Composite materials with tunable porosity, their preparation and use

Abstract

Provided herein are composite materials and methods for preparing the same for use in electrical energy storage systems (e.g., high-capacity batteries). The composite materials of the present disclosure include a three-dimensional carbon network and optional silicon particles. The composite materials further include macropores, at least some of which are formed by carbonizing sacrificial particles dispersed throughout the three-dimensional network. The macropores advantageously provide space to accommodate strains and stresses in the electrode structure due to volumetric changes of the silicon particles during charging and discharging of the electrical energy storage system.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of U.S. Provisional Patent Application No. 63 / 390,832, filed on July 20, 2022, entitled "Silicon Nanoparticles Comprising a Sacrificial Layer, Composite Materials Including Them, Preparation, and Uses Thereof," U.S. Provisional Patent Application No. 63 / 390,838, filed on July 20, 2022, entitled "Composite Materials Comprising Void Space, Preparation, and Uses Thereof," U.S. Provisional Patent Application No. 63 / 410,652, filed on September 28, 2022, entitled "Porous Carbon Materials Comprising a Carbon Additive," U.S. Provisional Patent Application No. 63 / 390,845, filed on July 20, 2022, entitled "Composite Materials with Tunable Porosity, Preparation, and Uses Thereof," and U.S. Provisional Patent Application No. 63 / 390,845, filed on July 20, 2022, entitled "Functionalized This application claims priority to and benefit of U.S. Provisional Patent Application No. 63 / 390,825, entitled "Silicon Nanoparticles, Composite Materials that Comprise Them, Preparation and Uses Thereof," all of which are incorporated herein by reference.

[0002] The present disclosure generally relates to porous composite materials that include a three-dimensional carbon network having pores (eg, macropores, micropores, and mesopores) dispersed throughout the three-dimensional carbon network. [Background technology]

[0003] High-capacity battery materials, such as lithium-ion batteries (LIBs), are recognized as the most promising energy storage technology for a wide range of applications, from home appliances and electric vehicles to renewable energy storage. Despite the various requirements for diverse applications, Li-ion batteries with large capacity and long cycle life are generally indispensable.

[0004] Silicon is one of the most promising anode materials for lithium-ion batteries because it has the highest known theoretical capacity and is abundant in the Earth's crust. Silicon has been shown to have a high theoretical gravimetric capacity of approximately 4200 mAh / g, compared to only 372 mAh / g for graphite. Therefore, silicon (Si) active material is considered a promising candidate for the next generation anode of lithium-ion batteries (LIBs).

[0005] However, silicon is known to experience a significant "breathing effect" during lithium insertion / deintercalation during continuous charge-discharge processes, negating its high-capacity advantages. That is, the volume of Si can expand to approximately 400% of its original size during lithiation (intercalation of lithium ions into silicon) and then shrink to various sizes during delithiation (extraction of lithium ions from silicon). This "breathing effect" can cause severe structural degradation, especially when Si is supported on a three-dimensional carbon network. Structural damage to the three-dimensional carbon network results in a loss of specific capacity and an increase in battery impedance. The significant volume change poses substantial challenges to maintaining the morphology of Si electrodes during cycling.

[0006] Therefore, there is a need for improved methods to control, select, modify, or enhance the surface properties and morphology of three-dimensional carbon support networks. Summary of the Invention

[0007] The present technology provides porous composite materials containing macropores, micropores, and / or mesopores. The porous composite materials include a three-dimensional carbon network with pores dispersed throughout the three-dimensional carbon network. The composite materials provided herein further include optional silicon particles embedded in the three-dimensional carbon network. At least a portion of the pores are formed by carbonizing a plurality of sacrificial particles dispersed throughout a three-dimensional carbon network precursor material. The pore volume, pore size, and pore distribution of the three-dimensional carbon network can be controlled by adjusting synthesis parameters, such as the method for preparing the composite material, the particle size of the sacrificial material, the amount of sacrificial particles used, and the materials used to form the sacrificial material. The electrochemically active material (e.g., silicon or silica) disposed within the porous three-dimensional carbon network disclosed herein can repeatedly expand and contract without significant damage to the three-dimensional carbon network.

[0008] In some embodiments, the composite material primarily comprises macropores. The presence of macropores offers several advantages, including providing space to accommodate the volume expansion of silicon particles (or other electrochemically active materials) during the charging process and stabilizing the composite material. Without wishing to be bound by theory, accommodating the volume expansion of silicon particles may delay the fracture of the three-dimensional carbon network resulting from successive charge-discharge battery cycles. The macropores can function as "absorbers" to accommodate strains and stresses in the overall electrode structure due to volume changes of silicon. That is, the presence of macropores may provide space for silicon (particles) during volume expansion and relieve mechanical compression of the three-dimensional carbon network, resulting in significantly improved structural integrity.

[0009] In one aspect, without wishing to be bound by theory, the composite material of the present technology containing macropores may maintain overall electrode integrity in terms of microscopic structure and electrical connectivity between the Si particles (even pulverized ones) and the current collector.

[0010] The macropores, which are sufficient to accommodate the volume expansion of silicon particles, not only provide free space to accommodate the volume expansion but also allow lithium ions (Li + ) diffusion and charge transfer kinetics, thereby improving battery power sources.

[0011] In one aspect, the materials provided in the present disclosure can advantageously prevent or reduce rapid capacity fading (e.g., within at least 10 cycles) in high capacity batteries.

[0012] The composite materials of the present technology can improve the performance of lithium ion batteries compared to lithium ion batteries having electrodes that do not have a composite material of the present disclosure, e.g., a composite material without voids, or a composite material with a different pore size distribution.

[0013] Provided herein is a composite material comprising a three-dimensional carbon network. The three-dimensional carbon network comprises micropores, mesopores, and macropores. At least a portion of the macropores of the composite material disclosed herein are formed by carbonizing a plurality of sacrificial particles dispersed throughout the three-dimensional network. In one embodiment, the macropores constitute a volume fraction of greater than about 50% of the total pore volume of the three-dimensional carbon network, and the micropores constitute a volume fraction of about 10% to about 50% of the total pore volume of the three-dimensional carbon network. The composite material has a density of about 0.5 to about 2.5 g / cm as measured by mercury pycnometry. 3 The skeletal density ranges from .

[0014] In some embodiments, the mesopores constitute a volume fraction of less than about 10% of the total pore volume of the three-dimensional carbon network, or less than 5% of the total pore volume of the three-dimensional carbon network.

[0015] In one embodiment, the macropores constitute a volume fraction of greater than about 50% of the total pore volume of the three-dimensional carbon network, the mesopores constitute a volume fraction of less than 10% of the total pore volume of the three-dimensional carbon network, and the micropores constitute a volume fraction equal to the remaining portion of the total pore volume of the three-dimensional carbon network.

[0016] In some embodiments, the volume fraction of macropores is at least 1.5 times the volume fraction of micropores. The volume fraction of macropores can be from about 1.5 times the volume fraction of micropores to about 2.5 times the volume fraction of micropores. In some embodiments, the volume fraction of macropores is at least 10 times the volume fraction of mesopores.

[0017] The three-dimensional carbon network of the composite materials described herein can have a total porosity of the three-dimensional carbon network greater than about 10%.

[0018] The three-dimensional carbon network of the composite materials described herein is approximately 0.1 cm 3 / g~0.3cm 3 / g of the macropore volume of the three-dimensional carbon network.

[0019] The three-dimensional carbon network of the composite materials described herein is approximately 0.1 cm 3 / g ~ approx. 0.4cm 3 / g of the total pore volume of the three-dimensional carbon network.

[0020] The three-dimensional carbon network of the composite materials described herein is approximately 50 m 2 / g or less than 25m 2 / g of the composite material.

[0021] The three-dimensional carbon network of the composite materials described herein is 0.03 cm 3 / g~0.25cm 3 / g.

[0022] In some embodiments, the composite material is in the form of beads. The composite material can have a particle size of about 3 μm to about 25 μm. The composite material can have a particle size distribution D50 in the range of about 5 μm to about 20 μm.

[0023] In some embodiments, the three-dimensional carbon network comprises amorphous carbon. In some embodiments, the three-dimensional carbon network is a xerogel. In some embodiments, the three-dimensional carbon network is an aerogel. In some embodiments, the three-dimensional carbon network is an ambigel, an aerogel-xerogel hybrid material, an aerogel-ambigel hybrid material, an aerogel-ambigel-xerogel hybrid material, or a combination thereof.

[0024] In some embodiments, the composite material comprises about 20% to about 85% silicon. In some embodiments, the silicon particles are dispersed throughout the three-dimensional carbon network. Macropores surround or contain the silicon particles within the three-dimensional carbon network, providing separation or space to accommodate the "breathing" of the silicon. In some embodiments, the silicon is trapped within the three-dimensional carbon network.

[0025] The silicon can be silicon particles in the composite material. In an embodiment, the silicon particles are disposed adjacent to the macropores. The silicon particles can have a particle size distribution D50 ranging from about 10 nm to about 100 μm. The silicon particles can be at least partially crystalline. The silicon particles have an oxygen content of about 2% to about 40%.

[0026] In one embodiment, the total volume of the macropores is about 1 to about 5 times greater than the total volume of the silicon particles.

[0027] In one embodiment, the composite material has a silicon content of about 2 wt% to about 30 wt%, the three-dimensional carbon network has a total porosity of about 5% to about 50%, and the three-dimensional carbon network has a total pore volume of about 0.10 mL / g to about 0.40 mL / g.

[0028] In one embodiment, the composite material has a silicon content of about 30 wt% to about 70 wt%, the three-dimensional carbon network has a total porosity of about 45% to about 70%, and the three-dimensional carbon network has a total pore volume of about 0.40 mL / g to about 1.0 mL / g.

[0029] In one embodiment, the composite material has a silicon content of about 70 wt% to about 98 wt%, the three-dimensional carbon network has a porosity of about 65% to about 75%, and the three-dimensional carbon network has a porosity of about 0.90 mL / g to about 1.4 mL / g.

[0030] In another aspect, provided herein is a method for improving the performance of an energy storage system. The method includes incorporating a composite material of the present disclosure into an electrode of a lithium-based energy storage device. In one aspect, when the composite material is incorporated into an electrode of a lithium-based energy storage device, the composite material has a gravimetric capacity of about 1200 mAh / g to about 3500 mAh / g. In one aspect, the composite material includes lithium or a lithium salt.

[0031] In yet another aspect, provided herein is an electrode comprising the composite material described herein.

[0032] In a further aspect, provided herein is an energy storage device comprising an electrode comprising a composite material described herein.

[0033] The present technology will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which: It should be noted that relative sizes in the figures are not necessarily to scale and are shown for illustrative purposes only. [Brief explanation of the drawings]

[0034] [Figure 1A] 1 illustrates an exemplary composite material comprising macropores according to the present disclosure. [Figure 1B] 1 illustrates an exemplary composite material comprising macropores according to the present disclosure. [Figure 1C] 1 illustrates an exemplary composite material including macropores, wherein silicon particles are at least partially disposed within the macropores, according to the present disclosure. [Figure 2A] 1 illustrates an exemplary composite material according to certain aspects of the present technique, and a method for processing the composite material to obtain a composite material comprising macropores. [Figure 2B] 1 illustrates an exemplary composite material according to certain aspects of the present technique, and a method for processing the composite material to obtain a composite material comprising macropores. [Figure 2C] 2C illustrates an exemplary composite material according to certain embodiments of the present technology, comprising a three-dimensional network, a sacrificial material, and silicon particles, each of which comprises a coating layer made from the sacrificial material. FIG. 2C further illustrates an exemplary method of processing the composite material to obtain a composite material comprising macropores and silicon particles, wherein the macropores at least partially surround or enclose the silicon particles. [Figure 3] 1 illustrates method steps for preparing an exemplary composite material according to aspects of the present disclosure. [Figure 4A] Photographs of porous polyimide (PI) composites made from carbon are shown. [Figure 4B] Photographs of porous PI composites made from silicon / carbon are shown. [Figure 5A] 1 shows a photograph of a porous polyamic acid (PAA) composite made from carbon. [Figure 5B] 1 shows a photograph of a porous PAA composite made from silicon / carbon. DETAILED DESCRIPTION OF THE INVENTION

[0035] Silicon (Si) is considered a promising alternative LIB anode material. During the alloying process, Li7Si3, Li 12 Si7、 Li 13 Si4, Li 15 Si4 and Li 22 A silicon-lithium alloy of Si5 is formed, of which Li 15 Si4 is 3579mAh g at room temperature -1 (2194Ah L -1 ) capacity, which is the highest theoretical capacity known for an anode material. Therefore, it is desirable to incorporate as much silicon as possible into the anode.

[0036] At the same time, the average voltage platform of Si (0.4V vs. Li / Li + ) is that of the graphite electrode (0.125V vs Li / Li + ), which makes it possible to avoid lithium plating and lithium dendrite formation on the surface of the anode material during the lithiation process. As a result, the safety performance of the battery can be significantly improved. In addition, Si has the advantages of abundant reserves in the earth's crust and low cost, which has further stimulated industrial interest in using silicon in batteries.

[0037] Despite these advantages, silicon still has significant drawbacks when used as an electrode material. The main problem with using Si in LIBs is its enormous volume expansion during lithiation. Si electrodes can expand by up to 400%, much more than the 10% expansion of graphite electrodes. The volume expansion leads to mechanical failure of Si.

[0038] Mechanical failure can occur in several ways. First, Si particles are gradually crushed by repeated volume changes, causing a loss of electrical contact between the active material and other components, including the conductive carbon and binder, resulting in a rapid decrease in capacity and cycling performance. Second, volume changes also gradually delaminate the active material from the current collector, resulting in a loss of electrical contact between the active material and the current collector and a decrease in electrode capacity after the first cycle. Third, the electrolyte gradually deteriorates. This is because the solid electrolyte interlayer (SEI) layer is continuously fractured and reformed due to the volume expansion / contraction behavior of the Si electrode during cycling, resulting in continuous exposure of new Si surfaces to the electrolyte. As a result, constant electrolyte degradation occurs on the highly reducing, newly lithiated Si surface, leading to irreversible capacity loss with each cycle and ultimately the end of the cell's life. Both mechanical failure and electrolyte degradation can cause the Si electrode to lose its electrochemical activity very rapidly during the cycling process.

[0039] The composite material provided herein eliminates or reduces at least one drawback of Si when used as an electrode material. Without wishing to be bound by theory, the composite material provided herein may generally be adaptable to changes in the volume of the active Si material during battery operation. Generally, the composite material of the present technology comprises custom or designed macropores that adapt to changes in the volume of silicon or silicon particles incorporated within the composite material.

[0040] In the following description, some examples are provided in the context of aqueous Li-ion batteries due to the current prevalence and popularity of Li-ion technology. However, such examples are provided merely to aid in understanding and explaining the underlying techniques, which may also be used in various other metal-ion batteries, e.g., Li + , Na + , Mg 2+ , Ca 2+ , and Al 3It should be understood that the present disclosure may be similarly applied to other aqueous metal-ion batteries, including, for example, aqueous electrolyte-containing batteries. The composite materials of the present disclosure may be used in other chemistries (e.g., batteries or catalysts) where the active particles undergo significant volume changes during their operation (e.g., reversible reduction-oxidation reactions), including, for example, aqueous electrolyte-containing batteries. definition

[0041] The articles "a" and "an" are used herein to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article.

[0042] Within the context of the present disclosure, the term "about" used throughout this specification is used to describe and explain small variations. For example, the term "about" can refer to ±10% or less, ±5% or less, for example, ±2% or less, ±1% or less, ±0.5% or less, ±0.2% or less, ±0.1% or less, or ±0.05% or less. All numerical values herein are modified by the term "about," whether explicitly stated or not. Values modified by the term "about" naturally include the specific value. For example, "about 5.0" must include 5.0.

[0043] Within the context of the present disclosure, the term "aerogel" or "aerogel material" refers to a solid object, regardless of shape or size, that includes a framework of interconnected solid structures with a corresponding network of interconnected pores integrated within the framework and that contains a gas, such as air, as a dispersed pore medium. As such, an aerogel, such as the carbon aerogels of the present application, is an open-ended, non-fluid colloidal or polymeric network that is extended throughout its entire volume by a gas. Aerogels (e.g., carbon aerogels) are generally prepared by removing solvent from a gel (a solvent-containing solid network) in a manner that minimizes or eliminates gel shrinkage by virtue of its capillary forces at the pore walls; in other words, by removing all swelling factors from a corresponding wet gel without substantial volume loss or network compression. Methods of solvent removal include, but are not limited to, supercritical drying (or drying using a supercritical fluid such that the low surface tension of the supercritical fluid exchanges with transient solvents in the gel), solvent exchange with a supercritical fluid followed by solvent exchange with a fluid that transitions to a supercritical state, subcritical or near-critical fluid drying, and sublimation of frozen solvent in a cryo-observation process. See, e.g., PCT Patent Application Publication No. WO2016127084A1.

[0044] Aerogels, such as carbon aerogels, contain a highly porous network of micro-, meso-, and macro-sized pores, and generally have aerogels with: (a) an average pore diameter in the range of about 2 nm to about 100 nm; (b) a porosity of at least 60% or greater; and (c) a porosity of about 100 nm. 2 / g or more, for example, about 100 to about 1000 m by nitrogen adsorption analysis 2 / g), and are characterized by their physical and structural properties (according to nitrogen porosimetry tests and helium pycnometry).

[0045] Thus, the aerogel materials of the present disclosure include any aerogel or other non-limiting cellular compound that meets the defining elements set forth in the preceding paragraph.

[0046] As used herein, the terms "xerogel" and "ambigel" refer to gels comprising an unconfined, non-fluid colloidal or polymeric network formed by removing all swelling factors from a corresponding wet gel without precautions taken to avoid substantial volume loss or compaction, such as under ambient pressure drying. In contrast to aerogels (e.g., carbon aerogels), xerogels, such as carbon xerogels, generally comprise compact structures. Xerogels experience substantial volume loss during ambient pressure drying and, as measured by nitrogen adsorption analysis, exhibit a volume loss of 0-100 m compared to aerogels. 2 / g, or approximately 0 to approximately 20m 2 / g.

[0047] Within the context of this disclosure, the term "continuous" refers to a layer that is free of gaps, holes, or any discontinuities, e.g., a continuous layer that does not include two (or more) component materials that are physically separated (or spaced apart) within the layer.

[0048] As used herein, the term "uniform" refers to a variation in thickness of a material (e.g., a coating of the present disclosure) of less than about 10%, less than about 5%, or less than about 1%.

[0049] Within the context of this disclosure, the term "capacity" refers to the specific amount of energy or charge a battery can store. Capacity is specifically measured as the discharge current a battery can deliver over time per unit mass. It is typically provided as ampere-hours or milliampere-hours per gram of total active material mass (Ah / g or mAh / g). For example, a battery with a 1 Ah capacity can deliver a current of 1 ampere for 1 hour, or 0.5 amperes for 2 hours, etc. Thus, 1 ampere-hour (Ah) is equal to 3,600 coulombs of charge. Similarly, the term "milliampere-hour (mAh)" also refers to a unit of storage capacity of a battery and is 1 / 1,000 of an ampere-hour. The capacity of a battery (especially the anode) may be determined by methods known in the art, including, but not limited to, applying a constant current load to a fully charged cell until the cell voltage reaches an end-of-discharge voltage value, multiplying the time to reach the end-of-discharge voltage by the constant current to determine the discharge capacity, and dividing the discharge capacity by the weight or volume of the electrode material. Within the context of this disclosure, capacity measurements are obtained according to this method unless otherwise specified. Unless otherwise specified, the capacity is reported for the 10th cycle of the battery.

[0050] As used herein, the term "electrode" refers to either a "cathode" or an "anode." As used herein, the term "positive electrode" is used interchangeably with cathode. Similarly, the term "negative electrode" is used interchangeably with anode.

[0051] Within the context of this disclosure, the term "dispersion" refers to a dispersion in which one substance (the dispersed phase) is distributed in discrete units throughout another substance (the continuous phase or medium). Generally, the dispersed phase is not substantially aggregated, but rather exists at intervals within the other substance. While dispersions include the aggregation or contact of a small number of particles (e.g., less than two, three, four, or five), the particles are generally uniformly spaced throughout the other substance.

[0052] Within the context of the present disclosure, the term "framework" or "framework structure" refers to the network of interconnected oligomeric, polymeric, or colloidal particles that form the solid structure of a gel or aerogel. The polymers or particles making up the framework structure typically have diameters of about 100 angstroms. However, the framework structure of the present disclosure can also include a network of interconnected oligomeric, polymeric, or colloidal particles of any diameter size that form the solid structure within a gel or aerogel.

[0053] Within the context of this disclosure, the term "pore size distribution" refers to the statistical distribution or relative amount of each pore size within a sample volume of a porous material. A narrower pore size distribution refers to a relatively large proportion of pores within a narrow range of pore sizes, thus optimizing the amount of pores that can accommodate electrochemically active species and maximizing the use of pore volume. Conversely, a wider pore size distribution refers to a relatively small proportion of pores within a narrow range of pore sizes. As such, pore size distribution is typically measured as a function of pore volume and reported as the unit size of the full width at half maximum of the main peak in a pore size distribution chart. The pore size distribution of a porous material can be determined by methods known in the art, including, but not limited to, surface area and porosity analyzers by nitrogen adsorption / desorption, which can calculate the pore size distribution. Within the context of this disclosure, pore size distribution measurements are obtained according to this method unless otherwise specified. In certain embodiments, the aerogel material (e.g., carbon-based aerogel material) can have a relatively narrow pore size distribution (full width at half maximum) of about 50 nm or less, 45 nm or less, 40 nm or less, 35 nm or less, 30 nm or less, 25 nm or less, 20 nm or less, 15 nm or less, 10 nm or less, 5 nm or less, or a range between any two of these values.

[0054] Within the context of the present disclosure, the term "pore volume" refers to the total pore volume within a sample of porous material. Total pore volume includes the total volume of micropores, the total volume of mesopores, and the total volume of macropores. As used herein, the term "micropores" refers to pores having a width less than 3 nm. As used herein, the term "mesopores" refers to pores having a width from 3 nm to 50 nm. As used herein, the term macropores refers to pores having a width greater than 50 nm. Pore volume is measured as the volume of pores within a porous material, particularly when the pores may be measurable and / or accessible by electrochemically active species such as another material, e.g., silicon particles. Pore volume is typically measured in cubic centimeters per gram (cm 3 / g or cc / g).

[0055] The pore volume of a porous material can be determined by methods known in the art, including, but not limited to, surface area and porosity analyzers by nitrogen adsorption / desorption, which can calculate the pore volume. Within the context of the present disclosure, pore volume measurements are obtained according to this method unless otherwise specified. In certain aspects, aerogel materials (e.g., carbon-based aerogel materials) without the incorporation of electrochemically active species, e.g., silicon, have a relatively large pore volume of about 1 cc / g or more, 1.5 cc / g or more, 2 cc / g or more, 2.5 cc / g or more, 3 cc / g or more, 3.5 cc / g or more, 4 cc / g or more, or within a range between any two of these values. In other embodiments, the aerogel material (e.g., carbon-based aerogel material) or composite material (with incorporation of an electrochemically active species, e.g., silicon) has a pore volume of about 0.3 cc / g or more, 0.6 cc / g or more, 0.9 cc / g or more, 1.2 cc / g or more, 1.5 cc / g or more, 1.8 cc / g or more, 2.1 cc / g or more, 2.4 cc / g or more, 2.7 cc / g or more, 3.0 cc / g or more, 3.3 cc / g or more, 3.6 cc / g or more, or within a range between any two of these values.

[0056] Within the context of the present disclosure, the term "porosity," when used with respect to the porous networks or composite materials disclosed herein, refers to the volume fraction of pores that do not contain additional material (e.g., electrochemically active species such as silicon particles) bound to the pore walls. For purposes of explanation and illustration, it should be noted that within the specific implementation of a silicon-doped porous network, e.g., aerogel, as the primary anode material in a LIB, porosity refers to the pores after the inclusion of silicon particles. As such, the porosity may be, for example, about 10% to 70% before the anode is in a lithiated state (to accommodate ion transport and silicon expansion) and about 1% to 50% after the anode is in a lithiated state (to accommodate ion transport). More generally, porosity may be determined by methods known in the art, including, for example, without limitation, the ratio of the pore volume of an aerogel material to its bulk density. Within the context of the present disclosure, porosity measurements are obtained according to this method unless otherwise specified. In certain embodiments, the aerogel materials of the present disclosure, such as carbon aerogel materials (carbon-based aerogel materials) or composite materials, have a porosity of about 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, or within a range between any two of these values.

[0057] It should be noted that pore volume and porosity are different measures of the same property of pore structure, namely, the "empty space" within the pore structure. For example, when silicon is used as the electrochemically active species contained within the pores of a porous network (e.g., a composite material as described herein), pore volume and porosity refer to the "empty" space, i.e., the space not utilized by silicon or carbon.

[0058] Within the context of the present disclosure, the term "pore size at the maximum peak from a distribution" refers to the value at a discernible peak on a graph illustrating a pore size distribution. The pore size at the maximum peak of a distribution is specifically measured as the pore size at which the largest percentage of pores are formed. This is typically reported as the pore size per unit length, e.g., micrometers or nanometers (nm). The pore size at the maximum peak from a distribution can be determined by methods known in the art, including, but not limited to, surface area and porosity analyzers by nitrogen adsorption / desorption, which can calculate the pore size distribution and determine the pore size at the maximum peak. Within the context of the present disclosure, measurements of the pore size at the maximum peak from a distribution are taken according to this method unless otherwise specified. In some embodiments, aerogel materials, e.g., carbon-based xerogel materials or composites of the present disclosure, have pore sizes at the maximum peak from a distribution greater than about 50 nm, between about 3 nm and about 50 nm, or less than 3 nm. In certain embodiments, the aerogel material, e.g., the carbon-based aerogel material or composite of the present disclosure, has a pore size at the largest peak from the distribution of about 150 nm or less, 140 nm or less, 130 nm or less, 120 nm or less, 110 nm or less, 100 nm or less, 90 nm or less, 80 nm or less, 70 nm or less, 60 nm or less, 50 nm or less, 40 nm or less, 30 nm or less, 20 nm or less, 10 nm or less, 5 nm or less, 2 nm or less, or within a range between any two of these values.

[0059] Within the context of this disclosure, the term "BET surface area" has its ordinary meaning, referring to the Brunauer-Emmett-Teller method for determining surface area by N2 adsorption measurements. 2 BET surface area, expressed in μm / g, is a measure of the total surface area of a porous material per unit of mass. Unless otherwise specified, "surface area" refers to BET surface area. Alternatively to BET surface area, for example, the external geometric surface area of polyimide or carbon beads can be calculated based on the diameter of the beads. Generally, such external geometric surface areas of beads of the present disclosure range from about 3 to about 700 μm 2 is within the range.

[0060] Within the context of the present disclosure, the terms "pyrolyze" or "pyrolysis" or "carbonization" refer to the heat-induced decomposition or conversion of an organic compound or composition to pure or substantially pure carbon. In each instance, the term "carbonization yield" refers to the percentage ratio of the weight of the resulting carbon to the weight of the organic compound or composition from which the carbon is produced.

[0061] As used herein, the term "particle size distribution D50" refers to the cumulative 50% size based on volume, which is the particle size at the 50% point on the cumulative curve (i.e., the diameter of the particle at the 50th percentile (median) of the particle's volume) when the particle size distribution is obtained on a volume basis and the cumulative curve is drawn so that the total volume is 100%.

[0062] Within the context of this disclosure, the term "density" refers to a measure of the mass per unit volume of a material (e.g., a composite material as described herein). The term "density" generally refers to the true or skeletal density of a material, as well as the bulk density of a material or composition. Density is typically measured in kg / m 3 or g / cm 3The density of a material or composite may be measured by methods known in the art, including, but not limited to, Standard Test Method for Dimensions and Density of Preformed Block and Board-Type Thermal Insulation (ASTM C303, ASTM International, West Conshohocken, Pa.); Standard Test Methods for Thickness and Density of Blanket or Batt Thermal Insulations (ASTM C167, ASTM International, West Conshohocken, Pa.); or Determination of the apparent density of preformed pipe insulation (ISO 18098, International Organization for Standardization, Switzerland).

[0063] Preferably, the aerogel materials (e.g., carbon-based aerogel materials) or composites of the present disclosure have a tap density of about 1.50 g / cc or less, about 1.40 g / cc or less, about 1.30 g / cc or less, about 1.20 g / cc or less, about 1.10 g / cc or less, about 1.00 g / cc or less, about 0.90 g / cc or less, about 0.80 g / cc or less, about 0.70 g / cc or less, about 0.60 g / cc or less, about 0.50 g / cc or less, about 0.40 g / cc or less, about 0.30 g / cc or less, about 0.20 g / cc or less, about 0.10 g / cc or less, or within a range between any two of these values, e.g., from about 0.15 g / cc to about 1.5 g / cc or more, particularly from about 0.50 g / cc to about 1.30 g / cc.

[0064] Preferably, the aerogel materials (e.g., carbon-based aerogel materials) or composites of the present disclosure have a helium framework density within the range of about 1.5 to about 2.5 / cc, for example, from about 1.5 to about 2.5 / cc.

[0065] Preferably, the aerogel materials (e.g., carbon-based aerogel materials) or composites of the present disclosure have a mercury skeletal density of from about 1.0 to about 2.3 / cc, for example, from about.

[0066] Preferably, the aerogel materials (e.g., carbon-based aerogel materials) or composite materials of the present disclosure have a bulk density of from about 0.5 to about 2.0 / cc, for example, from about.

[0067] composite material In one aspect, the composite materials provided herein provide high lithium storage capacity with improved cyclability.

[0068] 1A and 1B illustrate an exemplary composite material of the present disclosure comprising macropores. Referring to FIG. 1A, in one aspect, provided herein is a composite material 100 comprising micropores 110 or mesopores 112 (not shown), and a three-dimensional carbon network 130. The three-dimensional carbon network 130 may comprise a carbon aerogel, a carbon xerogel, a carbon ambigel, a carbon aerogel-xerogel hybrid material, a carbon aerogel-ambigel hybrid material, a carbon aerogel-ambigel-xerogel hybrid material, or a combination thereof.

[0069] 1B , in one aspect, provided herein is a composite material 120 comprising macropores 110, the composite material further comprising a three-dimensional carbon network 130 and silicon particles 140, the silicon particles 140 dispersed throughout the three-dimensional carbon network 130, and at least a portion of the macropores 110 formed by carbonizing a plurality of sacrificial particles 160 (not shown) dispersed throughout the three-dimensional network 130. The macropores at least partially surround or encompass the silicon particles and, as a result, can accommodate volume changes of the silicon particles.

[0070] Referring to FIG. 1C , in one embodiment, a composite material 125 is provided herein that includes silicon particles 140 at least partially disposed within macropores 110. At least some of the silicon particles 140 disposed or partially disposed within the macropores are formed by carbonizing sacrificial particles 160 (not shown) formed around the silicon particles 140. The composite material may further include a three-dimensional carbon network 130, where the macropores 110 and the silicon particles 140 therein are dispersed throughout the three-dimensional network 130. In some embodiments, the silicon is at least partially contained within the micropores and / or mesopores of the three-dimensional carbon network 130. That is, the silicon is disposed within the framework of the network. In some embodiments, the silicon is disposed within pores (e.g., macropores 110) within the three-dimensional carbon network 130. The silicon accepts lithium ions during charging and releases lithium ions during discharging. In certain embodiments, the three-dimensional carbon network 130 forms an interconnected structure around the silicon, which is connected to the network at multiple locations. In some embodiments, the three-dimensional network is a porous network.

[0071] In some embodiments, the three-dimensional network 130 comprises an aerogel, a xerogel, an ambigel, an aerogel-xerogel hybrid material, an aerogel-ambigel hybrid material, an aerogel-ambigel-xerogel hybrid material, or a combination thereof. In some embodiments, the three-dimensional network 130 is in the form of beads. In some embodiments, the beads are substantially spherical and have a diameter of about 100 nm to about 4 mm, or about 0.5 μm to about 15 μm, or about 1 μm to about 10 μm, or about 5 μm to about 4 mm.

[0072] Within the context of the present disclosure, the term "macropore" refers to pores with a diameter greater than about 50 nm. For example, in a composite material formed from carbonizing a sacrificial material, pores may be between about 50 nm and about 10 μm, between about 50 nm and about 10 μm, or between about 500 nm and about 5 μm. The space occupied by macropores refers to "empty" space, i.e., space not utilized by either silicon or the three-dimensional carbon network. Macropores surround or contain silicon particles, providing separation or space to accommodate silicon "breathing." At least a portion of the macropores in the composite materials disclosed herein are formed by carbonizing multiple sacrificial particles dispersed throughout the three-dimensional network 130 or around the silicon particles 140. The three-dimensional carbon network and / or three-dimensional network of the present disclosure may also include micropores and / or mesopores.

[0073] Within the context of the present disclosure, the term "micropore" refers to pores with a diameter smaller than 3 nm, the term "mesopore" refers to pores with a diameter between 3 nm and 50 nm, and the term "macropore" refers to pores with a diameter larger than 50 nm.

[0074] In certain embodiments, composite materials according to certain embodiments of the present technology have a bimodal pore size distribution composed of a first mode of pores and a second mode of pores, preferably having an average pore diameter in the range of about 50 nm to about 1000 nm and an average pore diameter in the range of about 100 nm to about 10 μm.

[0075] In certain embodiments, composite materials according to certain embodiments of the present technology have a multimodal pore size distribution consisting of a first mode of pores, a second mode of pores, and a third mode of pores. Preferably, the first mode of pores has an average pore diameter greater than 50 nm, the second mode of pores has an average pore diameter in the range of about 3 nm to about 50 nm, and the third mode of pores has an average pore diameter less than 3 nm.

[0076] 2A and 2B illustrate exemplary composite materials (200, 210, respectively) according to certain embodiments of the present technology, and a method 500 for processing the composite material to obtain a composite material comprising macropores. Referring to FIG. 2A, composite material 200 includes a three-dimensional network 150 and sacrificial particles 160, with sacrificial particles 160 dispersed throughout three-dimensional network 150.

[0077] In some embodiments, the composite materials (110, 120, 200, 210) of the present technology are in monolithic form, thin sheet form, or particulate form.

[0078] The sacrificial particles are generally provided from the same source and have a known desired particle size, shape, porosity, and other substantially similar material attributes. In some examples, the sacrificial particles have a diameter of less than about 15 μm, about 10 μm, about 8 μm, about 5 μm, about 2 μm, less than about 1000 nm, less than about 800 nm, less than about 500 nm, less than about 300 nm, less than about 250 nm, less than about 200 nm, less than about 150 nm, or less than about 100 nm.

[0079] Referring to FIG. 2B, composite material 210 includes three-dimensional network 150 , sacrificial particles 160 and silicon particles 140 , with sacrificial particles 160 and silicon particles 140 dispersed throughout three-dimensional network 150 .

[0080] 2C , composite material 220 includes a three-dimensional network 150, a sacrificial material 160, and silicon particles 140, each of which includes a coating layer 160A made from sacrificial material 160. Silicon particles 140 including coating layer 160A are dispersed throughout three-dimensional network 150. In some examples, silicon particles 140 have a diameter of less than about 10 μm, less than about 8 μm, less than about 5 μm, less than about 3 μm, less than about 2 μm, less than about 1000 nm, less than about 800 nm, less than about 500 nm, less than about 300 nm, less than about 250 nm, less than about 200 nm, less than about 150 nm, or less than about 100 nm.

[0081] To obtain composite materials (100, 120, and 125) according to some embodiments of the present technology, the composite materials (200, 210, or 220) provided herein include sacrificial particles that undergo pyrolysis (i.e., carbonization) 500. The sacrificial particles 160 may include poly(styrene), poly(ester), poly(methacrylate), poly(acrylate), poly(ethylene glycol), poly(acid amide), poly(norborene), or combinations thereof. In one embodiment, the sacrificial particles include poly(methyl methacrylate). The sacrificial particles do not have to be substantially spherical. In some examples, the sacrificial particles may be substantially spherical.

[0082] In some embodiments, the sacrificial particles and / or sacrificial layers have a carbonization yield of less than about 20 wt%. In some embodiments, the temperature of chemical decomposition of the sacrificial particles is in the range of about 130° C. to about 850° C. The sacrificial particles can be made of polymers, metals, natural and synthetic organics, salts, ceramic compounds, or combinations thereof.

[0083] In some embodiments, the composite materials of the present disclosure include a low bulk density material, such as a carbon aerogel. In some embodiments, the low bulk density material includes a skeletal framework comprising nanofibers, which form a pore structure comprising an array of interconnected pores. In some embodiments, such materials may have a fibrillar morphology. In some embodiments, the composite material is a carbon aerogel, a carbon xerogel, a carbon cryogel, or a carbon ambigel, or a combination thereof. In some embodiments, the composite material is an aerogel. In contrast to aerogels, xerogels, such as silica xerogels, generally comprise a compact structure. Xerogels experience substantial volume loss during ambient pressure drying and, as measured by nitrogen adsorption analysis, exhibit a volume loss of 0-100 m compared to aerogels. 2 / g, or approximately 0 to approximately 20m 2 / g. Additionally, xerogels have a densely packed fibrillar morphology compared to aerogels. Within the context of this disclosure, the term "fibrillar morphology" refers to the structural morphology of a nanoporous material (e.g., carbon aerogel) that includes struts, rods, fibers, or threads. Structurally, some embodiments of carbon networks have a fibrillar morphology with strut sizes that result in the narrow pore size distribution, porosity, and extended connectivity described above, among other properties. In any embodiment, the fibrillar morphology of the carbon network can include an average strut width of about 2-10 nm, or more specifically, about 2-5 nm.

[0084] Within the context of the present disclosure, the term "strut width" refers to the average diameter of the nanostruts, nanorods, nanofibers, or nanofilaments that form a material having a fibril morphology. This is typically reported in any unit length, e.g., micrometers or nm. Strut width can be determined by methods known in the art, including, but not limited to, scanning electron microscope image analysis. Within the context of the present disclosure, strut width measurements are obtained according to this method unless otherwise specified. In certain embodiments, materials or compositions of the present disclosure have a strut width of about 10 nm or less, 9 nm or less, 8 nm or less, 7 nm or less, 6 nm or less, 5 nm or less, 4 nm or less, 3 nm or less, 2 nm or less, or a range between any two of these values. An exemplary range for strut width is about 2-5 nm. Smaller strut widths such as these allow a greater amount of struts to be present within the network and thus in contact with electrochemically active species, thereby allowing more electrochemically active species to be present within the composite. This increases the electrical conductivity and mechanical strength.

[0085] 3, a method 300 illustrating the fabrication of a composite material according to embodiments of the present disclosure includes six steps (310, 320, 330, 340, 350, 360). In this method 300, at least a portion of the macropores are formed after pyrolysis of a three-dimensional network comprising optional silicon particles and sacrificial particles.

[0086] First, optional silicon particles and sacrificial particles are provided, as shown in step 310. Generally, the silicon particles should be homogeneous, i.e., they are typically provided from the same source and have a known and desired particle size, shape, porosity, and other material attributes that are substantially similar. Sacrificial particles are described above.

[0087] After providing the silicon particles (310), the method 300 optionally includes oxidizing and / or functionalizing the surface of the particles in step 320. One purpose of oxidizing and / or functionalizing the surface of the particles is to increase the hydrophilicity of the silicon particles (i.e., step 320). Oxidizing the surface of the silicon particles can result in complete or partial oxidation of the surface Si-H groups. That is, all or a certain percentage of the Si-H groups on the surface of the silicon particles are converted to Si-OH groups after the oxidation process. The silicon particles can be oxidized in a single step or multiple steps. The oxidation can be thermal (e.g., at high temperature under atmospheric conditions), chemical (e.g., with acid and / or oxidizing agents), electrochemical, or a combination thereof. Functionalizing the surface of the silicon particles can utilize hydroxyl functional groups on the surface of the silicon particles. The hydroxyl functional groups covalently react with silane groups of at least one functional group. Binding of the silane groups to the surface can facilitate further modification of the silicon particle surface. Additionally, the silane groups present on the surface of the silicon particles can aid in the dispersion of the silicon particles, which is important for further processing. The silicon particles can be functionalized with functional groups formed from molecules selected from 3-aminopropyltriethoxysilane (APTES), 3-aminopropyltrimethoxysilane (APTMS), N-(2-aminoethyl)-3-aminopropyltriethoxysilane (AEAPTES), and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AEAPTMS), and N-(6-aminohexyl)aminomethyltriethoxysilane (AHAMTES), or combinations thereof.

[0088] In step 330, the sacrificial particles provided in step 310 may optionally be crosslinked with a crosslinking agent and may optionally be functionalized with a polymeric modifier (e.g., a hydrophilic moiety). The polymeric modifier may serve to increase the hydrophilicity of the sacrificial particles.

[0089] In step 340, a sol-gel solution is provided. The silicon particles, sacrificial particles, and / or sacrificial material-coated silicon particles can be uniformly or non-uniformly dispersed in the provided sol-gel solution. In some embodiments, the particles are uniformly provided. The sol-gel solution can include a polar solvent and a precursor to a three-dimensional network. The precursor to the porous three-dimensional network can be an aerogel precursor, a xerogel precursor, an ambigel precursor, an aerogel-xerogel hybrid material precursor, an aerogel-ambigel hybrid material precursor, an aerogel-ambigel-xerogel hybrid material precursor, or a combination thereof. The polar solvent can include dimethyl sulfoxide (DMSO), dimethylformamide (DMF), ethyl acetate, n-methylpyrrolidone (NMP), dimethylacetamide (DMA), propylene carbonate, water, glycerin, propylene glycol, ethylene glycol, tetraethylene glycol, triethylene glycol, and trimethylene glycol, or a mixture thereof. The polar solvent selected must be suitable for dissolving or suspending the components, eg, the polymer (initiator) of the reaction (eg, the precursor of the three-dimensional network), the silicon particles.

[0090] Step 350 includes forming a composite material that includes a three-dimensional network, sacrificial particles dispersed throughout the three-dimensional network, silicon particles dispersed throughout the three-dimensional network, and / or sacrificial material-coated silicon particles dispersed throughout the three-dimensional network.

[0091] The processing in step 350 may include mixing the sol-gel solution with a non-immersion liquid (e.g., mineral oil, mineral spirits, and / or other liquid that cannot be immersed by the sol-gel solution) to form an emulsion of sol-gel solution droplets in the non-immersion liquid. Each sol-gel solution droplet contains silicon particles, sacrificial particles, and / or sacrificial material-coated silicon particles wrapped around them by the sol-gel solution. The sol-gel solution droplets are then separated from the non-immersion liquid and optionally washed to remove any non-immersion liquid remaining on the droplets. The precursor of the three-dimensional network in the sol-gel solution forms a three-dimensional network in the droplets. The method may further include subcritically drying, supercritically drying, spray drying, or ambient pressure drying the sol-gel solution droplets to form a three-dimensional porous network with the silicon particles, sacrificial particles, and / or sacrificial material-coated silicon particles disposed therein. The three-dimensional network may be an aerogel, a xerogel, or a hybrid thereof.

[0092] Alternatively, the processing in step 350 may include directly forming the three-dimensional network with the silicon particles, sacrificial particles, and / or sacrificial material-coated silicon particles dispersed therein without an emulsification process in a non-immersion liquid. For example, the sol-gel solution with the silicon particles, sacrificial particles, and / or sacrificial material-coated silicon particles dispersed therein may be directly dried in a spray dryer or oven while being stirred. During the drying process, the precursors of the three-dimensional network in the sol-gel solution form a three-dimensional network wrapped around the silicon particles, sacrificial particles, and / or sacrificial material-coated silicon particles.

[0093] Step 360 involves pyrolyzing the three-dimensional network to form a carbonized three-dimensional network containing optional silicon particles, sacrificial particles, and / or sacrificial material-coated silicon particles dispersed throughout the three-dimensional network, forming composite particles comprising macropores. At least a portion of the macropores may be formed by removal of sacrificial particles during the pyrolysis process. In one embodiment, the amount of sacrificial particles removed depends on the duration of the heat treatment, e.g., pyrolysis, applied to the porous network. In some embodiments, the pore size of the macropores depends on the amount of sacrificial particles removed by the pyrolysis process. For example, a higher temperature and / or longer duration of the pyrolysis process may result in larger pore sizes of the macropores than macropores formed by a pyrolysis process at a lower temperature and / or for a shorter period of time.

[0094] In some embodiments, the chemical decomposition temperature of the sacrificial particles is within a range of about 130° C. to about 850° C. In certain embodiments, treating the composite material to partially or completely remove the sacrificial particles creates voids (e.g., macropores) adjacent to or around the silicon particles.

[0095] In some embodiments, the method of preparing the composite material further comprises a step of subcritical or supercritical drying after processing of the sol-gel solution, hi some embodiments, the step of subcritical or supercritical drying results in the formation of an aerogel material, e.g., a xerogel, aerogel, etc.

[0096] Oxidizing the surfaces of the silicon particles can include an acid treatment step. In some embodiments, the acid treatment step includes the use of sulfochromic acid or HO (hydrogen peroxide). In some examples, the acid treatment step includes sonicating the plurality of silicon particles for a period of time, e.g., at least 5 minutes, at least 10 minutes, at least 20 minutes, at least 30 minutes, or at least 60 minutes. Oxidizing the surfaces of the plurality of silicon particles can include a pyrolysis step at a temperature of about 300°C, about 400°C, or about 500°C to about 600°C, about 650°C, about 700°C, about 800°C, about 850°C, or about 900°C. In some embodiments, the temperature is about 650°C. As used herein, the terms "pyrolyzing" or "pyrolysis" refer to the heat-induced decomposition or conversion of an organic compound or composition to pure or substantially pure carbon. Oxidizing the surfaces of the plurality of silicon particles can result in a reduction in the number of Si-H bonds on the surfaces of the silicon particles.

[0097] In some embodiments, the method for preparing a composite material of the present disclosure further comprises a step of subcritical or supercritical solvent removal, e.g., drying, after treating the plurality of silicon particles in the presence of a sol-gel solution (before or after the pyrolysis step). Methods of solvent removal include, but are not limited to, supercritical drying (or drying using a supercritical fluid, where the low surface tension of the supercritical fluid allows for exchange with the transient solvent in the gel), solvent exchange with a supercritical fluid followed by solvent exchange with a fluid that transitions to a supercritical state, subcritical fluid drying or near-critical fluid drying, and sublimation of the frozen solvent in a cryo-observation process. See, for example, PCT Patent Application Publication No. WO2016127084A1.

[0098] Composite materials may be in a variety of different physical forms. In some embodiments, a composite material may take the form of a monolith. As used herein, the term "monolith" refers to a material in which the majority (by weight) of the low-density skeletal framework contained in the composite material is in the form of a single, continuous, self-supporting object. With respect to aerogel materials, monolithic aerogel materials include aerogel materials that are initially formed to have a well-defined shape but may subsequently crack, fracture, or split into a non-self-replicating object. For example, an irregular mass may be considered a monolith. Monolithic aerogels may take the form of free-standing structures, or fiber-reinforced materials, or interpenetrating foams.

[0099] In other aspects, the composite material may be in particulate form, e.g., beads, or particles, resulting, for example, from the grinding of a monolithic material. As used herein, the term "bead" is meant to encompass small, discrete units or portions having a generally spherical shape. In some aspects, the composite beads are substantially spherical.

[0100] Composite materials in particulate form can have a variety of particle sizes. For spherical particles (e.g., beads), particle size is the diameter of the particle. For irregular particles, the term particle size refers to the largest dimension (e.g., length, width, or height). Particle size can vary depending on the physical form, method of preparation, and any subsequent physical steps performed. In some embodiments, composite materials in particulate form can have a particle size of about 1 micrometer to about 1 millimeter. For example, the composite material in particulate form can have a particle size of about 1 micrometer, about 2 micrometers, about 3 micrometers, about 4 micrometers, about 5 micrometers, about 6 micrometers, about 7 micrometers, about 8 micrometers, about 9 micrometers, about 10 micrometers, about 15 micrometers, about 20 micrometers, about 25 micrometers, about 30 micrometers, about 35 micrometers, about 40 micrometers, about 45 micrometers, about 50 micrometers, about 60 micrometers, about 70 micrometers, about 80 micrometers, about 90 micrometers, about 100 micrometers, about 200 micrometers, about 300 micrometers, about 400 micrometers, about 500 micrometers, about 600 micrometers, about 700 micrometers, about 800 micrometers, about 900 micrometers, about 1 millimeter, or a range between any two of these values.

[0101] In some embodiments, the composite material has a particle size D90 value of 40 micrometers or less. In some embodiments, the composite material has a particle size D10 value of at least 1 micrometer. In some embodiments, the composite material has a particle size D50 value in the range of about 5 micrometers to about 20 micrometers.

[0102] The density of the composite material can vary. In some embodiments, the composite material has a density of about 0.15 g / cm 3 ~Approx. 1.2g / cm 3 The tap density ranges from 0.1 to 1.0.

[0103] The surface area of the composite material can vary. For example, the surface area can be up to about 100 m 2 / g or 100m 2 In some embodiments, the composite material may have a viscosity of about 0.05 m / g. 2 / g~about 400m 2 In some embodiments, the composite material has a surface area in the range of at least about 0.1 m / g. 2 / g~about 10m 2 / g, approx. 1m 2 / g ~ approx. 25m 2 / g, approx. 1m 2 / g~about 50m 2 / g, approx. 1m 2 / g ~ approx. 1m 2 / g, or approximately 1 m 2 / g~about 300m 2 / g of surface area.

[0104] In some embodiments, the composite material comprises silicon in an amount of about 1% to about 85% by weight, e.g., about 2%, about 5%, about 10%, about 15%, about 20%, about 25%, about 30%, about 35%, about 40%, about 45%, or about 50% by weight, to about 55%, about 60%, about 65%, about 70%, about 75%, about 80%, or about 85% by weight, based on the total weight of the composite material.

[0105] In other embodiments, the composite material may be in particulate form, e.g., beads, or particles, resulting, for example, from the grinding of a monolithic material. As used herein, the term "bead" is meant to encompass small, discrete units or portions having a generally spherical shape. In some embodiments, the carbon-silicon composite beads are substantially spherical.

[0106] The capacity of the composite material can vary. In some embodiments, the composite material has a specific capacity of at least about 400 mAh / g. In some embodiments, the composite material has a specific capacity of about 400 mAh / g, about 500 mAh / g, about 600 mAh / g, about 700 mAh / g, about 800 mAh / g, about 900 mAh / g, about 1000 mAh / g, or about 1100 mAh / g. In some embodiments, the composite material has a specific capacity of 1200 mAh / g or greater, 1400 mAh / g or greater, 1600 mAh / g or greater, 1800 mAh / g or greater, 2000 mAh / g or greater, 2400 mAh / g or greater, 2800 mAh / g or greater, 3200 mAh / g or greater, or a range between any two of these values.

[0107] The electrical conductivity of anode materials can vary. Within the context of this disclosure, the term "conductivity" refers to a measurement of a material's ability to conduct electric current or to pass or allow the flow of electrons therethrough. Conductivity is specifically measured as the electrical conductance / susceptance / admittance of a material per unit size of the material. It is typically reported as S / m (Siemens / meter) or S / cm (Siemens / centimeter). The conductivity or resistivity of a material may be determined by methods known in the art, including, but not limited to, in-line four-point resistivity (using the ASTM F84-99 dual configuration test method). Within the context of this disclosure, unless otherwise specified, conductivity measurements are obtained according to ASTM F84-Resistivity (R) measurements, which are obtained by measuring voltage (V) divided by current (I). In certain embodiments, the anode materials of the present disclosure have a conductivity of about 10 S / cm or greater, 20 S / cm or greater, 30 S / cm or greater, 40 S / cm or greater, 50 S / cm or greater, 60 S / cm or greater, 70 S / cm or greater, 80 S / cm or greater, or a range between any two of these values.

[0108] 3D carbon network The three-dimensional carbon networks of the present disclosure include carbon-based networks selected from carbon aerogels, carbon xerogels, carbon ambigels, carbon aerogel-xerogel hybrid materials, carbon aerogel-ambigel hybrid materials, carbon aerogel-ambigel-xerogel hybrid materials, or combinations thereof. The three-dimensional carbon networks of the present disclosure may also be referred to as aerogels, aerogels, carbon aerogels, carbon aerogels, or carbon aerogel beads.

[0109] The aerogels used in the present disclosure can be carbonized to obtain a three-dimensional carbon network, e.g., the carbon-based aerogels of the present technology. Carbonization can be carried out by pyrolysis at high temperatures in an inert atmosphere. The carbonized forms of the aerogels used in the present disclosure can have a nitrogen content of 0-20%. Typical pyrolysis temperatures range from 500°C to 2000°C. The temperature can be increased to reduce the nitrogen content of the resulting carbon aerogel. Pyrolysis is typically carried out in an inert atmosphere (i.e., nitrogen, helium, neon, argon, or some combination).

[0110] In some embodiments, the three-dimensional carbon network comprises a polyimide-derived carbon aerogel or carbon xerogel. In some embodiments, the dried polyimide aerogel is exposed to a processing temperature of 300°C or higher, 400°C or higher, 600°C or higher, 800°C or higher, 1000°C or higher, 1200°C or higher, 1400°C or higher, 1600°C or higher, 1800°C or higher, 2000°C or higher, 2200°C or higher, 2400°C or higher, 2600°C or higher, 2800°C or higher, or a range between any two of these values, to carbonize the polyimide aerogel and obtain a polyimide-derived carbon aerogel.

[0111] The present disclosure involves the formation and use of three-dimensional carbon networks, such as carbon aerogels, as electrode materials in energy storage devices, e.g., as the primary anode material in LIBs. The pores of the porous network are designed, configured, and constructed to accommodate silicon or other semimetallic or metallic particles and the expansion of such particles upon lithiation in LIBs. Alternatively, the pores of the porous network may be filled with sulfides, hydrides, any suitable polymer, or other additives, with the benefit of contacting the additive with the conductive material to provide a more effective electrode.

[0112] To further extend the exemplary application in LIBs, when carbon-based aerogel materials as in the examples of the present disclosure are used as the primary electrode material (e.g., anode material), the carbon aerogel porous core has a narrow pore size distribution and provides high electrical conductivity, high mechanical strength, and morphology and sufficient pore volume (at final density) to accommodate a high weight percentage of silicon particles and their expansion.

[0113] In some instances, the surface of the three-dimensional carbon network may be modified via chemical, physical, or mechanical methods to enhance performance through electrochemically active species contained within the pores of the porous network.

[0114] It is further contemplated herein that three-dimensional carbon networks, and particularly carbon aerogels, can take the form of monolithic structures. Being essentially monolithic, carbon aerogels eliminate the need for any binder. In other words, the anode can be binderless. As used herein, the term "monolithic" refers to an aerogel material in which the majority (by weight) of the aerogel contained in the aerogel material or composition is in the form of a single, continuous, interconnected aerogel nanostructure. Monolithic carbon aerogel materials include carbon aerogel materials that are initially formed to have a single, interconnected gel or aerogel nanostructure but may subsequently crack, fracture, or split into non-single aerogel nanostructures. Monolithic aerogels can take the form of free-standing or reinforced (fiber or foam) materials. By comparison, using silicon lithiation as an example, silicon incorporated within monolithic aerogels can be more efficiently utilized relative to theoretical capacity compared to the same amount of silicon incorporated within a slurry using conventional processes.

[0115] Monolithic aerogel materials (e.g., monolithic carbon aerogel) are distinguished from particulate aerogel materials. The term "particulate aerogel material" refers to an aerogel material in which the majority (by weight) of the aerogel contained therein is in the form of particulates, particles, granules, beads, or powders, which can be combined or compressed together (i.e., via a binder, such as a polymer binder), but lack the interconnected aerogel nanostructure between the individual particles. Collectively, aerogel materials in this form are said to have a powder or particulate morphology (as opposed to a monolithic morphology). Note that despite the individual particles of the powder having a unitary structure, the individual particles are not considered monoliths herein. Integrating aerogel powder into an electrochemical cell typically involves preparing a paste or slurry from the powder, casting it onto a substrate, drying, and optionally calendaring.

[0116] Particulate aerogel materials, such as carbon aerogel beads, offer certain advantages. For example, particulate materials can be used as a direct replacement for other materials, such as graphite, in LIB anodes and anode manufacturing processes. Particulate materials can also provide improved lithium ion diffusion rates due to shorter diffusion paths within the particulate material. Particulate materials can also enable electrodes with increased packing density, for example, by tailoring particle size and packing arrangement. Particulate materials can also improve silicon access due to inter- and intra-particle porosity.

[0117] Carbon aerogels can be formed from inorganic materials, organic materials, or mixtures thereof. Carbon aerogels can be formed from inorganic aerogels, organic aerogels, or mixtures thereof. Inorganic aerogels, organic aerogels, or mixtures thereof can be carbonized to obtain the three-dimensional carbon network (e.g., porous carbon aerogel) of the present disclosure. Aerogels can be formed from inorganic materials, organic materials, or mixtures thereof. For example, when formed from organic materials such as phenol, resorcinol formaldehyde (RF), phloroglucinol-furfuraldehyde (PF), polyacrylonitrile (PAN), polyimide (PI), polyurethane (PU), polyurea (PUA), polyamine (PA), polybutadiene, polydicyclopentadiene, and their precursors or polymer derivatives, the organic aerogels can be carbonized (e.g., by pyrolysis) to form carbon aerogels that can have different or overlapping properties (e.g., pore volume, pore size distribution, morphology, etc.) depending on the precursor materials and methodology used.

[0118] organic aerogel Organic aerogels are generally formed from carbon-based polymer precursors. These polymeric materials include, but are not limited to, resorcinol formaldehyde (RF), polyimides, polyacrylates, polymethyl methacrylates, acrylate oligomers, polyoxyalkylenes, polyurethanes, polyphenols, polybutadienes, trialkoxysilyl-terminated polydimethylsiloxanes, polystyrenes, polyacrylonitriles, polyfurfural, melamine-formaldehyde, cresol formaldehyde, phenol-furfural, polyethers, polyols, polyisocyanates, polyhydroxybenzenes, polyvinyl alcohol dialdehydes, polycyanurates, polyacrylamides, various epoxies, agar, agarose, chitosan, and combinations thereof. As an example, organic RF aerogels are typically prepared from the sol-gel polymerization of resorcinol or melamine with formaldehyde under alkaline conditions.

[0119] In certain embodiments, the aerogels of the present disclosure include polyamic acids, polyimides, or combinations thereof, or are carbon aerogels obtained (i.e., derived) from polyamic acids or polyimides by carbonization. In certain embodiments, the aerogels include polyamic acids, polyimides, or combinations thereof, or are obtained by thermal decomposition of polyamic acids, polyimides, or combinations thereof. In some embodiments, the polyamic acids or polyimides are prepared in aqueous solutions (i.e., via aqueous sol-gel processes). References herein to aqueous solutions or aqueous sol-gel processes mean that the solutions or aqueous sol-gel processes are substantially free of any organic solvents. The term "substantially free of" as used herein in the context of organic solvents means that organic solvents have not been intentionally added and that more than trace amounts of organic solvents are not present. For example, in certain embodiments, the aqueous solutions can be characterized as containing less than 1% by volume of organic solvents, or less than 0.1% by volume, or less than 0.01%, or even 0% by volume of organic solvents.

[0120] The use of aqueous sol-gel processes has the advantage of providing rapid gelation, making the process amenable to configuration in a continuous process, for example, to prepare polyimide beads. Aqueous sol-gel processes for preparing polyamic acid and polyimide gel materials are economically preferable to traditional methods for producing such materials (e.g., expensive organic solvents are avoided and disposal costs are minimized) and "green" (i.e., beneficial from an environmental standpoint because potentially toxic organic solvents are avoided and the production of toxic by-products is minimized or eliminated), advantageously potentially reducing the overall number of operations that need to be performed to provide carbon or polyamic acid / polyimide gel materials. As disclosed in International Patent Application Publication No. WO2022 / 125835 and International Patent Application No. PCT / US2023 / 016821 (each of which is incorporated herein by reference in its entirety), polyamic acid and polyimide gels can be prepared in water, in monolithic or beaded form, and the gels can be converted to nanostructured aerogels with properties similar to aerogels prepared by conventional organic solvent-based processes, and the aerogels can be optionally pyrolyzed to form the corresponding carbon aerogels.

[0121] In some embodiments, the aerogels of the present disclosure are polyamic acid aerogels in monolithic or bead form, where the polyamic acid is prepared by acidifying an aqueous solution of the polyamic acid. In some embodiments, the polyamic acid is dissolved in water in the presence of a base (e.g., an alkali metal hydroxide or a non-nucleophilic amine base). In other embodiments, the polyamic acid is prepared in situ under aqueous conditions, thereby directly forming a polyamic acid salt solution. In some embodiments, the polyamic acid is any commercially available polyamic acid. In other embodiments, the polyamic acid is preformed ("preformed") and isolated, for example, prepared by reaction of a diamine and a tetracarboxylic dianhydride in an organic solvent according to conventional synthetic methods. In some embodiments, an aqueous solution of the polyamic acid salt is prepared in situ, for example, by reaction of a diamine and a tetracarboxylic dianhydride in the presence of a non-nucleophilic amine, thereby obtaining an aqueous solution of a polyamic acid ammonium salt. Suitable methods for preparing polyamic acid aerogels under such aqueous conditions are described in WO2022 / 125835 and PCT / US2023 / 016821 (previously incorporated by reference).

[0122] In some embodiments, the aerogels of the present disclosure are polyimide aerogels in monolithic or bead form, where the polyimide is prepared by thermal or chemical imidization of a polyamic acid in aqueous solution. Suitable methods for forming monoliths and beads under such aqueous conditions (e.g., using droplet or emulsion-based processes) are described in WO2022 / 125835 and PCT / US2023 / 016821 (previously incorporated by reference).

[0123] Organic / inorganic hybrid aerogel In some embodiments, the aerogels of the present disclosure are organic / inorganic hybrid aerogels. Organic / inorganic hybrid aerogels are composed primarily of organically modified silica ("ormosil"). These ormosil materials contain an organic component covalently bonded to the silica network. Ormosils are typically formed by the hydrolysis and condensation of organically modified silanes (R-Si(OX)3) with conventional alkoxide precursors (Y(OX)4). In these formulas, X can represent, for example, CH3, CH5, CH7, or CH9; Y can represent, for example, Si, Ti, Zr, or Al; and R can be any organic fragment, such as methyl, ethyl, propyl, butyl, isopropyl, methacrylate, acrylate, vinyl, or epoxide. The organic component in ormosil aerogels can be dispersed throughout the silica network or chemically bonded to it.

[0124] Silicon particles Silicon is generally present in the composite materials of the present disclosure as silicon particles. Within the context of the present disclosure, the term "silicon particles" refers to silicon or silicon-based materials having a range of particle sizes. The particle size of the silicon in the composite materials can vary. Silicon particles of the present disclosure can be nanoparticles, e.g., particles having two or three dimensions ranging from about 1 nm to about 150 nm. Silicon particles of the present disclosure can be microparticles, e.g., micron-sized particles having a maximum dimension, e.g., a diameter of a substantially spherical particle ranging from about 150 nm to about 10 micrometers or more. For example, silicon particles of the present disclosure can have a maximum dimension, e.g., a diameter of a substantially spherical particle, of about 10 nm, 50 nm, 60 nm, 80 nm, 100 nm, 120 nm, 130 nm, 140 nm, 150 nm, 180 nm, 200 nm, 500 nm, 1 micrometer, 1.5 micrometers, 2 micrometers, 3 micrometers, 5 micrometers, 10 micrometers, 20 micrometers, 40 micrometers, 50 micrometers, 100 micrometers, or a range between any two of these values.

[0125] In some embodiments, the silicon particles may be monodisperse or substantially monodisperse. In other embodiments, the silicon particles may have a particle size distribution. Within the context of the present disclosure, the dimensions of the silicon particles are provided based on the median of the particle size distribution, i.e., D50. In some embodiments, the silicon in the composite material has an average particle size of about 1 μm or less. In some embodiments, the silicon in the composite material has a particle size distribution D50 of about 10 nm to about 100 micrometers. In some embodiments, the silicon in the composite material has a particle size distribution D50 of about 10 nm, 50 nm, 60 nm, 80 nm, 100 nm, 120 nm, 130 nm, 140 nm, 150 nm, 180 nm, 200 nm, 500 nm, 1 micrometer, 1.5 micrometer, 2 micrometer, 3 micrometer, 5 micrometer, 10 micrometer, 20 micrometer, 40 micrometer, 50 micrometer, 100 micrometer, or substantially within a range between any two of these values.

[0126] The silicon particles of the present disclosure include silicon wires, crystalline silicon, amorphous silicon, silicon alloys, silicon oxides (SiO x ) and any combination thereof. Particles, e.g., particles of electrically active material such as silicon particles, can have a variety of shapes for the embodiments disclosed herein. In some embodiments, the silicon particles disclosed herein can be substantially spherical. In other embodiments, the particles of electrically active material can be substantially planar, cubic, oval, elliptical, discoid, or donut-shaped.

[0127] In one example, prior to the formation of the sacrificial layer, the silicon particle (e.g., silicon nanoparticle) surface can be modified with functional groups, which can help disperse the silicon particles in the porous network. In another example, the formation of the sacrificial layer can further help disperse the silicon particles in the porous network. In one example, the porous network can be a sol-gel, an aerogel, a xerogel, a foam structure, or the like. In some embodiments, the porous network is carbonized to obtain the three-dimensional carbon network of the present disclosure according to embodiments disclosed herein.

[0128] For example, functional groups can be covalently bonded to the surface of silicon particles. Prior to functionalization, the surface of silicon particles contains silane groups, such as silicon hydride and / or silicon oxide groups. In some embodiments, at least a portion of the silane and silicon oxide groups can be present in combination with the bonded functional groups after functionalization of the surface of the silicon particles; for example, the silicon particle surface can contain silane groups and covalently bonded functional groups, silicon oxide groups and covalently bonded functional groups, or both silane and silicon oxide groups and covalently bonded functional groups. The presence of functional groups on the surface of silicon particles can be detected by various techniques, for example, by infrared spectroscopy.

[0129] The surface of silicon particles can be functionalized with hydrophilic groups to help improve dispersion within the porous network. Without being bound by theory, functionalization with hydroxide groups results in improved covalent bonding between the surface groups of the silicon particles and the porous network. As a result, the functionalized silicon particles can be uniformly dispersed within the porous network. For example, hydrophilic hydroxide groups can be fused to the surface of the silicon particles with an unsaturated glycol to improve the hydrophilicity of the particle surface. Improving the hydrophilicity of the silicon particles allows the particles to become and remain more uniformly dispersed within the network, and to remain uniformly dispersed within the network during any additional processing (e.g., pyrolysis). In one example, functionalization via glycol can improve the dispersion of silicon particles within polyimide sol-gels and / or aerogels or carbon aerogels. Any suitable glycol can be used, including, but not limited to, ethylene glycol methyl ether methacrylate, poly(ethylene glycol) methyl ether methacrylate, among others.

[0130] In some embodiments, the individual silicon particles are heterogeneously dispersed throughout the three-dimensional carbon network. In some embodiments, the individual silicon particles are homogeneously dispersed throughout the three-dimensional carbon network. The term "homogeneously dispersed" refers to a distribution of Si particles throughout the three-dimensional carbon network without large variations in local concentration across the accessible network surface.

[0131] In some embodiments, about 30 wt% to about 70 wt%, or about 20 wt% to about 50 wt% of the dispersed individual silicon particles within the plurality of silicon particles are in an agglomerated state. In some embodiments, less than about 30 wt%, less than about 20 wt%, or less than about 10 wt% of the dispersed individual silicon particles within the plurality of silicon particles are in an agglomerated state. In some embodiments, homogeneously distributed Si particles can refer to a distribution of a plurality of Si particles throughout a porous polymer network with less than about 30 wt%, less than about 20 wt%, or less than about 10 wt% of the dispersed individual silicon particles in an agglomerated state within the plurality of silicon particles.

[0132] Lithium Additive Lithium additives can be added to the composite material. The lithium additive can include lithium metal and / or a lithium salt. In some embodiments, the lithium additive is less than about 30 wt %, less than about 25 wt %, less than 20 wt %, less than 15 wt %, or less than 10 wt % of the composite material. Exemplary lithium salts that can be used as additives in the composite material include, but are not limited to, dilithium(II) tetrabromonickelate, dilithium tetrachlorocopper(II), lithium azide, lithium benzoate, lithium bromide, lithium carbonate, lithium chloride, lithium cyclohexanebutanoate, lithium fluoride, lithium formate, lithium(V) hexafluoroarsenate, lithium hexafluorophosphate, lithium hydroxide, lithium iodate, lithium iodide, lithium metaborate, lithium perchlorate, lithium phosphate, lithium sulfate, lithium tetraborate, lithium tetrachloroaluminate, lithium tetrafluoroborate, lithium thiocyanate, lithium trifluoromethanesulfonate, and lithium trifluoromethanesulfonate.

[0133] Sacrificial particles In exemplary aspects, the composite material includes sacrificial particles. In some aspects, the sacrificial particles of the present disclosure are made from a sacrificial material. In some aspects, the sacrificial particles of the present disclosure include a sacrificial material.

[0134] Within the context of the present disclosure, the term "sacrificial material" refers to a material that is intended to be sacrificed or at least partially removed in response to mechanical, thermal, chemical, and / or electromagnetic conditions experienced by the material. For example, a sacrificial material can decompose when exposed to high temperatures or high and / or continuous stresses.

[0135] The sacrificial material can be selected from the group consisting of siloxane, polyolefin, polyurethane, phenolic resin, melamine, cellulose acetate, and polystyrene. In some cases, the material layer is in the form of a foam. In some embodiments, the sacrificial material can be worn away by exposure to mechanical (e.g., cyclic) loads. In some embodiments, the sacrificial layer decomposes after exposure to a single mechanical, chemical, and / or thermal event.

[0136] In some embodiments, the onset temperature of chemical decomposition of the sacrificial material ranges from about 100° C. to about 700° C., from about 100° C. to about 500° C., or from about 200° C. to about 400° C. The sacrificial particles can be made of polymers, metals, natural and synthetic organics, salts, ceramic compounds, or combinations thereof.

[0137] Polymers for use in the sacrificial material can be selected from a wide variety of thermoplastics, blends of thermoplastics, or thermosets. Examples of usable thermoplastics include polyacetal, polyacrylic, styrene acrylonitrile, polyolefin, acrylonitrile-butadiene-styrene, polycarbonate, polystyrene, polyethylene terephthalate, polybutylene terephthalate, polyamides, such as, but not limited to, nylon 6, nylon 6,6, nylon 6,10, nylon 6,12, nylon 11, or nylon 12, polyamideimide, polyarylate, polyurethane, ethylene propylene rubber (EPR), polyarylsulfone, polyethersulfone, polyphenylene sulfide, polyvinyl chloride, polysulfone, polyetherimide, polytetrafluoroethylene, fluorinated ethylene propylene, polychlorotrifluoroethylene, polyvinylidene fluoride, polyvinyl fluoride, polyetherketone, polyetheretherketone, polyetherketoneketone, etc., or a combination comprising at least one of the foregoing thermoplastics.

[0138] Examples of thermoplastic blends that can be used for the sacrificial material include acrylonitrile-butadiene-styrene / nylon, polycarbonate / acrylonitrile-butadiene-styrene, acrylonitrile-butadiene-styrene / polyvinyl chloride, polyphenylene ether / polystyrene, polyphenylene ether / nylon, polysulfone / acrylonitrile-butadiene-styrene, polycarbonate / thermoplastic urethane, polycarbonate / polyethylene terephthalate, polycarbonate / polybutylene terephthalate, thermoplastic elastomer alloys, polyethylene terephthalate / polybutylene terephthalate, styrene-maleic anhydride / acrylonitrile-butadiene-styrene, polyether ether ketone / polyethersulfone, styrene-butadiene rubber, polyethylene / nylon, polyethylene / polyacetal, ethylene propylene rubber (EPR), and the like, or combinations comprising at least one of the foregoing blends.

[0139] Examples of polymeric thermosets that can be used for the sacrificial material include polyurethanes, epoxies, phenolics, polyesters, polyamides, silicones, etc., or combinations comprising at least one of the foregoing thermosets. Mixtures of thermosets and mixtures of thermoplastics and thermosets can also be used.

[0140] In some embodiments, the sacrificial particles comprise a polymer having a thermal decomposition yield of less than 30 wt%, less than 20 wt%, less than 18 wt%, less than 15 wt%, less than 10 wt%, less than 8.0 wt%, or less than 5.0 wt%.

[0141] In some embodiments, the sacrificial particles are formed from a material selected from polymethyl methacrylate (PMMA), polyvinylpyrrolidone (PVP), polyvinyl acetate (PVAc), polyvinyl alcohol (PVA), polyacrylonitrile (PAN), polypropylene oxide (PEO), polypropylene oxide (PPO), polyethyleneimine (PEI), polyurethane, poly(3,4-ethylenedioxythiophene, PEDOT), polyvinyl butyral, polyethylene oxide copolymer, polypropylene oxide copolymer, polycarbonate (PC), polyvinyl chloride (PVC), polycaprolactone, polyvinylidene fluoride, polystyrene, or combinations thereof.

[0142] In some embodiments, the sacrificial particles comprise poly(styrene), poly(ester), poly(methacrylate), poly(acrylate), poly(ethylene glycol), poly(acid amide), poly(norborene), or combinations thereof. In one embodiment, the sacrificial particles comprise poly(methyl methacrylate).

[0143] The sacrificial particles are generally provided from the same source and have known desired particle sizes, shapes, porosities, and other substantially similar material attributes. In some examples, the sacrificial particles have diameters of less than 10 μm, less than 8 μm, less than 5 μm, less than 3 μm, less than 2 μm, less than 1000 nm, less than 800 nm, less than 500 nm, less than 300 nm, less than 250 nm, less than 200 nm, less than 150 nm, or less than 100 nm.

[0144] Composite Material Properties The composite materials can be characterized by the resulting pore volume, surface area (BET) and pore size distribution.

[0145] The composite materials described herein generally contain micropores (<3 nm), mesopores (3 nm-50 nm), and macropores (>50 nm). The composite materials described herein contain a three-dimensional carbon network with a substantial amount of macropores. In some embodiments, the total level of porosity of the three-dimensional carbon network is greater than 10%, greater than 20%, greater than 30%, greater than 40%, greater than 50%, greater than 60%, or greater than 70%. In some embodiments, the total level of porosity of the three-dimensional carbon network is 25%-35%, 30%-40%, 35%-45%, 40%-50%, 55%-65%, or 60%-70%.

[0146] In some embodiments, the total pore volume of the composite material is about 0.1 cm 3 / g ~ approx. 1.5cm 3 / g, 0.1cm 3 / g~1.0cm 3 / g, or 0.1cm 3 / g~0.5cm 3 / g, 0.1cm 3 / g ~ approx. 0.4cm 3 / g, 0.4cm 3 / g ~ approx. 1.0cm 3 / g, 0.9cm 3 / g ~ approx. 1.4cm 3 / g.

[0147] In some embodiments, the macropores constitute a volume fraction of greater than about 5%, greater than about 10%, greater than about 20%, greater than about 30%, greater than about 40%, greater than about 50%, greater than about 60%, greater than about 70%, or greater than about 80% of the total pore volume of the three-dimensional carbon network. In some embodiments, the macropores constitute a volume fraction of 45%-55%, 55%-65%, 65%-75%, or 70%-80% of the total pore volume of the three-dimensional carbon network. The composite materials described herein generally have a low volume fraction of mesopores. In some embodiments, the mesopores constitute a volume fraction of less than 20%, less than 10%, less than 5%, less than 2%, or less than 1% of the total pore volume of the three-dimensional carbon network. In some embodiments, the mesopores constitute a volume fraction of 10% to 20%, 5% to 10%, or 1% to 5% of the total pore volume of the three-dimensional carbon network.

[0148] The composite materials described herein contain a higher percentage of micropores compared to mesopores, and in some embodiments, the micropores constitute a volume fraction of less than 80%, 70%, 65%, 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, or 10% of the total pore volume of the three-dimensional carbon network. In some embodiments, the micropores constitute a volume fraction of about 10% to about 50%, about 10% to about 45%, about 10% to about 40%, about 10% to about 35%, about 10% to about 30%, about 10% to about 25%, about 10% to about 20%, about 10% to about 15%, about 15% to about 25%, about 25% to about 35%, about 35% to about 45%, or about 45% to about 55% of the total pore volume of the three-dimensional carbon network.

[0149] In some embodiments, the composite material has a skeletal density of about 1.0 g / mL to about 2.5 g / mL, about 1.5 g / mL to about 2.5 g / mL, about 1.0 g / mL to about 2.0 g / mL, or 1.0 g / mL to about 1.5 g / mL, as measured using helium pycnometry. In some embodiments, the composite material has a skeletal density of about 0.5 g / mL to about 2.5 g / mL, about 1.5 g / mL to about 2.5 g / mL, about 1.5 g / mL to about 2.0 g / mL, about 0.5 g / mL to about 2.0 g / mL, about 0.5 g / mL to about 1.5 g / mL, or about 0.5 g / mL to about 1.0 g / mL, as measured using mercury porosimetry. In some embodiments, the composite material has a bulk density, measured using mercury pycnometry, of 0.5 g / mL to about 2.5 g / mL, 0.5 g / mL to about 2.0 g / mL, about 0.5 g / mL to about 1.5 g / mL, or about 0.5 g / mL to about 1.0 g / mL.

[0150] Composite material properties can be determined using mercury intrusion porosimetry and helium pycnometry experiments. Mercury intrusion porosimetry can be used to determine porosity, pore size distribution, and pore volume for solid particles. During typical mercury intrusion porosimetry, a pressurized chamber is used to inject mercury into voids within a porous substrate. As pressure is applied, mercury fills larger pores first. As pressure increases, mercury can enter smaller pores. Mercury intrusion porosimetry can access and measure pores larger than approximately 3 nm. Mercury intrusion porosimetry can be used to measure bulk density, skeletal density, and porosity. Pores of different sizes can be excluded by varying the test parameters (e.g., pressure range). The lower pore size limit for mercury intrusion porosimetry is approximately 3 nm.

[0151] Helium pycnometry uses helium gas to measure the pore volume of a solid material. During helium pycnometry, the sample is sealed in a compartment and helium gas is added to the compartment. The helium gas penetrates deep into the small pores in the material. After the system equilibrates, the pressure change can be used to determine the skeletal density of the solid material. Helium pycnometry can access and measure pores larger than about 0.3 nm, for example, pores with sizes from about 3 nm to about 300 nm.

[0152] Using the mercury intrusion skeletal density measurements tested by mercury pycnometry (Hg skeletal density), the mercury intrusion bulk density tested by mercury pycnometry (Hg bulk density), and the He skeletal density tested by helium pycnometry (He skeletal density), it can be calculated according to the following formula:

number

[0153] "Hg skeletal density" (g / cm 3 ) is the mass (g) of a composite particle divided by the volume (cm 3 ) where the volume is measured by controlling (e.g., by pressure) mercury access to the pores of the particles greater than 3 nm during the measurement. This volume does not include the volume of mercury-accessible pores of the composite greater than 3 nm. Instead, the volume includes only the volume of the "skeleton" of the composite particle. The volume of pores less than 3 nm are considered part of the skeleton and are included in the skeleton density calculation.

[0154] "Hg bulk density" is the mass (g) of a composite particle divided by the volume (cm) of the particle. 3 ) where the volume is measured by controlling (for example, by pressure) so that mercury does not access the pores of the particles during the measurement. This volume includes the volume of the pores of the composite material, including those greater than 3 nm and less than 3 nm.

[0155] "He skeletal density" is the mass (g) of a composite particle divided by the volume (cm 3 ) where the volume is measured by controlling (e.g., by pressure) the helium to access the pores of the particles larger than 0.3 nm during the measurement. This volume does not include the volume of the helium-accessible pores of the composite material larger than 0.3 nm. Instead, the volume includes only the volume of the "skeleton" of the composite particle. The volume of pores smaller than 0.3 nm are considered part of the skeleton and are included in the skeleton density calculation.

[0156] The composite material may also contain pores that are inaccessible to either helium or mercury during helium or mercury pycnometry testing. For example, some of the pores formed by removing sacrificial particles may be enclosed in a three-dimensional network and therefore inaccessible to either helium or mercury pycnometry. These inaccessible pores are typically present in very small amounts in the composite materials disclosed herein. The inaccessible pores are treated as part of the skeleton volume without significant variation.

[0157] "Total bead level porosity" (%) refers to the ratio of the volume of pores within a composite particle to the volume of the composite particle. Total bead level porosity is calculated by equation (1). Total bead level porosity includes pores larger than 0.3 nm that are accessible by helium and mercury.

[0158] "Total pore volume" (cm 3 / g) refers to the total pore volume per unit weight of composite particle. The total pore volume is calculated by equation (2). The total pore volume includes pores larger than 0.3 nm that are accessible by helium and mercury.

[0159] "Micropore volume" (cm 3 / g) refers to the micropore volume per unit weight of composite particles. 3 / g) is the mercury skeletal density (g / cm) according to equation (3) 3 ) (cm 3 / g) and helium skeletal density (g / cm 3 ) (cm 3 / g). The micropore volume includes pores greater than 0.3 nm and less than 3 nm. Micropores are accessible by helium but not by mercury.

[0160] "Micropore volume percentage" (%) refers to the volume ratio of the micropore volume to the total pore volume. The micropore volume percentage is calculated by equation (4).

[0161] "Mesopore volume percentage" (%) refers to the volume ratio of mesopore volume to total pore volume. Mesopores refer to pores between about 3 nm and about 50 nm that are accessible by mercury. Pores smaller than 3 nm are not accessible by mercury. Mesopore volume percentage can be measured directly by excluding pores larger than 50 nm using mercury pycnometry. Mesopore volume percentage can also be obtained by subtracting the micropore volume percentage (calculated by Equation (4)) and macropore volume percentage (measured by mercury pycnometry) from the total pore volume percentage (100%).

[0162] "Macropore volume percentage" (%) refers to the volume ratio of macropore volume to total pore volume. Macropores are larger than about 50 nm that are accessible by mercury. Macropore volume percentage can be measured directly by excluding pores smaller than 50 nm using mercury pycnometry. Macropore volume percentage can also be obtained by subtracting the micropore volume percentage (calculated by Equation (4)) and mesopore volume percentage (measured by mercury pycnometry) from the total pore volume percentage (100%).

[0163] 4A / 4B and 5A / 5B show SEM images of the composites. In FIG. 4A, a composite made from polyimide (PI) without additives (e.g., silicone) is shown. In FIG. 4B, a composite made from PI with silicone added is shown. In FIG. 5A, a composite made from PAA without additives (e.g., silicone) is shown. In FIG. 5B, a composite made from PI with silicone added is shown. As can be seen from these figures, different conditions and reagents can result in different pore distributions and pore sizes.

[0164] Control of pore size and pore size distribution can be achieved according to the methods described herein. Various factors that can be adjusted to control pore size distribution include the composite fabrication method, the particle size of the sacrificial material particles, the amount of sacrificial particles used, and the materials used to form the sacrificial material. Furthermore, if coated additives (e.g., coated silicon particles) are present in the composite, the type of coating present in the composite, the thickness of the coating, and the amount of coated additive can be used to control the pore size distribution in the composite. Table 1 lists the helium (He) skeletal density, mercury (Hg) skeletal density, mercury (Hg) bulk density, and BET surface area of composites formed under various conditions. Table 2 lists the total bead-level porosity (%), total pore volume, and micropore, mesopore, and macropore distribution of composites formed under various conditions.

Table 1

Table 2

[0165] Referring to Tables 1 and 2, "aerogel Si / C" is a composite material made by mixing silicon particles with a sol-gel (e.g., a polyimide precursor) to form beads with the silicon particles embedded therein, which is processed by supercritical drying and carbonization to form an aerogel. "aerogel PMMA Si / C" is a composite material made by mixing silicon particles and PMMA particles with a sol-gel (e.g., a polyimide precursor) to form beads with the silicon particles and PMMA particles embedded therein, which is processed by supercritical drying and carbonization to form an aerogel. "xerogel Si / C" is a composite material made by mixing silicon particles with a sol-gel (e.g., a polyimide precursor) to form beads with the silicon particles embedded therein, which is processed by drying and pyrolysis to form a xerogel. "Xerogel Si / C - Slower Solvent Evaporation Rate" is a composite material made by mixing silicon particles with a sol-gel (e.g., a polyimide precursor) to form beads with embedded silicon particles, which are then dried and processed by pyrolysis to form a xerogel. The drying process of "Xerogel Si / C - Slower Solvent Evaporation Rate" is slower than that of "Xerogel Si / C." The slower evaporation rate is used to avoid the collapse of the gel network due to capillary forces of the evaporated solvent, thereby preserving more pores in the final carbonized xerogel particles. "PI Xerogel PMMA Si / C" is a composite material made by mixing silicon particles and PMMA particles with a polyimide precursor sol-gel to form beads with embedded silicon particles and PMMA particles, which are then dried and processed by pyrolysis to form a xerogel. "PAA xerogel PMMA Si / C" is a composite material made by mixing silicon particles and PMMA particles with polyamic acid (PAA) to form PAA beads with silicon particles and PMMA particles embedded in the beads, which are then processed by drying and pyrolysis to form a xerogel."PI xerogel PMMA Si / C-spray dried" is a composite made by mixing silicon particles and PMMA particles with a polyimide precursor sol-gel to form beads with embedded silicon particles and PMMA particles (using a spray-drying process), which are then processed by pyrolysis to form a xerogel. "PI_II xerogel PMMA C" is a composite made by mixing PMMA particles with a polyimide precursor sol-gel to form beads with embedded PMMA particles, which are then dried and processed by pyrolysis to form a xerogel. "PI xerogel PMMA C" is a repeat sample of "PI_II xerogel PMMA C." "PAA xerogel PMMA C" is a composite made by mixing PMMA particles with polyamic acid (PAA) to form PAA beads with embedded PMMA particles, which are then dried and processed by pyrolysis to form a xerogel. "PI Xerogel PMMA C-Spray Dried" is a composite material made by mixing PMMA particles with a polyimide precursor sol-gel to form beads (using a spray-drying process) with PMMA particles embedded in the beads, which are then processed by pyrolysis to form a xerogel.Further description of the synthesis of these composite materials can be found in U.S. Provisional Patent Application No. 63 / 390,832, filed July 20, 2022, entitled "Silicon Nanoparticles Comprising a Sacrificial Layer, Composite Materials Including Them, Preparation, and Uses Thereof," U.S. Provisional Patent Application No. 63 / 390,838, filed July 20, 2022, entitled "Composite Materials Comprising Void Space, Preparation, and Uses Thereof," U.S. Provisional Patent Application No. 63 / 410,652, filed September 28, 2022, entitled "Porous Carbon Materials Comprising a Carbon Additive," and U.S. Provisional Patent Application No. 63 / 410,652, filed July 20, 2022, entitled "Composite Materials with Tunable Porosity, Preparation, and Uses Thereof." No. 63 / 390,845, filed July 20, 2022, entitled "Functionalized Silicon Nanoparticles, Composite Materials that Comprise Them, Preparation and Uses Thereof," and U.S. Provisional Patent Application No. 63 / 390,825, filed July 20, 2022, entitled "Functionalized Silicon Nanoparticles, Composite Materials that Comprise Them, Preparation and Uses Thereof," all of which are incorporated herein by reference.

[0166] Lithium-ion battery A basic embodiment of a lithium-ion battery includes a cathode, an anode in electrical communication with the cathode, an electrolyte disposed between the anode and the cathode, and a separator also disposed between the anode and the cathode.

[0167] The electrolyte is an ionically conductive material and may include solvents, ionic liquids, metal salts, ions (e.g., metal ions or inorganic ions), polymers, ceramics, and other components. The electrolyte may be an organic or inorganic solid or liquid, such as a solvent (e.g., a non-aqueous solvent) containing a dissolved salt. Non-aqueous electrolytes include organic solvents such as cyclic carbonates, linear carbonates, fluorinated carbonates, benzonitrile, acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, γ-butyrolactone, dioxolane, 4-methyldioxolane, N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethylsulfoxide, dioxane, 1,2-dimethoxyethane, sulfolane, dichloroethane, chlorobenzene, nitrobenzene, diethylene glycol, dimethyl ether, and mixtures thereof. Examples of salts that can be included in the electrolyte include lithium salts, such as LiPF, LiBF, LiSbF, LiAsF, LiClO, LiCF, SO, Li(CF, SO)N, Li(FSO)N, LiC, F, SO, LiAlO, LiAlCl, LiN(C x F 2x+1 SO2)(C y F 2y-1 SO2), (x and y are natural numbers), LiC, LiI, and mixtures thereof. In some embodiments, the liquid molecules comprise an electrolyte solvent (electrolyte). The electrolyte solvent of the present disclosure can be selected from any of the suitable electrolytes described above. In particular, the electrolyte is selected from ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), fluoroethylene carbonate (FEC), fluorinated ether (F-EPE), 1,3-dioxolane (DOL), dimethoxyethane (DME), or a combination thereof.

[0168] The separator is typically a thin, porous, or semi-permeable insulating film with high ion permeability. The separator can be made of a polymer such as an olefin-based polymer (e.g., polyethylene, polypropylene, and / or polyvinylidene fluoride). When a solid polymer electrolyte is used as the electrolyte, the solid polymer electrolyte can also function as the separator.

[0169] The anode is comprised of an active anode material that participates in the electrochemical reaction during operation of the battery. Examples of anode active materials include elemental materials such as lithium, alloys of Si and Sn or alloys containing other lithium compounds, and intercalation host materials such as graphite. By way of example only, the anode active material may include metals and / or metalloids that are alloyable with lithium, its alloys, or its oxides. Metals and metalloids that can alloy with lithium include Si, Sn, Al, Ge, Pb, Bi, and Sb. For example, metal / metalloid oxides that can alloy with lithium include lithium titanate, vanadium oxide, lithium vanadium oxide, SnO2, or SiO2. x (0 <x<2)であってもよい。

[0170] The cathode is comprised of an active cathode material that participates in the electrochemical reactions during operation of the battery. The active cathode material may be a lithium composite oxide, including layered materials such as LiCoO2, olivine-type materials such as LiFePO4, spinel-type materials such as LiMn2O4, and similar materials. Spinel-type materials include those with a structure similar to natural spinel LiMn2O4, which contains small amounts of nickel cations in addition to lithium cations, and optionally anions other than manganate. By way of example, such materials have the formula LiNi (0.5-x) Mn 1.5 M x O4 (0≦x≦0.2, M is Mg, Zn, Co, Cu, Fe, Ti, Zr, Ru, or Cr).

[0171] Within the context of the present disclosure, the term "cycle life" refers to the number of complete charge / discharge cycles that an anode or battery (e.g., a LIB) can support before its capacity drops below about 80% of its original rated capacity. Cycle life can be affected by various factors, such as the mechanical strength of the underlying substrate (e.g., a carbon aerogel) and the maintenance of aerogel interconnectivity. Note that these factors actually remaining relatively unchanged over time is a surprising aspect of certain examples of the present disclosure. Cycle life can be determined by methods known in the art, including, but not limited to, cycling tests, in which a battery cell is subjected to repeated charge / discharge cycles at a predetermined current rate and operating voltage. Within the context of the present disclosure, cycle life measurements are obtained according to this method unless otherwise specified. An energy storage device, such as a battery, or an electrode thereof can have a cycle life of about 25 cycles or more, 50 cycles or more, 75 cycles or more, 100 cycles or more, 200 cycles or more, 300 cycles or more, 500 cycles or more, 1000 cycles or more, or a range between any two of these values.

[0172] The present disclosure includes an electrical energy storage device having at least one anode comprising a composite material of the present technology as described herein, at least one cathode, and an electrolyte containing lithium ions. The electrical energy storage device can have a first cycle efficiency (i.e., the cell's coulombic efficiency from the first charge and discharge) of at least 10%, 20%, 30%, 40%, 50%, 60%, 70%, any intervening value (e.g., 65%), or a range between any two of these values (e.g., a range of about 30% to about 50%). As previously described herein, the reversible capacity can be at least 150 mAh / g. The at least one cathode can be selected from the group consisting of conversion cathodes, such as lithium sulfide and lithium-air, and intercalation cathodes, such as phosphates and transition metal oxides.

[0173] According to different embodiments, the composite material of the present disclosure may be applied to both the positive and negative electrodes of an electrochemical energy storage device, or individually to the electrodes (either the positive or negative electrode). In various embodiments, the cathode, anode, or solid electrolyte material is coated with the composite material of the present technology. [Example]

[0174] The following examples are included to demonstrate non-limiting aspects of the present technology, however, as those of skill in the art will recognize in light of the present disclosure, many changes can be made in the specific embodiments disclosed and still obtain a like or similar result without departing from the spirit and scope of the present technology.

[0175] Example 1: Synthesis of Carbon Aerogel Microbeads (Reference) The reference carbon aerogel beads were prepared by imidization of an emulsified aqueous solution of polyamic acid triethylammonium salt, followed by pyrolysis of the resulting polyimide gel beads.

[0176] Polyimide gel beads were packed at approximately 0.073 g / cm 3A solution of 1,4-phenylenediamine was prepared at a target density of 1.0001 g. An aqueous solution of 1,4-phenylenediamine was prepared by mixing PDA (7.02 g; 65 mmol) with water (211 g) and then heating at 60°C until completely dissolved (approximately 8 min). The solution was cooled to room temperature and stirred. Triethylamine (21.8 ml; 2.4:1 mol / mol ratio relative to PMDA) was added, followed by stirring for 3 min. Pyromellitic dianhydride (PMDA; 14.2 g; 1:1 mol / mol ratio relative to PDA) was added to this mixture, followed by stirring for 3 h at room temperature. Acetic anhydride (26.4 ml; 4.3 mol / mol ratio relative to PMDA) was added to the resulting solution of the triethylammonium salt of polyamic acid, and the mixture was stirred for 50 s. At the end of that period, the sol was poured into an immiscible phase under high shear using a Ross mixer at 4000 rpm. An immiscible phase was prepared by dissolving 9.75 g of the surfactant Hypermer® B246SF (HLB6) in 650 mL of mineral spirits (5:1 ratio of mineral spirits to PI sol). The mixture was stirred at 4000 rpm for 3 minutes using a Ross mixer. After settling for 1 hour, the mixture was removed from the Ross mixer and the mineral spirits phase was decanted. The beads were washed with ethanol and collected by filtration. The beads were washed several times with ethanol to completely remove residual water and mineral spirits, and then dried at 68°C. The dried polyimide beads were pyrolyzed at 1050°C for 2 hours under nitrogen.

[0177] Example 2: Synthesis of sacrificial particles (PMMA nanospheres) without cross-linking Water (80 grams) and the monomer methyl methacrylate (20 grams) were added to a beaker, and the solution was stirred at 500 RPM on a hot plate for 15 minutes while controlling the solution temperature at 80°C. Ammonium persulfate (1.8 grams) was added to the solution as an initiator. The stirring speed was then reduced to 300 RPM after 60 minutes. When the color of the solution changed from clear to milky white, the stirring speed was increased again to 500 RPM. The solution was stirred for an additional 180 minutes, after which 2.1 grams of the polymer modifier hydroxyethyl methacrylate was added. The solution temperature was changed to 60°C, and the solution was stirred overnight. Synthesis of PMMA nanospheres in emulsion was completed by the next morning.

[0178] Example 3: Synthesis of cross-linked sacrificial particles (PMMA nanospheres) Water (80 grams) and the monomer methyl methacrylate (20 grams) were added to a beaker, and the solution was stirred on a hot plate at 500 RPM for 15 minutes while controlling the solution temperature at 80°C. Ammonium persulfate (1.8 grams) was added to the solution as an initiator. The stirring speed was then reduced to 300 RPM after 60 minutes. When the color of the solution changed from clear to milky white, the stirring speed was increased again to 500 RPM. 1,3-butanediol dimethacrylate (1.8 grams) was immediately added to the solution as a crosslinking agent. The solution was stirred for an additional 180 minutes, after which a polymeric modifier (hydroxyethyl methacrylate; 2.1 grams) was added. The solution temperature was then changed to 60°C and stirred overnight. Synthesis of PMMA nanospheres in emulsion was completed by the next morning.

[0179] Example 4: Oxidation of silicon particles Commercially available silicon particles may or may not contain oxidized (partially or completely) silicon particles, and therefore, depending on the surface functional groups of the silicon particles provided by the commercial supplier, the oxidation step provided herein is optional.

[0180] Silicon particles (100–3000 nm; available from Evonik; 10–100 g) were either heated in the humidified atmosphere at temperatures ranging from 400 to 850 °C for 1–5 h or dispersed in 0.1–5 M sulfochromic acid (10–1000 mL) or 1–10 M H2O2 (hydrogen peroxide; 10–1000 mL). For Si dispersion, the solution was heated to 50–120 °C for 1–10 h with constant stirring to obtain hydroxyl functional groups (or silanol groups) on the surface of the silicon particles. In principle, other oxidizing agents can also be used for this purpose. After 1–10 h of stirring, the solution was cooled to room temperature and centrifuged to obtain the oxidized silicon particles. The resulting silicon particles were washed 3–5 times with 100–3000 mL volumes of water to remove residual acid and then dried under ambient conditions for 3–10 h. The 2105 and 1993 cm -1 The decrease in band intensity at 1052 cm -1 Surface oxidation was confirmed by IR spectroscopy, as evidenced by an increase in band intensity at 1000 . Oxidation by heating the dry powder can also be confirmed by the mass increase after treatment.

[0181] Example 5: Synthesis of composite Si / C materials containing macropores In a typical synthesis, 12.7 g of p-phenylenediamine (PDA) was added to 313 g of water in a beaker and stirred for 30 minutes until all of the PDA was dissolved. Next, 28.5 g of triethylamine was added to the solution and stirred for 10 minutes. 25.5 g of benzene-1,2,4,5-tetracarboxylic anhydride was then added to the above solution and stirred for 4 hours. Next, 1.5-25 g of PMMA and, optionally, 14.4 g of silicon dioxide particles were added to the above solution and stirred for 10 minutes. Next, 51.4 g of acetic anhydride was poured into the above suspension and stirred for 50 seconds. After that, it was poured into 1200 mL of mineral spirits containing a surfactant while mixing at 3600 rpm. The resulting emulsion was then aged overnight and then filtered. After filtration, the resulting material was rinsed several times with ethanol and dried in an oven at 70 °C. The dried material was carbonized at 800-1200 °C for 2-10 h under an inert gas atmosphere (N or Ar) to obtain the final product.

[0182] While the present disclosure has been particularly shown and described with reference to illustrative embodiments thereof, it will be apparent to those skilled in the art that various changes in form and details may be made therein without departing from the scope of the technology encompassed by the appended claims.

Claims

1. 1. A composite material comprising a three-dimensional carbon network, the three-dimensional carbon network comprises micropores, mesopores, and macropores, the macropores comprising a volume fraction of greater than about 50% of the total pore volume of the three-dimensional carbon network, and the micropores comprising a volume fraction of about 10% to about 50% of the total pore volume of the three-dimensional carbon network; The composite material has a density of about 0.5 to about 2.5 g / cm as measured by mercury specific gravity measurement. ３ The composite material has a skeletal density in the range of

2. 10. The composite material of claim 1, wherein the mesopores constitute a volume fraction of less than about 10% of the total pore volume of the three-dimensional carbon network.

3. 10. The composite material of claim 1, wherein the mesopores constitute a volume fraction of less than about 5% of the total pore volume of the three-dimensional carbon network.

4. 2. The composite material of claim 1, wherein the macropores constitute a volume fraction of greater than about 50% of the total pore volume of the three-dimensional carbon network, the mesopores constitute a volume fraction of less than 10% of the total pore volume of the three-dimensional carbon network, and the micropores constitute a volume fraction equal to the remaining portion of the total pore volume of the three-dimensional carbon network.

5. 2. The composite material of claim 1, wherein the volume fraction of the macropores is at least 1.5 times the volume fraction of the micropores.

6. 2. The composite material of claim 1, wherein the volume fraction of the macropores is from about 1.5 times the volume fraction of the micropores to about 2.5 times the volume fraction of the micropores.

7. 2. The composite material of claim 1, wherein the volume fraction of the macropores is at least 10 times the volume fraction of the mesopores.

8. 10. The composite material of claim 1, wherein the three-dimensional carbon network has a total porosity of less than about 10%.

9. The volume of the macropores of the three-dimensional carbon network is about 0.1 cm ３ / g ~ approx. 0.3cm ３ The composite material of claim 1, wherein the tensile strength is 1 / g.

10. The total pore volume of the three-dimensional carbon network is about 0.1 cm ３ / g ~ approx. 0.4cm ３ The composite material of claim 1, wherein the tensile strength is 1 / g.

11. The BET surface area of the composite material is about 50 m ２ 10. The composite material of claim 1, wherein the tensile strength is less than 1000 kJ / g.

12. The BET surface area of the composite material is about 25 m ２ 10. The composite material of claim 1, wherein the tensile strength is less than 1000 kJ / g.

13. The three-dimensional carbon network is 0.03 cm ３ / g to 0.25 cm ３ 10. The composite material of claim 1, comprising a mercury inaccessible volume in the range of 1000 u / g.

14. The composite material of claim 1 , wherein the composite material is in the form of beads.

15. The composite material of claim 1 , wherein the composite material has a particle size of about 3 μm to about 25 μm.

16. 10. The composite material of claim 1, wherein the composite material has a particle size distribution D50 in the range of about 5 μm to about 20 μm.

17. The composite material of claim 1 , wherein the three-dimensional carbon network comprises amorphous carbon.

18. The composite material of claim 1 , wherein the three-dimensional carbon network is a xerogel.

19. The composite material of claim 1 , wherein the three-dimensional carbon network is an aerogel.

20. 10. The composite material of claim 1, wherein the three-dimensional carbon network is an ambigel, an aerogel-xerogel hybrid material, an aerogel-ambigel hybrid material, an aerogel-ambigel-xerogel hybrid material, or a combination thereof.

21. The composite material of claim 1 further comprising about 20% to about 85% silicon.

22. 22. The composite material of claim 21 , wherein at least a portion of the silicon is entrapped within the three-dimensional carbon network.

23. 22. The composite material of claim 21, wherein the silicon comprises silicon particles.

24. 24. The composite material of claim 23, wherein the silicon particles are disposed adjacent to the macropores.

25. 24. The composite material of claim 23, wherein the silicon particles have a particle size distribution D50 in the range of about 10 nm to about 100 μm.

26. 24. The composite material of claim 23, wherein the silicon particles are at least partially crystalline.

27. 24. The composite material of claim 23, wherein the silicon particles have an oxygen content of between 2% and 40%.

28. 24. The composite material of claim 23, wherein the total volume of the macropores is about 1 to about 5 times greater than the total volume of the silicon particles.

29. 22. The composite material of claim 21, wherein the composite material has a silicon content of about 2 wt % to about 30 wt %, the three-dimensional carbon network has a total porosity of about 5% to about 50%, and the three-dimensional carbon network has a total pore volume of about 0.10 mL / g to about 0.40 mL / g.

30. 22. The composite material of claim 21, wherein the composite material has a silicon content of about 30 wt % to about 70 wt %, the three-dimensional carbon network has a total porosity of about 45% to about 70%, and the three-dimensional carbon network has a total pore volume of about 0.40 mL / g to about 1.0 mL / g.

31. 22. The composite material of claim 21, wherein the composite material has a silicon content of about 70 wt% to about 98 wt%, the three-dimensional carbon network has a porosity of about 65% to about 75%, and the three-dimensional carbon network has a porosity of about 0.90 mL / g to about 1.4 mL / g.

32. 22. The composite material of claim 21, wherein when the composite material is incorporated into an electrode of a lithium-based energy storage device, the composite material has a gravimetric capacity of about 1200 mAh / g to about 3500 mAh / g.

33. 10. The composite material of claim 1, further comprising lithium and / or a lithium salt.

34. An electrode comprising the composite material of claim 1.

35. 35. An energy storage device comprising the electrode of claim 34.

36. 22. An electrode comprising the composite material of claim 21.

37. 37. An energy storage device comprising the electrode of claim 36.

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