Silicon-carbon composites with improved electrochemical properties

Abstract

Silicon-carbon composite materials and related methods are disclosed that solve the problem of providing amorphous nanosized silicon incorporated within porous carbon. Compared to other inferior materials and methods disclosed in the prior art, the materials and methods disclosed herein have been found to have significant advantages in a variety of applications, including energy storage devices, such as lithium-ion batteries.

Description

[Technical Field]

[0001] Embodiments of the present invention generally relate to improving the electrochemical properties and performance of silicon-carbon composites, which address the challenges of providing amorphous nanosized silicon incorporated within porous carbon. The silicon-carbon composites are fabricated by impregnating amorphous nanosized silicon into the pores of a porous scaffold via chemical vapor infiltration. Suitable porous scaffolds include, but are not limited to, porous carbon scaffolds, such as carbons having a pore volume containing micropores (less than 2 nm), mesopores (2-50 nm), and / or macropores (greater than 50 nm). Suitable precursors for carbon scaffolds include, but are not limited to, sugars and polyols, organic acids, phenolic compounds, crosslinkers, and amine compounds. Suitable composite materials include, but are not limited to, silicon materials. Silicon precursors include, but are not limited to, silicon-containing gases, such as silane, higher silanes (such as di-, tri-, and / or tetrasilane), and / or chlorosilanes (such as mono-, di-, tri-, and tetrachlorosilane), and mixtures thereof. Chemical vapor infiltration (CVI) of silicon 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.

[0002] A key achievement in this regard is achieving the desired morphology of silicon, i.e., amorphous nano-sized silicon. Yet another key achievement is achieving silicon impregnation into the pores of porous carbon. Yet another key achievement is achieving improved electrochemical properties of silicon-carbon composites. Such improvements include increasing the graphitic nature and / or electrical conductivity of the carbon scaffold, where electrical conductivity includes electronic and / or ionic conductivity. Such silicon-carbon composites with enhanced electrochemical properties have utility as anode materials for energy storage devices, such as lithium-ion batteries. Also disclosed herein are manufacturing processes for preparing silicon-carbon composites with enhanced electrochemical properties.

[0003] Description of related fields CVI is a process in which a gaseous substrate reacts within a porous scaffold material. This approach can be used to fabricate composite materials (e.g., silicon-carbon composites) by decomposing a silicon-containing gas within a porous carbon scaffold at high temperatures. This approach can be used to fabricate a variety of composite materials, with particular interest in silicon-carbon (Si-C) composites. Such Si-C composites have utility as energy storage materials, such as anode materials in lithium-ion batteries (LIBs). LIBs have the potential to replace many currently used devices in many applications, including electric vehicles, home appliances, and grid storage. For example, current automotive lead-acid batteries are unsuitable for next-generation fully electric and hybrid electric vehicles due to the irreversible and stable formation of sulfates during discharge. Lithium-ion batteries have the potential to replace currently used lead-based systems due to their capacity and other considerations.

[0004] To this end, there continues to be intense interest in developing new LIB anode materials, especially silicon, which has a 10-fold higher gravimetric capacity compared to conventional graphite. However, silicon exhibits large volume changes during cycling, resulting in electrode degradation and destabilization of the solid electrolyte interface (SEI). The most common improvement approach is to reduce the particle size of silicon, either as individual particles or within the matrix (e.g., D V,50 <150 nm, e.g., D V,50 <100 nm, e.g., D V,50 <50nm, e.g., D V,50 <20nm, e.g., D V,50 <10 nm, e.g., D V,50 <5nm, e.g., D V,50 <2 nm). To date, nanoscale silicon fabrication techniques involve high-temperature reduction of silicon oxide, extensive grain reduction, multi-step toxic etching, and / or other costly processes. Similarly, common matrix approaches involve expensive materials such as graphene or nanographite and / or require complex processes and coatings.

[0005] Scientific literature has shown that non-graphitizable (hard) carbons are useful as LIB anode materials (Liu Y, Xue JS, Zheng T, Dahn JR. Carbon 1996, 34:193-200; Wu YP, Fang SB, Jiang YY. 1998, 75:201-206; Buiel E, Dahn JR. Electrochim Acta 1999, 45:121-130). The basis for this improved performance stems from the disordered nature of graphene layers, which allows Li ions to intercalate on both sides of the graphene, theoretically doubling the stoichiometric Li content relative to crystalline graphite. Furthermore, the disordered structure enhances the rated capacity of the material by allowing Li ions to intercalate isotropically, in contrast to graphite, where lithiation only occurs parallel to the graphene stack plane. Despite these desirable electrochemical properties, amorphous carbon has not seen widespread deployment in commercial Li-ion batteries, primarily due to its low FCE and low bulk density (<1 g / cc). Instead, amorphous carbon is more commonly used as a low-mass additive and coating for other active battery components to improve electrical conductivity and inhibit surface-side reactions.

[0006] In recent years, amorphous carbon has attracted considerable attention as a material for LIB batteries and as a coating for silicon anode materials. Such silicon-carbon core-shell structures not only improve conductivity but also have the ability to mitigate the expansion that occurs when silicon is lithiated, thereby stabilizing cycle stability and minimizing problems related to particle pulverization, separation, 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 method include a lack of suitable silicon starting materials for the coating process, and an intrinsic lack of engineering voids within the carbon-coated silicon core-shell composite particles to accommodate the expansion of silicon during lithiation. This inevitably leads to a lack of cycle stability due to the breakdown of the core-shell structure and SEI layer. (Beattie SD, Larcher D, Morcrette M, Simon B, Tarascon, JM. J Electrochem Soc 2008 155:A158-A163). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] U.S. Patent Application No. 7,723,262 [Patent Document 2] U.S. Patent Application No. 8,293,818 [Patent Document 3] U.S. Patent Application No. 8,404,384 [Patent Document 4] U.S. Patent Application No. 8,654,507 [Patent Document 5] U.S. Patent Application No. 8916296 [License 6] U.S. Patent Application No. 9269502 [License 7] U.S. Patent Application No. 10590277 [License 8] U.S. Patent and Trademark Office Publication No. 2016 / 745197 [License 9] The U.S. National Volunteer No. 63 / 083614 [Non-licensed literature]

[0008] [Non-licensed Document 1] Liu Y, Xue, JS, Zheng T, Dahn, JR. Carbon 1996, 34:193-200; Wu, YP, Fang, SB, Jiang, YY. 1998, 75:201-206 [Non-licensed Document 2] Buiel E, Dahn JR. Electrochim Acta 1999 45:121-130 [Non-licensed Document 3] Jung, Y, Lee K, Oh, S. Electrochim Acta 2007 52:7061-7067 [Non-licensed Document 4] Zuo P, Yin G, Ma Y.. Electrochim Acta 2007 52:4878-4883 [Non-licensed Document 5] Ng SH, Wang J, Wexler D, Chew SY, Liu HK. J Phys Chem C 2007 111:11131-11138 [Non-licensed Document 6] Beattie SD, Larcher D, Morcrette M, Simon B, Tarascon, JM. J Electrochem Soc 2008 155:A158-A163 [Non-licensed Document 7] The Chemistry and Applications of Metal-Organic Frameworks, Hiroyasu Furukawa et al. Science 341 , ( 2013 ); DOI: 10.1126 / science.1230444

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[0009] An alternative structure to the core-shell structure is one in which amorphous nano-sized silicon is uniformly distributed within the voids of a porous carbon scaffold. Porous carbon has desirable properties: (i) The porosity of carbon provides void volume, which adapts to the expansion of silicon during lithiation, thus reducing the net expansion of composite particles at the electrode level; (ii) The disordered graphene network enhances electrical conductivity to silicon, thus enabling faster charge / discharge rates; and, (iii) The nanoporous structure functions as a template for the synthesis of silicon, thus defining its size, distribution, and morphology. Give. [Means for solving the problem]

[0010] To this end, the desired inverse hierarchical structure can be achieved by using CVI, where a silicon-containing gas can completely penetrate the nanoporous carbon and decompose into nanosized silicon there. The CVI approach offers several advantages in terms of silicon structure. One advantage is that the nanoporous carbon provides nucleation sites for silicon growth while defining the maximum particle shape and size. Confining silicon growth within the nanoporous structure reduces susceptibility to cracking or pulverization and reduces contacts caused by expansion. Furthermore, this structure encourages nanosized silicon to remain in the amorphous phase. This property, especially in combination with the proximity of silicon within a conductive carbon scaffold, offers the opportunity for high charge / discharge rates. This system provides a fast-acting, solid-state lithium diffusion pathway, which directly delivers lithium ions to the nanoscale silicon interface. Another advantage of silicon provided by CVI within a carbon scaffold is the lack of undesirable crystallized Li. 15 The inhibition of the formation of the Si4 layer. Yet another advantage is that the CVI process provides voids inside the grains.

[0011] Thermogravimetric analysis (TGA) may be used to quantify the percentage of silicon that comprises the introduced silicon-carbon composite. For this purpose, the silicon-composite is heated from 25°C to 1100°C. Without being bound by theory, at that temperature, all the carbon is burned and all the silicon is oxidized to SiO2. Thus, the percentage of silicon that comprises the silicon-carbon composite can be calculated using the following formula: %Si=100×[[M1100×(28 / (28+(16×2)))] / M°] [In the formula, when a silicon-carbon composite is heated in the atmosphere from about 25°C to about 1100°C, M1100 is the mass of the silicon-carbon composite at 1100°C, and M° is the minimum mass of the silicon-carbon composite at 30°C to 200°C, and these masses are determined by thermogravimetric analysis.] It is calculated from

[0012] Thermogravimetric analysis (TGA) may be used to measure the relative amount of silicon impregnated into the pores of porous carbon. TGA can be used to assess the percentage of silicon present 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 silicon-carbon composites are heated under air, samples exhibit a mass increase between 300°C and 500°C, reflecting the onset of oxidation of silicon to SiO2. The samples then exhibit a mass loss as the carbon burns off. The samples then exhibit a mass increase, reflecting the resumption of silicon conversion to SiO2, which increases until silicon oxidation is complete, toward an asymptotic value of 1100°C. For the purposes of this analysis, the minimum mass recorded for the sample heated from 800°C to 1100°C is assumed to represent the point at which carbon combustion is complete. Further mass increase beyond this point corresponds to the oxidation of silicon to SiO2, and the total mass at the end of oxidation is SiO2. Thus, the percentage of unoxidized silicon after carbon combustion relative to the total weight of silicon is given by the following formula: Z=1.875×[(M1100-M) / M1100]×100% where M is the mass of the sample after oxidation is complete at 1100°C, and M is the minimum mass recorded for the sample heated from 800°C to 1100°C. It can be calculated by:

[0013] Without being bound by theory, the temperature at which silicon oxidizes under TGA conditions is related to the length scale of the oxide coating on silicon due to the diffusion of oxygen atoms through the oxide layer. Thus, silicon present within the carbon pores will oxidize at a lower temperature than silicon deposits on the particle surface, due to the necessarily thinner coating on the particle surface. Thus, the calculation of Z can be used to quantitatively assess the fraction of silicon that is not impregnated within the pores of a porous carbon scaffold.

[0014] The graphitic vs. amorphous nature of carbon can be determined by various methods known in the art, including, but not limited to, high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and Raman spectroscopy. The latter two methods have been shown to be suitable for quantification, as well as correlations (Z. Zhang and Q. Wang, Crystals 2017, 7(1):5).

[0015] With XRD, graphiticity of carbon materials can be assessed by monitoring peak intensities at various 2θ values ​​corresponding to various Miller indices. Without being bound by theory, primarily due to strong anisotropy in the structure, graphite diffraction lines are classified into various groups, such as 001, hk0, and hk1 indices. One such group is "002," which corresponds to the basal plane of graphite and is located at approximately 26° 2θ; this peak is prominent in highly graphitic carbon materials. Carbon materials with a lower degree of graphiticity can be characterized by very broad "001" lines (e.g., 002) and shifts (e.g., approximately 23° 2θ) due to a lower degree of stacking, and asymmetric hk lines (e.g., "10," corresponding to approximately 43° 2θ).

[0016] Regarding Raman spectroscopy, as reported in previous literature, this method can also be used to evaluate the graphiticity of carbon (L. Bokobza J.-L. Bruneel and M. Couzi, Carbon 2015, 1:77-94). For this purpose, the graphiticity of carbon materials can be determined by the G band (approximately 1550-1650 cm). -1 ) to the D band (approximately 1300-1400 cm -1 ) can be evaluated by monitoring the ratio of the peak intensities of the D / I Gis a measure of the graphiticity of carbon and is measured either from the direct peak intensity or by deconvolution. In the latter case, an additional deconvoluted peak, D4 (approximately 1000-1200 cm -1 ), and D3 (approximately 1450-1550 cm -1 Without being bound by theory, the D4 and / or D3 bands are present in highly defective carbons such as carbon black and are associated with amorphous carbon and / or hydrocarbon and / or aliphatic moieties attached to the basic structural units of graphite.

[0017] Quick summary Silicon-carbon composite materials with enhanced electrochemical properties and performance, and related methods, are disclosed that solve the problem of providing amorphous nano-sized silicon incorporated within porous carbon. Compared to other inferior materials and methods described in the prior art, the materials and methods disclosed herein have found superior utility in a variety of applications, including energy storage devices (e.g., lithium-ion batteries, etc.). [Brief explanation of the drawings]

[0018] [Figure 1] Relationship between Z and average Coulombic efficiency for various silicon-carbon composites. [Figure 2] Differential capacity vs. voltage plot for silicon-carbon composite 3 at the second cycle using a half cell. [Figure 3] Differential capacity vs. voltage plot for silicon-carbon composite 3 at cycles 2 to 5 using a half cell. [Figure 4] Plot of dQ / dV vs V for various silicon-carbon composites. [Figure 5] Calculation example of φ for silicon-carbon composite 3. [Figure 6]Z vs φ plot for various silicon-carbon composites. [Figure 7] Raman spectra of carbon scaffold samples 11 and 15. [Figure 8] Raman spectra of carbon scaffold Sample 12 and Sample 10. [Figure 9] Raman spectra of carbon scaffold samples 13 and 14. [Figure 10] Surface area of ​​carbon scaffold samples before and after heat treatment at different temperatures.

[0019] Detailed Description 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 present invention may be practiced without these details. In other instances, well-known structures have not been shown or described in detail to avoid unnecessarily obscuring the description of the embodiments. Unless otherwise noted, in the following specification and claims, the term "comprise" and its derivatives, such as "comprises" and "comprising," are to be interpreted in an open and inclusive sense, i.e., "including, but not limited to." Furthermore, the headings provided herein are for convenience only and do not interpret the scope or meaning of the claimed invention.

[0020] Throughout this specification, a reference to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification do not necessarily all refer to the same embodiment. Furthermore, particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. Also, as used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural references unless otherwise indicated. Note also that the term "or" is generally used to include "and / or" unless otherwise indicated. DETAILED DESCRIPTION OF THE INVENTION

[0021] A. Porous scaffold material For purposes of embodiments of the present invention, a porous scaffold impregnated with silicon may be used. In this aspect, the porous scaffold can comprise a variety of materials. In some embodiments, the porous scaffold comprises primarily carbon, e.g., hard carbon. Other allotropes of carbon, such as graphite, amorphous carbon, diamond, C60, carbon nanotubes (e.g., single-walled and / or multi-walled), graphene, and / or carbon fibers, are also contemplated in other embodiments. The introduction of pores into carbon materials can be achieved by various techniques. For example, pores in carbon materials can be achieved by modulation of polymer precursors and / or processing conditions during the preparation of the porous carbon materials, as described in detail in the following sections.

[0022] In other embodiments, the porous scaffold comprises a polymeric material. For this purpose, various embodiments contemplate a wide range of polymers having utility, including, but not limited to, inorganic polymers, organic polymers, and addition polymers. Inorganic polymers of the present invention include, but are not limited to, silicon-silicon homochain polymers, such as polysilanes, silicon carbides, polygermanes, and polystannanes. Further examples of inorganic polymers include, but are not limited to, heterochain polymers, such as polyborazylenes, polysiloxanes, such as polydimethylsiloxane (PDMS), polymethylhydrosiloxane (PMHS), and polydiphenylsiloxane, polysilazanes, such as perhydridopolysilazane (PHPS), polyphosphazenes, and poly(dichlorophosphazenes), as well as polyphosphates, polythiazyls, 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, polylactic acid, polyglycolide, and combinations thereof, phenolic resins, polyamides, polyaramids, polyethylene terephthalate, polychloroprene, polyacrylonitrile, polyaniline, polyimides, poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PDOT:PSS), and other organic polymers known in the art. Organic polymers can be synthetic or natural. In some embodiments, the polymer is a polysaccharide, such as starch, cellulose, cellobiose, amylose, amylopectin, gum arabic, lignin, and the like. In some embodiments, the polysaccharide is derived from the caramelization of monosaccharides or oligosaccharides (e.g., fructose, glucose, sucrose, maltose, and raffinose).

[0023] In certain embodiments, the porous scaffold polymer material includes a coordination polymer. Coordination polymers in this embodiment include, but are not limited to, metal-organic frameworks (MOFs). Techniques for producing MOFs, as well as exemplary MOF species, are known in the art and are described in the following literature (The Chemistry and Applications of Metal-Organic Frameworks, Hiroyasu Furukawa et al., Science 341, (2013); DOI: 0.1126 / science.1230444). MOFs in the present invention include, but are not limited to, Basolite™ materials and zeolitic imidazolate frameworks (ZIFs).

[0024] With the large number of polymers envisioned as having the potential to provide porous matrices, various processing approaches are envisioned in various embodiments to achieve the above-mentioned pores. In this regard, there are numerous general methods for imparting pores to various materials, including those known in the art (e.g., emulsification, micelle formation, gasification, dissolution followed by solvent removal (e.g., freeze-drying), axial compaction and sintering, gravity sintering, powder rolling and sintering, metal spraying, metal coating and sintering, metal injection molding and sintering, etc.). Other approaches to creating porous polymeric materials are also envisioned, including, for example, the creation of porous gels such as freeze-dried gels and aerogels.

[0025] In certain embodiments, the porous scaffold material comprises a porous ceramic material. In certain embodiments, the porous scaffold material comprises a porous ceramic foam. In this aspect, general methods for imparting pores to ceramic materials are varied and include, but are not limited to, fabricating porous materials as known in the art. In this aspect, general methods and materials suitable for containing porous ceramics include, but are not limited to, porous aluminum oxide, porous zirconia-toughened alumina, porous partially stabilized zirconia, porous alumina, porous sintered silicon carbide, sintered silicon nitride, porous cordierite, porous zirconium oxide, and clay-bonded silicon carbide.

[0026] In certain embodiments, the porous scaffold comprises porous silica or other oxygen-containing silicon material. The preparation of sol gels and silicon gels comprising other porous silica materials is known in the art.

[0027] In certain 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 Hastelloy, porous titanium, porous copper, porous brass, porous gold, porous silver, porous germanium, and other metals known in the art that can form porous structures. In some embodiments, the porous scaffold material comprises a porous metal foam. The types and manufacturing methods of the relevant metals are known in the art. Such methods include, but are not limited to, casting (including foaming, infiltration, and lost-foam casting), sublimation (chemical and physical), formation of gas eutectic, powder metallurgy techniques (such as powder sintering, compaction in the presence of foaming agents, and fiber metallurgy).

[0028] B. Porous carbon scaffold Methods for preparing porous carbon materials from polymer precursors are known in the art. For example, methods for preparing carbon materials are described in U.S. Patent Application Nos. 7,723,262, 8,293,818, 8,404,384, 8,654,507, 8,916,296, 9,269,502, 10,590,277, and U.S. Patent Application Publication No. 2016 / 745197, the disclosures of all of which are incorporated herein by reference in their entireties for all purposes.

[0029] Thus, in one embodiment, the present disclosure provides a method for preparing any of the carbon materials or polymer gels described above. The carbon material may be synthesized by pyrolysis of any single precursor, such as a sugar material (sucrose, fructose, glucose, dextrin, maltodextrin, starch, amylopectin, amylose, lignin, gum arabic, and other sugars known in the art, and combinations thereof). Alternatively, the carbon material may be synthesized by pyrolysis of a composite resin. The composite resin may be formed, for example, by a sol-gel process using a polymer precursor with a crosslinker in a suitable solvent. The polymer precursor may include, for example, phenol, resorcinol, bisphenol A, urea, melamine, and other suitable compounds known in the art, and combinations thereof. The suitable solvent may include, for example, water, ethanol, methanol, and other solvents known in the art, and combinations thereof. Examples of crosslinking agents include formaldehyde, hexamethylenetetramine, furfural, and other crosslinking agents known in the art, as well as combinations thereof. The resins may be acidic or basic and may contain a catalyst. The catalyst may be volatile or non-volatile. Pyrolysis temperatures and reaction times may vary, as known in the art.

[0030] In some embodiments, the methods of the present invention involve the preparation of a polymer gel by a sol-gel process, a condensation process, or a crosslinking process (wherein the process involves a monomer precursor and a crosslinker, two polymers in a system and a crosslinker, or a single polymer and a crosslinker), followed by pyrolysis of the polymer gel. The polymer gel may be dried (e.g., freeze-dried) prior to pyrolysis; however, drying is not necessary.

[0031] Where the polymerization reaction produces a resin / polymer with the required carbon backbone, the carbon properties of interest can be derived from a variety of polymer chemistries. Various polymer species include novolacs, resoles, acrylates, styrenes, urethanes, rubbers (neoprene, styrene-butadiene, etc.), nylons, etc. Preparation of any of the above polymer resins can occur by a variety of processes (including, for example, sol-gel, emulsion / suspension, solid-state, liquid-state, melt-state, etc.) for the polymerization and crosslinking process.

[0032] In some embodiments, the electrochemical modifier is introduced into the material as a polymer. For example, an organic or carbon-containing polymer (e.g., RF) is copolymerized with the polymer and contains the electrochemical modifier. In one embodiment, the electrochemical modifier-containing polymer contains silicon. In one embodiment, the polymer is tetraethylorthosilane (TEOS). In one embodiment, a TEOS solution is added to the RF solution before or during polymerization. In other embodiments, the polymer is a polysilane having side groups. In some examples, these side groups are methyl groups, and in other examples, these side groups are phenyl groups. In some examples, the side chains contain a Group 14 element (silicon, germanium, tin, or lead). In other examples, the side chains contain a Group 13 element (boron, aluminum, boron, gallium, indium). In other examples, the side chains contain a Group 15 element (nitrogen, phosphorus, arsenic). In other examples, the side chains contain a Group 16 element (oxygen, sulfur, selenium).

[0033] In other embodiments, the electrochemical modifier comprises a silole. In some examples, it is a phenol-silole or a silafluorene. In other examples, it is a poly-silole or a poly-silafluorene. In some examples, silicon is replaced with germanium (germole or germafluorene), tin (stannole or stannafluorene), nitrogen (carbazole), or phosphorus (phosphole, phosphafluorene). In all examples, the heteroatom-containing material can be a small molecule, oligomer, or polymer. The phosphorus atom may or may not be bonded to oxygen.

[0034] In some embodiments, the reactant comprises phosphorus. In certain other embodiments, the phosphorus is in the form of phosphoric acid. In certain other embodiments, the phosphorus may be in the form of a salt, the anion of which comprises one or more phosphate, phosphorous acid, phosphide, hydrogen phosphate, dihydrogen phosphate, hexafluorophosphate, hypophosphorous acid, polyphosphate, or pyrophosphate ions, or a combination thereof. In other embodiments, the phosphorus may be in the form of a salt, the cation of which comprises one or more phosphonium ions. Non-phosphate salts comprising any of the anions or cation pairs of the above embodiments can be selected from those known and described in the art. In this embodiment, exemplary cations that pair with the phosphate-containing anions include, but are not limited to, ammonium, tetraethylammonium, and tetramethylammonium ions. In this embodiment, exemplary anions that pair with the phosphate-containing cations include, but are not limited to, carbonate, dicarbonate, and acetate ions.

[0035] In some embodiments, the catalyst comprises a volatile base catalyst. For example, in one embodiment, the volatile base catalyst comprises ammonium carbonate, ammonium bicarbonate, ammonium acetate, ammonium hydroxide, or a combination thereof. In yet another embodiment, the volatile base catalyst is ammonium carbonate. In another embodiment, the volatile base catalyst is ammonium acetate.

[0036] In yet other embodiments, the methods of the present invention include mixing an acid. In certain 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 and does not dissolve one or more other polymer precursors.

[0037] The acid may be selected from a number of acids suitable for the polymerization process. For example, in some embodiments, the acid is acetic acid, and in other embodiments, the acid is oxalic acid. In further embodiments, the acid is mixed with the first or second solvent in an acid to solvent ratio of 99:1, 90:10, 75:25, 50:50, 25:75, 20:80, 10:90, or 1:99. In other embodiments, the acid is acetic acid and the first or second solvent is water. In other embodiments, the acidification is achieved by the addition of a solid acid.

[0038] The total amount of acid in the mixture can be varied to alter the properties of the final product. In some embodiments, the acid is present in the mixture at about 1% to about 50% by weight. In other embodiments, the acid is present at about 5% to about 25% by weight. In other embodiments, the acid is present at about 10% to about 20% by weight (e.g., about 10%, about 15%, about 20%).

[0039] In certain embodiments, polymer precursor components are blended together and then held at a temperature and time sufficient for polymerization to complete. One or more polymer precursor components may have a particle size of less than 20 mm (e.g., less than 10 mm, less than 7 mm, less than 5 mm, less than 2 mm, less than 1 mm, less than 100 microns, less than 10 microns). In some embodiments, the particle size of one or more polymer precursor components decreases during the blending process.

[0040] Blending one or more polymer precursor components in a solvent-free environment can be achieved by methods described in the art (e.g., ball milling, jet milling, Fritsch milling, planetary mixing, and other mixing methods relating to mixing or blending solid particles while controlling process conditions (e.g., temperature)). The mixing or blending process can be achieved before, during, and / or after incubation at the reaction temperature (or a combination thereof).

[0041] The reaction parameters include aging the blend mixture at room temperature for a sufficient time for one or more polymer precursors to react with each other and form a polymer. In this regard, a suitable aging temperature is in the range of approximately room temperature to or near the melting point of one or more polymer precursors. In some embodiments, a suitable aging temperature is in the range of approximately room temperature to or near the glass transition temperature of one or more polymer precursors. For example, in some embodiments, the solvent-free mixture is aged at about 20°C to about 600°C (e.g., about 20°C to about 500°C, e.g., about 20°C to about 400°C, e.g., about 20°C to about 300°C, e.g., about 20°C to about 200°C). In certain embodiments, the solvent-free mixture is aged at about 50°C to about 250°C.

[0042] The reaction time is generally sufficient for the polymer precursor to react and produce a polymer. For example, the mixture may be aged for 1 to 48 hours at any given time, or longer or shorter depending on the desired result. Typical embodiments include aging in the range of about 2 to about 48 hours, for example, about 12 hours in some embodiments and about 4 to 8 hours (e.g., 6 hours) in other embodiments.

[0043] In certain embodiments, an electrochemical modifier is introduced during the polymerization process described above. For example, in some embodiments, the electrochemical modifier, which may be in the form of metal particles, metal paste, metal salt, metal oxide, or molten metal, may be dissolved or suspended in the mixture that produces the gel resin.

[0044] Typical electrochemical modifiers used to create composite materials may fall into one or more chemical classifications. In some embodiments, the electrochemical modifier is a lithium salt, and is not particularly limited, but includes, for example, 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.

[0045] In certain embodiments, the electrochemical modifier comprises a metal, and typical species include, but are not limited to, aluminum isopropoxide, manganese acetate, nickel acetate, iron acetate, tin chloride, silicon chloride, and combinations thereof. In certain embodiments, the electrochemical modifier is a phosphate compound, and typical species include, but are not limited to, phytic acid, phosphoric acid, ammonium dihydrogen phosphate, and combinations thereof. In certain embodiments, the electrochemical modifier comprises silicon, and typical species include, but are not limited to, silicon powder, silicon nanotubes, polycrystalline silicon, nanocrystalline silicon, amorphous silicon, porous silicon, nanosized silicon, nano-featured silicon, nano-sized and nano-featured silicon, silicyne, and black silicon, and combinations thereof.

[0046] Electrochemical modifiers may be coupled to various polymer systems either by physical mixing or chemical reaction with latent (or secondary) polymer functional groups. Examples of latent polymer functional groups include, but are not limited to, epoxide groups, unsaturations (double or triple bonds), acid groups, alcohol groups, base groups, etc. Crosslinking with latent functional groups may occur through reaction with heteroatoms (e.g., vulcanization reactions with sulfur and acid / base / ring-opening reactions with phosphoric acid), reaction with organic acids or bases (as described above), coordination to transition metals (e.g., titanium, chromium, manganese, iron, cobalt, nickel, copper, zinc, zirconium, niobium, molybdenum, silver, gold, etc.), ring-opening or ring-closing reactions (e.g., rotaxanes, spiro compounds, etc.).

[0047] Furthermore, electrochemical modifiers can be added to polymer systems by physical blending. Physical blending is not particularly limited, but may include, for example, melt blending of polymers and / or copolymers, incorporation of discrete particles, vapor phase chemical growth of electrochemical modifiers, and coprecipitation of electrochemical modifiers and the main polymer material.

[0048] In some examples, the electrochemical modifier may be added via a solid, solution, or suspension of the metal salt. The metal salt solid, solution, or suspension may contain an acid and / or alcohol to enhance the solubility of the metal salt. In other further variations, the polymer gel (either before or after any drying step) comes into contact with a paste containing the electrochemical modifier. In yet another variation, the polymer gel (either before or after any drying step) comes into contact with a metal or metal oxide containing the desired electrochemical modifier.

[0049] In addition to the electrochemical modifiers exemplified above, the composite material may contain one or more additional forms (i.e., allotropes) of carbon. In this regard, the inclusion of various allotropes of carbon (graphite, amorphous carbon, conductive carbon, carbon black, diamond, C60, carbon nanotubes (e.g., single-layer and / or multi-layer), graphene, and / or carbon fiber, etc.) in the composite material has been found to be effective in optimizing the electrochemical properties of the composite material. Various allotropes of carbon can be introduced into the carbon material at any stage of the preparation process described herein (e.g., during the dissolution phase, gelation phase, curing phase, pyrolysis phase, milling phase, or after milling). In some embodiments, the second carbon foam is introduced into the composite material by adding the second carbon foam during or before polymerization of the polymer gel, as described in more detail herein. The polymerized polymer gel containing the second carbon foam is processed according to the general method described herein to obtain a carbon material containing the second allotrope of carbon.

[0050] In a preferred embodiment, carbon is produced from precursors that require little or no solvent for processing. The structure of polymer precursors suitable for use in low-solvent or essentially solvent-free reaction mixtures is not particularly limited, provided that the polymer precursors can be reacted with other polymer precursors or a second polymer precursor to produce 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, polyalcohols, sugars, alkylamines, aromatic amines, aldehydes, ketones, carboxylic acids, esters, ureas, acid halides, and isocyanates.

[0051] In one embodiment using a low-solvent or essentially solvent-free reaction mixture, the method includes the use of first and second polymer precursors, and in some embodiments, one of the first or second polymer precursors is a carbonyl-containing compound and the other 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, the phenolic compound of the above method 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 a further embodiment, the phenolic compound is resorcinol, phenol, or a combination thereof, and the aldehyde compound is formaldehyde. In a further embodiment, the phenolic compound is resorcinol and the aldehyde compound is formaldehyde. In some embodiments, the polymer precursors are alcohols and carbonyl compounds (e.g., resorcinol and aldehyde), and they are present in a ratio of approximately 0.5:1.0.

[0052] Suitable polymer precursor materials for the low-solvent or essentially solvent-free reaction mixtures described herein include (a) alcohols, phenolic compounds, and other mono- or polyhydroxy compounds, and (b) aldehydes, ketones, and combinations thereof. Representative alcohols in this embodiment include linear and branched, saturated, and unsaturated alcohols. Suitable phenolic compounds include polyhydroxybenzenes (such as dihydroxy or trihydroxybenzenes). Representative polyhydroxybenzenes include resorcinol (i.e., 1,3-dihydroxybenzene), catechol, hydroquinone, and phloroglucinol. Other suitable compounds in this regard are bisphenols (e.g., bisphenol A). Mixtures of two or more polyhydroxybenzenes can also be used. Phenols (monohydroxybenzenes) can also be used. Representative polyhydroxy compounds include sugars (e.g., glucose, sucrose, fructose, chitin, and other polyols such as mannitol). Aldehydes in this embodiment include the following: straight-chain saturated aldehydes, such as methanal (formaldehyde), ethanal (acetaldehyde), propanal (propionaldehyde), and butanal (butyraldehyde); Linear unsaturated aldehydes, such as ethenone and other ketenes, as well as 2-propenal (acrylaldehyde), 2-butenal (crotonaldehyde), and 3-butenal; Branched-chain saturated and unsaturated aldehydes; and Aromatic aldehydes, such as benzaldehyde, salicylic aldehyde, hydrocinnamaldehyde, etc. Includes the following ketones: linear saturated ketones, such as propanone and 2-butanone; straight-chain unsaturated ketones, such as propenone, 2-butenone, and 3-butenone (methyl vinyl ketone); Branched-chain saturated and unsaturated ketones; and Aromatic ketones, such as methyl benzyl ketone (phenylacetone) and ethyl benzyl ketone The polymer precursor material may be a combination of the precursors listed above.

[0053] In some embodiments, one polymer precursor in a low-solvent or essentially solvent-free reaction mixture is an alcohol-containing species, and the other polymer precursor is a carbonyl-containing species. The relative amounts of alcohol-containing species (e.g., alcohols, phenolic compounds, and mono- or poly-hydroxy compounds, or combinations thereof) reacted with the carbonyl-containing species (e.g., aldehydes, ketones, or combinations thereof) can vary substantially. In some embodiments, the ratio of alcohol-containing species to aldehyde species is selected so that the total moles of reactive alcohol groups in the alcohol-containing species are approximately equal to the total moles of reactive carbonyl groups in the aldehyde-containing species. Similarly, the ratio of alcohol-containing species to ketone species can be selected so that the total moles of reactive alcohol groups in the alcohol-containing species are approximately equal to the total moles of reactive carbonyl groups in the ketone-containing species. The same general 1:1 molar ratio remains true when the carbonyl-containing species includes a combination of aldehyde and ketone species.

[0054] In other embodiments, the polymer precursor in the solvent-poor or essentially 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 a combination thereof. Other embodiments include a polymer precursor selected from isocyanates or other activated carbonyl compounds (e.g., acid halides, etc.).

[0055] Some embodiments of the disclosed method involve the preparation of solvent-poor or solvent-free polymer gels (and carbon materials) containing electrochemical modifiers. Examples of 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 modifiers can be included at any step during the preparation process. For example, some electrochemical modifiers are mixed with the mixture, the polymer phase, or a subsequent phase.

[0056] Blending of one or more polymer precursor components in the absence of a solvent can be accomplished by methods described in the art, such as ball milling, jet milling, Fritsch milling, planetary mixing, and other mixing methods involving mixing or blending solid particles while controlling process conditions (e.g., temperature). The mixing or blending process can be accomplished before, during, and / or after (or a combination thereof) incubation at the reaction temperature.

[0057] The reaction parameters include aging the blend mixture at a temperature and for a time sufficient to allow one or more polymer precursors to react with one another and form a polymer. In this regard, suitable aging temperatures range from about room temperature to a temperature at or near the melting point of one or more polymer precursors. In some embodiments, suitable aging temperatures range from about room temperature to a temperature at or near the glass transition temperature of one or more polymer precursors. For example, in some embodiments, the solvent-free mixture is aged at about 20°C to about 600°C, such as about 20°C to about 500°C, e.g., about 20°C to about 400°C, e.g., about 20°C to about 300°C, e.g., about 20°C to about 200°C. In certain embodiments, the solvent-free mixture is aged at about 50°C to 250°C.

[0058] Porous carbon materials can be achieved by the thermal decomposition of polymers produced from the precursor materials described above. In some embodiments, the porous carbon material comprises amorphous activated carbon, which is produced by thermal decomposition, physical or chemical activation, or a combination thereof, in either a single-process or a series of processes.

[0059] The thermal decomposition temperature and processing time may vary, for example, processing times include 1 to 10 minutes, 10 to 30 minutes, 30 minutes to 1 hour, 1 to 2 hours, 2 to 4 hours, 4 to 24 hours, etc. The temperature may also vary, for example, thermal decomposition temperatures include 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, 1150°C to 1250°C, etc. In some embodiments, the thermal decomposition temperature varies from 650°C to 1100°C. Thermal decomposition can be achieved in an inert gas (e.g., nitrogen or argon).

[0060] In some embodiments, alternative gases are used to achieve further carbon activation. In certain embodiments, thermal decomposition and activation were performed simultaneously. Suitable gases for achieving carbon activation are not particularly limited but include, for example, carbon dioxide, carbon monoxide, water (water vapor), air, oxygen, and further combinations thereof. The activation temperature and processing time may vary, for example, processing times include 1 to 10 minutes, 10 to 30 minutes, 30 minutes to 1 hour, 1 to 2 hours, 2 to 4 hours, 4 to 24 hours, etc. The temperature can vary, for example, the thermal decomposition temperature includes 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, 1150°C to 1250°C, etc. In some embodiments, thermal decomposition and activation occur in a range of 650°C to 1100°C.

[0061] In some embodiments, pyrolysis and activation are performed simultaneously to prepare porous carbon scaffolds. In such embodiments, the process gas may remain the same during the process, or the composition of the process gas may be changed during the process. In some embodiments, the addition of an activated gas (e.g., CO, steam, or a combination thereof) is added to the process gas following a temperature and time sufficient to pyrolyze the solid carbon precursor.

[0062] Suitable gases for achieving carbon activation include, but are not limited to, carbon dioxide, carbon monoxide, water (steam), air, oxygen, and further combinations thereof. Activation temperatures and treatment times can vary, including treatment times of 1 minute to 10 minutes, 10 minutes to 30 minutes, 30 minutes to 1 hour, 1 hour to 2 hours, 2 hours to 4 hours, 4 hours to 24 hours, etc. Temperatures can also vary, including pyrolysis temperatures of 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, 1150°C to 1250°C, etc. In some embodiments, the thermal decomposition and activation occur at temperatures ranging from 650°C to 1100°C.

[0063] The carbon may be subjected to particle size reduction before pyrolysis, and / or after pyrolysis, and / or after activation. Particle size reduction can be achieved by various methods known in the art, such as jet milling in the presence of various gases, including air, nitrogen, argon, helium, supercritical steam, and other gases known in the art. Other particle size reduction methods are contemplated, including grinding, ball milling, jet milling, water jet milling, and other approaches known in the art.

[0064] The porous carbon scaffold may be in the form of particles. The particle size and particle size distribution can be measured by various methods known in the art and can be expressed on a volume fraction basis. In this regard, the Dv,50 of the carbon scaffold may be 10 nm to 10 mm, and include, for example, 100 nm to 1 mm, for example 1 μm to 100 μm, for example 2 μm to 50 μm, for example 3 μm to 30 μm, for example 4 μm to 20 μm, for example 5 μm to 10 μm, etc. In certain embodiments, the Dv,50 is less than 1 mm, and includes, 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, etc. In certain embodiments, Dv,100 is less than 1 mm and includes, for example, less than 100 μm, less than 50 μm, less than 30 μm, less than 20 μm, less than 10 μm, less than 8 μm, less than 5 μm, less than 3 μm, less than 1 μm, etc. In certain embodiments, Dv,99 is less than 1 mm and includes, for example, less than 100 μm, less than 50 μm, less than 30 μm, less than 20 μm, less than 10 μm, less than 8 μm, less than 5 μm, less than 3 μm, less than 1 μm, etc. In certain embodiments, Dv,90 is less than 1 mm and includes, for example, less than 100 μm, less than 50 μm, less than 30 μm, less than 20 μm, less than 10 μm, less than 8 μm, less than 5 μm, less than 3 μm, less than 1 μm, etc. In certain embodiments, Dv,0 is greater than 10 nm and includes, for example, greater than 100 nm, greater than 500 nm, greater than 1 μm, greater than 2 μm, greater than 5 μm, greater than 10 μm, etc. In certain embodiments, Dv,1 is greater than 10 nm and includes, for example, greater than 100 nm, greater than 500 nm, greater than 1 μm, greater than 2 μm, greater than 5 μm, greater than 10 μm, etc. In certain embodiments, Dv,10 is greater than 10 nm and includes, for example, greater than 100 nm, greater than 500 nm, greater than 1 μm, greater than 2 μm, greater than 5 μm, greater than 10 μm, etc.

[0065] In some embodiments, the porous carbon scaffold is 400 mm 2 It is possible to have a surface area of ​​more than 500 m / g, e.g. 2 / g or more, e.g., 750m 2 / g or more, e.g., 1000m 2 / g or more, e.g., 1250m 2 / g or more, e.g., 1500m 2 / g or more, e.g., 1750m 2 / g or more, e.g., 2000m 2 / g or more, e.g., 2500m 2 / g or more, e.g., 3000m 2 / g, etc. In other embodiments, the surface area of ​​the porous carbon scaffold is greater than 500 m 2 In some embodiments, the surface area of ​​the porous carbon scaffold can be less than 200 m / g. 2 / g~500m 2 / g. In some embodiments, the surface area of ​​the porous carbon scaffold is greater than 100 m 2 / g~200m 2 / g. In some embodiments, the surface area of ​​the porous carbon scaffold is 50 m 2 / g~100m 2 / g. In some embodiments, the surface area of ​​the porous carbon scaffold is 10 m 2 / g~50m 2 / g. In some embodiments, the surface area of ​​the porous carbon scaffold is 10 m 2 / g.

[0066] In some embodiments, the pore volume of the porous carbon scaffold is less than or equal to 0.4 cm 3 / g, e.g., 0.5 cm 3 / g or more, e.g., 0.6 cm 3 / g, e.g., 0.7 cm 3 / g or more, e.g., 0.8 cm 3 / g or more, e.g., 0.9 cm 3 / g or more, e.g., 1.0 cm 3 / g or more, e.g., 1.1 cm 3 / g or more, e.g., 1.2 cm 3 / g or more, e.g., 1.4 cm 3 / g or more, e.g., 1.6 cm 3 / g or more, e.g., 1.8 cm 3 / g or more, e.g., 2.0 cm 3 / g, etc. In other embodiments, the pore volume of the porous silicon scaffold is greater than or equal to 0.5 cm 3 Less than, for example, 0.1 cm 3 / g~0.5cm 3 / g. In certain embodiments, the pore volume of the porous silicon scaffold is 0.01 cm 3 / g~0.1cm 3 / g.

[0067] In some embodiments, the porous carbon scaffold is an amorphous activated carbon having a pore volume of 0.2 to 2.0 cm. 3 / g. In certain embodiments, the carbon is an amorphous activated carbon having a pore volume of 0.4 to 1.5 cm. 3 / g. In certain embodiments, the carbon is an amorphous activated carbon having a pore volume of 0.5 to 1.2 cm. 3 / g. In certain embodiments, the carbon is an amorphous activated carbon having a pore volume of 0.6 to 1.0 cm. 3 / g.

[0068] In other embodiments, the porous carbon scaffold has a density of 1.0 g / cm 3 including tap densities less than, for example, 0.8 g / cm 3 Less than, for example, 0.6 g / cm 3 Less than, for example, 0.5 g / cm 3 Less than, for example, 0.4 g / cm 3 Less than, for example, 0.3 g / cm 3 Less than, for example, 0.2 g / cm 3 Less than, for example, 0.1 g / cm 3 Includes less than, etc.

[0069] 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 herein include pH values ​​ranging from less than 1 to about 14, including less than 5, 5-8, or greater than 8. In some embodiments, the pH of the porous carbon is less than 4, less than 3, less than 2, or less than 1. In other embodiments, the pH of the porous carbon is between about 5-6, about 6-7, about 7-8, 8-9, or 9-10. In still other embodiments, the pH of the porous carbon is high, such as greater than 8, greater than 9, greater than 10, greater than 11, greater than 12, or greater than 13.

[0070] The pore volume distribution of the porous carbon scaffold can vary. For example, the % micropores can include less than 30%, such as less than 20%, such as less than 10%, such as less than 5%, such as less than 4%, such as less than 3%, such as less than 2%, such as less than 1%, such as less than 0.5%, such as less than 0.2%, such as less than 0.1%, etc. In certain embodiments, there is no detectable micropore volume in the porous carbon scaffold.

[0071] The mesopores contained in the porous carbon scaffold can vary. For example, the % mesopores can include less than 30%, such as less than 20%, such as less than 10%, such as less than 5%, such as less than 4%, such as less than 3%, such as less than 2%, such as less than 1%, such as less than 0.5%, such as less than 0.2%, such as less than 0.1%, etc. In certain embodiments, there is no detectable mesopore volume in the porous carbon scaffold.

[0072] In some embodiments, the pore volume distribution of the porous carbon scaffold comprises more than 50% macropores, such as more than 60% macropores, such as more than 70% macropores, for example more than 80% macropores, such as more than 90% macropores, for example more than 95% macropores, such as more than 98% macropores, for example more than 99% macropores, such as more than 99.5% macropores, for example more than 99.9% macropores, etc.

[0073] In certain preferred embodiments, the pore volume of the porous carbon scaffold comprises a blend of micropores, mesopores, and macropores. Thus, in certain embodiments, the porous carbon scaffold comprises 0-20% micropores, 30-70% mesopores, and less than 10% macropores. In other specific embodiments, the porous carbon scaffold comprises 0-20% micropores, 0-20% mesopores, and 70-95% macropores. In other specific embodiments, the porous carbon scaffold comprises 20-50% micropores, 50-80% mesopores, and 0-10% macropores. In other specific embodiments, the porous carbon scaffold comprises 40-60% micropores, 40-60% mesopores, and 0-10% macropores. In other specific embodiments, the porous carbon scaffold comprises 80-95% micropores, 0-10% mesopores, and 0-10% macropores. In other specific embodiments, the porous carbon scaffold comprises 0-10% micropores, 30-50% mesopores, and 50-70% macropores. In other specific embodiments, the porous carbon scaffold comprises 0-10% micropores, 70-80% mesopores, and 0-20% macropores. In other specific embodiments, the porous carbon scaffold comprises 0-20% micropores, 70-95% mesopores, and 0-10% macropores. In other specific embodiments, the porous carbon scaffold comprises 0-10% micropores, 70-95% mesopores, and 0-20% macropores.

[0074] In certain embodiments, the percentage of pore volume representing pores of 100-1000A (10-100nm) in the porous carbon scaffold includes more than 30% of the total pore volume, for example more than 40% of the total pore volume, for example more than 50% of the total pore volume, for example more than 60% of the total pore volume, for example more than 70% of the total pore volume, for example more than 80% of the total pore volume, for example more than 90% of the total pore volume, for example more than 95% of the total pore volume, for example more than 98% of the total pore volume, for example more than 99% of the total pore volume, for example more than 99.5% of the total pore volume, for example more than 99.9% of the total pore volume.

[0075] In certain embodiments, the pycnometry density of the porous carbon scaffold is in the range of about 1 g / cc to about 3 g / cc, for example, in the range of about 1.5 g / cc to about 2.3 g / cc. In other embodiments, the scaffold density is in the range of about 1.5 g / cc to about 1.6 g / cc, about 1.6 g / cc to about 1.7 g / cc, about 1.7 g / cc to about 1.8 g / cc, about 1.8 g / cc to about 1.9 g / cc, about 1.9 g / cc to about 2.0 g / cc, about 2.0 g / cc to about 2.1 g / cc, about 2.1 g / cc to about 2.2 g / cc, about 2.2 g / cc to about 2.3 g / cc, about 2.3 g / cc to about 2.4 g / cc, and about 2.4 g / cc to about 2.5 g / cc.

[0076] C. Manufacturing of silicon by chemical vapor impregnation (CVI) Chemical vapor deposition (CVD) is a method in which a substrate provides a solid surface containing the first component of a composite, and a gas thermally decomposes on the solid surface of the first component to provide the second component of the composite. Such a CVD approach can be used, for example, to produce Si-C composite materials in which silicon is coated on the outer surface of silicon particles. Alternatively, chemical vapor infiltration (CVI) is a method in which a substrate provides a porous scaffold containing the first component of a composite, and a gas thermally decomposes within the pores of the porous scaffold material to provide the second component of the composite.

[0077] In one embodiment, silicon is created within the pores of the porous carbon scaffold by exposing the porous carbon particles to a silicon-containing precursor gas at elevated temperature and in the presence of a silicon-containing gas, preferably silane, to decompose the silicon-containing gas into silicon. In some embodiments, the silicon-containing gas may include higher silanes (such as di-, tri-, and / or tetrasilane), chlorosilanes (such as mono-, di-, tri-, and tetrachlorosilane), or mixtures thereof.

[0078] The silicon-containing precursor gas may be mixed with other inert gases, such as nitrogen gas, hydrogen gas, argon gas, helium gas, or a combination thereof, etc. The treatment temperature and time may vary, for example, the temperature may be 200°C to 900°C, for example, 200°C to 250°C, for example, 250°C to 300°C, for example, 300°C to 350°C, for example, 300°C to 400°C, for example, 350°C to 450°C, for example, 350°C to 400°C, for example, 400°C to 500°C, for example, 500°C to 600°C, for example, 600°C to 700°C, for example, 700°C to 800°C, for example, 800°C to 900°C, for example, 600°C to 1100°C, etc.

[0079] The gas mixture may comprise 0.1-1% silane and the remainder an inert gas. Alternatively, the gas mixture may comprise 1-10% silane and the remainder an inert gas. Alternatively, the gas mixture may comprise 10-20% silane and the remainder an inert gas. Alternatively, the gas mixture may comprise 20-50% silane and the remainder an inert gas. Alternatively, the gas mixture may comprise greater than 50% silane and the remainder an inert gas. Alternatively, the gas may comprise essentially 100% silane gas. Suitable inert gases include, but are not limited to, hydrogen, nitrogen, argon, and combinations thereof.

[0080] The pressure in the CVI process can vary. In some embodiments, the pressure is atmospheric. In some embodiments, the pressure is less than atmospheric. In some embodiments, the pressure is greater than atmospheric.

[0081] D. Physicochemical and electrochemical properties of silicon-carbon composites Without wishing to be bound by theory, it is believed that the nanosized silicon results from loading the porous carbon scaffold into the desired pore volume structure (e.g., silicon-filled pores in the range of 5 nm to 1000 nm, or other ranges disclosed elsewhere herein), which, along with advantageous properties of the other components of the composite (including low surface area, low pycnometric density), results in a composite having a variety of advantageous properties (e.g., electrochemical performance) when the composite comprises an anode for a lithium ion energy storage device.

[0082] In certain embodiments, the silicon particles embedded within the composite have nanosized features, which may have a characteristic length scale of preferably less than 1 μm, preferably less than 300 nm, preferably less than 150 nm, preferably less than 100 nm, preferably less than 50 nm, preferably less than 30 nm, preferably less than 15 nm, preferably less than 10 nm, preferably less than 5 nm.

[0083] In certain embodiments, the silicon embedded within the composite is spherical in shape. In other specific embodiments, the porous silicon particles are non-spherical, e.g., rod-like or fibrous in structure. In some embodiments, the silicon is present as a layer coating the inside of the pores within the porous carbon scaffold. The depth of this silicon layer may vary, e.g., 5 nm to 10 nm, e.g., 5 nm to 20 nm, e.g., 5 nm to 30 nm, e.g., 5 nm to 33 nm, e.g., 10 nm to 30 nm, e.g., 10 nm to 50 nm, e.g., 10 nm to 100 nm, e.g., 10 nm to 150 nm, e.g., 50 nm to 150 nm, e.g., 100 nm to 300 nm, e.g., 300 nm to 1000 nm, etc.

[0084] In some embodiments, the silicon embedded within the composite is nanosized and resides within the pores of a porous carbon scaffold. For example, the embedded silicon may be impregnated and deposited into pores within porous carbon particles by CVI or other suitable processes (where the diameter of the pores is 5–1000 nm, including, for example, 10–500 nm, 10–200 nm, 10–100 nm, 33–150 nm, 20–100 nm, etc.). Other ranges of carbon pore size with respect to fragmentary pore volume are similarly assumed, whether they are micropores, mesopores, or macropores.

[0085] Embodiments of composites with highly durable lithium intercalation disclosed herein improve numerous properties of electrical energy storage devices, such as lithium-ion batteries. In some embodiments, the silicon-carbon composites disclosed herein exhibit a Z of less than 10, for example, less than 5, less than 4, less than 3, less than 2, less than 1, less than 0.1, less than 0.01, less than 0.001, etc. In certain embodiments, Z is 0.

[0086] In certain preferred embodiments, the silicon-carbon composite includes a combination of preferably low Z and other desired physicochemical and / or electrochemical properties, or a combination of several other desired physicochemical and / or electrochemical properties. A description of specific embodiments regarding property combinations of the silicon-carbon composite is shown in Table 1 below.

[0087] Specific Properties of Silicon-Carbon Composite Embodiments [Table 1]

[0088] According to Table 1, silicon-carbon composites can include a variety of property combinations. For example, silicon-carbon composites can have Z less than 10, 100m 2 For example, silicon-carbon composites may have a surface area of ​​less than 10, a first cycle efficiency of greater than 80%, and a reversible capacity of 1300 mAh / g or greater. 2 For example, silicon-carbon composites may have a surface area of ​​less than 10, a first cycle efficiency of greater than 80%, and a reversible capacity of 1600 mAh / g or greater. 2 For example, silicon-carbon composites may have a surface area of ​​less than 10, a first cycle efficiency of greater than 85%, and a reversible capacity of 1600 mAh / g or greater. 2 For example, silicon-carbon composites may have a surface area of ​​less than 10, a first cycle efficiency of greater than 85%, and a reversible capacity of 1600 mAh / g or greater. 2 For example, silicon-carbon composites may have a surface area of ​​less than 10, a first cycle efficiency of greater than 90%, and a reversible capacity of 1600 mAh / g or greater. 2 / g, first cycle efficiency greater than 90%, and reversible capacity greater than or equal to 1800 mAh / g.

[0089] The silicon-carbon composite can include a combination of the above properties, and the carbon scaffold can also include properties described herein. Accordingly, a description of a specific embodiment of a combination of physical properties for a silicon-carbon composite is provided below in Table 2.

[0090] Specific Properties of Silicon-Carbon Composite Embodiments [Table 2]

[0091] As used herein, the percentages "microporosity," "mesoporosity," and "macroporosity" refer to the percentage of micropores, mesopores, and macropores, respectively, relative to the total pore volume. For example, a carbon scaffold having 90% microporosity is a carbon scaffold in which 90% of the total pore volume of the carbon scaffold is formed by micropores.

[0092] According to Table 2, silicon-carbon composites can contain various combinations of physical properties. For example, silicon-carbon composites have an I of 0.7 or less. D / I G , Z less than 10, 100m 2 Surface area less than / g, first cycle efficiency greater than 80%, reversible capacity of 1600mAh / g or more, silicon content of 15% to 85%, and 0.2 to 1.2cm² 3 / g of total pore volume of the carbon scaffold (wherein the pore volume includes more than 80% micropores, less than 20% mesopores, and less than 10% macropores). For example, the silicon-carbon composite may have an I of 0.7 or less. D / I G , Z less than 10, 20m 2 Surface area less than / g, first cycle efficiency greater than 85%, reversible capacity of 1600mAh / g or more, silicon content of 15% to 85%, and 0.2 to 1.2cm² 3 / g of total pore volume of the carbon scaffold (wherein the pore volume of the scaffold comprises more than 80% micropores, less than 20% mesopores, and less than 10% macropores). For example, the silicon-carbon composite may have an I of 0.7 or less. D / I G , Z less than 10, 10m 2 Surface area less than / g, first cycle efficiency greater than 85%, reversible capacity of 1600mAh / g or more, silicon content of 15-85%, and 0.2-1.2cm² 3 / g of total pore volume of the carbon scaffold (wherein the pore volume of the scaffold comprises more than 80% micropores, less than 20% mesopores, and less than 10% macropores). For example, the silicon-carbon composite may have an I of 0.7 or less. D / I G , Z less than 10, 10m 2 / g surface area, greater than 90% first cycle efficiency, greater than 1600 mAh / g reversible capacity, 15% to 85% silicon content, and 0.2 to 1.2 cm 3 / g of total pore volume of the carbon scaffold (wherein the pore volume of the scaffold comprises more than 80% micropores, less than 20% mesopores, and less than 10% macropores). For example, the silicon-carbon composite may have an I of 0.7 or less. D / I G , Z less than 10, 10m 2 / g surface area, greater than 90% first cycle efficiency, greater than 1800 mAh / g reversible capacity, 15% to 85% silicon content, and 0.2 to 1.2 cm 3 / g of total pore volume of the carbon scaffold, where the pore volume of the scaffold includes more than 80% micropores, less than 20% mesopores, and less than 10% macropores.

[0093] Without being bound by theory, it is believed that the loading of silicon into the pores of the porous carbon traps the pores within the porous carbon scaffold particles, creating inaccessible volumes, e.g., volumes inaccessible to nitrogen gas. Thus, the silicon-carbon composite material has a density of 2.1 g / cm 3 exhibiting a pycnometric density of less than, for example, 2.0 g / cm 3 Less than, for example, 1.9 g / cm 3 Less than, for example, 1.8 g / cm 3 Less than, for example, 1.7 g / cm 3 Less than, for example, 1.6 g / cm 3 Less than, for example, 1.4 g / cm 3 Less than, for example, 1.2 g / cm 3 Less than, for example, 1.0 g / cm 3 Indicates less than, etc.

[0094] In some embodiments, the silicon-carbon composite material is 1.7 g / cm³. 3 ~2.1g / cm 3 The pycnometric density may also be shown, for example, 1.7 g / cm³. 3 ~1.8g / cm 3 , e.g., 1.8 g / cm 3 ~1.9g / cm 3 , e.g., 1.9 g / cm 3 ~2.0g / cm 3 , e.g., 2.0 g / cm 3 ~2.1g / cm 3 The following may be indicated. In some embodiments, the silicon-carbon composite material is 1.8 g / cm³. 3 ~2.1g / cm 3 It may exhibit a pycnometric density of 1.8 g / cm³. In some embodiments, the silicon-carbon composite material has a density of 1.8 g / cm³. 3 ~2.0g / cm 3 It may exhibit a pycnometric density of 1.9 g / cm³. In some embodiments, the silicon-carbon composite material has a density of 1.9 g / cm³. 3 ~2.1g / cm 3 It can show a pycnometric density of

[0095] The pore volume of the composite material exhibiting highly durable lithium intercalation is 0.01 cm³. 3 / g~0.2cm 3 It can be / g. In certain embodiments, the pore volume of the composite material is 0.01 cm³. 3 / g~0.15cm 3 / g, for example 0.01 cm 3 / g~0.1cm 3 / g, e.g., 0.01 cm 3 / g~0.05cm 3 / g, etc.

[0096] The particle size distribution of composites exhibiting very durable lithium intercalation is equally important for both power performance and volumetric capacity. Increased packing may also increase volumetric capacity. In one embodiment, the distribution is either Gaussian with a sharp peak, bimodal, or polymodal (more than two distinct peaks, e.g., trimodal). The particle size properties of the composites may be described by Dv0 (smallest particle in the distribution), Dv50 (average particle size), and Dv100 (maximum size of the largest particle). The optimal combination of particle packing and performance is a combination of the following size ranges: Particle size reduction in such embodiments can be achieved, for example, by jet milling in the presence of various gases, as known in the art. Examples of such gases include air, nitrogen, argon, helium, supercritical steam, and others known in the art.

[0097] In one embodiment, the Dv0 of the composite material may be in the range of 1 nm to 5 μm. In another embodiment, the Dv0 of the composite is in the range of 5 nm to 1 μm, for example, 5 to 500 nm, for example, 5 to 100 nm, for example, 10 to 50 nm. In another embodiment, the Dv0 of the composite is in the range of 500 nm to 2 μm, for example, 750 nm to 1 μm, or 1 to 2 μm. In another embodiment, the Dv0 of the composite is 2 to 5 μm, or greater than 5 μm.

[0098] In some embodiments, the Dv50 of the composite material is in the range of 5 nm to 20 μm. In other embodiments, the Dv50 of the composite is in the range of 5 nm to 1 μm, such as 5 to 500 nm, such as 5 to 100 nm, or 10 to 50 nm. In other embodiments, the Dv50 of the composite is in the range of 500 nm to 2 μm, 750 nm to 1 μm, or 1 to 2 μm. In other further embodiments, the Dv50 of the composite is in the range of 1 to 1000 μm, such as 1 to 100 μm, such as 1 to 100 μm, such as 1 to 10 μm, such as 2 to 20 μm, such as 3 to 15 μm, or 4 to 8 μm. In certain embodiments, the Dv50 is greater than 20 μm, such as greater than 50 μm, for example greater than 100 μm.

[0099] The span is given by: (Dv50) / (Dv90-Dv10) [where Dv10, Dv50, and Dv90 represent particle sizes at 10%, 50%, and 90% of the volume distribution, respectively] The span can vary, for example, from 100 to 10, 10 to 5, 5 to 2, or 2 to 1. In some embodiments, the span may be less than 1. In certain embodiments, the particle size distribution of the composite containing carbon and porous silicon material may be multimodal (e.g., bimodal or trimodal).

[0100] The surface functionality of the composite materials disclosed herein that exhibit highly durable lithium intercalation may be modified to obtain desired electrochemical properties. For particulate composite materials, such properties include the concentration of atomic species at the surface of the composite relative to the interior of the composite. Such differences in atomic species concentration at the surface versus the interior of a particulate composite can be measured, for example, by X-ray photoelectron spectroscopy (XPS), as is known in the art.

[0101] Another property that can predict surface functionality is the pH of the composite material. The composite materials disclosed herein include those having a pH ranging from less than 1 to about 14, including, for example, less than 5, 5-8, or greater than 8. In some embodiments, the pH of the composite material is less than 4, less than 3, less than 2, or less than 1. In other embodiments, the pH of the composite material is about 5-6, about 6-7, about 7-8, 8-9, or 9-10. In still further embodiments, the pH of the composite material is high, such as greater than 8, greater than 9, greater than 10, greater than 11, greater than 12, or greater than 13.

[0102] Silicon-carbon composites can contain varying amounts of carbon, oxygen, hydrogen, and nitrogen, as determined by gas chromatography CHNO analysis. In one embodiment, the carbon content of the composite is greater than 98 wt.%, or greater than 99.9 wt.%, as determined by CHNO analysis. In another embodiment, the carbon content of the silicon-carbon composite ranges from 10 to 90 wt.%, including, for example, 20 to 80 wt.%, such as, for example, 30 to 70 wt.%, such as, for example, 40 to 60 wt.%, etc.

[0103] In some embodiments, the silicon-carbon composite has a nitrogen content in the range of 0-90%, such as 0.1-1%, for example 1-3%, for example 1-5%, for example 1-10%, for example 10-20%, for example 20-30%, for example 30-90%.

[0104] In some embodiments, the oxygen content is in the range of 0-90%, such as 0.1-1%, for example 1-3%, for example 1-5%, for example 1-10%, for example 10-20%, for example 20-30%, for example 30-90%, etc.

[0105] Silicon-carbon composite materials may incorporate electrochemical modifiers selected to optimize the electrochemical properties of the unmodified composite. The electrochemical modifiers may be introduced in the pore structure and / or on the surface of the porous carbon scaffold, within embedded silicon, or within the final layer of carbon, or by conductive polymers, coatings, or numerous other methods. For example, in some embodiments, the composite material includes a coating of the electrochemical modifier (e.g., silicon, or Al2O3) on the surface of the carbon material. In some embodiments, the composite material contains more than about 100 ppm of the electrochemical modifier. In certain embodiments, the electrochemical modifier is selected from iron, tin, silicon, nickel, aluminum, and manganese.

[0106] In certain embodiments, the electrochemical modifier comprises elements (e.g., silicon, tin, sulfur) that have the ability to lithiate lithium metal at 3 to 0 V. In other embodiments, the electrochemical modifier comprises metal oxides (e.g., iron oxide, molybdenum oxide, titanium oxide) that have the ability to lithiate lithium metal at 3 to 0 V. In further embodiments, the electrochemical modifier comprises elements (e.g., aluminum, manganese, nickel, metal phosphates) that do not lithiate lithium metal at 3 to 0 V. In further embodiments, the electrochemical modifier comprises nonmetallic elements (e.g., fluorine, nitrogen, hydrogen). In further embodiments, the electrochemical modifier comprises any of the above electrochemical modifiers, or any combination thereof (e.g., tin-silicon, nickel-titanium oxide).

[0107] The electrochemical modifier may be provided in a number of forms. For example, in some embodiments, the electrochemical modifier comprises a salt. In other embodiments, the electrochemical modifier comprises one or more elements in elemental form, such as iron, tin, silicon, nickel, or manganese. In other embodiments, the electrochemical modifier comprises one or more elements in oxide form, such as iron oxide, tin oxide, silicon oxide, nickel oxide, aluminum oxide, or manganese oxide.

[0108] The electrochemical properties of the composite material can be modified, at least in part, by the amount of electrochemical modifier in the material, where the electrochemical modifier is an alloy material such as silicon, tin, indium, aluminum, germanium, or gallium. Thus, in some embodiments, the composite material comprises 0.10% or more, 0.25% or more, 0.50% or more, 1.0% or more, 5.0% or more, 10% or more, 25% or more, 50% or more, 75% or more, 90% or more, 95% or more, 99% or more, or 99.5% or more of the electrochemical modifier.

[0109] The particle size of the composite material may expand upon lithiation compared to the unlithiated state. For example, the expansion coefficient is defined as the ratio of the average particle size of the composite material containing the porous silicon material upon lithiation divided by the average particle size under non-lithiation conditions. As described in the art, the expansion coefficient is relatively large for known, non-optimal silicon-containing materials, e.g., about 4X (corresponding to a 400% volume expansion upon lithiation). The present inventors have discovered composite materials containing porous silicon material that can exhibit lower expansion coefficients, e.g., expansion coefficients that can vary from 3.5 to 4.0, 3.0 to 3.5, 2.5 to 3.0, 2.0 to 2.5, 1.5 to 2.0, or 1.0 to 1.5.

[0110] It is envisioned that the composite material in certain embodiments contains a portion of trapped pore volume, i.e., a portion of void volume that is inaccessible to nitrogen gas, where the void volume can be measured by nitrogen gas adsorption measurements. Without being bound by theory, this trapped pore volume is important in that it provides a volume into which silicon can expand upon lithiation.

[0111] In certain embodiments, the ratio of the trapped void volume to the silicon volume containing the composite particles is 0.1:1 to 10:1. For example, the ratio of the trapped void volume to the silicon volume containing the composite particles is 1:1 to 5:1, or 5:1 to 10:1. In some embodiments, the ratio of the trapped void volume to the silicon volume containing the composite particles is between 2:1 and 5:1, or about 3:1, which can efficiently accommodate the maximum expansion of silicon during lithiation.

[0112] In certain embodiments, the electrochemical performance of the composites disclosed herein is tested in half-cells; otherwise, the performance of composites with highly durable lithium intercalations disclosed herein is tested in full cells (e.g., a full-cell coin cell, a full-cell pouch cell, a prismatic cell, or battery configurations known in the art, etc.). The anode configurations of composites with highly durable lithium intercalations disclosed herein include a variety of types, as known in the art. Further formulation components are not particularly limited but include conductive additives, such as conductive carbon (e.g., Super C45, Super P, and Ketjenblack carbon), conductive polymers, and binders (e.g., styrene-butadiene rubber sodium carboxymethylcellulose (SBR-Na-CMC), polyvinylidene fluoride (PVDF), polyimide (PI), and polyacrylic acid (PAA)), and combinations thereof. In certain embodiments, the binder may include lithium ions as counterions.

[0113] Other species containing electrodes are known in the art. The weight percent of active material in the electrode can vary, such as 1-5 wt %, for example, 5-15 wt %, for example, 15-25 wt %, for example, 25-35 wt %, for example, 35-45 wt %, for example, 45-55 wt %, for example, 55-65 wt %, for example, 65-75 wt %, for example, 75-85 wt %, for example, 85-95 wt %, etc. In some embodiments, the active material comprises 80-95% of the electrode. In certain embodiments, the amount of conductive additive in the electrode can vary, such as 1-5 wt %, for example, 5-15 wt %, for example, 15-25 wt %, for example, 25-35 wt %, etc. In some embodiments, the amount of conductive additive in the electrode is 5-25 wt %. In certain embodiments, the amount of binder may vary, for example, 1-5% by weight, 5-15% by weight, 15-25% by weight, 25-35% by weight, etc. In certain embodiments, the amount of conductive additive in the electrode is 5-25% by weight.

[0114] The silicon-carbon composite material is pre-lithiated as known in the art. In certain embodiments, pre-lithiation is accomplished electrochemically, e.g., in a half-cell prior to construction of a lithiated anode comprising the porous silicon material in a full-cell lithium-ion battery. In certain embodiments, pre-lithiation is accomplished by doping the cathode with a lithium-containing compound (e.g., a lithium-containing salt). Suitable lithium salts in this embodiment include, but are not limited to, for example, dilithium tetrabromonickel(II), dilithium tetrachlorocuprate(II), lithium azide, lithium benzoate, lithium bromide, lithium carbonate, lithium chloride, lithium cyclohexanebutyrate, lithium fluoride, lithium formate, lithium hexafluoroarsenate(V), lithium hexafluorophosphate, lithium hydroxide, lithium iodate, lithium metaborate, lithium perchlorate, lithium phosphate, lithium sulfate, lithium tetraborate, lithium tetrachloroaluminate, lithium tetrafluoroborate, lithium thiocyanate, lithium trifluoromethanesulfonate, and combinations thereof.

[0115] Anodes comprising silicon-carbon composites can be paired with a variety of cathode materials to produce full-cell lithium-ion batteries. Examples of suitable cathode materials are known in the art. Such cathode materials include, but are not limited to, LiCoO (LiCoO), LiNi 0.8 Co 0.15 Al 0.05 O2(NCA), LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 This includes O2 (NMC), LiMn2O4 and its variants (LMO), and LiFePO4 (LFP), etc.

[0116] With respect to a full-cell lithium-ion battery including an anode further comprising a silicon-carbon composite material, the cathode-anode pair can vary. For example, the cathode-anode capacity ratio can vary from 0.7 to 1.3. In certain embodiments, the cathode-anode capacity ratio can vary from 0.7 to 1.0, for example, from 0.8 to 1.0, for example, from 0.85 to 1.0, for example, from 0.9 to 1.0, for example, from 0.95 to 1.0. In other embodiments, the cathode-anode capacity ratio can vary from 1.0 to 1.3, for example, from 1.0 to 1.2, for example, from 1.0 to 1.15, for example, from 1.0 to 1.1, for example, from 1.0 to 1.05. In yet another embodiment, the ratio of the cathode to anode capacity may vary from 0.8 to 1.2, such as from 0.9 to 1.1, for example from 0.95 to 1.05.

[0117] With respect to a full-cell lithium-ion battery including an anode further comprising a silicon-carbon composite material, the voltage window during charging and discharging can vary. In this regard, the voltage window can vary depending on the various characteristics of the lithium-ion battery, as is known in the art. For example, as is known in the art, the choice of cathode plays a role in the selected voltage window. The voltage window can vary, for example, 2.0V to 5.0V for the potential relative to Li / Li+, and can range from 2.5V to 4.5V, 2.5V to 4.2V, and so on.

[0118] With respect to a full-cell lithium-ion battery including an anode further comprising a silicon-carbon composite material, there can be various methods for conditioning the cell, as is known in the art. For example, conditioning can be achieved by performing multiple charge and discharge cycles at various rates, for example, at a rate slower than the desired cycle rate. As is known in the art, the conditioning process may further include the steps of opening the lithium-ion battery, evacuating all gases generated during the conditioning process, and subsequently resealing the lithium-ion battery.

[0119] For full-cell lithium-ion batteries including an anode further comprising a silicon-carbon composite material, the cycle rate can vary as known in the art, e.g., the rate can vary from C / 20 to 20C, e.g., C / 10 to 10C, e.g., C / 5 to 5C, etc. In certain embodiments, the cycle rate is C / 10. In certain embodiments, the cycle rate is C / 5. In certain embodiments, the cycle rate is C / 2. In certain embodiments, the cycle rate is 1C. In certain embodiments, the cycle rate is 1C with periodic reductions to slower rates (e.g., applying a C / 10 rate reduction every 20 cycles). In certain embodiments, the cycle rate is 2C. In certain embodiments, the cycle rate is 4C. In certain embodiments, the cycle rate is 5C. In certain embodiments, the cycle rate is 10C. In certain embodiments, the cycle rate is 20C.

[0120] The first cycle efficiency of the highly durable lithium intercalation composites disclosed herein was measured by comparing the lithium inserted into the anode during the first cycle, prior to prior lithiation, with the lithium extracted from the anode during the first cycle. When insertion and extraction are equal, the efficiency is 100%. As is known in the art, anode materials can be tested in half-cells, where the counter electrode is lithium metal, the electrolyte is 1 M LiPF6, and 1:1 ethylene carbonate:diethyl carbonate (EC:DEC), and a commercially available polypropylene separator is used. In certain embodiments, the electrolyte can contain various additives known to enhance performance, such as fluoroethylene carbonate (FEC) or other related fluorinated carbonate compounds, or ester cosolvents (e.g., methyl butanoate, vinylene carbonate, etc.), and other additives known to enhance the electrochemical performance of silicon-containing anode materials.

[0121] Coulomb efficiency can be averaged, for example, in half-cell testing, it can be averaged over cycles 7 to 25. In certain embodiments, the average efficiency of a composite with very durable lithium intercalation is greater than 0.9 or greater than 90%. In certain embodiments, the average efficiency is greater than 0.95 or greater than 95%. In certain embodiments, the average efficiency is 0.99 or higher, and includes, for example, 0.991 or higher, 0.992 or higher, 0.993 or higher, 0.994 or higher, 0.995 or higher, 0.996 or higher, 0.997 or higher, 0.998 or higher, 0.999 or higher, 0.9991 or higher, 0.9992 or higher, 0.9993 or higher, 0.9994 or higher, 0.9995 or higher, 0.9996 or higher, 0.9997 or higher, 0.9998 or higher, 0.9999 or higher, etc.

[0122] In still other embodiments, the present disclosure provides composite materials that exhibit highly durable lithium intercalation, wherein the composite materials, when incorporated into an electrode of a lithium-based energy storage device, have a volumetric capacity that is at least 10% higher than when incorporated into an electrode of a lithium-based energy storage device that includes a graphite electrode. In some embodiments, the lithium-based energy storage device is a lithium-ion battery. In some embodiments, the composite materials have a volumetric capacity in a lithium-based energy storage device that is at least 5%, at least 10%, or at least 15% higher than a similar electrical energy storage device with a graphite electrode. In still other embodiments, the composite materials have a volumetric capacity in a lithium-based energy storage device that is at least 20%, at least 30%, at least 40%, at least 50%, at least 200%, at least 100%, at least 150%, or at least 200% higher than a similar electrical energy storage device with a graphite electrode.

[0123] The composite material may be pre-lithiated as is known in the art. These lithium atoms may or may not be separable from carbon. The number of lithium atoms relative to six carbon atoms is determined by the following formula, which is known to those skilled in the art: #Li=Q×3.6×MM / (C%×F) [Here, Q is the lithium extraction capacity (mAh / g) measured at a voltage of 5mV to 2.0V relative to lithium metal, MM is the molecular mass of 72 or 6 carbon atoms, F is the Faraday constant (96500), and C% is the weight percentage of carbon present in the structure, measured by CHNO or XPS.] It can be calculated by:

[0124] The composite material can be characterized by the ratio of lithium atoms to carbon atoms (Li:C), which can be between about 0:6 and 2:6. In some embodiments, the Li:C is between about 0.05:6 and 1.9:6. In other embodiments, the lithium is in ionic and not metallic form, and the maximum Li:C ratio is 2.2:6. In certain other embodiments, the Li:C ratio is between about 1.2:6 and about 2:6, between about 1.3:6 and about 1.9:6, between about 1.4:6 and about 1.9:6, between about 1.6:6 and about 1.8:6, or between about 1.7:6 and about 1.8:6. In other embodiments, the Li:C ratio is greater than 1:6, greater than 1.2:6, greater than 1.4:6, greater than 1.6:6, or greater than 1.8:6. In further other embodiments, the Li:C ratio is about 1.4:6, about 1.5:6, about 1.6:6, about 1.7:6, about 1.8:6, or about 2:6. In certain embodiments, the Li:C ratio is about 1.78:6.

[0125] In certain embodiments, the composite material comprises a Li:C ratio ranging from about 1:6 to about 2.5:6, from about 1.4:6 to about 2.2:6, or from about 1.4:6 to about 2:6. In yet other embodiments, the composite material does not necessarily contain lithium, but instead has a lithium uptake capacity, i.e., the ability to absorb a certain amount of lithium, for example, during cycling of the material between two voltage conditions (for a lithium-ion half cell, a typical voltage window is 0 to 3 V, including, e.g., 0.005 to 2.7 V, e.g., 0.005 to 1 V, e.g., 0.005 to 0.8 V, etc.). Without wishing to be bound by theory, the lithium uptake capacity of the composite material contributes to its superior performance in lithium-based energy storage devices. Lithium uptake capacity is expressed as the ratio of lithium atoms replaced by the composite. In other specific embodiments, composite materials exhibiting highly durable lithium intercalation include lithium uptake capacities ranging from 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, etc.

[0126] In certain other embodiments, the lithium uptake capacity ranges 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, etc. In other embodiments, the lithium uptake capacity is greater than 1:6, greater than 1.2:6, greater than 1.4:6, greater than 1.6:6, or greater than 1.8:6. In still 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 one particular embodiment, the Li:C ratio is about 1.78:6.

[0127] D. Improving the graphiticity of porous carbon scaffolds In certain embodiments, the electrochemical properties of the silicon-carbon material may be enhanced by enhancing the electrochemical properties of the carbon scaffold. In some embodiments, improving the graphiticity of the carbon scaffold results in increased electrical conductivity (ionic and / or electronic conductivity) and / or reduced reactivity upon contact with various other components present in LIBs (e.g., electrolyte components) and / or other beneficial properties, such as a more stable SEI formed in LIBs.

[0128] The graphiticity of the carbon scaffold may be increased by heat treatment of the porous carbon scaffold, resulting in a partial transformation of the carbon structure from amorphous to graphite. To this end, the heat treatment temperature can be 900°C or higher, such as 1000°C or higher, 1100°C or higher, 1200°C or higher, 1300°C or higher, 1400°C or higher, 1500°C or higher, 1600°C or higher, 1700°C or higher, 1800°C or higher, 2000°C or higher, or 3000°C or higher. In some embodiments, the heat treatment temperature is 1000°C to 3000°C, for example, 1000°C to 2700°C, for example, 1000°C to 2500°C, for example, 1000°C to 2300°C, for example, 1000°C to 2000°C, for example, 1100°C to 3000°C, for example, 1100°C to 2700°C, for example, 1100°C to 2500°C, for example, 1100°C to 2000°C, for example, 1200°C to 2000°C, for example, 1100°C to 1700°C.

[0129] In some embodiments, the pressure during the heat treatment can be less than atmospheric pressure. In certain other embodiments, the pressure during the heat treatment can be greater than atmospheric pressure. In preferred embodiments, the pressure during heating of the porous carbon scaffold can be atmospheric pressure. The heat treatment can be performed for a variety of times, for example, from 1 minute to 24 hours. In some embodiments, the heat treatment can be performed for more than 24 hours. In some embodiments, a relatively rapid heating, a relatively short treatment time, and a relatively rapid cooling are preferred to minimize the effect of the heat treatment on the total pore volume and pore volume distribution in the porous carbon. In some embodiments, the treatment time is from 1 hour to 24 hours, including, for example, from 1 hour to 2 hours, from 2 hours to 4 hours, from 4 hours to 8 hours, from 8 hours to 24 hours, etc.

[0130] In some embodiments, microwave energy can be used to heat and / or otherwise enhance the graphiticity of the carbon scaffold. Without being bound by theory, carbon particles are efficient microwave absorbers, and a reactor can be envisioned in which the particles are heated by microwave irradiation prior to introducing a silicon-containing gas to deposit on the particles.

[0131] Because temperature is related to the average kinetic energy (energy of movement) of the atoms or molecules in a material, agitating the molecules increases the temperature of the material. Thus, dipole rotation is the mechanism by which energy in the form of electromagnetic radiation can increase the temperature of an object. Dipole rotation is a mechanism commonly referred to as dielectric heating and is most widely found in microwave ovens. It is most effective with liquid water but less effective with fats, sugars, and other carbon-containing materials.

[0132] Dielectric heating involves the heating of electrically insulating materials due to dielectric losses. A change in the electric field across the material dissipates energy as molecules attempt to align with the continuously changing electric field. This change in electric field can occur either through electromagnetic waves propagating in free space (as in a microwave oven) or through rapidly changing electric fields within a capacitor. In the latter case, there are no freely propagating electromagnetic waves, and the change in electric field would appear similar to the electrical components in the near-field of an antenna. In this case, at radio frequency (RF) frequencies, no actual RF is generated or absorbed, even though heating is achieved by changing the electric field within the capacitive cavity. In this sense, the effect is a direct electrical analog of magnetic induction heating, which is also a near-field effect (and therefore does not involve RF).

[0133] At very high frequencies, the wavelength of the electromagnetic field becomes smaller than the distance between the metal walls of the heating cavity, or even the dimensions of the walls themselves. This is the case inside a microwave oven. In such cases, conventional far-field electromagnetic waves form (the cavity no longer functions as a pure capacitor, but rather as an antenna), are absorbed, and generate heat, but the dipole rotation mechanism of thermal evaporation remains unchanged. However, microwaves are not as efficient at producing the heating effects of low-frequency fields that rely on slower molecular motions, such as those caused by ion drag.

[0134] Microwave heating is a subcategory of dielectric heating at frequencies above 100 MHz. At these frequencies, electromagnetic waves can be emitted from a small emitter through space to a target. Modern microwave ovens use electromagnetic waves with very large frequencies and short wavelengths, resulting in electric fields, compared to RF heaters. A typical household microwave oven operates at 2.45 GHz, but 915 MHz ovens also exist. This means that the wavelength used in microwave heating is 12 cm or 33 cm (4.7 in or 13.0 in). This is very efficient, but has poor penetration and dielectric heating. While a set of plates, like a capacitor, can be used at microwave frequencies, they are not necessary. Microwaves already exist as far-field electromagnetic radiation, and their absorption does not require the proximity of a small antenna, as in RF heating. Therefore, the (non-metallic) material to be heated can simply be placed in the path of the wave, and heating occurs non-contact.

[0135] Thus, microwave absorbing materials can dissipate electromagnetic waves by converting them into thermal energy. Without being bound by theory, the microwave absorption ability of a material is primarily determined by its relative permittivity, relative permeability, electromagnetic impedance matching, and the microstructure of the material (e.g., its porosity and / or nanostructure, or microstructure). When a microwave beam is irradiated onto the surface of a microwave absorbing material, a suitable matching condition in the electromagnetic impedance can make the reflectance of the incident microwaves nearly zero, ultimately allowing the transfer of thermal energy into the absorbing material.

[0136] From here Carbon materials can absorb microwaves, i.e., they are easily heated by microwave radiation (i.e., infrared and radio waves in the region of the electromagnetic spectrum). More specifically, they are defined as waves with wavelengths between 0.001 and 1 m (which corresponds to frequencies between 300 and 0.3 GHz). The susceptibility of carbon to heating in a microwave field is defined by the dielectric loss tangent: tanδ = ε′′ / ε′. The dielectric loss tangent consists of two parameters: the dielectric constant (or permittivity, real part) ε′, and the dielectric loss factor (or permittivity, imaginary part) ε′′; i.e., ε = ε′-iε′′ (where ε is the complex permittivity). The dielectric constant (ε′) determines how much of the incident energy is reflected and how much is absorbed. The dielectric loss factor (ε′′) is a measure of the dissipation of electrical energy in the form of heat within the material. Optimal microwave energy coupling requires a combination of moderate ε' and high ε'' values ​​(and very high tan δ) to convert microwave energy into thermal energy. Thus, while some materials lack a sufficiently high loss factor for dielectric heating (i.e., microwaves are transparent), others, such as some inorganic oxides and most carbon materials, are very good microwave absorbers. On the other hand, conductive materials reflect microwaves. For example, graphite and highly graphitic carbons can reflect a large portion of microwave radiation. In the case of carbon, where delocalized π electrons are free to move over a relatively large area, an additional, very interesting phenomenon can occur. If the kinetic energy of some electrons increases, they can be ejected from the material, potentially ionizing the surrounding atmosphere. At a macroscopic level, this phenomenon is considered the formation of a spark or arc discharge. However, at a microscopic level, these hot spots are actually plasmas. Most of the time, these plasmas can be considered microplasmas, both in terms of space and time. The intense generation of such microplasmas may have important implications for related methods, as they are confined to very small regions of space and last only a short time.

[0137] Without being bound by theory, heating carbon materials by microwave heating offers the following advantages over conventional heating: i) non-contact heating; ii) energy transfer instead of heat transfer; iii) rapid heating; iv) selective material heating; v) large-volume heating; vi) fast start-up and shutdown; vii) heating from within the material; and viii) a higher level of safety and automation. The high capacity of carbon materials for absorbing microwave energy and converting it to heat is shown in Table 3 (adapted from J.A. Menendez, A. Arenillas, B. Fidalgo, Y. Fernandez, L. Zubizarreta, E.G. Calvo, J.M. Bermudez, "Microwave heating processes involving carbon materials," Fuel Processing Technology, 2010, 91 (1), 1-8). Table 3 also shows examples of the dielectric loss tangent for various carbons. As can be seen, the dielectric loss tangent of most carbons (except coal) is higher than that of distilled water (tan δ=0.118 for distilled water at 2.45 GHz and room temperature).

[0138] Examples of dielectric loss tangents for various carbon materials at a frequency of 2.45 GHz and room temperature. [Table 3]

[0139] Whether conventional heat treatment or microwave treatment is used to improve the graphiticity of a porous carbon scaffold, it is important to consider its impact on the total pore volume and pore volume distribution. To this end, the total pore volume and pore volume distribution of the porous carbon scaffold can be measured by gas adsorption analysis, e.g., nitrogen and / or carbon dioxide gas adsorption analysis, as known in the art. In this method, the pore volume and pore volume distribution can be measured before and after the graphiticity improvement treatment. In some embodiments, the surface area of ​​the porous carbon scaffold after treatment is at least 30 m 2 / g decrease, e.g., at least 50m 2 / g, e.g., at least 100m 2 / g, e.g., at least 200m 2 / g, e.g., at least 300m 2 / g, e.g., at least 500m 2 / g. In some embodiments, the pore volume of the porous carbon scaffold after treatment is at least 0.01 cm 3 / g, e.g., at least 0.05 cm 3 / g, e.g., at least 0.1 cm 3 / g, e.g., at least 0.2 cm 3 / g, e.g., at least 0.3 cm 3 / g, e.g., at least 0.5 cm 3 / g, decreases.

[0140] In some embodiments, the surface area of ​​the porous carbon scaffold after treatment is at least 30 m 2 / g increase, e.g., at least 50m 2 / g, e.g., at least 100m 2 / g, e.g., at least 200m 2 / g, e.g., at least 300m 2 / g, e.g., at least 500m 2 / g. In some embodiments, the pore volume of the porous carbon scaffold after treatment is at least 0.01 cm 3 / g increase, e.g., at least 0.05 cm 3 / g, e.g., at least 0.1 cm 3 / g, e.g., at least 0.2 cm 3 / g, e.g., at least 0.3 cm 3 / g, e.g., at least 0.5 cm 3 / g increases. In certain embodiments where the surface area of ​​the porous carbon scaffold is increased after treatment and / or the pore volume of the porous carbon scaffold is increased after treatment, the porous carbon scaffold includes an electrochemical modifier that acts as a graphitization catalyst, such as Al, Cr, Mn, Fe, Co, Ni, Ca, Ti, V, Mo, or W, or a combination thereof.

[0141] Without being bound by theory, graphitization of a porous carbon scaffold containing a graphitization catalyst occurs under much milder conditions, e.g., shorter times and / or lower temperatures, compared to graphitization of a porous carbon scaffold not containing a graphitization catalyst. The graphitization catalyst can be introduced at various stages of the method for preparing a silicon-carbon composite. For example, the graphitization catalyst can be added to a solid precursor material prior to pyrolysis and subsequent activation to obtain a porous carbon scaffold containing the graphitization catalyst. In one embodiment, the graphitization catalyst can be added to a solid precursor material prior to simultaneous pyrolysis and activation to obtain a porous carbon scaffold containing the graphitization catalyst. In another embodiment, the graphitization catalyst can be added to a pyrolyzed porous carbon material prior to activation to obtain a porous carbon scaffold containing the graphitization catalyst. In another embodiment, the graphitization catalyst can be added to an activated porous carbon material to obtain a porous carbon scaffold containing the graphitization catalyst.

[0142] Graphitization can be achieved at various stages in the process of preparing a silicon-carbon composite. For example, a pyrolyzed porous carbon material can be graphitized prior to activation and subsequent CVI processing to obtain a silicon-carbon composite. In one embodiment, an activated porous carbon material can be graphitized prior to CVI processing to obtain a silicon-carbon composite.

[0143] Comminution to reduce particle size can be performed at various stages in the process for preparing silicon-carbon composite materials. For example, a pyrolyzed porous carbon material can be milled prior to graphitization and subsequent activation and CVI to obtain silicon-carbon composite particles. In another embodiment, a pyrolyzed and graphitized porous carbon material can be milled prior to activation and subsequent CVI to obtain silicon-carbon composite particles. In another embodiment, an activated porous carbon material can be milled prior to graphitization and subsequent CVI to obtain silicon-carbon composite particles. In another embodiment, an activated and graphitized porous carbon material can be milled prior to CVI to obtain silicon-carbon composite particles.

[0144] With respect to the above embodiments, the degree of graphiticity of the carbon may differ between the carbon particle surface and the pore surface within the carbon particle. In some embodiments, the degree of graphiticity of the carbon is greater at the carbon particle surface compared to the pore surface within the carbon particle. Without being bound by theory, such embodiments may improve the electrical and / or ionic conductivity of the particle surface, thereby providing electrochemical advantages when the silicon-carbon composite particles are used as anodes in lithium batteries (e.g., including increased rated capacity, faster charge and / or discharge, improved high temperature stability and / or calendar life due to a more stable SEI and lower carbon surface reactivity, etc.).

[0145] In some embodiments, the silicon-carbon composite material comprises a particle size distribution, and the degree of graphiticity of the carbon particles varies depending on the particle size of the carbon particles. For this characterization, the silicon-carbon composite particles can be size-fractionated (as known in the art) to obtain two or more fractions of material, where each fraction has a different Dv50. For example, the silicon-carbon composite particles can be fractionated into one fraction having a Dv50 of less than 1 μm and another fraction having a Dv50 of greater than 1 μm. The difference in graphiticity of the two fractions can be compared, e.g., measured by Raman spectroscopy. D / I G Therefore, the graphiticity difference between the two fractions can be calculated by the following formula: ΔI D / I G =([I D / I G ]Dv,50>1-[I D / I G ]Dv,50<1) [In the formula, [I D / I G ]Dv,50>1 is the fraction of particles with a Dv50 greater than 1 D / I G [I D / I G ]Dv,50<1 is the fraction of particles with a Dv50 less than 1 D / I G That is the case. It can be expressed as follows: Therefore, ΔI D / I G may be 0 to 2, for example 0 to 1, for example 0.01 to 0.8, for example 0.01 to 0.7, for example 0.01 to 0.6, for example 0.01 to 0.5, for example 0.01 to 0.4, for example 0.01 to 0.3, for example 0.01 to 0.2, for example 0.01 to 0.1, for example 0.1 to 0.8, for example 0.1 to 0.7, for example 0.1 to 0.6, for example 0.1 to 0.5, for example 0.1 to 0.4, for example 0.1 to 0.3, for example 0.1 to 0.2, for example 0.1 to 0.7, for example 0.2 to 0.6, for example 0.3 to 0.5, etc.

[0146] In some embodiments, the electrochemical properties of the porous carbon scaffold and / or silicon-carbon composite can be enhanced by the addition of conductive carbon additive particles, including, but not limited to, graphite particles, Super C45 particles, Super P particles, carbon black particles, nanoscale carbon particles (e.g., carbon nanotubes or other carbon nanostructures), and combinations thereof. In such embodiments, the addition of the conductive carbon additive facilitates improving the electrical conductivity, packing density, and / or electrochemical efficiency of the doped porous carbon scaffold and / or silicon-carbon composite produced therefrom.

[0147] To this end, the addition of conductive carbon additive particles can be performed at various stages in the preparation of silicon-carbon composites. In one embodiment, the conductive carbon additive particles are added to a carbon precursor used to fabricate a porous carbon scaffold, followed by pyrolysis, activation, and graphitization of the porous carbon scaffold, followed by CVI processing to produce a silicon-carbon composite. In another embodiment, the conductive carbon additive particles are added to a carbon precursor used to fabricate a porous carbon scaffold, followed by pyrolysis, graphitization, and activation of the porous carbon scaffold, followed by CVI processing to produce a silicon-carbon composite. In another embodiment, the conductive carbon additive particles are added to a carbon precursor used to fabricate a porous carbon scaffold, followed by pyrolysis, activation, and graphitization of the porous carbon scaffold, followed by CVI processing to produce a silicon-carbon composite.

[0148] In such embodiments, the addition of the conductive carbon additive functions as a graphitization catalyst for the graphitization of the porous carbon scaffold. In other embodiments, the addition of the conductive carbon additive facilitates improving the electrical conductivity, packing density, and / or electrochemical efficiency of the doped porous carbon scaffold and / or silicon-carbon composites made therefrom.

[0149] In yet other embodiments, the electrochemical properties of the porous carbon scaffold and / or silicon-carbon composite can be enhanced by adding conductive carbon additive particles to the pyrolyzed porous carbon scaffold prior to graphitization and subsequent activation, followed by CVI processing to prepare a silicon-carbon composite. In yet other embodiments, the electrochemical properties of the porous carbon scaffold and / or silicon-carbon composite can be enhanced by adding conductive carbon additive particles to the activated porous carbon scaffold prior to graphitization and subsequent activation, followed by CVI processing to prepare a silicon-carbon composite.

[0150] The presence ratio of the conductive carbon additive as a percentage of the total mass of the porous carbon can vary, for example, the conductive carbon additive can comprise 0.1% to 90% of the total mass of the porous carbon scaffold, such as 1% to 50%, for example 1% to 40%, for example 1% to 30%, for example 1% to 20%, for example 1% to 10%, for example 1% to 5%, for example 5% to 10%, for example 10% to 20%, for example 20% to 30%, for example 30% to 40%, for example 40% to 50%, etc.

[0151] example Example 1. Fabrication of Silicon-Carbon Composite by CVI. The physical properties of the carbon scaffold (Carbon Scaffold 1) used to fabricate the silicon-carbon composite are listed in Table 3 below. A silicon-carbon composite (Silicon-Carbon Composite 1) was fabricated by CVI using Carbon Scaffold 1 as follows: A 0.2-gram mass of amorphous porous carbon was placed in a 2-inch by 2-inch ceramic crucible and placed in the center of a horizontal tube furnace. The furnace was sealed and purged with nitrogen gas at 500 cubic centimeters per minute (ccm). The furnace temperature was increased at 20°C per minute to a peak temperature of 450°C and maintained for 30 minutes. At this point, the nitrogen was turned off, and subsequently silane and hydrogen were introduced at flow rates of 50 ccm and 450 ccm, respectively, for a total of 30 minutes. The silane and nitrogen were then turned off, and nitrogen was again introduced into the furnace to purge the air inside. At the same time, the furnace was turned off and allowed to cool to ambient temperature, and the finished Si-C material was then removed from the furnace.

[0152] Description of the carbon scaffold used in Example 1. [Table 4]

[0153] Example 2. Analysis of various silicon-composite materials. Carbon scaffold materials using various carbon scaffold materials were characterized by nitrogen adsorption gas analysis to measure the specific surface area, total pore volume, and the percentage of pore volume including micropores, mesopores, and macropores. The characterization data of the carbon scaffold materials, i.e., the surface area, pore volume, and pore volume distribution (fraction of micropores, fraction of mesopores, and fraction of macropores) of the carbon scaffold (all measured by nitrogen adsorption analysis), are shown in Table 5.

[0154] Physical properties of various carbon scaffold materials [Table 5]

[0155] Using the carbon scaffold samples listed in Table 5, various silicon-carbon composite materials were fabricated by the CVI method in a static bed configuration, as generally described in Example 1. These silicon-carbon samples were prepared under process conditions ranging from silane concentration of 1.25% to 100%; dilution gas of nitrogen or hydrogen; and starting mass of carbon scaffold of 0.2 g to 700 g.

[0156] The surface area of ​​the silicon-carbon composite was measured. Furthermore, the silicon content and Z of the silicon-carbon composite were determined by TGA analysis. The silicon-carbon composite was tested using a half-cell coin cell. The anode of the half-cell coin cell can contain 60-90% silicon-carbon composite, 5-20% Na-CMC (as a binder), and 5-20% Super C45 (as a conductivity enhancer), and the electrolyte can contain 2:1 ethylene carbonate:diethylene carbonate, 1M LiPF6, and 10% fluoroethylene carbonate. The half-cell coin cell can be cycled for 5 cycles at 25°C and a rate of C / 5, and then cycled at a rate of C / 10. The voltage can be cycled from 0V to 0.8V, or from 0V to 1.5V. From the data of half-cell and coin cells, the maximum capacity can be measured, and the average Coulomb efficiency (CE) from cycle 7 to cycle 20 can also be measured. The physicochemical and electrochemical properties of various silicon-carbon composite materials are shown in Table 6.

[0157] Physical properties of various silicon-carbon composite materials [Table 6]

[0158] Figure 1 shows a plot of the average Coulomb efficiency as a function of Z. As can be seen, the average Coulomb efficiency for silicon-carbon samples with low Z values ​​increased dramatically. In particular, all silicon-carbon samples with Z less than 10.0 showed an average Coulomb efficiency of 0.9941 or higher, and all silicon-carbon samples with Z greater than 10 (silicon-carbon composite samples 12 to 16) were observed to have an average Coulomb efficiency of 0.9909 or lower. Although not bound by theory, higher Coulomb efficiencies for silicon-carbon samples with Z less than 10 result in superior cycle stability in full-cell lithium-ion batteries. Further investigation of the table revealed a surprising and unexpected result: a combination of silicon-carbon composite samples with Z less than 10 and silicon-carbon composite samples further containing carbon scaffolds with microporosity greater than 69.1 showed an average Coulomb efficiency of 0.9969 or higher.

[0159] Therefore, in a more preferred embodiment, the silicon-carbon composite material includes Z less than 10, for example Z less than 5, for example Z less than 3, for example Z less than 2, for example Z less than 1, for example Z less than 0.5, for example Z less than 0.1, or Z 0.

[0160] In certain preferred embodiments, the silicon-carbon composite comprises a carbon scaffold having a Z of less than 10 and greater than 70% microporosity, such as a Z of less than 10 and greater than 80% microporosity, for example a Z of less than 10 and greater than 90% microporosity, for example a Z of less than 10 and greater than 95% microporosity, for example a Z of less than 5 and greater than 70% microporosity, for example a Z of less than 5 and greater than 80% microporosity, for example a Z of less than 5 and greater than 90% microporosity, for example a Z of less than 5 and greater than 95% microporosity, for example a Z of less than 3 and greater than 70% microporosity, for example a Z of less than 3 and greater than 80% microporosity, for example a Z of less than 3 and greater than 90% microporosity, for example a Z of less than 2 and greater than 70% microporosity, for example a Z of less than 2 and greater than 80% microporosity, for example a Z of less than 2 and greater than 90% microporosity, for example a Z of less than 2 and more than 95% microporosity, such as less than 1 Z and more than 70% microporosity, for example less than 1 Z and more than 80% microporosity, for example less than 1 Z and more than 90% microporosity, such as less than 1 Z and more than 95% microporosity, for example less than 0.5 Z and more than 70% microporosity, for example less than 0.5 Z and more than 80% microporosity, for example less than 0.5 Z and more than 90% microporosity, such as less than 0.5 Z and more than 95 % microporosity, such as a Z less than 0.1 and more than 70% microporosity, for example a Z less than 0.1 and more than 80% microporosity, for example a Z less than 0.1 and more than 90% microporosity, for example a Z less than 0.1 and more than 95% microporosity, such as a Z of 0 and more than 70% microporosity, for example a Z of 0 and more than 80% microporosity, for example a Z of 0 and more than 90% microporosity, for example a Z of 0 and more than 95% microporosity, etc.

[0161] In certain preferred embodiments, the silicon-carbon composite has a Z of less than 10, greater than 70% microporosity, 15% to 85% silicon, and 100m 2 / g, e.g., Z less than 10, greater than 70% microporosity, 15% to 85% silicon, and 50 m 2 / g, e.g., Z less than 10, greater than 70% microporosity, 15% to 85% silicon, and 30 m 2 / g, e.g., Z less than 10, greater than 70% microporosity, 15% to 85% silicon, and 10 m 2 / g, e.g., Z less than 10, greater than 70% microporosity, 15% to 85% silicon, and 5m 2 / g, e.g., Z less than 10, greater than 80% microporosity, 15% to 85% silicon, and 50 m 2 / g, e.g., Z less than 10, greater than 80% microporosity, 15% to 85% silicon, and 30 m 2 / g, e.g., Z less than 10, greater than 80% microporosity, 15% to 85% silicon, and 10 m 2 / g, e.g., Z less than 10, greater than 80% microporosity, 15% to 85% silicon, and 5m 2 / g, e.g., Z less than 10, greater than 90% microporosity, 15% to 85% silicon, and 50 m 2 / g, e.g., Z less than 10, greater than 90% microporosity, 15% to 85% silicon, and 30 m 2 / g, e.g., Z less than 10, greater than 90% microporosity, 15% to 85% silicon, and 10 m 2 / g, e.g., Z less than 10, greater than 90% microporosity, 15% to 85% silicon, and 5m 2 / g, e.g., Z less than 10, greater than 95% microporosity, 15% to 85% silicon, and 50 m 2 / g, e.g., Z less than 10, greater than 95% microporosity, 15% to 85% silicon, and 30 m 2 / g, e.g., Z less than 10, greater than 95% microporosity, 15% to 85% silicon, and 10 m 2 / g, e.g., Z less than 10, greater than 95% microporosity, 15% to 85% silicon, and 5m 2 / g, etc.

[0162] In certain preferred embodiments, the silicon-carbon composite has a Z of less than 10, greater than 70% microporosity, 30% to 60% silicon, and 100m 2 / g, e.g., Z less than 10, greater than 70% microporosity, 30% to 60% silicon, and 50m 2 / g, e.g., Z less than 10, greater than 70% microporosity, 30% to 60% silicon, and 30 m 2 / g, e.g., Z less than 10, greater than 70% microporosity, 30% to 60% silicon, and 10 m 2 / g, e.g., Z less than 10, greater than 70% microporosity, 30% to 60% silicon, and 5m 2 / g, e.g., Z less than 10, greater than 80% microporosity, 30% to 60% silicon, and 50 m 2 / g, e.g., Z less than 10, greater than 80% microporosity, 30% to 60% silicon, and 30 m 2 / g, e.g., Z less than 10, greater than 80% microporosity, 30% to 60% silicon, and 10 m 2 / g, e.g., Z less than 10, greater than 80% microporosity, 30% to 60% silicon, and 5m 2 / g, e.g., Z less than 10, greater than 90% microporosity, 30% to 60% silicon, and 50 m 2 / g, e.g., Z less than 10, greater than 90% microporosity, 30% to 60% silicon, and 30 m 2 / g, e.g., Z less than 10, greater than 90% microporosity, 30% to 60% silicon, and 10 m 2 / g, e.g., Z less than 10, greater than 90% microporosity, 30% to 60% silicon, and 5m 2 / g, e.g., Z less than 10, greater than 95% microporosity, 30% to 60% silicon, and 50 m 2 / g, e.g., Z less than 10, greater than 95% microporosity, 30% to 60% silicon, and 30 m 2 / g, e.g., Z less than 10, greater than 95% microporosity, 30% to 60% silicon, and 10 m 2 / g, e.g., Z less than 10, greater than 95% microporosity, 30% to 60% silicon, and 5m 2 / g, etc.

[0163] Example 3. dV / dQ in Silicon-Carbon Composites. Differential capacity curves (dQ / dv vs. voltage) are frequently used as a nondestructive tool to understand phase transformations as a function of voltage in lithium battery electrodes (M.N. Obrovac 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 Nanostructured Silicon-Based Lithium Ion Batteries via In Situ NMR Spectroscopy. Nat. Commun. 5:3217). The differential capacity plots shown here were calculated from data obtained by galvanostatic cycling from 5 mV to 0.8 V at a 0.1 C rate in half-cell coin cells at 25°C.Typical differential capacity curves for half-cells versus lithium for silicon-based materials 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); M.N. Obrovac 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 SiO2-based composite anode by prelithiation of stabilized lithium metal powder, Journal of Power Sources 347 (2017) 170-177). The lithiation behavior in the first cycle depends on the crystallinity and oxygen content of the silicon, among other factors.

[0164] After the first cycle, prior amorphous silicon materials in the art exhibit two distinct phase transition peaks in a dQ / dV vs. V plot for lithiation, and similarly, two distinct phase transition peaks in a dQ / dV vs. V plot for delithiation. For lithiation, one peak corresponds to a lithium-poor Li-Si alloy phase occurring between 0.2 and 0.4 V, and the other peak corresponds to a lithium-rich Li-Si alloy phase occurring below 0.15 V. For delithiation, one delithiation peak corresponds to lithium extraction occurring below 0.4 V, and the other delithiation peak corresponds to lithium extraction occurring between 0.4 and 0.55 V. During lithiation, Li15 When the Si4 phase is formed, it is delithiated at approximately 0.45 V, resulting in a very narrow and sharp peak.

[0165] Figure 2 shows the dQ / dV vs voltage curve for cycle 2 in a silicon-carbon composite material corresponding to silicon-carbon composite 3 of Example 1. Silicon-carbon composite 3 contains Z at 0.6. For ease of identification, the plots are divided into regimes I, II, III, IV, V, and VI. Regimes I (0.8V~0.4V), II (0.4V~0.15V), and III (0.15V~0V) include the lithiation potential, while regimes IV (0V~0.4V), V (0.4V~0.55V), and VI (0.55V~0.8V) include the delithiation potential. As described above, the earlier amorphous silicon-based materials in the art showed phase transition peaks at the lithiation potential in two regimes (regimes II and III), and phase transition peaks at the delithiation potential in two regimes (regimes IV and V).

[0166] As can be seen from Figure 2, the dQ / dV vs voltage curve revealed a surprising and unexpected result: silicon-carbon composite 3, containing Z 0.6, also exhibits two more peaks in the dQ / dV vs V curve, namely regime 1 at the lithiation potential and regime VI at the delithiation potential. As shown in Figure 3, all six peaks are reversible and are similarly observed in subsequent cycles.

[0167] Without being bound by theory, the trimodal behavior of the dQ / dV vs V curves shown above is novel and also reflects a novel morphology of silicon.

[0168] Notably, the novel peaks observed in Regime I and Regime VI are more pronounced in certain scaffold matrices and are completely absent in other samples (silicon-carbon composite samples with Z greater than 10, see description and table below) that represent prior art.

[0169] The dQ / dV vs V curve for silicon-carbon composite 3, in which the new peaks in regime I and regime VI are evident, is shown in Figure 4. Also shown in Figure 4 are the dQ / dV vs V curves for silicon-carbon composite 15, silicon-carbon composite 16, and silicon-carbon composite 14 (all three samples containing Z greater than 10), which, in contrast, lack any peaks in regime I or regime VI.

[0170] Without being bound by theory, these new peaks observed in Regime I and Regime VI are related to the properties of silicon infiltrated into the porous carbon scaffold, i.e., related to the interactions and properties between the porous carbon scaffold, silicon infiltrated into the porous carbon scaffold by CVI, and lithium. To provide a quantitative analysis, the inventors have calculated the peak I normalized with respect to Peak III using the following formula: φ = (Maximum peak height dQ / dV in Regime I) / (Maximum peak height dQ / dV in Regime III) [where dQ / dV is measured in half-cell coin cells, with regime 1 being 0.8 V to 0.4 V and regime III being 0.15 V to 0 V; the half-cell coin cells were fabricated as known in the art.] The parameter φ was defined as follows: If a Si-C sample exhibits a graphite-related peak in regime III of the differential curve, the former peak is removed in favor of the Li-Si-related phase transition peak for the calculation of coefficient D. In this example, a half-cell co-in cell contains an anode containing 60-90% silicon-carbon composite, 5-20% SBR-Na-CMC, and 5-20% Super C45. An example of the calculation of φ for silicon-carbon composite 3 is shown in Figure 5. In this example, the maximum peak height in regime I was -2.39 and was found at 0.53 V. Similarly, the maximum peak height in regime III was -9.71 at 0.04 V. In this example, φ can be calculated using the above formula, yielding φ = -2.39 / -9.71 = 0.25. The value of φ was determined from the half-cell co-in cell data for various silicon-carbon composites shown in Example 2. These data are summarized in Table 7.

[0171] Physical properties of various silicon-carbon materials [Table 7]

[0172] The data in Table 7 revealed an unexpected relationship between decreasing Z and increasing φ. All silicon-carbon composites with Z less than 10 had a φ of 0.13 or greater, and all silicon-carbon composites with Z greater than 10 had a φ of less than 0.13. In fact, all silicon-carbon composites with Z greater than 10 had a φ of 0. This relationship is also evident in Figure 6. Without being bound by theory, silicon materials with a φ of 0.10 or greater (e.g., a φ of 0.13 or greater) correspond to novel morphologies of silicon. Alternatively, silicon materials with a φ of greater than 0 correspond to novel morphologies of silicon. Without being bound by theory, silicon materials with a φ of greater than 0 are characteristic of silicon materials that are amorphous, nanosized, and silicon trapped in pores (e.g., in the pores of a porous carbon scaffold). Silicon-carbon composites with silicon with a φ of 0.10 or greater (e.g., a φ of 0.13 or greater) correspond to novel silicon-carbon composites. Aside from that, silicon-carbon composite materials containing a diameter greater than 0 correspond to novel silicon-carbon composite materials.

[0173] In certain embodiments, the silicon-carbon composite comprises a φ of 0.1 or greater, a φ of 0.11 or greater, a φ of 0.12 or greater, a φ of 0.13 or greater, a φ of 0.14 or greater, a φ of 0.15 or greater, a φ of 0.16 or greater, a φ of 0.17 or greater, a φ of 0.18 or greater, a φ of 0.19 or greater, a φ of 0.20 or greater, a φ of 0.24 or greater, a φ of 0.25 or greater, a φ of 0.30 or greater, or a φ of 0.35 or greater. In some embodiments, φ is greater than 0. In some embodiments, φ is 0.001 or greater, φ is 0.01 or greater, φ is 0.02 or greater, φ is 0.05 or greater, φ is 0.1 or greater, φ is 0.11 or greater, or φ is 0.12 or greater.

[0174] In certain embodiments, the silicon-carbon composite material consists of a carbon scaffold with a Z of less than 10 and a microporosity of more than 70%, and 30-60% silicon, 100m 2 Includes a surface area of ​​less than / g and a diameter of 0.1 or greater, for example, Z less than 10, microporosity greater than 70%, silicon content of 30-60%, and 50m 2Surface area less than / g, and φ greater than 0.1, e.g., Z less than 10, microporosity greater than 70%, silicon 30-60%, 30m 2 Surface area less than / g, and φ greater than 0.1, e.g., Z less than 10, microporosity greater than 70%, silicon 30-60%, 10m 2 Surface area less than / g, and φ greater than 0.1, e.g., Z less than 10, microporosity greater than 70%, 5m 2 This includes a surface area of ​​less than / g and a diameter of 0.1 or greater, etc.

[0175] In certain embodiments, the silicon-carbon composite material is a carbon scaffold with a Z of less than 10 and a microporosity of more than 70%, containing 40-60% silicon, and 100m 2 Includes a surface area of ​​less than / g and a diameter of 0.1 or greater, for example, Z less than 10, microporosity greater than 70%, silicon 40-60%, 50m 2 Surface area less than / g, and diameter greater than 0.1, e.g., Z less than 10, microporosity greater than 70%, silicon 40-60%, 30m 2 Surface area less than / g, and φ greater than 0.1, e.g., Z less than 10, microporosity greater than 70%, silicon 40-60%, 10m 2 Surface area less than / g, and diameter greater than 0.1, e.g., Z less than 10, microporosity greater than 70%, silicon 40-60%, 5m 2 This includes a surface area of ​​less than / g and a diameter of 0.1 or greater, etc.

[0176] In certain embodiments, the silicon-carbon composite material consists of a carbon scaffold with a Z of less than 10 and a microporosity of more than 70%, and 30-60% silicon, 100m 2 Includes a surface area less than / g and a φ greater than 0, for example, Z less than 10, microporosity greater than 70%, silicon 30-60%, 50m 2 Surface area less than / g, and φ greater than 0, e.g., Z less than 10, microporosity greater than 70%, silicon 30-60%, 30m 2 Surface area less than / g, and φ greater than 0, e.g., Z less than 10, microporosity greater than 70%, silicon 30-60%, 10m2 / g, and φ greater than 0, e.g., Z less than 10, microporosity greater than 70%, 30-60% silicon, 5m 2 / g and φ greater than 0.

[0177] In certain embodiments, the silicon-carbon composite material is a carbon scaffold with a Z of less than 10 and a microporosity of more than 70%, containing 40-60% silicon, and 100m 2 / g, and φ greater than 0, e.g., Z less than 10, microporosity greater than 70%, 40-60% silicon, 50m 2 / g, and φ greater than 0, e.g., Z less than 10, microporosity greater than 70%, 40-60% silicon, 30m 2 / g, and φ greater than 0, e.g., Z less than 10, microporosity greater than 70%, 40-60% silicon, 10m 2 / g, and φ greater than 0, e.g., Z less than 10, microporosity greater than 70%, silicon between 40 and 60%, 5m 2 / g and φ greater than 0.

[0178] In certain embodiments, the silicon-carbon composite has a Z of less than 10, a carbon scaffold with greater than 80% microporosity, 30-60% silicon, 100m 2 / g, and φ of 0.1 or greater, e.g., Z less than 10, microporosity greater than 80%, 30-60% silicon, 50m 2 / g, and φ ≥ 0.1, e.g. Z < 10, microporosity > 80%, 30-60% silicon, 30m 2 / g, and φ ≥ 0.1, e.g. Z < 10, microporosity > 80%, 30-60% silicon, 10m 2 / g, and φ ≥ 0.1, e.g. Z < 10, microporosity > 80%, silicon 30-60%, 5m 2 This includes a surface area of ​​less than / g and a diameter of 0.1 or greater, etc.

[0179] In certain embodiments, the silicon-carbon composite has a Z of less than 10, a carbon scaffold with greater than 80% microporosity, 40-60% silicon, 100m 2 / g, and φ of 0.1 or greater, e.g., Z less than 10, microporosity greater than 80%, 40-60% silicon, 50m 2 / g, and φ ≥ 0.1, e.g. Z < 10, microporosity > 80%, silicon 40-60%, 30m 2 / g, and φ ≥ 0.1, e.g. Z < 10, microporosity > 80%, silicon 40-60%, 10m 2 / g, and φ ≥ 0.1, e.g. Z < 10, microporosity > 80%, silicon 40-60%, 5m 2 This includes a surface area of ​​less than / g and a diameter of 0.1 or greater, etc.

[0180] In certain embodiments, the silicon-carbon composite has a Z of less than 10, a carbon scaffold with greater than 80% microporosity, 30-60% silicon, 100m 2 / g, and φ greater than 0, e.g., Z less than 10, microporosity greater than 80%, 30-60% silicon, 50m 2 / g, and φ greater than 0, e.g., Z less than 10, microporosity greater than 80%, 30-60% silicon, 30m 2 / g, and φ greater than 0, e.g., Z less than 10, microporosity greater than 80%, 30-60% silicon, 10m 2 / g, and φ greater than 0, e.g., Z less than 10, microporosity greater than 80%, 30-60% silicon, 5m 2 / g and φ greater than 0.

[0181] In certain embodiments, the silicon-carbon composite has a Z of less than 10, a carbon scaffold with greater than 80% microporosity, 40-60% silicon, 100m 2 / g, and φ greater than 0, e.g., Z less than 10, microporosity greater than 80%, 40-60% silicon, 50m 2 / g, and φ greater than 0, e.g., Z less than 10, microporosity greater than 80%, 40-60% silicon, 30m 2 / g, and φ greater than 0, e.g., Z less than 10, microporosity greater than 80%, 40-60% silicon, 10m 2 / g, and φ greater than 0, e.g., Z less than 10, microporosity greater than 80%, 40-60% silicon, 5m 2 / g and φ greater than 0.

[0182] In certain embodiments, the silicon-carbon composite material is a carbon scaffold with a Z of less than 10 and a microporosity of more than 90%, containing 30-60% silicon, and 100m 2 / g, and φ of 0.1 or greater, e.g., Z less than 10, greater than 90% microporosity, 30-60% silicon, 50m 2 / g, and φ ≥ 0.1, e.g. Z < 10, microporosity > 90%, 30-60% silicon, 30m 2 / g, and φ ≥ 0.1, e.g. Z < 10, microporosity > 90%, 30-60% silicon, 10m 2 / g, and φ ≥ 0.1, e.g. Z < 10, microporosity > 90%, 30-60% silicon, 5m 2 This includes a surface area of ​​less than / g and a diameter of 0.1 or greater, etc.

[0183] In certain embodiments, the silicon-carbon composite material is a carbon scaffold with a Z of less than 10 and a microporosity of more than 90%, containing 40-60% silicon, and 100m 2 / g, and φ of 0.1 or greater, e.g., Z less than 10, greater than 90% microporosity, 40-60% silicon, 50m 2 / g, and φ ≥ 0.1, e.g. Z < 10, microporosity > 90%, silicon 40-60%, 30m2 / g, and φ ≥ 0.1, e.g. Z < 10, microporosity > 90%, silicon 40-60%, 10m 2 / g, and φ ≥ 0.1, e.g. Z < 10, microporosity > 90%, silicon 40-60%, 5m 2 This includes a surface area of ​​less than / g and a diameter of 0.1 or greater, etc.

[0184] In certain embodiments, the silicon-carbon composite material is a carbon scaffold with a Z of less than 10 and a microporosity of more than 90%, containing 30-60% silicon, and 100m 2 / g, and φ greater than 0, e.g., Z less than 10, greater than 90% microporosity, 30-60% silicon, 50m 2 / g, and φ greater than 0, e.g., Z less than 10, microporosity greater than 90%, 30-60% silicon, 30m 2 / g, and φ greater than 0, e.g., Z less than 10, microporosity greater than 90%, 30-60% silicon, 10m 2 / g, and φ greater than 0, e.g., Z less than 10, microporosity greater than 90%, 30-60% silicon, 5m 2 / g and φ greater than 0.

[0185] In certain embodiments, the silicon-carbon composite material is a carbon scaffold with a Z of less than 10 and a microporosity of more than 90%, containing 40-60% silicon, and 100m 2 / g, and φ greater than 0, e.g., Z less than 10, greater than 90% microporosity, 40-60% silicon, 50m 2 / g, and φ greater than 0, e.g., Z less than 10, microporosity greater than 90%, 40-60% silicon, 30m 2 / g, and φ greater than 0, e.g., Z less than 10, microporosity greater than 90%, 40-60% silicon, 10m 2 / g, and φ greater than 0, e.g., Z less than 10, microporosity greater than 90%, 40-60% silicon, 5m2 / g and φ greater than 0.

[0186] In certain embodiments, the silicon-carbon composite has a Z of less than 10, a carbon scaffold with greater than 95% microporosity, 30-60% silicon, 100m 2 / g, and φ of 0.1 or greater, e.g., Z less than 10, greater than 95% microporosity, 30-60% silicon, 50m 2 / g, and φ ≥ 0.1, e.g. Z < 5, microporosity > 95%, 30-60% silicon, 30m 2 / g, and φ ≥ 0.1, e.g. Z < 10, microporosity > 95%, 30-60% silicon, 10m 2 / g, and φ ≥ 0.1, e.g. Z < 10, microporosity > 95%, 30-60% silicon, 5m 2 This includes a surface area of ​​less than / g and a diameter of 0.1 or greater, etc.

[0187] In certain embodiments, the silicon-carbon composite has a Z of less than 10, a carbon scaffold with greater than 95% microporosity, 40-60% silicon, 100m 2 / g, and φ of 0.1 or greater, e.g., Z less than 10, greater than 95% microporosity, 40-60% silicon, 50m 2 / g, and φ ≥ 0.1, e.g. Z < 10, microporosity > 95%, silicon 40-60%, 30m 2 / g, and φ ≥ 0.1, e.g. Z < 10, microporosity > 95%, 40-60% silicon, 10m 2 / g, and φ ≥ 0.1, e.g. Z < 10, microporosity > 95%, 40-60% silicon, 5m 2 This includes a surface area of ​​less than / g and a diameter of 0.1 or greater, etc.

[0188] In certain embodiments, the silicon-carbon composite has a Z of less than 10, a carbon scaffold with greater than 95% microporosity, 30-60% silicon, 100m 2 / g, and φ of 0.1 or greater, e.g., Z less than 10, greater than 95% microporosity, 30-60% silicon, 50m 2 / g, and φ ≥ 0.1, e.g. Z < 10, microporosity > 95%, 30-60% silicon, 30m 2 / g, and φ ≥ 0.1, e.g. Z < 10, microporosity > 95%, 30-60% silicon, 10m 2 / g, and φ ≥ 0.1, e.g. Z < 10, microporosity > 95%, 30-60% silicon, 5m 2 This includes a surface area of ​​less than / g and a diameter of 0.1 or greater, etc.

[0189] In certain embodiments, the silicon-carbon composite has a Z of less than 10, a carbon scaffold with greater than 95% microporosity, 40-60% silicon, 100m 2 / g, and φ greater than 0, e.g., Z less than 10, greater than 95% microporosity, 40-60% silicon, 50m 2 / g, and φ greater than 0, e.g., Z less than 10, microporosity greater than 95%, 40-60% silicon, 30m 2 / g, and φ greater than 0, e.g., Z less than 10, microporosity greater than 95%, 40-60% silicon, 10m 2 / g, and φ greater than 0, e.g., Z less than 10, microporosity greater than 95%, 40-60% silicon, 5m 2 / g and φ greater than 0.

[0190] Example 4. Particle size distribution of various carbon scaffold materials. The particle size distribution of various carbon scaffold materials was measured by a laser diffraction particle size analyzer known in the art. Specifically, the data for Dv1, Dv10, Dv50, Dv90, and Dv100 are shown in Table 8.

[0191] Physical properties of various carbon scaffold materials [Table 8]

[0192] Example 5. Measurement of graphiticity of porous carbon scaffolds by Raman spectroscopy. Various porous carbon scaffold samples were prepared by solvent-free treatment, which involved mixing bisphenol A (BPA) and hexamethylenetetramine (HMT), which are solid carbon precursors, and heating them to 650-1100°C using process gases containing nitrogen, carbon dioxide, vapor, or a combination thereof, and maintaining the mixture for 1-6 hours. The characteristics of these porous carbon scaffolds were measured (weight ratio of precursor BPA:HMT used in the solvent-free treatment, surface area and pore volume measured by nitrogen gas adsorption analysis of the prepared porous carbon scaffolds, and I measured by Raman spectroscopy). D / I G The results are shown in Table 9 below. For the preparation of carbon scaffold sample 14, the carbon precursor was polymerized by heating it at 150°C to 250°C for several hours prior to carbonization.

[0193] Physical properties of various carbon scaffold materials [Table 9]

[0194] Figure 7 shows a comparison of the Raman spectral analyses of carbon scaffold sample 11 and carbon scaffold sample 15. In these samples, the weight ratio of the precursor BPA to HMT was in the range of 2.44:1 to 3:1, and the process gases were different; specifically, the process gas used in the processing of carbon scaffold sample 11 contained CO2, while the process gas used in the processing of carbon scaffold sample 15 contained vapor. In these two samples, the measured I D / IG are comparable (ranging from 0.79 to 0.80), and thus the two samples contain comparable graphiticity.

[0195] Figure 8 shows a comparison of Raman spectral analyses of carbon scaffold sample 12 and carbon scaffold sample 10. In these samples, the weight ratio of the precursor BPA to HMT differed, being 9:1 (carbon scaffold sample 12) and 1:3 (carbon scaffold sample 10), and the process gas in both samples was vapor. I D / I G (0.79) is the I of carbon scaffold sample 10 D / I G (0.85). Thus, carbon scaffold sample 12 contains a higher degree of graphitization than carbon scaffold sample 10.

[0196] Figure 9 shows a comparison of the Raman spectral analyses of carbon scaffold sample 13 and carbon scaffold sample 14. In these samples, the weight ratio of the precursor BPA to HMT was in the range of 2.44:1 to 3:1, and the process gases were different. Specifically, the process gas used in the preparation of carbon scaffold sample 13 contained CO2, while the process gas used in the preparation of carbon scaffold sample 14 contained vapor, and in the preparation of carbon scaffold sample 14, a polymer step was performed before carbonization. As can be seen, the I D / I G (0.78) is the I of carbon scaffold sample 14 D / I GIt was lower than (0.88). Thus, carbon scaffold sample 13 has a higher degree of graphitization compared to carbon scaffold sample 14. Although not bound by theory, the polymerization step performed before carbonization in the preparation of carbon scaffold sample 14 increases the degree of polymer growth associated with polymer nucleation. Thus, it reduces the number of defects in the polymer structure and reduces the number of defects in the carbon structure of the produced porous carbon scaffold. Consequently, the degree of defects in the carbon structure of carbon scaffold sample 13 is relatively high. Although not bound by theory, the degree of large defects in the carbon structure of carbon scaffold sample 13 makes this sample more graphitized, and the measured I for this sample D / I G This is consistent with the fact that it is low.

[0197] Silicon-carbon composite particles can be prepared from a mixture of solid carbon precursor materials according to various embodiments, in various order of process steps. Examples of such embodiments are shown in Table 10. Note that each process sequence is performed to process the mixture of carbon precursors, but polymerization is carried out either as a separate step before the thermal decomposition proceeds or during the thermal decomposition step.

[0198] Various embodiments of preparing silicon-composite particles in various sequences of various process steps [Table 10]

[0199] For all the above process sequences, the graphitic nature of the porous carbon scaffolds can be confirmed from Raman spectra. D / I G In some embodiments, the silicon-carbon composite has an I of less than 0.9. D / I GFor example, the porous carbon scaffold has an I of less than 0.8. D / I G , e.g., I less than 0.7 D / I G , e.g., I less than 0.6 D / I G , e.g., I less than 0.5 D / I G , e.g., I less than 0.4 D / I G , e.g., I less than 0.3 D / I G , e.g., I less than 0.2 D / I G , e.g., I less than 0.1 D / I G , e.g., I less than 0.01 D / I G , e.g., I less than 0.001 D / I G , etc.

[0200] Example 6. Demonstration of the reduction in specific surface area and total pore volume of carbon caused by graphitization treatment. 500-2000 m 2 Various pyrolyzed and activated carbons with specific surface area values ​​in the range of / g were treated at 1000°C to 2850°C for 1 to 6 hours under inert gas (e.g., nitrogen or argon). As shown in Figure 10, a decrease in specific surface area was observed with increasing treatment temperature (corresponding to the graphitization of carbon).

[0201] Table 11 shows representative data for several pyrolyzed carbon materials (including pyrolyzed and activated carbon materials). These carbon materials underwent heat treatment as described above. Table 12 shows data for the materials after heat treatment.

[0202] Various carbon materials [Table 11] NA means no data available.

[0203] Various carbon materials after graphitization treatment [Table 12] NA means no data available.

[0204] In Table 12, as is well known in the art, I D / I G The data was calculated from the Raman spectrum, and the graphite crystal size (L a ) data were calculated by XRD. The decrease in pore volume with increasing treatment temperature favored the retention of mesopores and macropores, but the proportion of micropores decreased. D / I G The ratio increased with increasing treatment temperature, which is consistent with the transition from amorphous carbon to graphite. The size of the graphite crystallites calculated from XRD increased with increasing treatment temperature, which also suggests the transition from amorphous carbon to graphite.

[0205] The sheet resistance of carbon scaffolds 17 and 18 was measured according to the sheet resistance method. The sheet resistance method involves preparing a carbon scaffold slurry, a polymer binder, and deionized water, and casting them as thin films. Subsequently, using four probes, the sheet resistance was measured by passing DC current through the two outer probes, and the voltage drop was measured through the two inner probes. The sheet resistance was then calculated using the following formula:

number

[0206] The pycnometric densities of treated carbon scaffold 6, treated carbon scaffold 7, and treated carbon scaffold 8 were 1.67 g / cm³, respectively. 3 , 1.52g / cm 3 , and 1.75 g / cm 3 Surprisingly, these data are much lower than the theoretical values ​​for graphite. Without being bound by theory, such low pycnometric density reflects the porosity within the graphitic carbon. In some embodiments, the processed carbon scaffold has a density of 2.0 g / cm 3 It shows a pycnometric density of less than 1.9 g / cm³, for example. 3 Less than, for example, 1.8 g / cm 3 Less than, for example, 1.7 g / cm 3 Less than, for example, 1.6 g / cm 3 Less than, for example, 1.5 g / cm 3 Less than, for example, 1.4 g / cm 3 Less than, etc.

[0207] Example 7. Fabrication of silicon-carbon composites from porous carbon scaffold materials. Various silicon-carbon composites were fabricated by treating porous carbon scaffolds at elevated temperatures in the presence of silane gas, as generally described herein. Various process sequences were used, as shown in Table 10. Physicochemical and electrochemical characterization data for these silicon-carbon composites are shown in Tables 13 and 14, respectively.

[0208] Physicochemical properties of various silicon-carbon materials [Table 13]

[0209] Electrochemical properties of various silicon-carbon materials [Table 14]

[0210] Example 8. Comparison of activation after graphitization in carbon with various pore volumes. In this example, the inventors compared two different process sequences based on the characterization of the carbon scaffolds produced. For this purpose, the inventors compared treated carbon scaffold 1 and treated carbon scaffold 2 (both samples were produced by processing a carbon precursor and achieving graphitization through polymerization, pyrolysis, activation, pulverization, and heat treatment) with treated carbon scaffold 8 (produced by processing a carbon precursor and achieving graphitization through polymerization, pyrolysis, pulverization, and heat treatment). Treated carbon scaffold 1 and treated carbon scaffold 2 could not be activated; that is, after treatment at 900-950°C for 4-6 hours in the presence of an active gas (the above and / or carbon dioxide), the surface area and pore volume were only 13 m³, respectively. 2 / g and 0.0206cm 3 / g, and 1.86m 2 / g and 0.0024cm 3 It was observed that the value was / g. In both cases, the surface area and pore volume decreased rather than increased. On the other hand, the fact that the treated carbon scaffold 8 achieved an increase in surface area and pore volume under similar conditions was a surprising and unexpected result. Specifically, the final values ​​of surface area and pore volume were 40.5 m². 2 / g and 0.0539cm 3 Without being bound by theory, graphitization of pyrolyzed carbon results in carbon that can be converted to high surface area and pore volume upon subsequent activation, e.g., 40 m 2 / g and 0.05cm 3 / g or more, for example, 80m 2 / g and 0.1cm 3 / g or more, for example, 400m 2 / g and 0.5cm 3 / g or more, for example, 500m 2 / g and 0.6cm 3 / g or more, e.g., 1000m 2 / g and 0.5cm3 / g or more, e.g., 1500m 2 / g and 0.6cm 3 / g or more, etc.

[0211] Description of the embodiment

[0212] Embodiment 1. A method for producing silicon-carbon composite particles, the following: a. To provide a mixture of solid carbon precursor materials; b. The above mixture is thermally decomposed at 650°C to 1100°C in the presence of an inert gas; c. Activating the thermally decomposed carbon material at 650°C to 1100°C in the presence of an active gas; d. Grinding activated carbon material; e. Graphitizing porous carbon scaffold particles at 1200°C to 3000°C in the presence of an inert gas; f. Heating the above porous carbon scaffold particles at 400°C to 525°C in the presence of silane gas; and g. Silicon-carbon composites including the following: I below i.0.9 D / I G , and carbon scaffolds containing pore volume with over 70% microporosity. a manufacturing method comprising:

[0213] Embodiment 2. A method for producing silicon-carbon composite particles, the following: a. To provide a mixture of solid carbon precursor materials; b. The above mixture is thermally decomposed at 650°C to 1100°C in the presence of an inert gas; c. Activating the thermally decomposed carbon material at 650°C to 1100°C in the presence of an active gas; d. Grinding the activated carbon material at 1200°C to 3000°C in the presence of an inert gas; e. Graphitizing porous carbon scaffold particles; f. heating the porous carbon scaffold particles at 350°C to 550°C in the presence of silane gas; and g. Silicon-carbon composites including the following: I below i.0.9 D / I G and a carbon scaffold comprising a pore volume having greater than 70% microporosity; and ii.φ greater than or equal to 0.1. Here, φ is expressed as φ = (maximum peak height dQ / dV in regime I) / (maximum peak height dQ / dV in regime III) [wherein dQ / dV is measured in a half-cell coin cell, with regime I being 0.8V to 0.4V and regime III being 0.15V to 0V]. a manufacturing method comprising:

[0214] Embodiment 3. A method of making silicon-carbon composite particles, comprising: a. To provide a mixture of solid carbon precursor materials; b. The above mixture is thermally decomposed at 650°C to 1100°C in the presence of an inert gas; c. Activating the thermally decomposed carbon material at 650°C to 1100°C in the presence of an active gas; d. Grinding activated carbon material; e. Graphitizing porous carbon scaffold particles at 1200°C to 3000°C in the presence of an inert gas; f. heating the porous carbon scaffold particles at 350°C to 550°C in the presence of silane gas; and g. Silicon-carbon composites including the following: I below i.0.9 D / I G and a carbon scaffold comprising a pore volume having greater than 50% microporosity; and ii. Z is less than 10, where Z is expressed as Z = 1.875 × ((M-M) / M) × 100% (wherein, when a silicon-carbon composite is heated in the atmosphere from 25°C to about 1100°C, M is the mass of the silicon-carbon composite at 1100°C, and M is the minimum mass of the silicon-carbon composite at 800°C to 1100°C, as measured by thermogravimetric analysis). a manufacturing method comprising:

[0215] Embodiment 4. A method for producing silicon-carbon composite particles, the following: a. To provide a mixture of solid carbon precursor materials; b. The above mixture is thermally decomposed at 650°C to 1100°C in the presence of an inert gas; c. Activating the thermally decomposed carbon material at 650°C to 1100°C in the presence of an active gas; d. Grinding activated carbon material; e. Graphitizing porous carbon scaffold particles at 1200°C to 3000°C in the presence of an inert gas; f. heating the porous carbon scaffold particles at 350°C to 550°C in the presence of silane gas; and g. Silicon-carbon composites including the following: i. I less than 0.9 D / I G , and carbon scaffolds containing pore volume with microporosity exceeding 70%; ii. Silicone content of 30% to 60% by weight; iii. Z less than 10, where Z is expressed as Z = 1.875 × ((M-M) / M) × 100% (wherein, when a silicon-carbon composite is heated in the atmosphere from 25°C to about 1100°C, M is the mass of the silicon-carbon composite at 1100°C, and M is the minimum mass of the silicon-carbon composite at 800°C to 1100°C, as measured by thermogravimetric analysis); iv.30m 2 Surface area less than / g; and v. φ is 0.1 or more, where φ is expressed as φ = (maximum peak height dQ / dV in regime I) / (maximum peak height dQ / dV in regime III) [where dQ / dV is measured in a half-cell coin cell, regime I is 0.8 V to 0.4 V, and regime III is 0.15 V to 0 V]. a manufacturing method comprising:

[0216] Embodiment 5. A method for producing silicon-carbon composite particles, the following: a. To provide a mixture of solid carbon precursor materials; b. The above mixture is thermally decomposed at 650°C to 1100°C in the presence of an inert gas; c. Activating the thermally decomposed carbon material at 650°C to 1100°C in the presence of an active gas; d. Graphitizing activated carbon materials at 1200°C to 3000°C in the presence of an inert gas; e. Grinding porous carbon scaffolds; f. Heating the particles of the porous carbon scaffold described above at 350°C to 550°C in the presence of silane gas; and g. Silicon-carbon composites including the following: i. I less than 0.9 D / I G , and carbon scaffolds containing pore volume with over 70% microporosity. a manufacturing method comprising:

[0217] Embodiment 6. A method for producing silicon-carbon composite particles, the following: a. To provide a mixture of solid carbon precursor materials; b. The above mixture is thermally decomposed at 650°C to 1100°C in the presence of an inert gas; c. Activating the thermally decomposed carbon material at 650°C to 1100°C in the presence of an active gas; d. Graphitizing activated carbon materials at 1200°C to 3000°C in the presence of an inert gas; e. Grinding porous carbon scaffolds; f. heating the particles of the porous carbon scaffold in the presence of silane gas at 350°C to 550°C; and g. Silicon-carbon composites including the following: i. I less than 0.9 D / I G and a carbon scaffold comprising a pore volume having greater than 70% microporosity; and ii.φ greater than or equal to 0.1. Here, φ is expressed as φ = (maximum peak height dQ / dV in regime I) / (maximum peak height dQ / dV in regime III) [wherein dQ / dV is measured in a half-cell coin cell, with regime I being 0.8V to 0.4V and regime III being 0.15V to 0V]. a manufacturing method comprising:

[0218] Embodiment 7. A method for producing silicon-carbon composite particles, comprising: a. To provide a mixture of solid carbon precursor materials; b. The above mixture is thermally decomposed at 650°C to 1100°C in the presence of an inert gas; c. Activating the thermally decomposed carbon material at 650°C to 1100°C in the presence of an active gas; d. Graphitizing activated carbon materials at 1200°C to 3000°C in the presence of an inert gas; e. Grinding porous carbon scaffolds; f. heating the porous carbon scaffold particles in the presence of silane gas at 350°C to 550°C; and g. Silicon-carbon composites including the following: i. I less than 0.9 D / I G and a carbon scaffold comprising a pore volume having greater than 70% microporosity; and ii. Z is less than 10, where Z is expressed as Z = 1.875 × ((M-M) / M) × 100% (wherein, when a silicon-carbon composite is heated in the atmosphere from 25°C to about 1100°C, M is the mass of the silicon-carbon composite at 1100°C, and M is the minimum mass of the silicon-carbon composite at 800°C to 1100°C, as measured by thermogravimetric analysis). a manufacturing method comprising:

[0219] Embodiment 8. A method for producing silicon-carbon composite particles, comprising: a. To provide a mixture of solid carbon precursor materials; b. The above mixture is thermally decomposed at 650°C to 1100°C in the presence of an inert gas; c. Activating the thermally decomposed carbon material at 650°C to 1100°C in the presence of an active gas; d. Graphitizing activated carbon materials at 1200°C to 3000°C in the presence of an inert gas; e. Grinding porous carbon scaffolds; f. heating the porous carbon scaffold particles in the presence of silane gas at 350°C to 550°C; and g. Silicon-carbon composites including the following: i. I less than 0.9 D / I G , and a carbon scaffold comprising a pore volume having greater than 50% microporosity; ii. Silicone content of 30% to 60% by weight; iii. Z less than 10, where Z is expressed as Z = 1.875 × ((M-M) / M) × 100% (wherein, when a silicon-carbon composite is heated in the atmosphere from 25°C to about 1100°C, M is the mass of the silicon-carbon composite at 1100°C, and M is the minimum mass of the silicon-carbon composite at 800°C to 1100°C, as measured by thermogravimetric analysis); iv.30m 2 Surface area less than / g; and v. φ is 0.1 or more, where φ is expressed as φ = (maximum peak height dQ / dV in regime I) / (maximum peak height dQ / dV in regime III) [where dQ / dV is measured in a half-cell coin cell, regime I is 0.8 V to 0.4 V, and regime III is 0.15 V to 0 V]. a manufacturing method comprising:

[0220] Embodiment 9. A method for producing silicon-carbon composite particles according to any one of Embodiments 1 to 8, having microporosity with a pore volume of more than 80%.

[0221] Embodiment 10. A method for producing silicon-carbon composite particles according to any one of Embodiments 1 to 9, having microporosity with a pore volume of more than 90%.

[0222] Embodiment 11. A method for producing silicon-carbon composite particles according to any one of Embodiments 1 to 10, having microporosity with a pore volume of more than 95%.

[0223] Embodiment 12. A method for producing silicon-carbon composite particles according to any one of Embodiments 1 to 11, wherein porous carbon scaffold particles are heated at 400°C to 525°C in the presence of silane gas.

[0224] Embodiment 13. A method for producing silicon-carbon composite particles according to any one of Embodiments 1 to 12, wherein the silicon content of the silicon-carbon composite is 40 to 60%.

[0225] Embodiment 14. A method for producing silicon-carbon composite particles according to any one of Embodiments 1 to 13, wherein the silicon-carbon composite contains Z less than 5.

[0226] Embodiment 15. The silicon-carbon composite is 10 m 2A method for producing silicon-carbon composite particles according to any one of Embodiments 1 to 14, including a surface area of ​​less than / g.

[0227] Embodiment 16. The method for producing silicon-carbon composite particles according to any one of Embodiments 1 to 15, wherein the silicon-carbon composite comprises a φ of 0.2 or greater, where φ is expressed as φ=(maximum peak height dQ / dV in Regime I) / (maximum peak height dQ / dV in Regime III), where dQ / dV is measured in a half-cell coin cell, and Regime I is 0.8 V to 0.4 V, and Regime III is 0.15 V to 0 V.

[0228] Embodiment 17. The method for producing silicon-carbon composite particles according to any one of Embodiments 1 to 16, wherein the silicon-carbon composite comprises a φ of 0.3 or greater, where φ is expressed as φ=(maximum peak height dQ / dV in Regime I) / (maximum peak height dQ / dV in Regime III), where dQ / dV is measured in a half-cell coin cell, and Regime I is 0.8 V to 0.4 V, and Regime III is 0.15 V to 0 V.

[0229] Embodiment 18. A method of making silicon-carbon composite particles according to any one of embodiments 1 to 17, wherein the silicon-carbon composite comprises a Dv50 of 5 nm to 20 microns.

[0230] Embodiment 19. A method of making silicon-carbon composite particles according to any one of embodiments 1 to 18, wherein the silicon-carbon composite comprises a capacity of greater than 900 mA / g.

[0231] Embodiment 20. The method of making silicon-carbon composite particles according to any one of embodiments 1 to 19, wherein the silicon-carbon composite comprises a capacity of greater than 1300 mA / g.

[0232] Embodiment 21. A method of making silicon-carbon composite particles according to any one of embodiments 1 to 20, wherein the silicon-carbon composite comprises a capacity of greater than 1600 mA / g.

[0233] Embodiment 22. The porous carbon scaffold has an I of less than 0.8 D / I G 22. The method for producing silicon-carbon composite particles according to any one of embodiments 1 to 21, comprising:

[0234] Embodiment 23. The porous carbon scaffold has an I of less than 0.7 D / I G 23. The method for producing silicon-carbon composite particles according to any one of embodiments 1 to 22, comprising:

[0235] Embodiment 24. The porous carbon scaffold has an I of less than 0.6 D / I G 24. The method for producing silicon-carbon composite particles according to any one of embodiments 1 to 23, comprising:

[0236] Embodiment 25. The porous carbon scaffold has an I of less than 0.5 D / I G 25. The method for producing silicon-carbon composite particles according to any one of embodiments 1 to 24, comprising:

[0237] Embodiment 26. The porous carbon scaffold has an I of less than 0.4 D / I G 26. The method for producing silicon-carbon composite particles according to any one of embodiments 1 to 25, comprising:

[0238] Embodiment 27. The porous carbon scaffold has an I of less than 0.3 D / I G 27. The method for producing silicon-carbon composite particles according to any one of embodiments 1 to 26, comprising:

[0239] Embodiment 28. The porous carbon scaffold has an I of less than 0.2 D / I G 28. The method for producing silicon-carbon composite particles according to any one of embodiments 1 to 27, comprising:

[0240] Embodiment 29. The porous carbon scaffold has an I of less than 0.1 D / I G 29. The method for producing silicon-carbon composite particles according to any one of embodiments 1 to 28, comprising:

[0241] Embodiment 30. The porous carbon scaffold has an I of less than 0.01 D / I G 29. The method for producing silicon-carbon composite particles according to any one of embodiments 1 to 29, comprising:

[0242] Embodiment 31. The porous carbon scaffold has an I of less than 0.001 D / I G 31. The method for producing silicon-carbon composite particles according to any one of embodiments 1 to 30, comprising:

[0243] Embodiment 32. A method for producing silicon-carbon composite particles according to any one of Embodiments 1 to 31, wherein graphitization is achieved by heating carbon to 1100°C to 3000°C in the presence of an inert gas.

[0244] Embodiment 33. A method for producing silicon-carbon composite particles according to any one of Embodiments 1 to 32, wherein graphitization is achieved by heating the carbon by microwave irradiation.

[0245] Embodiment 34. A method for producing silicon-carbon composite particles according to any one of Embodiments 1 to 33, wherein the porous carbon scaffold comprises Al, Cr, Mn, Fe, Co, Ni, Ca, Ti, V, Mo, or W, or a combination thereof. [Background technology]

[0246] Embodiment 35. A method for producing silicon-carbon composite particles according to any one of Embodiments 1 to 34, wherein the porous carbon scaffold contains conductive carbon additive particles.

[0247] Embodiment 36. The method of making silicon-carbon composite particles of embodiment 35, wherein the conductive carbon additive particles comprise graphite particles, Super C45 particles, Super P particles, carbon black particles, nanoscale carbon particles (such as carbon nanotubes or other carbon nanostructures), or combinations thereof.

[0248] Embodiment 37. A method for producing silicon-carbon composite particles according to any one of embodiments 1 to 36, wherein the inert gas is nitrogen gas.

[0249] Embodiment 38. A method for producing silicon-carbon composite particles according to any one of Embodiments 1 to 36, wherein the active gas is carbon dioxide, vapor, or a combination thereof.

[0250] Embodiment 39. A silicon-carbon composite comprising: a.I less than 0.9 D / I G , and carbon scaffolds containing pore volume with over 70% microporosity. b. A silicon content of 30% to 60% by weight; c. Z less than 10, where Z is expressed as Z = 1.875 × ((M1100 - M) / M1100) × 100% (wherein, when a silicon-carbon composite is heated in the atmosphere from 25°C to about 1100°C, M1100 is the mass of the silicon-carbon composite at 1100°C, and M is the minimum mass of the silicon-carbon composite at 800°C to 1100°C, as measured by thermogravimetric analysis); d.30m 2 Surface area less than / g; and e. φ of 0.1 or more, where φ is expressed as φ = (maximum peak height dQ / dV in regime I) / (maximum peak height dQ / dV in regime III) [where dQ / dV is measured in a half-cell coin cell, regime I is 0.8 V to 0.4 V, and regime III is 0.15 V to 0 V]. A silicon-carbon composite comprising:

[0251] Embodiment 40. The silicon-carbon composite of embodiment 39, wherein the porous carbon scaffold comprises 40% to 60% silicon by weight.

[0252] Embodiment 41. The silicon-carbon composite of any one of embodiments 39 to 40, wherein the silicon-carbon composite comprises Z less than 5.

[0253] Embodiment 42. The silicon-carbon composite is 10 m 2 42. The silicon-carbon composite of any one of embodiments 39 to 41, comprising a surface area of ​​less than 1 / g.

[0254] Embodiment 43. A silicon-carbon composite according to any one of embodiments 39 to 42, wherein the silicon-carbon composite comprises a φ of 0.2 or greater.

[0255] Embodiment 44. A silicon-carbon composite according to any one of embodiments 39 to 43, wherein the silicon-carbon composite comprises a φ of 0.3 or greater.

[0256] Embodiment 45. The silicon-carbon composite of any one of embodiments 39 to 44, wherein the silicon-carbon composite comprises a Dv50 of 5 nm to 20 microns.

[0257] Embodiment 46. The silicon-carbon composite of any one of embodiments 39 to 45, wherein the silicon-carbon composite comprises a capacity greater than 900 mA / g.

[0258] Embodiment 47. A silicon-carbon composite according to any one of Embodiments 39 to 46, wherein the silicon-carbon composite has a capacity greater than 1300 mA / g.

[0259] Embodiment 48. A silicon-carbon composite according to any one of Embodiments 39 to 47, wherein the silicon-carbon composite has a capacity of more than 1600 mA / g.

[0260] Embodiment 49. The porous carbon scaffold has an I of less than 0.8 D / I G 49. The silicon-carbon composite of any one of embodiments 39 to 48, comprising:

[0261] Embodiment 50. The porous carbon scaffold has an I of less than 0.7 D / I G 50. The silicon-carbon composite of any one of embodiments 39 to 49, comprising:

[0262] Embodiment 51. The porous carbon scaffold has an I of less than 0.6 D / I G 51. The silicon-carbon composite of any one of embodiments 39 to 50, comprising:

[0263] Embodiment 52. The porous carbon scaffold has an I of less than 0.5 D / I G 52. The silicon-carbon composite of any one of embodiments 39 to 51, comprising:

[0264] Embodiment 53. The porous carbon scaffold has an I of less than 0.4 D / I G 53. The silicon-carbon composite of any one of embodiments 39 to 52, comprising:

[0265] Embodiment 54. The porous carbon scaffold has an I of less than 0.3 D / I G54. The silicon-carbon composite of any one of embodiments 39 to 53, comprising:

[0266] Embodiment 55. The porous carbon scaffold has an I of less than 0.2 D / I G 55. The silicon-carbon composite of any one of embodiments 39 to 54, comprising:

[0267] Embodiment 56. The porous carbon scaffold has an I of less than 0.1 D / I G 56. The silicon-carbon composite of any one of embodiments 39 to 55, comprising:

[0268] Embodiment 57. The porous carbon scaffold has an I of less than 0.01 D / I G 57. The silicon-carbon composite of any one of embodiments 39 to 56, comprising:

[0269] Embodiment 58. The porous carbon scaffold has an I of less than 0.001 D / I G 58. The silicon-carbon composite of any one of embodiments 39 to 57, comprising:

[0270] Embodiment 59. A silicon-carbon composite according to any one of embodiments 39 to 58, wherein the porous carbon scaffold comprises Al, Cr, Mn, Fe, Co, Ni, Ca, Ti, V, Mo, or W, or a combination thereof.

[0271] Embodiment 60. A silicon-carbon composite according to any one of Embodiments 39 to 59, wherein the porous carbon scaffold includes conductive carbon additive particles (e.g., graphite particles, Super C45 particles, Super P particles, carbon black particles, nanoscale carbon particles (carbon nanotubes, or other carbon nanostructures, etc.), or combinations thereof, etc.).

[0272] Embodiment 61. A silicon-carbon composite according to any one of embodiments 39 to 60, wherein the silicon-carbon composite comprises a Dv50 of 5 nm to 20 microns.

[0273] Embodiment 62: The silicon-carbon composite has a ΔI of 0.1 to 0.7. D / I G 62. The silicon-carbon composite of any one of embodiments 39 to 61, comprising: D / I G is the following formula: ΔI D / I G =((I D / I G )Dv,50>1-(I D / I G )Dv,50<1) [In the formula, (I D / I G )Dv,50>1 is the fraction of particles with Dv50 greater than 1. D / I G , and (I D / I G )Dv,50<1 is the fraction of particles with Dv50 less than 1. D / I G That is the case. It is expressed as:

[0274] ΔI in embodiment 63.0.1 to 0.7 D / I G Silicon-carbon composite, where ΔI D / I G is the following formula: ΔI D / I G =((I D / I G )Dv,50>1-(I D / I G )Dv,50<1) [In the formula, (I D / I G )Dv,50>1 is the fraction of particles with Dv50 greater than 1. D / I G , and (ID / I G )Dv,50<1 is the fraction of particles with Dv50 less than 1. D / I G That is the case. It is expressed as:

[0275] Embodiment 64. A method for producing silicon-carbon composite particles, the following: a. To provide a mixture of solid carbon precursor materials; b. The above mixture is thermally decomposed at 650°C to 1100°C in the presence of an inert gas; c. Activating the thermally decomposed carbon material at 650°C to 1100°C in the presence of an active gas; d. Graphitizing activated carbon materials at 1200°C to 3000°C in the presence of an inert gas; e. Grinding porous carbon scaffolds; f. heating the porous carbon scaffold particles in the presence of silane gas at 350°C to 550°C; and g. Silicon-carbon composites including the following: i. I less than 0.9 D / I G , and carbon scaffolds containing pore volume with microporosity exceeding 70%; ii. Silicone content of 30% to 60% by weight; iii. Z less than 10, where Z is expressed as Z = 1.875 × ((M-M) / M) × 100% (wherein, when a silicon-carbon composite is heated in the atmosphere from 25°C to about 1100°C, M is the mass of the silicon-carbon composite at 1100°C, and M is the minimum mass of the silicon-carbon composite at 800°C to 1100°C, as measured by thermogravimetric analysis); iv.30m 2 surface area less than / g; v. φ is 0.1 or more, where φ is expressed as φ = (maximum peak height dQ / dV in regime I) / (maximum peak height dQ / dV in regime III) [where dQ / dV is measured in a half-cell coin cell, regime I is 0.8 V to 0.4 V, and regime III is 0.15 V to 0 V]; vi. First cycle efficiency of 75% or more; vii. Average Coulombic efficiency of 0.998 or greater; and viii. Capacity of 1000mAh / g or more; a manufacturing method comprising:

[0276] Embodiment 65. A method for producing silicon-carbon composite particles, comprising: a. To provide a mixture of solid carbon precursor materials; b. The above mixture is thermally decomposed at 650°C to 1100°C in the presence of an inert gas; c. Activating the thermally decomposed carbon material at 650°C to 1100°C in the presence of an active gas; d. Graphitizing activated carbon materials at 1200°C to 3000°C in the presence of an inert gas; e. Grinding porous carbon scaffolds; f. heating the porous carbon scaffold particles in the presence of silane gas at 350°C to 550°C; and g. Silicon-carbon composites including the following: i. I less than 0.9 D / I G , and carbon scaffolds containing pore volume with microporosity exceeding 70%; ii. Silicone content of 30% to 60% by weight; iii. Z less than 10, where Z is expressed as Z = 1.875 × ((M-M) / M) × 100% (wherein, when a silicon-carbon composite is heated in the atmosphere from 25°C to about 1100°C, M is the mass of the silicon-carbon composite at 1100°C, and M is the minimum mass of the silicon-carbon composite at 800°C to 1100°C, as measured by thermogravimetric analysis); iv.30m 2 surface area less than / g; v. φ is 0.2 or more, where φ is expressed as φ = (maximum peak height dQ / dV in regime I) / (maximum peak height dQ / dV in regime III) [where dQ / dV is measured in a half-cell coin cell, regime I is 0.8 V to 0.4 V, and regime III is 0.15 V to 0 V]; vi. First cycle efficiency of 90% or higher; vii. Average Coulomb efficiency of 0.999 or higher; and viii. Capacity of 1400mAh / g or more, a manufacturing method comprising:

[0277] Embodiment 66. A method for producing graphitized activated carbon particles, the following: a. To provide a mixture of solid carbon precursor materials; b. The above mixture is thermally decomposed at 650°C to 1100°C in the presence of an inert gas; c. Grinding the pyrolysis-decomposed porous carbon scaffold; d. Graphitizing activated carbon materials at 1200°C to 3000°C in the presence of an inert gas; and e. Activating the thermally decomposed carbon material at 650°C to 1100°C in the presence of an active gas. A manufacturing method that includes this.

[0278] Embodiment 67. A material comprising graphitized activated carbon particles, wherein: a.40m 2 Surface area of ​​ / g or more; b.0.05cm3 / g or more pore volume; c. 5A or more L a and d.0.8 or less I D / I G Including, materials.

[0279] Embodiment 68. A material comprising graphitized activated carbon particles, wherein: a.400m 2 Surface area of ​​ / g or more; b.0.5cm 3 / g or more pore volume; c. 5A or more L a and d.0.8 or less I D / I G Including, materials.

[0280] Embodiment 69. A material comprising graphitized activated carbon particles, wherein: a.1000m 2 Surface area of ​​ / g or more; b.0.6cm 3 / g or more pore volume; c. 5A or more L a and d.0.8 or less I D / I G Including, materials.

[0281] From the above, it will be understood that while specific embodiments of the present invention have been described herein for disclosure purposes, various modifications may be made without departing from the spirit and scope of the invention. Accordingly, the present invention is not limited except as provided for in the appended claims.

[0282] This application claims priority to U.S. Provisional Application No. 63 / 083,614 (filed September 25, 2020), the disclosure of which is incorporated herein by reference in its entirety.

Claims

1. 1. A method for producing silicon-carbon composite particles, comprising: a. providing a mixture of solid carbon precursor materials; b) pyrolyzing the mixture at 650°C to 1100°C in the presence of nitrogen gas to obtain a pyrolyzed carbon material; c) activating the pyrolyzed carbon material at 650°C to 1100°C in the presence of carbon dioxide gas, steam, or a combination thereof to obtain an activated carbon material; d. crushing the activated carbon material to obtain porous carbon scaffold particles; e. heating the porous carbon scaffold particles at 1100°C to 3000°C in the presence of nitrogen to obtain graphitized porous carbon scaffold particles; and f. heating the graphitized porous carbon scaffold particles at 400°C to 525°C in the presence of silane gas to obtain silicon-carbon composite particles; Where: the silicon-carbon composite particles have an I D / I G ratio of less than 0.8; and the pore volume of the silicon-carbon composite particles has a microporosity of greater than 70%; A manufacturing method comprising:

2. The method described in claim 1, wherein the solid carbon precursor material comprises bisphenol A and hexamethylenetetramine.

3. The method of claim 1, wherein the pore volume of the silicon-carbon composite particles has a microporosity of greater than 80%.

4. The method of claim 1, wherein the pore volume of the silicon-carbon composite particles has a microporosity of greater than 90%.

5. The method of claim 1, wherein the pore volume of the silicon-carbon composite particles has a microporosity of greater than 95%.

6. I / D / I of the silicon-carbon composite particles Ｇ The method according to claim 1, wherein is less than 0.

7.

7. The I D / I of the silicon-carbon composite particles Ｇ The method of claim 1 , wherein is less than 0.

6.

8. 1. A method for producing silicon-carbon composite particles, comprising: a. providing a mixture of solid carbon precursor materials; b. The mixture is thermally decomposed in the presence of nitrogen gas at 650°C to 1100°C to obtain the thermally decomposed carbon material; c) activating the pyrolyzed carbon material at 650°C to 1100°C in the presence of carbon dioxide gas, steam, or a combination thereof to obtain an activated carbon material; d. crushing the activated carbon material to obtain porous carbon scaffold particles; e. heating the porous carbon scaffold particles at 1100°C to 3000°C in the presence of nitrogen to obtain graphitized porous carbon scaffold particles; and f. heating the graphitized porous carbon scaffold particles at 400°C to 525°C in the presence of silane gas to obtain silicon-carbon composite particles; Where: the silicon-carbon composite particles have an I D / I G ratio of less than 0.8; the pore volume of said silicon-carbon composite particles has a microporosity of greater than 70%; The silicon content of the silicon-carbon composite particles is 40% to 60% by weight; The silicon-carbon composite particles have Z less than 10, where Z is a compound of the following formula: Z=1.875×((M1100-M) / M1100)×100 [wherein, when the silicon-carbon composite particles are heated in air from about 25°C to about 1100°C, M is the mass of the silicon-carbon composite particles at 1100°C, and M is the minimum mass of the silicon-carbon composite particles at 800°C to 1100°C, as measured by thermogravimetric analysis.] It is represented by; the silicon-carbon composite particles have a surface area of ​​less than 30 m 2 / g; and The silicon-carbon composite particles have a φ of 0.1 or more, where φ is expressed by the following formula: φ=(maximum peak height dQ / dV in regime I) / (maximum peak height dQ / dV in regime III) [where dQ / dV is measured in a half-cell coin cell, regime I is 0.8 V to 0.4 V, and regime III is 0.15 V to 0 V] is expressed as A manufacturing method comprising:

9. The method of claim 8, wherein the solid carbon precursor material comprises bisphenol A and hexamethylenetetramine.

10. The method of claim 8, wherein the pore volume of the silicon-carbon composite particles has a microporosity of greater than 80%.

11. The I D / I of the silicon-carbon composite particles Ｇ The method of claim 8, wherein is less than 0.

7.

12. The method of claim 8, wherein Z of the silicon-carbon composite particles is less than 5.

13. The surface area of ​​the silicon-carbon composite particles is 10 m ２ 9. The method of claim 8, wherein the .alpha.-hydroxybenzoate is less than 1 / g.

14. The method according to claim 8, wherein the φ of the silicon-carbon composite particles is 0.2 or more.

15. 1. A silicon-carbon composite comprising: a. I less than 0.8 Ｄ / I Ｇ , and carbon scaffolds containing pore volume with more than 70% microporosity; b. a silicon content of 40% to 60% by weight; c. Z less than 10, where Z is a group having the formula: Z=1.875×((M1100-M) / M1100)×100 [In the formula, when a silicon-carbon composite is heated in air from 25°C to about 1100°C, M1100 is the mass of the silicon-carbon composite at 1100°C, and M is the minimum mass of the silicon-carbon composite at 800°C to 1100°C, as measured by thermogravimetric analysis.] Represented by: d. 30 m ２ / g surface area; and e. φ greater than or equal to 0.1, where φ is given by the following formula: φ=(maximum peak height dQ / dV in regime I) / (maximum peak height dQ / dV in regime III) [where dQ / dV is measured in a half-cell coin cell, regime I is 0.8 V to 0.4 V, and regime III is 0.15 V to 0 V] is expressed as A silicon-carbon composite, including [the aforementioned material].

16. The silicon-carbon composite according to claim 15, having a microporosity of more than 80% in pore volume.

17. The silicon-carbon composite I Ｄ / I Ｇ The silicon-carbon composite according to claim 15, wherein is less than 0.

7.

18. The silicon-carbon composite according to claim 15, wherein Z is less than 5.

19. Surface area is 10m ２ The silicon-carbon composite according to claim 15, wherein the amount is less than / g.

20. The silicon-carbon composite according to claim 15, wherein the φ is 0.2 or greater.

21. 16. The silicon-carbon composite of claim 15, further comprising Al, Cr, Mn, Fe, Co, Ni, Ca, Ti, V, Mo, or W, or a combination thereof.

22. The silicon-carbon composite according to claim 15, further comprising Ni.

23. The silicon-carbon composite according to claim 15, further comprising conductive carbon additive particles.

24. 16. The silicon-carbon composite of claim 15, further comprising graphite particles, carbon black particles, nanoscale carbon particles, or a combination thereof.

25. The silicon-carbon composite according to claim 15, further comprising conductive carbon additive particles.

26. The silicon-carbon composite according to claim 15, comprising Dv50 ranging from 5 nm to 20 microns.

27. 1. A method for producing silicon-carbon composite particles, comprising: a. providing a mixture of solid carbon precursor materials; b. The mixture is thermally decomposed at 650°C to 1100°C in the presence of an inert gas to obtain the thermally decomposed carbon material; c. The thermally decomposed carbon material is activated at 650°C to 1100°C in the presence of an active gas to obtain an activated carbon material; d. The activated carbon material is graphitized at 1200°C to 3000°C in the presence of an inert gas to obtain a graphitized porous carbon scaffold; e. Grinding the graphitized porous carbon scaffold to obtain porous carbon scaffold particles; and f. The porous carbon scaffold particles are heated at 350°C to 550°C in the presence of silane gas to obtain silicon-carbon composite particles. Where: The I / G ratio of the silicon-carbon composite particles is less than 0.9; the pore volume of said silicon-carbon composite particles has a microporosity of greater than 70%; The silicon content of the silicon-carbon composite particles is 30% to 60% by weight; The silicon-carbon composite particles have Z less than 10, where Z is a compound of the following formula: Z=1.875×((M1100-M) / M1100)×100 [wherein, when the silicon-carbon composite particles are heated in air from about 25°C to about 1100°C, M is the mass of the silicon-carbon composite particles at 1100°C, and M is the minimum mass of the silicon-carbon composite particles at 800°C to 1100°C, as measured by thermogravimetric analysis.] It is represented by; The surface area of ​​the silicon-carbon composite particles is less than 30 m² / g; and The φ of the silicon-carbon composite particle is 0.2 or greater, where φ is given by the following formula: φ=(maximum peak height dQ / dV in regime I) / (maximum peak height dQ / dV in regime III) [where dQ / dV is measured in a half-cell coin cell, regime I is 0.8 V to 0.4 V, and regime III is 0.15 V to 0 V] It is represented by; The first cycle efficiency of the silicon-carbon composite particles is 90% or more; The average Coulomb efficiency of the silicon-carbon composite particles is 0.999 or higher; and The capacity of the silicon-carbon composite particles is 1400 mAh / g or more. A manufacturing method comprising:

28. A method for producing graphitized activated carbon particles, the following: a. providing a mixture of solid carbon precursor materials; b. The mixture is thermally decomposed at 650°C to 1100°C in the presence of an inert gas to obtain a thermally decomposed porous carbon scaffold; c. The thermally decomposed porous carbon scaffold is pulverized to obtain porous carbon scaffold particles; d. activating the porous carbon scaffold particles at 650°C to 1100°C in the presence of an active gas to obtain activated carbon particles; and e. graphitizing the activated carbon particles at 1200°C to 3000°C in the presence of an inert gas to obtain graphitized activated carbon particles; A manufacturing method comprising:

29. A method for producing graphitized activated carbon particles, the following: a. providing a mixture of solid carbon precursor materials; b. The mixture is thermally decomposed at 650°C to 1100°C in the presence of an inert gas to obtain a thermally decomposed porous carbon scaffold; c) activating the pyrolyzed porous carbon scaffold at 650°C to 1100°C in the presence of an active gas to obtain an activated porous carbon scaffold; d. graphitizing the porous carbon scaffold at 1200°C to 3000°C in the presence of an inert gas to obtain a graphitized activated carbon scaffold; and e. The graphitized activated carbon scaffold is crushed to obtain graphitized activated carbon particles. A manufacturing method comprising:

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