / g, For example, a Z value less than 10 and a micropore content >95%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 30 m². 2 / g, For example, a Z value less than 10 and a micropore content >95%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 10 m². 2 / g, For example, a Z value less than 10 and a micropore content >95%, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area less than 5 m². 2 / g,

[0196] In some embodiments, the silicon-carbon composite comprises a carbon scaffold with a Z-axis of less than 10 and >95% micropores, and wherein the silicon-carbon composite further comprises 40%-60% silicon and has a surface area of ​​less than 100 m². 2 / g, For example, a Z value less than 10 and a micropore content >95%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 50 m². 2 / g, For example, a Z value less than 10 and a micropore content >95%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 30 m². 2 / g, For example, a Z value less than 10 and a micropore content >95%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 10 m². 2 / g, For example, a Z value less than 10 and a micropore content >95%, wherein the silicon-carbon composite also contains 40%-60% silicon and has a surface area less than 5 m². 2 / g,

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

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

[0199] In some embodiments, the silicon-carbon composite comprises a carbon scaffold with a Z-axis of less than 10 and >80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency ≥0.9969; for example, silicon-carbon composites contain a Z of less than 10 and a carbon scaffold with >80% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency ≥0.9970; for example, silicon-carbon composites containing a Z of less than 10 and a carbon scaffold with >80% micropores, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency ≥0.9975; for example, silicon-carbon composites containing a Z of less than 10 and a carbon scaffold with >80% micropores, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency >0.9980; for example, silicon-carbon composites contain a Z of less than 10 and a carbon scaffold with >80% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency ≥0.9985; for example, silicon-carbon composites containing a Z of less than 10 and a carbon scaffold with >80% micropores, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency ≥0.9990; for example, silicon-carbon composites containing a Z of less than 10 and a carbon scaffold with >80% micropores, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency ≥0.9995; for example, silicon-carbon composites containing a Z of less than 10 and a carbon scaffold with >80% micropores, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And the average coulomb efficiency is ≥0.9999.

[0200] In some embodiments, the silicon-carbon composite comprises a carbon scaffold with a Z-axis of less than 10 and >80% micropores, and wherein the silicon-carbon composite further comprises 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency ≥0.9969; for example, silicon-carbon composites contain a Z of less than 10 and a carbon scaffold with >80% micropores, and wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency ≥0.9970; for example, silicon-carbon composites containing a Z of less than 10 and a carbon scaffold with >80% micropores, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency ≥0.9975; for example, silicon-carbon composites containing a Z of less than 10 and a carbon scaffold with >80% micropores, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency ≥0.9980; for example, silicon-carbon composites containing a Z of less than 10 and a carbon scaffold with >80% micropores, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency ≥0.9985; for example, silicon-carbon composites containing a Z of less than 10 and a carbon scaffold with >80% micropores, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency ≥0.9990; for example, silicon-carbon composites containing a Z of less than 10 and a carbon scaffold with >80% micropores, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And an average coulombic efficiency ≥0.9995; for example, silicon-carbon composites containing a Z of less than 10 and a carbon scaffold with >80% micropores, wherein the silicon-carbon composite also contains 30%-60% silicon and has a surface area of ​​less than 30 m². 2 / g、 And the average coulomb efficiency is ≥0.9999.

[0201] Example 4. Particle size distribution of various carbon scaffold materials. The particle size distribution of various carbon scaffold materials was determined using a laser diffraction particle size analyzer known in the art. Table 7 shows the data, specifically Dv,1, Dv10, Dv50, Dv,90, and Dv,100.

[0202] Table 4. Properties of various carbon support materials.

[0203]

[0204]

[0205] Example 5. A lithium-silicon battery including an anode comprising a composite containing silicon and carbon, both group 14 elements. This novel composite containing 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 example.

[0206] A lithium-silicon battery includes an anode comprising a composite containing silicon and carbon, both group 14 elements. The concentration of the composite containing silicon and carbon, by dry weight, in the anode can vary, for example, from 1% to 90%, from 5% to 95%, or from 10% to 70%. In some embodiments, the concentration of the composite containing silicon and carbon, by dry weight, in the anode is 5% to 25%, 25% to 35%, 35% to 50%, 50% to 70%, or greater than 70%.

[0207] The anode may also include other components. These other components include graphite, conductive carbon additives, and binders, and combinations thereof.

[0208] In some embodiments, the lithium-silicon battery includes an anode comprising graphite or a combination thereof. Exemplary graphite includes, but is not limited to, natural graphite, synthetic graphite, nanographite, or combinations thereof. The concentration of graphite in the anode, on a dry weight basis, can vary, for example, from 5% to 95%, from 10% to 70%, from 20% to 60%, from 30% to 50%. In some embodiments, the lithium-silicon battery includes a graphite-free anode.

[0209] 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, externally conductive carbon black, highly conductive carbon black, Super C, Super P, Super [C45 or C65], Ketjenblack carbon, acetylene black, fullerene, graphene, carbon fiber, carbon nanofiber, carbon nanotube, or combinations thereof. The concentration of the conductive carbon additive in the anode, by dry weight, can 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%. In some embodiments, for example, where the anode does not contain graphite, the concentration of the conductive carbon additive, by dry weight, can be from 5% to 20%, for example, from 10% to 20%, for example, from 14% to 16%.

[0210] In a preferred embodiment, the lithium-silicon battery includes an anode comprising an adhesive or a combination thereof. Exemplary adhesives include, but are not limited to, polyvinylidene fluoride (PVDF), styrene-butadiene rubber (SBR), sodium carboxymethyl cellulose (Na-CMC), polyacrylonitrile (PAN), polyacrylic acid latex, polyacrylic acid (PAA), polyvinyl alcohol (PVA), polyethylene glycol (PEG), polyamide-imide (PAI), polyimide (PI), and combinations thereof. In some embodiments, the adhesive may contain lithium ions as counterions. The concentration of the adhesive in the anode, on a dry weight basis, can 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%. In some embodiments, for example, where the anode does not contain graphite, the concentration of the adhesive, on a dry weight basis, can be from 5% to 20%, for example, from 10% to 20%, for example, from 14% to 16%.

[0211] The anode of a lithium-silicon battery comprises a composite containing silicon (a Group 14 element) and carbon, and the anode also includes a 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 some preferred embodiments, the porosity of the dry anode is 30% to 50%. In some preferred embodiments, the porosity of the dry anode is 10% to 50%.

[0212] A lithium-silicon battery includes an anode comprising a composite material containing silicon and carbon, both group 14 elements, and 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), and lithium nickel manganese cobalt oxide (LiNi... x Mn y Co zO2)(NMC, where 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 some preferred embodiments, the anode is NMC811.

[0213] Lithium-silicon batteries involve a ratio known as the N / P ratio, which describes the capacity ratio between the anode and cathode in the battery pack. The N / P ratio is important for determining the energy density of lithium-silicon batteries. Without being bound by theory, a lower N / P ratio provides less excess anode, thus resulting in 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 anode... The presence of this material allows for the reduction of the excess anode required in the battery to avoid deposition. Therefore, without being bound by theory, the novel anode material described in this paper contains… For example For example For example For example This allows for lower N / P ratios and higher energy densities in lithium-silicon batteries. In some embodiments, the N / P ratio is >1.1, for example, >1.2, >1.3, >1.4, >1.5, or >2.0. In some preferred embodiments, the N / P ratio is ≤2.0, for example, ≤1.5, ≤1.4, ≤1.3, ≤1.2, ≤1.1, ≤1.0, ≤0.9, or ≤0.8.

[0214] Lithium-silicon batteries include an electrolyte, which comprises 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 carbonates (F-AEC), fluorinated linear carbonates (F-EMC), dimethylacrylamide (DMAA), succinic anhydride (SA), tris(trimethylsilyl)borate (TTMB), tris(trimethylsilyl)phosphate (TTSP), 1,3-propanesulfonyl lactone (PS), fluorinated ethers (F-EPE), fluoroethylene carbonate (FEC), performance-enhanced silicone 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, for example, salt concentration >1.2, >1.3, >1.4, >1.5, or >2.0 M. In some preferred embodiments, the electrolyte salt concentration is <2.0 M, for example, electrolyte salt concentration <1.5, <1.4, <1.3, <1.2, <1.1, <1.0, or <0.9 M.

[0215] Lithium-silicon batteries, including those comprising a complex of group 14 elements silicon and carbon, also include a separator to maintain the separation of the anode and cathode. The separator can be made of one or more layers of polymer material, or coated with aromatic polyamide, ceramic, or fluoride materials. Exemplary separator materials include, but are not limited to, nonwoven fibers (cotton, nylon, polyester, glass), polymer membranes (polyethylene, polypropylene, polytetrafluoroethylene, polyvinyl chloride), ceramics, and naturally occurring substances (rubber, asbestos, wood). In some 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, including microporous grafted polymers, poly(methyl methacrylate) grafted and siloxane grafted polyethylene, polyvinylidene fluoride (PVDF) nanofiber webs, and polytriphenylamine (PTPA).

[0216] Lithium-silicon batteries, including those comprising group 14 elements silicon and carbon, cycle 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 lithium-silicon batteries with higher energy densities. Therefore, without being bound by theory, the novel anode material described herein comprises... For example For example For example For example This allows for a lower lower limit of the voltage window, and consequently, higher energy density lithium-silicon batteries. In some embodiments, the lower limit of the voltage window is ≤3.0V, for example ≤2.9V, ≤2.8V, ≤2.7V, ≤2.6V, ≤2.5V, ≤2.4V, or ≤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, for example ≥4.0V, for example 4.0V, or 4.1V, or 4.2V, or 4.3V, or 4.4V, or 4.5V, or 4.6V, or 4.7V, or 4.8V, or 4.9V, or 5.0V.

[0217] Detailed Implementation Plan

[0218] Implementation Plan 1. Materials, which exhibit The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0219] Implementation Plan 2. Materials, which exhibit The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0220] Implementation Scheme 3. Silicon-carbon composite material, which exhibits The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0221] Implementation Scheme 4. Silicon-carbon composite material, which exhibits The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0222] Implementation Scheme 5. A silicon-carbon composite material containing Z<10 and The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0223] Implementation Scheme 6. A silicon-carbon composite material containing Z<10 and The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0224] Implementation Scheme 7. Silicon-carbon composite material, which contains Z<10 and surface area<100m² 2 / g and The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0225] Implementation Scheme 8. Silicon-carbon composite material, which contains Z<10 and surface area<100m² 2 / g and The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0226] Implementation Scheme 9. Silicon-carbon composite material, comprising Z<10 and surface area<50m² 2 / g and The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0227] Implementation Scheme 10. Silicon-carbon composite material, comprising Z<10 and surface area<50m² 2 / g and The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0228] Implementation Scheme 11. Silicon-carbon composite material, comprising Z<10 and surface area<30m² 2 / g and The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0229] Implementation Scheme 12. Silicon-carbon composite material, comprising Z<10 and surface area<30m² 2 / g and The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0230] Implementation Scheme 13. Silicon-carbon composite material, which contains Z<10 and surface area<10m² 2 / g and The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0231] Implementation Scheme 14. Silicon-carbon composite material, which contains Z<10 and surface area<10m² 2 / g and The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0232] Implementation Scheme 15. Silicon-carbon composite material, comprising Z<10 and surface area<5m² 2 / g and The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0233] Implementation Scheme 16. Silicon-carbon composite material, comprising Z<10 and surface area<5m² 2 / g and The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0234] Implementation Scheme 17. A silicon-carbon composite material containing 30% to 60% silicon by weight, Z < 10, and surface area < 50 m². 2 / g and The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0235] Implementation Scheme 18. A silicon-carbon composite material comprising 30% to 60% silicon by weight, Z < 10, and surface area < 50 m². 2 / g and The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0236] Implementation Scheme 19. A silicon-carbon composite material comprising 30% to 60% silicon by weight, Z < 10, and surface area < 30 m². 2 / g and The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0237] Implementation Scheme 20. A silicon-carbon composite material comprising 30% to 60% silicon by weight, Z < 10, and surface area < 30 m². 2 / g and The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0238] Implementation Scheme 21. A silicon-carbon composite material comprising 30% to 60% silicon by weight, Z < 10, and surface area < 10 m². 2 / g and The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0239] Implementation Scheme 22. A silicon-carbon composite material comprising 30% to 60% silicon by weight, Z < 10, and surface area < 10 m². 2 / g and The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0240] Implementation Scheme 23. A silicon-carbon composite material comprising 30% to 60% silicon by weight, Z < 10, and surface area < 5 m². 2 / g and The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0241] Implementation Scheme 24. A silicon-carbon composite material comprising 30% to 60% silicon by weight, Z < 10, and surface area < 5 m². 2 / g and The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0242] Implementation Scheme 25. A silicon-carbon composite material comprising 30% to 60% silicon by weight, Z < 10, and surface area < 50 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >70% micropores.

[0243] Implementation Scheme 26. A silicon-carbon composite material comprising 30% to 60% silicon by weight, Z < 10, and surface area < 50 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >70% micropores.

[0244] Implementation Scheme 27. A silicon-carbon composite material comprising 30% to 60% silicon by weight, Z < 10, and a surface area < 30 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >70% micropores.

[0245] Implementation Scheme 28. A silicon-carbon composite material comprising 30% to 60% silicon by weight, Z < 10, and surface area < 30 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >70% micropores.

[0246] Implementation Scheme 29. A silicon-carbon composite material comprising 30% to 60% silicon by weight, Z < 10, and surface area < 10 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >70% micropores.

[0247] Implementation Scheme 30. A silicon-carbon composite material comprising 30% to 60% silicon by weight, Z < 10, and surface area < 10 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >70% micropores.

[0248] Implementation Scheme 31. A silicon-carbon composite material comprising 30% to 60% silicon by weight, Z < 10, and surface area < 5 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >70% micropores.

[0249] Implementation Scheme 32. A silicon-carbon composite material comprising 30% to 60% silicon by weight, Z < 10, and surface area < 5 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >70% micropores.

[0250] Implementation Scheme 33. A silicon-carbon composite material comprising 30% to 60% silicon by weight, Z < 510, and surface area < 30 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >80% micropores.

[0251] Implementation Scheme 34. A silicon-carbon composite material comprising 30% to 60% silicon by weight, Z < 10, and surface area < 30 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >80% micropores.

[0252] Implementation Scheme 35. A silicon-carbon composite material comprising 30% to 60% silicon by weight, Z < 10, and surface area < 10 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >80% micropores.

[0253] Implementation Scheme 36. A silicon-carbon composite material comprising 30% to 60% silicon by weight, Z < 10, and surface area < 10 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >80% micropores.

[0254] Implementation Scheme 37. A silicon-carbon composite material comprising 30% to 60% silicon by weight, Z < 10, and surface area < 5 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >80% micropores.

[0255] Implementation Scheme 38. A silicon-carbon composite material comprising 30% to 60% silicon by weight, Z < 10, and surface area < 5 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >80% micropores.

[0256] Implementation Scheme 39. A silicon-carbon composite material comprising 30% to 60% silicon by weight, Z < 10, and surface area < 30 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >90% micropores.

[0257] Implementation Scheme 40. A silicon-carbon composite material comprising 30% to 60% silicon by weight, Z < 10, and a surface area < 30 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >90% micropores.

[0258] Implementation Scheme 41. A silicon-carbon composite material comprising 30% to 60% silicon by weight, Z < 10, and surface area < 10 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >90% micropores.

[0259] Implementation Scheme 42. A silicon-carbon composite material comprising 30% to 60% silicon by weight, Z < 10, and surface area < 10 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >90% micropores.

[0260] Implementation Scheme 43. A silicon-carbon composite material comprising 30% to 60% silicon by weight, Z < 10, and surface area < 5 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >90% micropores.

[0261] Implementation Scheme 44. A silicon-carbon composite material comprising 30% to 60% silicon by weight, Z < 10, and surface area < 5 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >90% micropores.

[0262] Implementation Scheme 45. A silicon-carbon composite material comprising 30% to 60% silicon by weight, Z < 10, and a surface area < 30 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >95% micropores.

[0263] Implementation Scheme 46. A silicon-carbon composite material comprising 30% to 60% silicon by weight, Z < 10, and a surface area < 30 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >95% micropores.

[0264] Implementation Scheme 47. A silicon-carbon composite material comprising 30% to 60% silicon by weight, Z < 10, and surface area < 10 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >95% micropores.

[0265] Implementation Scheme 48. A silicon-carbon composite material comprising 30% to 60% silicon by weight, Z < 10, and surface area < 10 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >95% micropores.

[0266] Implementation Scheme 49. A silicon-carbon composite material comprising 30% to 60% silicon by weight, Z < 10, and surface area < 5 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >95% micropores.

[0267] Implementation Scheme 50. A silicon-carbon composite material comprising 30% to 60% silicon by weight, Z < 10, and surface area < 5 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >95% micropores.

[0268] Implementation Scheme 51. A silicon-carbon composite according to any one of Implementation Schemes 1 to 50, wherein the silicon-carbon composite comprises a Dv50 of 5 nm to 20 micrometers.

[0269] Implementation Scheme 52. The silicon-carbon composite according to any one of Implementation Schemes 1 to 51, wherein the silicon-carbon composite has a capacity greater than 900 mAh / g.

[0270] Implementation Scheme 53. The silicon-carbon composite according to any one of Implementation Schemes 1 to 51, wherein the silicon-carbon composite has a capacity greater than 1300 mAh / g.

[0271] Implementation Scheme 54. The silicon-carbon composite according to any one of Implementation Schemes 1 to 51, wherein the silicon-carbon composite has a capacity greater than 1600 mAh / g.

[0272] Implementation Scheme 55. An energy storage device comprising a silicon-carbon composite according to any one of Implementation Schemes 1 to 53.

[0273] Implementation Scheme 56. A lithium-ion battery comprising a silicon-carbon composite according to any one of Implementation Schemes 1 to 53.

[0274] Implementation Scheme 57. A silicon-carbon composite material comprising 40% to 60% silicon by weight, Z < 10, and surface area < 50 m². 2 / g and The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0275] Implementation Scheme 58. A silicon-carbon composite material comprising 40% to 60% silicon by weight, Z < 10, and a surface area < 30 m². 2 / g and The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0276] Implementation Scheme 59. A silicon-carbon composite material comprising 40% to 60% silicon by weight, Z < 10, and surface area < 30 m². 2 / g and The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0277] Implementation Scheme 60. A silicon-carbon composite material comprising 40% to 60% silicon by weight, Z < 10, and surface area < 10 m². 2 / g and The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0278] Implementation Scheme 61. A silicon-carbon composite material comprising 40% to 60% silicon by weight, Z < 10, and surface area < 10 m². 2 / g and The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0279] Implementation Scheme 62. A silicon-carbon composite material comprising 40% to 60% silicon by weight, Z < 10, and surface area < 5 m². 2 / g and The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0280] Implementation Scheme 63. A silicon-carbon composite material comprising 40% to 60% silicon by weight, Z < 10, and surface area < 5 m². 2 / g and The dQ / dV was measured in a half-cell button cell, with region I being 0.8V-0.4V and region III being 0.15V-0V.

[0281] Implementation Scheme 64. A silicon-carbon composite material comprising 40% to 60% silicon by weight, Z < 10, and surface area < 50 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >70% micropores.

[0282] Implementation Scheme 65. A silicon-carbon composite material comprising 40% to 60% silicon by weight, Z < 10, and surface area < 50 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >70% micropores.

[0283] Implementation Scheme 66. A silicon-carbon composite material comprising 40% to 60% silicon by weight, Z < 10, and surface area < 30 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >70% micropores.

[0284] Implementation Scheme 67. A silicon-carbon composite material comprising 40% to 60% silicon by weight, Z < 10, and surface area < 30 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >70% micropores.

[0285] Implementation Scheme 68. A silicon-carbon composite material comprising 40% to 60% silicon by weight, Z < 10, and surface area < 10 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >70% micropores.

[0286] Implementation Scheme 69. A silicon-carbon composite material comprising 40% to 60% silicon by weight, Z < 10, and surface area < 10 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >70% micropores.

[0287] Implementation Scheme 70. A silicon-carbon composite material comprising 40% to 60% silicon by weight, Z < 10, and surface area < 5 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >70% micropores.

[0288] Implementation Scheme 71. A silicon-carbon composite material comprising 40% to 60% silicon by weight, Z < 10, and surface area < 5 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >70% micropores.

[0289] Implementation Scheme 72. A silicon-carbon composite material comprising 40% to 60% silicon by weight, Z < 510, and surface area < 30 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >80% micropores.

[0290] Implementation Scheme 73. A silicon-carbon composite material comprising 40% to 60% silicon by weight, Z < 10, and surface area < 30 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >80% micropores.

[0291] Implementation Scheme 74. A silicon-carbon composite material comprising 40% to 60% silicon by weight, Z < 10, and surface area < 10 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >80% micropores.

[0292] Implementation Scheme 75. A silicon-carbon composite material comprising 40% to 60% silicon by weight, Z < 10, and surface area < 10 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >80% micropores.

[0293] Implementation Scheme 76. A silicon-carbon composite material comprising 40% to 60% silicon by weight, Z < 10, and surface area < 5 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >80% micropores.

[0294] Implementation Scheme 77. A silicon-carbon composite material comprising 40% to 60% silicon by weight, Z < 10, and surface area < 5 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >80% micropores.

[0295] Implementation Scheme 78. A silicon-carbon composite material comprising 40% to 60% silicon by weight, Z < 10, and surface area < 30 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >90% micropores.

[0296] Implementation Scheme 79. A silicon-carbon composite material comprising 40% to 60% silicon by weight, Z < 10, and surface area < 30 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >90% micropores.

[0297] Implementation Scheme 80. A silicon-carbon composite material comprising 40% to 60% silicon by weight, Z < 10, and surface area < 10 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >90% micropores.

[0298] Implementation Scheme 81. A silicon-carbon composite material comprising 40% to 60% silicon by weight, Z < 10, and surface area < 10 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >90% micropores.

[0299] Implementation Scheme 82. A silicon-carbon composite material comprising 40% to 60% silicon by weight, Z < 10, and surface area < 5 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >90% micropores.

[0300] Implementation Scheme 83. A silicon-carbon composite material comprising 40% to 60% silicon by weight, Z < 10, and surface area < 5 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >90% micropores.

[0301] Implementation Scheme 84. A silicon-carbon composite material comprising 40% to 60% silicon by weight, Z < 10, and surface area < 30 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >95% micropores.

[0302] Implementation Scheme 85. A silicon-carbon composite material comprising 40% to 60% silicon by weight, Z < 10, and a surface area < 30 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >95% micropores.

[0303] Implementation Scheme 86. A silicon-carbon composite material comprising 40% to 60% silicon by weight, Z < 10, and surface area < 10 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >95% micropores.

[0304] Implementation Scheme 87. A silicon-carbon composite material comprising 40% to 60% silicon by weight, Z < 10, and surface area < 10 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >95% micropores.

[0305] Implementation Scheme 88. A silicon-carbon composite material comprising 40% to 60% silicon by weight, Z < 10, and surface area < 5 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >95% micropores.

[0306] Implementation Scheme 89. A silicon-carbon composite material comprising 40% to 60% silicon by weight, Z < 10, and surface area < 5 m². 2 / g and The measurements included dQ / dV in a half-cell coin cell, with region I being 0.8V-0.4V and region III being 0.15V-0V, and a carbon support containing pore volumes, wherein the pore volumes comprised >95% micropores.

[0307] Implementation Scheme 90. A silicon-carbon composite according to any one of Implementation Schemes 57 to 89, wherein the silicon-carbon composite comprises a Dv50 of 5 nm to 20 micrometers.

[0308] Implementation Scheme 91. The silicon-carbon composite according to any one of Implementation Schemes 57 to 89, wherein the silicon-carbon composite has a capacity greater than 900 mAh / g.

[0309] Implementation Scheme 92. The silicon-carbon composite according to any one of Implementation Schemes 57 to 89, wherein the silicon-carbon composite has a capacity greater than 1300 mAh / g.

[0310] Implementation Scheme 93. The silicon-carbon composite according to any one of Implementation Schemes 57 to 89, wherein the silicon-carbon composite has a capacity greater than 1600 mAh / g.

[0311] Implementation Scheme 94. An energy storage device comprising a silicon-carbon composite according to any one of Implementation Schemes 57 to 89.

[0312] Implementation Scheme 95. A lithium-ion battery comprising a silicon-carbon composite according to any one of Implementation Schemes 57 to 89.

[0313] Implementation Plan 96. Any one of Implementation Plans 1 to 95, wherein

[0314] Implementation Plan 97. Any one of Implementation Plans 1 to 95, wherein

[0315] Implementation Plan 98. Any one of Implementation Plans 1 to 95, wherein

[0316] Implementation Plan 99. Any one of Implementation Plans 1 to 95, wherein

[0317] Implementation Plan 100. Any one of Implementation Plans 1 to 95, wherein

[0318] As can be understood from the foregoing, although specific embodiments of the invention have been described herein for illustrative purposes, various modifications may be made without departing from the spirit and scope of the invention. Therefore, the invention is not limited except by the appended claims.

[0319] All U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications and non-patent publications mentioned and / or listed in the application data sheets in this specification, including but not limited to U.S. Application Serial No. 16 / 996,694 filed August 18, 2020, U.S. Provisional Patent Application Serial No. 63 / 075,566 filed September 8, 2020, U.S. Patent Application Serial No. 17 / 336,104 filed June 1, 2021, and U.S. Patent Application Serial No. 17 / 336,085 filed June 1, 2021, are incorporated herein by reference in their entirety.

Claims

1. A silicon-carbon composite comprising: a. a carbon scaffold comprising a pore volume, wherein the pore volume comprises greater than 80% micropores; b. a silicon content of 30% to 60% by weight; c. a Z of less than 5, 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 as determined by thermogravimetric analysis when the silicon-carbon composite is heated in air from about 25 °C to about 1100 °C; d. less than 30 m 2 / g of surface area; and e. greater than or equal to 0.12 wherein = (maximum peak height dQ / dV in Region I) / (maximum peak height dQ / dV in Region III), wherein dQ / dV is measured in half-cell coin cells and Region I is 0.8 V - 0.4 V and Region III is 0.15 V - 0 V.

2. The silicon-carbon composite of claim 1, wherein the pore volume comprises greater than 90% micropores.

3. The silicon-carbon composite of claim 1, wherein the pore volume comprises greater than 95% micropores.

4. The silicon-carbon composite of claim 1, comprising a surface area of less than 10 m 2 / g.

5. The silicon-carbon composite of claim 2, comprising a surface area of less than 10 m2 / g. 2 / g.

6. The silicon-carbon composite of claim 1, wherein the silicon-carbon composite comprises a Dv50 of 5 nm to 20 microns.

7. The silicon-carbon composite of claim 2, wherein the silicon-carbon composite comprises a Dv50 of 5 nm to 20 microns.

8. The silicon-carbon composite of claim 1, wherein the silicon-carbon composite comprises a capacity of greater than 900 mAh / g.

9. The silicon-carbon composite of claim 2, wherein the silicon-carbon composite comprises a capacity of greater than 900 mAh / g.

10. The silicon-carbon composite of claim 1, further comprising lithium ions.

11. The silicon-carbon composite of claim 2, further comprising lithium ions.

12. The silicon-carbon composite of any one of claims 1 to 11, wherein > 0.

13.

13. The silicon-carbon composite of any one of claims 1 to 11, wherein > 0.

14.

14. The silicon-carbon composite of any one of claims 1 to 11, wherein > 0.15.

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