Silicon / graphene oxide composites

Abstract

The present disclosure relates to a method for producing a silicon microparticle (SiMP) composite anode material for lithium-ion batteries. The method comprises providing dispersions of SiMPs and graphene oxide (GO) in tetrahydrofuran, mixing the dispersions, injecting the combined dispersion into n-hexane to form a wrapping structure via aggregation and precipitation of GO and SiMP, laser scribing the resulting SiMP / GO film to reduce the GO to laser-scribed graphene (LSG) and simultaneously forming silicon oxide (SiOx) and silicon carbide (SiC) protection layers on the SiMPs to alleviate severe volume change, and removing the n-hexane by evaporation through thermal treatment to obtain the SiMP / LSG composite anode material. This method significantly improves the cycling performance of SiMPs, effectively doubling the cycle life of batteries compared with simple physical mixing methods, thus providing a scalable and efficient solution to produce high-performing SiMP composite anode materials in lithium-ion batteries.

Description

SILICON / GRAPHENE OXIDE COMPOSITESRelated Applications

[0001] This application is related to provisional patent application serial number 63 / 556,920, filed February 23, 2024, the disclosure of which is hereby incorporated herein by reference in its entirety.Field of the Disclosure

[0002] The present disclosure relates to a method for producing a silicon microparticles composite anode material for lithium-ion batteries, substantially improving cycling performance and doubling the cycle life compared with physical mixing methods.Background

[0003] The global electric vehicle (EV) sales have doubled in 2022 compared with 2021 : over 10 million EVs were sold in 2022, which reflects a dynamic global shift toward a greener society. Leaving aside the debate about whether the promotion of EVs will solve environmental problems, various difficulties still need to be overcome in order to further expand the use of EVs. Surveys have revealed that the top reasons not to purchase an EV as one’s next car are range anxiety, long charging time, the high cost of EVs, and the lack of infrastructure. Solving these issues could lower the barrier toward adopting EVs and, thus, encourage people to purchase them. Extending the driving range of EVs on a single charge is an effective solution, because it alleviates range anxiety and reduces the charging frequency. The range can be extended by increasing the energy density of lithium-ion batteries (LIBs), which is a key component that powers EVs. There are three major approaches to increase the energy density of LIBs: (1 ) increase the capacities of the cathode and the anode, (2) increase the voltage, and / or(3) reduce the use of inactive cell components such as separator, current collector, and packaging materials. Among these, intensive research and development have been conducted to use silicon-based materials as anodes for LIBs because silicon has an almost 10 times higher theoretical specific capacity than the conventional graphite anode (3579 mAh g-1vs. 372 mAhg-1), while maintaining a relatively low working potential (0.3 V vs. Li / Li+). Additionally, the conventional electrode production process can be used for silicon anodes, thereby benefiting from the huge investments made in LIB manufacturing.

[0004] In this regard, silicon anodes have emerged as a promising alternative to conventional graphite anodes in lithium-ion batteries, thanks to their ten times higher theoretical specific capacity compared with graphite anodes. Moreover, silicon microparticles (SiMPs) present a significantly lower production cost than silicon nanoparticles (SiNPs), making them an attractive option for large-scale battery manufacturing. However, the practical implementation of SiMPs as anode materials has been hindered by their poorer cycle life relative to SiNPs due to their larger size and resulting susceptibility to significant volume change during charging and discharging.

[0005] Various strategies have been explored to address this challenge, including the creation of wrapping structures where SiMPs are enveloped by carbon layers. While this approach has proved effective in significantly improving the cycling performance of SiMPs, existing synthesis processes remain complex, time-consuming, and energy-intensive, limiting their scalability for industrial applications.

[0006] Consequently, there is a pressing need for a facile, efficient, and cost-effective method to produce SiMP composite anode materials that retain the high capacity of silicon while mitigating the negative effects of volume change during cycling.Summary

[0007] The present disclosure relates to a method for producing a silicon microparticle (SiMP) composite anode material for lithium-ion batteries. The method comprises providing dispersions of SiMPs and graphene oxide (GO) in solvent that disperses both materials, mixing the dispersions, injecting the combined dispersion into solvent that does not disperse the materials, herein referred to as “antisolvent”, to form a wrapping structure via aggregation and precipitation of GO and SiMP (which is referred to as the “reprecipitation method” in this application), removing the solvent, laser scribing the resulting SiMP / GO film to reduce the GO to laser-scribed graphene (LSG) andsimultaneously form silicon oxide (SiOx) and silicon carbide (SiC) protection layers on the SiMPs to help alleviate severe volumetric related degradation to obtain the SiMP / LSG composite anode material. This method substantially improves the cycling performance of SiMPs and doubles the cycle life of lithium-ion batteries compared with simple physical mixing methods, thus providing a scalable and efficient solution to produce high-performing SiMP composite anode materials in lithium-ion batteries.

[0008] Silicon microparticles have gained significant attention as a lithium- ion battery anode material due to their 10 times higher theoretical specific capacity compared with conventional graphite anodes and their much lower production cost than silicon nanoparticles (SiNPs). However, SiMPs have suffered from poorer cycle life relative to SiNPs because their larger size makes them more susceptible to volumetric degradation during charging and discharging. Creating a wrapping structure in which SiMPs are enveloped by carbon layers has proved to be an effective strategy to significantly improve the cycling performance of SiMPs. However, the synthesis processes are complex, time-consuming, and energy-consuming, and are therefore not scalable. Disclosed is a wrapping structure created by using a simple, rapid, and scalable reprecipitation method. A graphene oxide (GO) and SiMP dispersion in solvent is injected into antisolvent, in which GO and SiMP by themselves cannot disperse. GO and SiMP therefore aggregate and precipitate immediately after injection to form a wrapping structure. The resulting SiMP / GO film is laser scribed to reduce GO to a laser-scribed graphene (LSG). Simultaneously, SiOx and SiC protection layers form on the SiMPs through the laser process, which alleviates severe volume change. Owing to these desirable characteristics, the modified reprecipitation method successfully doubles the cycle life of SiMP / graphene composites compared with the simple physically mixing method (50.2% vs. 24.0% retention at the 100th cycle). The reprecipitation method opens a new synthetic strategy for SiMP / carbon composites.

[0009] In another aspect, any of the foregoing aspects individually or together, and / or various separate aspects and features as described herein, may be combined for additional advantage. Any of the various features andelements as disclosed herein may be combined with one or more other disclosed features and elements unless indicated to the contrary herein.

[0010] Those skilled in the art will appreciate the scope of the present disclosure and realize additional aspects thereof after reading the following detailed description of the preferred embodiments in association with the accompanying drawing figures.Brief Description of the Drawing Figures

[0011] The accompanying drawing figures incorporated in and forming a part of this specification illustrate several aspects of the disclosure and, together with the description, serve to explain the principles of the disclosure.

[0012] FIG. 1 is a graph showing the elemental ratios of reprecipitation silicon microparticles / graphene oxide (RP-SiMP / GO), RP-SiMP / laser-scribed graphene (LSG), simple mixing (SM)-SiMP / GO, and SM-SiMP / LSG, as measured by X-ray photoelectron spectroscopy (XPS) survey analysis.

[0013] FIG. 2 is an optical image of the electrodes; RP-SiMP / GO films (left) and RP-SiMP / LSG films (right).

[0014] FIG. 3 is a graph showing the cycle performance of a thermally reduced RP-SiMP / reduced graphene oxide (rGO)Zcarboxymethyl cellulose (CMC) composite (300 °C for 30 min).

[0015] FIG. 4 is a plot showing the specific discharge capacities of RP- SiMP / LSG composites lasered once (Laser x1 ), twice (Laser x2), and four times (Laser x4), at various current densities: 0.2, 0.5, 1.0, 2.0, 5.0, 10.0, 15.0, 20.0, and 0.2 A gsi+c-1.

[0016] FIG. 5 is scanning electron microscope (SEM) images of RP- SiMP / LSG (a) before the hydraulic press (top view) and (b) after the hydraulic press (side view).

[0017] FIG. 6 is transmission electron microscope (TEM) images of (a) and (b) RP-SiMP / GO and (c) RP-SiMP / LSG composites.

[0018] FIG. 7 illustrates (a) the concept of the typical reprecipitation method to prepare organic nanoparticles; (b) the graphene oxide dispersions in different organic solvents; and (c) a solvent miscibility chart showing that tetrahydrofuran (solvent A candidate) and hexane (solvent B candidate) are miscible, as shown in the red sguare.

[0019] FIG. 8 Charge and discharge profiles of (a) reprecipitated, thermally treated silicon microparticle-LSG material (RP-TT-SiMP / LSG) and (b) RP- SiMP / LSG composites for the first and second discharge / charge cycles;(c) specific discharge capacities at various current densities: 0.2, 0.5, 1.0, 2.0, 5.0, 10.0, 15.0, 20.0, and 0.2 A gsi+c-1and (d) specific discharge capacities at 2.0 A gsi+c-1(the first three cycles were performed at 0.5 A gsi+c-1).

[0020] FIG. 9 SEM images of the RP-TT-Si / GO composite before (a) and after (b) laser treatment and TEM images of the RP-TT-Si / GO composite before (c) and after (d) incorporation of the particles into an FhO-based battery slurry.

[0021] FIG. 10 illustrates an overview of the modified scalable reprecipitation method that according to the present disclosure provides a simple, rapid, room-temperature method to prepare SiMPs / LSG composites having a wrapping structure where the outer carbon layers wrap the inner SiMPs.

[0022] FIG. 11 presents TEM images (a) and (b), SEM images (c) and (d), thermo-gravimetric analysis (TGA) curves (e), and X-ray diffraction (XRD) patterns (f) of RP-SiMP / GO and RP-SiMP / LSG.

[0023] FIG. 12 presents (a)-(c) XPS survey spectra, C 1 s spectra, and silicon 2p spectra of RP-SiMP / GO, RP-SiMP / LSG, SM-SiMP / GO, and SM- SiMP / LSG composites; (d) SEM images of the RP-SiMP / LSG film from a side angle before and after removal of surface layers; and (e) and (f) XPS C 1 s and silicon 2p depth profiles.

[0024] FIG. 13 presents charge / discharge profiles (a) and (b); specific discharge capacities at various current densities (c); and changes in discharge capacity / coulombic efficiency over cycles (d) and (e); high mass loading test (f); cyclic voltammetry (CV) curves (g); and Nyquist plots before / after CV tests (h) of RP-SiMP / LSG, RP-SiMP / GO, SM- SiMP / graphene / CMC, and SM-SiMP / carbon black / CMC composites.Detailed Description

[0025] The embodiments set forth below represent the necessary information to enable those skilled in the art to practice the embodiments and illustrate the best mode of practicing the embodiments. Upon reading thefollowing description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure and the accompanying claims.

[0026] It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the present disclosure. As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items.

[0027] It will be understood that when an element such as a layer, region, or substrate is referred to as being “on” or extending “onto” another element, it can be directly on or extend directly onto the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” or extending “directly onto” another element, there are no intervening elements present. Likewise, it will be understood that when an element such as a layer, region, or substrate is referred to as being “over” or extending “over” another element, it can be directly over or extend directly over the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly over” or extending “directly over” another element, there are no intervening elements present. It will also be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements present.

[0028] Relative terms such as “below” or “above” or “upper” or “lower” or “horizontal” or “vertical” may be used herein to describe a relationship of one element, layer, or region to another element, layer, or region as illustrated in the Figures. It will be understood that these terms and those discussed aboveare intended to encompass different orientations of the device in addition to the orientation depicted in the Figures.

[0029] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes,” and / or “including” when used herein specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0030] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0031] Embodiments are described herein with reference to schematic illustrations of embodiments of the disclosure. As such, the actual dimensions of the layers and elements can be different, and variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and / or tolerances, are expected. For example, a region illustrated or described as square or rectangular can have rounded or curved features, and regions shown as straight lines may have some irregularity. Thus, the regions illustrated in the figures are schematic and their shapes are not intended to illustrate the precise shape of a region of a device and are not intended to limit the scope of the disclosure. Additionally, sizes of structures or regions may be exaggerated relative to other structures or regions for illustrative purposes and, thus, are provided to illustrate the general structures of the present subject matter and may or may not be drawn to scale. Common elements between figures may be shown herein with common element numbers and may not be subsequently re-described.

[0032] The present disclosure provides a wrapping structure that is created by way of a rapid and scalable reprecipitation method. A graphene oxide (GO) and silicon microparticles (SiMPs) dispersion in a solvent and / or combination of solvents that disperses both materials (e.g., water, ethylene glycol, N-dimethylformamide, N-methyl-2-pyrrolidone, and tetrahydrofuran), in which the SiMPs have an average diameter of between 1 nanometers (nm) and 50 micrometers (pm) and the GO has an average thickness of between 0.5 nm and 1 pm and has an average flake diameter of between 10 nm and 1000 pm, is injected into a solvent and / or combination of solvents that does not disperse the materials, herein referred to as “antisolvent” (e.g., dichloromethane, n-hexane, hexanes, or toluene), in which GO and SiMPs by themselves cannot disperse. GO and SiMPs therefore aggregate and precipitate immediately after injection to form a wrapping structure. The resulting SiMP / GO film is laser scribed to reduce GO to laser-scribed graphene (LSG). Simultaneously, silicon oxide (SiOx) and silicon carbide (SiC) protection layers form on the SiMPs through the laser process, which helps alleviate severe volumetric degradation. Owing to these desirable characteristics, the modified reprecipitation method successfully doubles the cycle life of SiMP / graphene composites compared with the simple physical mixing method (50.2% vs. 24.0% retention at the 100th cycle). The modified reprecipitation method opens a new synthetic strategy for SiMP / carbon composites.

[0033] FIG. 1 summarizes the elemental ratios of the SiMPs / carbon composites prepared by the reprecipitation (RP) method (RP-SiMP / GO and RP-SiMP / LSG) and the simple mixing (SM) method (SM-SiMP / GO and SM- SiMP / LSG), as measured by the X-ray photoelectron spectroscopy (XPS) survey analysis.

[0034] FIG. 2 is an optical image of the electrode films before and after the laser-scribing process (RP-SiMP / GO and RP-SiMP / LSG). The SiMP / GO precipitate in antisolvent was drop-cast onto a copper current collector and dried at 60 °C for 30 minutes (the greenish-brown films on the left side of the image). After laser scribing, SiMP / LSG was formed and the color of the film became darker, suggesting an increase in electrical conductivity (RP- SiMP / LSG).

[0035] As an alternate reduction process, thermal reduction was conducted for SiMP / GO composites at 300 °C for 30 minutes in air. The resulting powder SiMP / reduced graphene oxide (rGO) was mixed with carboxymethyl cellulose (CMC) in water with a weight ratio of SiMP / rGO composite: CMC = 9:1 . For a coin cell so fabricated, a cycling performance test was conducted at 0.5 A g-1for the initial three cycles to form uniform solid-electrolyte interphase (SEI) layers, and 2.0 A g-1for the rest of the cycles. The specific discharge capacity declined after the first few cycles (483.7 mAh g at the fourth cycle and 60.3 mAh g at the 100th cycle), as shown in FIG. 3.

[0036] The effect of the laser-scribing process on the battery performance was investigated, and the results are shown in FIG. 4. The RP-SiMP / GO composites were laser scribed once, twice, or four times. The resulting composites are named “Laser x1 ,” “Laser x2,” and “Laser x4,” respectively. As shown in FIG. 4, “Laser x1” showed the highest capacity among these three composites.

[0037] FIG. 5 shows scanning electron microscope (SEM) images of RP- SiMP / LSG (a) before the hydraulic press (top view) and (b) after the hydraulic press (side view).

[0038] FIG. 6 shows transmission electron microscope images of (a) and (b) RP-SiMP / GO and (c) RP-SiMP / LSG composites.

[0039] Although silicon nanoparticles (SiNPs) have been investigated intensively as an anode material and their cycle life has improved to nearly meet the industrial standard after decades of research, the production cost of SiNPs remains high, making SiNPs not particularly useful in real battery cells. On the other hand, SiMPs have much lower production costs because they are generated as a waste product in the semiconductor and solar cell industries. Despite their advantage in cost, SiMPs suffer from a poorer cycling life compared with SiNPs. The degradation of silicon anodes is mainly caused by the large volume expansion and shrinkage of silicon during the lithiation and delithiation processes. Silicon particles are pulverized during each cycle, creating fresh surfaces where solid-electrolyte interface (SEI) layers grow.SiMPs are more susceptible to volume changes than SiNPs due to their larger size, resulting in poorer cycling performance. Several promising approacheshave been proposed to prevent the never-ending fragmentation and regrowth of SEI layers, including the development of electrolytes that form thin, uniform, and elastic SEI layers on silicon surfaces and thus prevent further growth of the SEI, and the development of elastic binders, which keeps even pulverized silicon particles together without disintegration. Another effective approach is to prepare silicon and carbon composites, creating a wrapping structure where the outer carbon layers envelop the inner SiMPs. The carbon layers can buffer the volume change of SiMPs and provide conductive pathways to semiconductive SiMPs and most importantly protect SiMPs from the electrolyte, suppressing unnecessary SEI formation on the SiMPs. However, the synthesis processes are complicated, time-consuming, and energyconsuming and are therefore not scalable, which hinders mass production. The easiest process is the simple physical mixing of silicon particles and two- dimensional carbon materials; however, this usually results in poor cycling performance because silicon particles are exposed to the electrolyte directly owing to the lack of a wrapping structure. Therefore, an inexpensive and scalable process must be developed to prepare a SiMP / carbon composite with a high-quality wrapping structure.

[0040] Disclosed is a wrapping structure using a simple, rapid, roomtemperature, and therefore scalable reprecipitation-inspired method. Reprecipitation methods are often used to prepare organic nanocrystals simply by injecting the solution of the target compound X into a poor solvent while stirring, as shown in FIG. 7, part (a). Compound X forms nanoparticles and precipitates immediately after injection. There are several requirements for the reprecipitation method: (1 ) compound X should dissolve in solvent A, (2) compound X should not dissolve in solvent B, and (3) solvents A and B should be miscible.

[0041] The disclosed modified reprecipitation method creates a wrapping structure in which SiMPs are enveloped by graphene sheets, as shown in FIG. 10. Tetrahydrofuran and n-hexane were chosen as solvents A and B, respectively, because GO and silicon particles can disperse in tetrahydrofuran very well while neither can disperse in n-hexane, and importantly, tetrahydrofuran and n-hexane are miscible with each other (FIG. 7, parts (b) and (c)). Graphene oxide and SiMP aggregate and precipitate immediatelyafter injecting GO and SiMP dispersions in tetrahydrofuran into n-hexane to form the wrapping structure. Thereafter, a CO2 laser is applied to a film of SiMP / GO to reduce GO to LSG. Simultaneously, SiOx and SiC layers form on the SiMPs through a laser process. These coatings act as protection layers to alleviate the severe volume changes of the SiMPs and therefore suppress unnecessary SEI formation. Owing to the formation of the wrapping structure and the SiOx and SiC protection layers, SiMP / LSG prepared by the modified reprecipitation (RP) method (RP-SiMP / LSG) exhibits an improved cycling life compared with SiMP / graphene / carboxymethyl cellulose (CMC) composites prepared by a simple mixing method (SM-SiMP / graphene / CMC). The modified reprecipitation method combined with the laser reduction under air, vacuum, argon, nitrogen, and / or any other type of atmospheric condition, is a simple, rapid, room-temperature, and therefore scalable process, which is an improved synthesis approach in this field and could potentially solve the current challenges that occur when trying to create SiMP wrapping structures.PRESERVING THE WRAPPING STRUCTURE OF GRAPHENE OXIDE AROUND SILICON PARTICLES

[0042] Further disclosed is a method for producing silicon / GO composites to preserve the wrapping structure of GO around silicon particles via thermal treatment of the particles following the previously described reprecipitation method. This process is necessary for these particles to be incorporated into typical battery slurries used for industrial production of lithium-ion batteries as it preserves the wrapping structure and improves battery performance.

[0043] Following the addition of the silicon particle-GO (Si-GO) dispersion into the antisolvent as previously described, the Si-GO particles are collected and thermally treated in either ambient atmosphere, inert atmosphere, vacuum, and / or any other type of atmospheric condition and / or liquid environment. These thermally treated particles are then incorporated into a typical battery slurry and made into an electrode for lithium-ion batteries with or without using a laser-scribing technique to convert GO into LSG.

[0044] FIG. 8 shows that thermal treatment of the Si-GO composite materials produced via the reprecipitation method greatly improves battery rate and cycle performance. After 100 cycles, the reprecipitated, thermallytreated silicon microparticle-LSG material (RP-TT-SiMP / LSG) still retains ~50% of its initial capacity at 527 mAh / g, whereas the reprecipitated non- thermally treated silicon microparticle-LSG material (RP-SiMP / LSG) has less than half of that specific capacity at 243 mAh / g. FIG. 9 shows the preservation of the wrapping structure both before and after the laser-scribing process and shows that the wrapping structure is preserved when these materials are incorporated into a battery slurry solution. This process is necessary to preserve the integrity of these materials and not compromise their performance when they are used in industrial battery manufacturing processes. While the result depicted in FIGS. 8 and 9 were achieved by thermally treating the Si-GO material at 108 °C for about an hour, other predetermined thermal treatment temperatures and predetermined thermal treatment time periods are usable.

[0045] In this regard and in certain embodiments, the thermal treatment of the Si-GO occurs at a temperature ranging from approximately 50 °C to 600 °C. In some embodiments, the thermal treatment of the Si-GO is at a temperature of at least about 50 °C. In some embodiments, the thermal treatment of the Si-GO reaches a temperature of at most about 600 °C. In some embodiments, the thermal treatment of the Si-GO reaches a temperature of about 50 °C to about 100 °C, about 50 °C to about 150 °C, about 50 °C to about 200 °C, about 50 °C to about 250 °C, about 50 °C to about 300 °C, about 50 °C to about 350 °C, about 50 °C to about 400 °C, about 50 °C to about 450 °C, about 50 °C to about 500 °C, about 50 °C to about 550 °C, about 50 °C to about 600 °C, about 100 °C to about 200 °C, about 100 °C to about 300 °C, about 100 °C to about 400 °C, about 100 °C to about 500 °C, about 100 °C to about 600 °C, about 200 °C to about 300 °C, about 200 °C to about 400 °C, about 200 °C to about 500 °C, about 200 °C to about 600 °C, about 300 °C to about 400 °C, about 300 °C to about 500 °C, about 300 °C to about 600 °C, about 400 °C to about 500 °C, about 400 °C to about 600 °C, or about 500 °C to about 600 °C. In some embodiments, the thermal treatment of the Si-GO reaches a temperature of about 50 °C, about 100 °C, about 150 °C, about 200 °C, about 250 °C, about 300 °C, about 350 °C, about 400 °C, about 450 °C, about 500 °C, about 550 °C, or about 600 °C. In some embodiments, the thermal treatment of the Si-GO reaches atemperature of at least about 100 °C, about 150 °C, about 200 °C, about 250 °C, about 300 °C, about 350 °C, about 400 °C, about 450 °C, about 500 °C, about 550 °C, or about 600 °C. In some embodiments, the thermal treatment of the Si-GO reaches a temperature of at most about 50 °C, about 100 °C, about 150 °C, about 200 °C, about 250 °C, about 300 °C, about 350 °C, about 400 °C, about 450 °C, about 500 °C, about 550 °C, or about 600 °C.

[0046] In some embodiments, the thermal treatment of the Si-GO lasts for a period of time of about 5 minutes to about 60 minutes. Note that in general thermally treating the Si-GO at higher temperatures will require shorter treatment time periods. For example, at 600 °C the thermal treatment of the Si-GO lasts for a period of time of about 5 minutes. In some embodiments, the thermal treatment of the Si-GO lasts for a period of time of at most about 60 minutes. In some embodiments, the thermal treatment of the Si-GO lasts for a period of time of about 5 minutes to about 10 minutes, about 5 minutes to about 15 minutes, about 5 minutes to about 20 minutes, about 5 minutes to about 25 minutes, about 5 minutes to about 30 minutes, about 5 minutes to about 35 minutes, about 5 minutes to about 40 minutes, about 5 minutes to about 45 minutes, about 5 minutes to about 50 minutes, about 5 minutes to about 55 minutes, about 5 minutes to about 60 minutes, about 10 minutes to about 15 minutes, about 10 minutes to about 20 minutes, about 10 minutes to about 25 minutes, about 10 minutes to about 30 minutes, about 10 minutes to about 35 minutes, about 10 minutes to about 40 minutes, about 10 minutes to about 45 minutes, about 10 minutes to about 50 minutes, about 10 minutes to about 55 minutes, about 10 minutes to about 60 minutes, about 15 minutes to about 20 minutes, about 15 minutes to about 25 minutes, about 15 minutes to about 30 minutes, about 15 minutes to about 35 minutes, about 15 minutes to about 40 minutes, about 15 minutes to about 45 minutes, about 15 minutes to about 50 minutes, about 15 minutes to about 55 minutes, about 15 minutes to about 60 minutes, about 20 minutes to about 25 minutes, about 20 minutes to about 30 minutes, about 20 minutes to about 35 minutes, about 20 minutes to about 40 minutes, about 20 minutes to about 45 minutes, about 20 minutes to about 50 minutes, about 20 minutes to about 55 minutes, about 20 minutes to about 60 minutes, about 25 minutes to about 30 minutes, about 25 minutes toabout 35 minutes, about 25 minutes to about 40 minutes, about 25 minutes to about 45 minutes, about 25 minutes to about 50 minutes, about 25 minutes to about 55 minutes, about 25 minutes to about 60 minutes, about 30 minutes to about 35 minutes, about 30 minutes to about 40 minutes, about 30 minutes to about 45 minutes, about 30 minutes to about 50 minutes, about 30 minutes to about 55 minutes, about 30 minutes to about 60 minutes, about 35 minutes to about 40 minutes, about 35 minutes to about 45 minutes, about 35 minutes to about 50 minutes, about 35 minutes to about 55 minutes, about 35 minutes to about 60 minutes, about 40 minutes to about 45 minutes, about 40 minutes to about 50 minutes, about 40 minutes to about 55 minutes, about 40 minutes to about 60 minutes, about 45 minutes to about 50 minutes, about 45 minutes to about 55 minutes, about 45 minutes to about 60 minutes, about 50 minutes to about 55 minutes, about 50 minutes to about 60 minutes, or about 55 minutes to about 60 minutes. In some embodiments, the thermal treatment of the Si-GO lasts for a period of time of about 5 minutes, about 10 minutes, about 15 minutes, about 20 minutes, about 25 minutes, about 30 minutes, about 35 minutes, about 40 minutes, about 45 minutes, about 50 minutes, about 55 minutes, or about 60 minutes. In some embodiments, the thermal treatment of the Si-GO lasts for a period of time of at least about 10 minutes, about 15 minutes, about 20 minutes, about 25 minutes, about 30 minutes, about 35 minutes, about 40 minutes, about 45 minutes, about 50 minutes, about 55 minutes, or about 60 minutes. In some embodiments, the thermal treatment of the Si-GO lasts for a period of time of at most about 5 minutes, about 10 minutes, about 15 minutes, about 20 minutes, about 25 minutes, about 30 minutes, about 35 minutes, about 40 minutes, about 45 minutes, about 50 minutes, about 55 minutes, or about 60 minutes.

[0047] In some embodiments, the thermal treatment of the Si-GO lasts for a period of time of about 1 hour to about 24 hours. In some embodiments, the thermal treatment of the Si-GO lasts for a period of time of at least about1 hour. In some embodiments, the thermal treatment of the Si-GO lasts for a period of time of at most about 24 hours. In some embodiments, the thermal treatment of the Si-GO lasts for a period of time of about 1 hour to about 5 hours, about 1 hour to about 6 hours, about 1 hour to about 7 hours, about 1 hour to about 8 hours, about 1 hour to about 9 hours, about 1 hour to about10 hours, about 1 hour to about 11 hours, about 1 hour to about 12 hours, about 1 hour to about 13 hours, about 1 hour to about 14 hours, about 1 hour to about 16 hours, about 1 hour to about 18 hours, about 1 hour to about 20 hours, about 1 hour to about 22 hours, about 1 hour to about 24 hours, about 5 hours to about 6 hours, about 5 hours to about 7 hours, about 5 hours to about 8 hours, about 5 hours to about 9 hours, about 5 hours to about 10 hours, about 5 hours to about 11 hours, about 5 hours to about 12 hours, about 5 hours to about 13 hours, about 5 hours to about 14 hours, about5 hours to about 16 hours, about 5 hours to about 18 hours, about 5 hours to about 20 hours, about 5 hours to about 22 hours, about 5 hours to about24 hours, about 6 hours to about 7 hours, about 6 hours to about 8 hours, about 6 hours to about 9 hours, about 6 hours to about 10 hours, about6 hours to about 11 hours, about 6 hours to about 12 hours, about 6 hours to about 13 hours, about 6 hours to about 14 hours, about 6 hours to about16 hours, about 6 hours to about 18 hours, about 6 hours to about 20 hours, about 6 hours to about 22 hours, about 6 hours to about 24 hours, about7 hours to about 8 hours, about 7 hours to about 9 hours, about 7 hours to about 10 hours, about 7 hours to about 11 hours, about 7 hours to about12 hours, about 7 hours to about 13 hours, about 7 hours to about 14 hours, about 7 hours to about 16 hours, about 7 hours to about 18 hours, about7 hours to about 20 hours, about 7 hours to about 22 hours, about 7 hours to about 24 hours, about 8 hours to about 9 hours, about 8 hours to about 10 hours, about 8 hours to about 11 hours, about 8 hours to about 12 hours, about 8 hours to about 13 hours, about 8 hours to about 14 hours, about8 hours to about 16 hours, about 8 hours to about 18 hours, about 8 hours to about 20 hours, about 8 hours to about 22 hours, about 8 hours to about24 hours, about 9 hours to about 10 hours, about 9 hours to about 11 hours, about 9 hours to about 12 hours, about 9 hours to about 13 hours, about9 hours to about 14 hours, about 9 hours to about 16 hours, about 9 hours to about 18 hours, about 9 hours to about 20 hours, about 9 hours to about22 hours, about 9 hours to about 24 hours, about 10 hours to about 11 hours, about 10 hours to about 12 hours, about 10 hours to about 13 hours, about10 hours to about 14 hours, about 10 hours to about 16 hours, about 10 hours to about 18 hours, about 10 hours to about 20 hours, about 10 hours to about22 hours, about 10 hours to about 24 hours, about 11 hours to about12 hours, about 11 hours to about 13 hours, about 11 hours to about14 hours, about 11 hours to about 16 hours, about 11 hours to about18 hours, about 11 hours to about 20 hours, about 11 hours to about22 hours, about 11 hours to about 24 hours, about 12 hours to about13 hours, about 12 hours to about 14 hours, about 12 hours to about16 hours, about 12 hours to about 18 hours, about 12 hours to about20 hours, about 12 hours to about 22 hours, about 12 hours to about24 hours, about 13 hours to about 14 hours, about 13 hours to about16 hours, about 13 hours to about 18 hours, about 13 hours to about20 hours, about 13 hours to about 22 hours, about 13 hours to about24 hours, about 14 hours to about 16 hours, about 14 hours to about18 hours, about 14 hours to about 20 hours, about 14 hours to about22 hours, about 14 hours to about 24 hours, about 16 hours to about18 hours, about 16 hours to about 20 hours, about 16 hours to about22 hours, about 16 hours to about 24 hours, about 18 hours to about20 hours, about 18 hours to about 22 hours, about 18 hours to about24 hours, about 20 hours to about 22 hours, about 20 hours to about24 hours, or about 22 hours to about 24 hours. In some embodiments, the thermal treatment of the Si-GO lasts for a period of time of about 4 hours, about 5 hours, about 6 hours, about 7 hours, about 8 hours, about 9 hours, about 10 hours, about 11 hours, about 12 hours, about 13 hours, about 14 hours, about 16 hours, about 18 hours, about 20 hours, about 22 hours, or about 24 hours. In some embodiments, the thermal treatment in the Si-GO lasts for a period of time of at least about 5 hours, about 6 hours, about7 hours, about 8 hours, about 9 hours, about 10 hours, about 11 hours, about 12 hours, about 13 hours, about 14 hours, about 16 hours, about 18 hours, about 20 hours, about 22 hours, or about 24 hours. In some embodiments, the thermal treatment in the Si-GO lasts for a period of time of at most about 4 hours, about 5 hours, about 6 hours, about 7 hours, about 8 hours, about 9 hours, about 10 hours, about 11 hours, about 12 hours, about 13 hours, about 14 hours, about 16 hours, about 18 hours, about 20 hours, about 22 hours, or about 24 hours.

[0048] In some embodiments, the Si-GO is thermally treated at a temperature of about -100 °C to about 50 °C. In some embodiments the Si-GO is thermally treated at a temperature of at least about -100 °C. In some embodiments, the Si-GO is thermally treated at a temperature of at most about 50 °C. In some embodiments, the Si-GO is thermally treated at a temperature of about -100 °C to about -80 °C, about -100 °C to about -60 °C, about -100 °C to about -40 °C, about -100 °C to about -20 °C, about -100 °C to about 0 °C, about -100 °C to about 20 °C, about -100 °C to about 40 °C, about -100 °C to about 50 °C, about -80 °C to about -60 °C, about -80 °C to about -40 °C, about -80 °C to about -20 °C, about -80 °C to about 0 °C, about -80 °C to about 20 °C, about -80 °C to about 40 °C, about -80 °C to about 50 °C, about -60 °C to about -40 °C, about -60 °C to about -20 °C, about -60 °C to about 0 °C, about -60 °C to about 20 °C, about -60 °C to about 40 °C, about -60 °C to about 50 °C, about -40 °C to about -20 °C, about -40 °C to about 0 °C, about -40 °C to about 20 °C, about -40 °C to about 40 °C, about -40 °C to about 50 °C, about -20 °C to about 0 °C, about -20 °C to about 20 °C, about -20 °C to about 40 °C, about -20 °C to about 50 °C, about 0 °C to about 20 °C, about 0 °C to about 40 °C, about 0 °C to about 50 °C, or about 20 °C to about 50 °C. In some embodiments, the Si-GO is thermally treated at a temperature of about -100 °C, about -80 °C, about -60 °C, about -40 °C, about -20 °C, about 0 °C, about 20 °C, about 40 °C, or about 50 °C. In some embodiments, the Si-GO is thermally treated a temperature of at least about -80 °C, about -60 °C, about -40 °C, about -20 °C, about 0 °C, about 20 °C, about 40 °C, or about 50 °C. In some embodiments, the solution is maintained at a temperature of at most about -100 °C, about -80 °C, about -60 °C, about -40 °C, about -20 °C, about 0 °C, about 20 °C, about 40 °C, or about 50 °C.

[0049] In some embodiments, the thermal treatment at the relatively colder temperatures such as -100 °C lasts over a time period of about 7 days to about 84 days. In some embodiments, the thermal treatment lasts over a time period of at least about 7 days. In some embodiments, the thermal treatment lasts over a time period of at most about 84 days. In some embodiments, the thermal treatment lasts over a time period of about 7 days to about 14 days, about 7 days to about 21 days, about 7 days to about 28 days, about 7 daysto about 35 days, about 7 days to about 42 days, about 7 days to about 49 days, about 7 days to about 56 days, about 7 days to about 63 days, about 7 days to about 70 days, about 7 days to about 77 days, about 7 days to about 84 days, about 14 days to about 21 days, about 14 days to about 28 days, about 14 days to about 35 days, about 14 days to about 42 days, about 14 days to about 49 days, about 14 days to about 56 days, about 14 days to about 63 days, about 14 days to about 70 days, about 14 days to about 77 days, about 14 days to about 84 days, about 21 days to about 28 days, about 21 days to about 35 days, about 21 days to about 42 days, about 21 days to about 49 days, about 21 days to about 56 days, about 21 days to about 63 days, about 21 days to about 70 days, about 21 days to about 77 days, about 21 days to about 84 days, about 28 days to about 35 days, about 28 days to about 42 days, about 28 days to about 49 days, about 28 days to about 56 days, about 28 days to about 63 days, about 28 days to about 70 days, about 28 days to about 77 days, about 28 days to about 84 days, about 35 days to about 42 days, about 35 days to about 49 days, about 35 days to about 56 days, about 35 days to about 63 days, about 35 days to about 70 days, about 35 days to about 77 days, about 35 days to about 84 days, about 42 days to about 49 days, about 42 days to about 56 days, about 42 days to about 63 days, about 42 days to about 70 days, about 42 days to about 77 days, about 42 days to about 84 days, about 49 days to about 56 days, about 49 days to about 63 days, about 49 days to about 70 days, about 49 days to about 77 days, about 49 days to about 84 days, about 56 days to about 63 days, about 56 days to about 70 days, about 56 days to about 77 days, about 56 days to about 84 days, about 63 days to about 70 days, about 63 days to about 77 days, about 63 days to about 84 days, about 70 days to about 77 days, about 70 days to about 84 days, or about 77 days to about 84 days. In some embodiments, the thermal treatment lasts over a time period of about 7 days, about 14 days, about 21 days, about 28 days, about 35 days, about 42 days, about 49 days, about 56 days, about 63 days, about 70 days, about 77 days, or about 84 days. In some embodiments, the thermal treatment lasts over a time period of at least about 14 days, about 21 days, about 28 days, about 35 days, about 42 days, about 49 days, about 56 days, about 63 days, about 70 days, about77 days, or about 84 days. In some embodiments, the thermal treatment lasts over a time period of at most about 7 days, about 14 days, about 21 days, about 28 days, about 35 days, about 42 days, about 49 days, about 56 days, about 63 days, about 70 days, about 77 days, or about 84 days.EXPERIMENTAL DETAILS

[0050] The following experimental results disclose quantities used in an experiment conducted according to this disclosure. It is to be understood that these experimental values are non-limiting and may be scaled to different ranges. Moreover, various combinations of these quantities can yield a wide variety of concentrations of silicon-graphene composite material. This scalability demonstrates the versatility of disclosed methods and materials across different applications.

[0051] Preparation of the RP-Silicon / LSG Electrode. Silicon microparticles (SiMPs, 1 -3 pm) were purchased from US Research Nanomaterials, Inc., and GO (300-800 nm) was purchased from Cheap Tubes Inc. SiMPs (100 mg) and GO powder (100 milligrams [mg]) were sonicated for 1 h in 15 mL of tetrahydrofuran solvent. The resulting dispersion (15 milliliters [mL]) was injected slowly into n-hexane solvent (200 mL) with vigorous stirring, as shown in FIG. 10. The stirring was stopped after the injection, and the SiMP / GO composite precipitated to the bottom of the beaker. The precipitate was directly drop-cast onto a copper current collector and then dried at 60 °C under air for 30 minutes (min). The resulting SiMP / GO film was laser scribed by a 40 W full-spectrum laser muse two-dimensional vision desktop CO2 laser cutter with a 10% power setting. The as-prepared SiMP / LSG film on a copper current collector was pressed at 7500 pounds (lb) with an area of 31.2 square centimeters (cm2) using a hydraulic press. The pressed film was punched out with a 10 millimeter (mm)-diameter punch and then dried at 80 °C under vacuum overnight. The dried electrodes were transferred into an argon-filled glovebox for battery assembly.

[0052] Preparation of SM-SiMP / Graphene / CMC and SM-SiMP / Carbon Black / CMC Electrodes. The same SiMPs were used for the preparation of the SM-SiMP / graphene / CMC and SM-SiMP / carbon black / CMC electrodes. Graphene powder was provided by Nanotech Energy Inc., and carbon black(Ketjenblack EC600JD) was purchased from MSE Supplies LLC. Carboxymethyl cellulose was purchased from MTI Corporation, and N-methyl- 2-pyrrolidone (NMP) was purchased from Sigma-Aldrich. First, CMC was dissolved in NMP solvent by using a Thinky mixer (AR-100). SiMPs and carbon materials (graphene or carbon black) were physically mixed for 10 min using a mortar and pestle and then added into the CMC solution and mixed with a Thinky mixer. The weight ratios of each component were 45 wt % SiMPs, 45 wt % graphene or carbon black, and 10 wt % CMC. The resulting slurry was coated onto a copper current collector with a thickness of 100 pm and then dried at 60 °C under air. The resulting film was pressed at 7500 lb with an area of 31 .2 cm2using a hydraulic press. The pressed film was punched out with a 10 mm-diameter punch and then dried at 80 °C under vacuum overnight. The dried electrodes were transferred into an argon-filled glovebox for battery assembly.

[0053] Characterization. Scanning electron microscopy images were taken using a JEOL JSM-6610 SEM instrument with 30 kV voltage. The TEM images were taken using a Titan 80-300 TEM. Thermogravimetric analysis (TGA) was conducted using a Thermogravimetric Analyzer TGA 8000 (PerkinElmer) with a ramp-up rate of 10 °C min-1to 700 °C and airflow of 30 mL min-1. The X-ray photoelectron spectroscopy (XPS) spectra were obtained by using a Kratos Axis Ultra DLD spectrometer equipped with a monochromatic Al Ka X-ray source. Xray diffraction (XRD) patterns were taken with a powder X-ray diffractometer (PANalytical, X’Pert PRO) from 20° to 80° with a scan rate of 0.05° s-1using copper Ka radiation (A = 1 .54184 A). The mass of each electrode was measured using a Mettler Toledo MX5 microbalance with ±1 pg of sensitivity.

[0054] Coin Cell Assembly and Battery Performance Tests. The dried electrodes were carried into a glovebox filled with argon to assemble the coin cells. CR2032 coin cells were used for this project. A polished lithium chip was used as a counter and reference electrode, and 1 .0 M LiPF6 in EC:DMC (1 :1 volume ratio) with a 10% FEC solution was used as the electrolyte. A glass fiber sheet (GA-55, ADVANTEC) was used as a separator.

[0055] The electrochemical properties were tested by using a BST8-MA potentiostat (MTI Corp.). Both rate and cycle performance were assessed bygalvanostatic charge and discharge tests with a voltage window between 1 .5 and 0.01 V vs. Li / Li+. All electrochemical tests were conducted at room temperature (-25 °C). The current density and specific gravimetric capacity were calculated based on the total weight of the silicon / carbon composites (gsi+c), measured by a Mettler Toledo MX5 microbalance with ±1 pg sensitivity. The rate performance test includes galvanostatic charge and discharge tests at current densities of 0.2, 0.5, 1 .0, 2.0, 5.0, 10, 15, and 20 A g-1for three cycles at each current density. The cyclability tests were conducted using a current density of 0.5 A g-1for the initial three cycles followed by a current density of 2.0 A g-1for the rest of the cycles with a voltage window between 1.5 V and 0.01 V vs. Li / Li+. The retention rate was calculated based on the discharge capacity at the fourth cycle, which corresponds to the first cycle at 2.0 A g-1.RESULTS AND DISCUSSION

[0056] Morphological and Structural Characterization. The morphologies of SiMP / GO and SiMP / LSG prepared by the modified reprecipitation method, named RP-SiMP / GO and RP-SiMP / LSG, respectively, were characterized by using TEM and SEM. FIG. 11 , parts (a)-(d), compares the TEM and SEM images of RP-SiMP / GO and RP-SiMP / LSG, before and after laser reduction, respectively. FIG. 11 , part (a), is a TEM image of RP- SiMP / GO showing that SiMPs, the black particles, are wrapped by GO sheets. The formation of a wrapping structure was also confirmed by SEM, where SiMPs, the white particles, are wrapped by the GO sheets, as shown in FIG. 11 , part (c). Therefore, this confirms that the wrapping structure was successfully formed by using the modified reprecipitation method. Additional TEM images (FIG. 6, parts (a) and (b)) show that the distance from the surface of the precipitation secondary particles to the surface of the inner silicon particles, which corresponds to the thickness of the wrapping layers made of carbon sheets, ranges from -0.14 pm to several micrometers.However, the wrapping structure was then destroyed by the laser reduction process, as shown in the TEM and SEM images of RP-SiMP / LSG (FIG. 11 , parts (b) and (d)). When TEM images before and after laser scribing are compared, RP-SiMP / LSG has a lot of small wrinkles instead of a few largewrinkles, which were observed in the RP-SiMP / GO composite. SEM images also show that RP-SiMP / GO has large GO sheets covering SiMPs while RP- SiMP / LSG has exfoliated LSG sheets with porous structures. This is because the laser irradiation exfoliated the stacked GO sheets to form a porous LSG 3D structure, which would enable the fast ion transport within the electrode and therefore improve the rate performance. The thickness of the covering layers made of LSG ranges from ~0.6 to several micrometers, as shown in FIG. 6, part (c). A simple thermal annealing reduction was investigated as an alternative reduction process and is discussed in Challenges and Future Directions.

[0057] Physical and Chemical Properties. FIG. 11 , part (e), presents the TGA curves of RP-SiMP / GO and RP-SiMP / LSG along with the bare SiMPs. The weight of bare SiMPs reached 100.3% after thermal treatment from 30 °C to 700 °C using a ramp-up rate of 10 °C min-1in air. This slight increase in weight can be attributed to the oxidation of SiMPs. The TGA curves of RP- SiMP / GO and RP-SiMP / LSG consist of three regions: the loss of water below 150 °C, the loss of functional groups from GO or LSG between 150 °C to 300 °C, and the combustion of carbon and the oxidation of silicon particles above 300 °C. The weight loss caused by the loss of oxygen-functional groups was 14.8% for RP-SiMP / GO, and just 2.8% for RP-SiMP / LSG, confirming that LSG has few oxygen functional groups, and therefore laser reduction was successfully performed. The ratios of water content were 4.9% and 0.9% for RP-SiMP / GO and RP-SiMP / LSG, respectively, which can be attributed to the amount of oxygen-functional groups on the surface of LSG and GO: fewer water molecules absorbed through hydrogen bonding for LSG because of fewer oxygen-functional groups. The weight at 700 °C increased from 56.0% (RP-SiMP / GO) to 81.7% (RP-SiMP / LSG), suggesting that RP- SiMP / LSG has a higher silicon weight ratio. This can be attributed to the loss of carbon weight by the reduction of GO to LSG and the formation of SiC. Carbon usually bums off by 600 °C; however, it does not bum off once it forms SiC. The formation of SiC was also confirmed by XRD analysis and XPS, as shown in FIG. 11 , part (f), and FIG. 12, part (c).

[0058] X-ray diffraction patterns were taken for both composites (FIG. 11 , part (f)). The XRD patterns of RP-SiMP / GO exhibited peaks from only puresilicon. On the other hand, the RP-SiMP / LSG composite showed peaks from SiC along with pure silicon, confirming that SiC was formed after the laser scribing process (RP-SiMP / LSG).

[0059] FIG. 12, parts (a)-(c), compares the XPS spectra of SiMP / GO and SiMP / LSG composites prepared by the modified reprecipitation method and the simple mixing method. SiMP / GO and SiMP / LSG composites prepared by the simple mixing method are named “SM-SiMP / GO” and “SM-SiMP / LSG”. FIG. 12, part (a), compares the survey spectra along with the surface elemental ratios. The surface elemental ratios are also summarized in FIG. 1. The silicon ratio of RP-SiMP / GO at the surface was 3.9%, whereas that of SM-SiMP / GO was 11 .6%. This result is consistent with the findings by TEM and SEM analyses in FIG. 11 , parts (a)-(d): SiMPs in the RP-SiMP / GO composite are wrapped by GO sheets, and therefore, less silicon was detected by XPS. The surface silicon ratio increased after laser scribing from 3.9% (RP-SiMP / GO) to 7.5% (RP-SiMP / LSG). This means that more silicon is exposed after laser scribing because of the destruction of the wrapping structure as confirmed by TEM and SEM analyses in the previous section. However, the surface silicon ratio of RP-SiMP / LSG is still lower than that of SM-SiMP / LSG (7.5% vs. 28.0%), meaning that more silicon is still protected by LSG sheets when the modified reprecipitation method is used. Therefore, the modified reprecipitation method is still effective to protect silicon particles with graphene sheets even when it is combined with the laser scribing process. FIG. 12, parts (b) and (c), compares the C 1s and silicon 2p spectra. As for the XPS C 1s spectra (FIG. 12, part (b)), the same trends were observed for both composites prepared by the modified reprecipitation method and the simple mixing method: the SiMP / GO composites before laser (RP-SiMP / GO and SM-SiMP / GO) showed more dominant peaks from oxygen-containing functional groups such as C-O, C 0, and COOH, than the SiMP / LSG composites after laser (RP-SiMP / LSG and SM-SiMP / LSG). This means that GO has been successfully reduced to LSG by the laser scribing process. The color of the composites also reflects the reduction of GO to LSG: the color turns black from brown after laser irradiation (FIG. 2), confirming an increase in electrical conductivity. FIG. 12, part (c), shows the silicon 2p XPS spectra. Two separate peaks that are mainly derived from thepure silicon, and silicon oxides were observed for both the RP-SiMP / GO and SM-SiMP / GO composites. However, the pure silicon peak in the SM- SiMP / LSG composites disappeared after laser scribing and a new Si-C peak arose at -100.4 eV. The formation of the Si-C peak is also confirmed by XRD analysis, as shown in FIG. 11 , part (f). While the silicon peaks were clearly detected for the composites prepared by the simple mixing method, the detection of silicon was weak for the composites prepared by the reprecipitation method. This can be explained by the fact that the measuring depth of XPS is limited to the top surface (normally 1 -10 nm), and the composites prepared by the reprecipitation method have covering layers made of carbon sheets the thickness of which is approximately several micrometers (FIG. 6). Therefore, it is hard to detect the inner silicon particles by XPS. This indicates that the detected silicon peaks in RP-SiMP / GO and RP-SiMP / LSG composites mostly came from the isolated bare silicon particles, which failed to form the wrapping structure. The isolated bare silicon particles did not form SiC during the laser scribing process because they were not wrapped by carbon sheets adequately, and thus, a clear silicon-C peak was not detected for the RP-SiMP / LSG composites. Please note that this does not mean that SiC was not formed in the RP-SiMP / LSG composites because SiC was clearly detected by XRD (FIG. 11 , part (f)). SiC was not detected in the RP-SiMP / LSG composites by XPS for the reasons explained above.

[0060] It is important to understand the penetration depth of the laser because it could be possible that the bottom layer of the high-mass-loading electrode films is not reduced by laser scribing because the laser might not be able to reach the bottom of the films, while high-mass-loading electrodes are required for practical applications. Therefore, an XPS analysis was conducted along the depth direction of the RP-SiMP / LSG film. A 36.9 pm-thick electrode was prepared for this analysis. The surface layers were simply removed using Scotch tape, and the same film was used for all of the XPS analyses along with the depth studies. FIG. 12, part (d), shows the SEM images of the RP- SiMP / LSG film from a side angle before and after removal of the surface layer. Sample (A) is the original film before the surface layer removal by Scotch tape, having a 36.9 pm thickness. Samples (B)-(D) show the film afterthe first, second, and third removal of the surface layers using Scotch tape. The thickness of the film was 20.8 pm, 9.6 pm, and 6.3 pm, respectively. Therefore, sample (A) shows the XPS spectra of the top surface of the film (depth = 0 pm), while samples (B)-(D) show the XPS spectra at depths of 16.1 pm, 27.3 pm, and 30.6 pm, respectively. The collected XPS C 1 s spectra along the depth direction are displayed in FIG. 12, part (e). The shoulder peaks derived from the oxygen-functional groups that range from 286 eV to 290 eV were suppressed at all depths (A)-(D), meaning that GO was reduced to LSG by laser irradiation even at the bottom of the film. FIG. 12, part (f), shows the XPS silicon 2p spectra along the depth direction. The spectrum at the very surface of the film (sample (A) at a depth = 0 pm) and the spectrum at the depth of 16.1 pm (sample (B)) mainly consists of a single peak around 103.2 eV, which is derived from Si4+(SiO2). This suggests that the surface of SiMPs present from the top layer of the film to a depth of 16.1 pm is oxidized by laser irradiation. The silicon 2p spectra at the depth of 27.3 pm (sample (C)) and 30.6 pm (sample (D)) consisted of two separate peaks mainly from Si4+(SiO2) average and pure silicon, which indicates that the SiMPs’ surfaces at the bottom of the film below a depth of 27.3 pm are not fully oxidized by the laser. Therefore, the laser irradiation is powerful enough to reduce the GO present at the bottom of the film to LSG and to oxidize the surface of the SiMPs present at the top layer of the film (up to a depth of 16.1 pm) to silicon oxides. However, the laser was not powerful enough to fully oxidize the surface of the SiMPs present at the bottom of the film (below a depth of 27.3 pm) to silicon oxides.

[0061] Battery Performance of the Silicon / LSG Composites. Battery performance was analyzed, as shown in FIG. 13. The charge and discharge profiles of RP-SiMP / LSG and RP-SiMP / GO for the first and second cycles are shown in FIG. 13, parts (a) and (b). For both electrodes, the discharge curves for the first cycle consist of two regions: a plateau region (0.01 V to 0.12 V vs. Li / Li+) and a slope region (above 0.12 V vs. Li / Li+). The slope discharge capacities, which are defined as the capacities obtained from the slope region above 0.12 V, for the initial cycle, were 432.2 mAh and 877.3 mAh gsi+c-1for RP-SiMP / LSG and RP-SiMP / GO, respectively. In general, the capacitor-like slope capacity derived from the surface absorption of lithium ions is highlyreversible because a Faradaic reaction is not involved. However, the slope capacities in the initial cycle were not highly reversible: the slope charge capacities in the first cycle were 224.5 mAh gsi+c-1(RP-SiMP / LSG) and 396.0 mAh gsi+c-1(RP-SiMP / GO). This is mainly due to the irreversible formation of solid electrolyte interface (SEI) layers on the electrode materials during the first discharge process. In fact, the irreversible capacities in the initial cycle were 627.9 gsi+c-1and 1131.1 gsi+c-1for RP-SiMP / LSG and RP- SiMP / GO, respectively. Since RP-SiMP / GO has a higher carbon weight ratio than RP-SiMP / LSG as shown in FIG. 11 , part (e), and both GO and LSG have one to two orders of magnitude higher specific surface area than silicon microparticles, more SEI layers likely form on the carbon in RP-SiMP / GO, resulting in a higher irreversible capacity. Also, it is known that the formation of silicon oxide layers on pure silicon alleviates the volume change of silicon particles by suppressing unnecessary SEI formation. Since SiMPs in the RP- SiMP / LSG electrode form SiOx and SiC layers on the surface as shown in the XRD in FIG. 11 , part (f), RP-SiMP / LSG exhibited a smaller irreversible capacity than RP-SiMP / GO. The lower reversible capacity of RP-SiMP / LSG compared with RP-SiMP / GO in the initial cycle can be attributed to the formation of silicon oxides and SiC. The theoretical capacities of silicon monoxide (SiO) and silicon dioxide (SiO2) are 1965 mAh g-1and 2680 mAh g-1, respectively, both of which are lower than that of pure silicon (3579 mAh g-1). Silicon carbide, on the other hand, is electrochemically inactive and thus does not contribute to the capacity. Therefore, the formation of silicon oxides and SiC lowers the weight ratio of pure silicon and likely causes the decrease in initial capacity.

[0062] The rate capabilities were tested for both RP-SiMP / LSG and RP- SiMP / GO with various current densities: 0.2, 0.5, 1.0, 2.0, 5.0, 10.0, 15.0, 20.0, and 0.2 A in gsi+c-1. The obtained specific discharge capacities are presented in FIG. 13, part (c). Although both RP-SiMP / LSG and RP-SiMP / GO showed similar capacities at the lowest current density of 0.2 A gsi+c-1, RP- SiMP / LSG retained higher capacities at higher current densities; RP- SiMP / LSG retained 710.0 mAh of gsi+c-1at 2.0 A gsi+c-1, whereas RP- SiMP / GO retained 383.3 mAh of gsi+c-1. Therefore, the laser scribing process critically improved the rate performance of the electrode by enhancing theelectrical conductivity through the conversion of GO to LSG and by forming the 3D porous structure, as described in the previous section (FIG. 11 , parts (c) and (d)).

[0063] FIG. 13, parts (d) and (e), compares the cycling capability of the electrodes prepared by the modified reprecipitation method (RP-SiMP / LSG and RP-SiMP / GO) and the simple mixing method (SM-SiMP / carbon black / CMC and SM-SiMP / graphene / CMC). Carbon black and graphene were chosen as the conductive carbon additives for the electrodes prepared by a simple mixing method. FIG. 13, part (d), displays the changes in specific discharge capacities for 100 cycles. In order to form uniform SEI layers on the surface, the electrodes were cycled with a low current density (0.5 A gsi+c-1) for the first three cycles, and then they were cycled with a higher current density of 2.0 A gsi+c-1for the rest of the cycles. The discharge capacity of the SM-SiMP / carbon black / CMC electrode declined severely and reached 82.9 mAh gsi+c-1after the initial three cycles. This is because SiMPs were directly exposed to the electrolyte, and therefore the formation of pulverized dead silicon particles could not be suppressed. On the other hand, SM- SiMP / graphene / CMC retained higher capacity than SM-SiMP / carbon black / CMC; it retained 791 .6 mAh gsi+c-1at the fourth cycle and 189.6 mAh gsi+c-1at the 100th cycle (24.0% capacity retention at the 100th cycle). Therefore, forming a composite of SiMPs and graphene helps improve the cycling performance of SiMPs effectively because graphene sheets protect SiMPs from the electrolyte and the fragmentation and regrowth of SEI layers were suppressed. Further improvement in the cycling performance was achieved when the modified reprecipitation method was used. The RP- SiMP / LSG composite electrode retained 882.8 mAh gsi+c-1at the fourth cycle and 443.1 mAh gsi+c-1at the 100th cycle (50.2% capacity retention at the 100th cycle). Therefore, the modified reprecipitation method doubled the cycle life of SiMP / graphene composites compared with the simple mixing method (50.2% vs. 24.0% at the 100th cycle). The initial Coulombic efficiency of RP- SiMP / LSG was 68.1 %, which was the highest among the composites in this study, as shown in FIG. 13, part (e). This could be due to the lower level of exposure of SiMPs to the electrolyte, as shown in the XPS survey analysis in FIG. 12, part (a). Additionally, since RP-SiMP / GO composites have a highercarbon weight ratio than RP-SiMP / LSG as shown in FIG. 11 , part (e), and both GO and graphene have one to two orders of magnitude higher specific surface area than silicon microparticles, more SEI layers could form on the carbon in RP-SiMP / GO, resulting in a higher irreversible capacity and a lower initial Coulombic efficiency. The higher Coulombic efficiency of the RP- SiMP / LSG composites at the following cycles can be attributed to the formation of silicon oxide layers and SiC layers on the SiMP surfaces through laser scribing, according to the XRD and XPS results (FIGS. 11 , part (f), and 12, part (c)), which help protect the SiMPs and improve their cycling ability. These layers work as a mechanical protective coating to mitigate the severe volume changes of SiMPs during the lithiation and delithiation processes.

[0064] Mass loading is an important metric that determines the overall energy density and power density of the battery cell. In many cases, higher mass loading impairs the intrinsic performance of the material by hindering the fast ion transport within the electrode and by increasing the electrical resistance. Loading more mass onto an electrode without sacrificing the intrinsic battery performance is highly desirable. Therefore, the effect of electrode mass loading on the battery performance of the RP-SiMP / LSG composite was investigated at 0.5 A gsi+c-1current density, as shown in FIG. 13, part (f). Theoretically, the relationship between the specific areal capacity (mAh cm-2) and the mass loading (mg cm-2) must be proportional when the intrinsic battery performance is not impaired by a high mass loading. A linear relationship was found below the mass loading of 1 .0 mg cm-2, as shown in FIG. 13, part (f), which means that the mass loading can be increased up to approximately 1 .0 mg cm-2without sacrificing the intrinsic performance of the RP-SiMP / LSG composite. However, once the mass loading reached 1.0 mg cm-2, the specific areal capacity stopped increasing linearly and the maximum specific areal capacity achieved was 1.66 mAh cm-2at a mass loading of 1 .68 mg cm-2. Considering that a specific areal capacity exceeding 2 mAh cm-2to 3 mAh cm-2is believed necessary for many applications, further improvements are needed to make the RP- SiMP / LSG composite competitive in practical cells. The main reason why the RP-SiMP / LSG composite cannot yet achieve a higher mass loading could be the severe aggregation of the particles, as shown in FIG. 2. The RP-SiMP / GOprecipitate in n-hexane, which is shown in FIG. 10, was directly drop-cast onto a copper current collector without being mixed with a binder in other solvents, such as water and N-methyl-2-pyrrolidone (NMP). Since SiMPs and GO do not disperse in n-hexane, the wrapping structure where SiMPs are wrapped by GO sheets is preserved. However, when the RP-SiMP / GO composite is mixed in other solvents such as water and NMP, the wrapping structure is ruined because both SiMPs and GO disperse in these solvents. Therefore, the traditional slurry process cannot be used in this case, and thus, the dropcasting method was employed, which resulted in a poor quality of the electrode film, as shown in FIG. 2. In order to solve this issue, the wrapping structure could be fixed by forming covalent bonds between the covering carbon sheets and the inner SiMPs. This is a promising approach that would enable the traditional slurry process to be used, and high-quality electrode films could be prepared to achieve the desired higher mass loading.

[0065] The cyclic voltammetry (CV) curves of the RP-SiMP / LSG and RP- SiMP / GO composites are shown in FIG. 13, part (g). Cyclic voltammetry curves were tested with a scan rate of 0.2 mV s-1for five cycles. The CV peaks became higher at the fifth cycle compared with the second cycle, meaning that the electrode was activated in the initial few cycles. This could be caused by a relaxation of the microstructure within the electrode in the initial cycles, making more sites available at the fifth cycle. The increase in peak intensity, which is often mentioned as “activation,” and what causes the activation include the breakdown of the surface native layers on silicon particles by lithium-ion diffusion, a kinetic enhancement in the electrode, the remaining crystalline silicon in the inner particles, and the increase in ionic conductivity during the initial cycles, for example. The peak height of RP- SiMP / LSG was higher than that of RP-SiMP / GO, indicating that it has more active sites within the electrode. This phenomenon can be attributed to the improved electrical conductivity through the conversion of GO to LSG and the formation of 3D porous structures. The Nyquist plots of RP-SiMP / LSG and RP-SiMP / GO before and after the CV tests are shown in FIG. 13, part (h). The semicircle represents the charge-transfer resistance. The RP-SiMP / LSG composite showed a smaller semicircle than the RP-SiMP / GO composite, which is due to the higher electrical conductivity of LSG compared with GO.The semicircles decreased in size following the CV cycles for both RP- SiMP / LSG and RP-SiMP / GO composites, meaning that the charge-transfer resistance decreased after several cycles due to the electrode activation, as discussed above.

[0066] The modified reprecipitation method successfully improved the cycle life of SiMPs even though it is a simple, rapid, room-temperature, and thus scalable process, which could potentially lower the production costs of SiMP / carbon composites to make silicon-based next-generation LIBs economically possible. The RP-SiMP / GO that precipitated in n-hexane (FIG. 10) was directly drop-cast onto a copper current collector. Other embodiments strengthen the wrapping structure by forming covalent bonds between the wrapping carbon sheets and inner SiMPs. This would enable the use of the traditional slurry process, because the structure would be preserved due to strong chemical bonding.

[0067] The disclosed modified reprecipitation method has been demonstrated to be a simple, rapid, room-temperature, and thus scalable process to prepare SiMPs and two-dimensional carbon composites for lithium- ion batteries. The TEM and SEM observations revealed that SiMPs were wrapped by GO sheets when the modified reprecipitation method was used. Thereafter, the SiMP / GO composite was laser scribed to form the SiMP / LSG composite. Through the laser scribing process, GO was reduced to LSG by forming a well-exfoliated graphene 3D network structure. Simultaneously, silicon oxides and silicon carbide layers were formed on the surface of the SiMPs, which work as protection layers to alleviate the severe volume change of SiMPs during lithiation and delithiation. Owing to these unique and desirable material characteristics, the SiMPs / LSG composite prepared by the reprecipitation method and laser scribing (RP-SiMPs / LSG) showed superior battery performance to the SiMP / graphene / CMC composite prepared by a simple mixing method (SM-SiMP / graphene / CMC). As for cycling stability tests, the RP-SiMPs / LSG retained 50.2% of its capacity at the 100th cycle while the SM-SiMP / graphene / CMC retained only 24.0%. The modified reprecipitation method has provided a new direction for the simple and scalable synthesis of SiMP / two-dimensional carbon composites, which couldlower the production costs of SiMP / carbon composites to make silicon-based next-generation LIBs economically feasible. While the disclosed processes in accordance with the present disclosure has been successfully demonstrated for wrapping silicon particles in graphene oxide, it should be noted that this method can be applied to wrap other materials without limitation to silicon and graphene oxide.

[0068] In this regard, the disclosed method involves synthesizing a composite material by initially mixing two-dimensional (2D) and three- dimensional (3D) material entities within a solvent to create a homogeneous dispersion. This mixture is then introduced into an antisolvent environment, where the 2D and 3D material entities undergo aggregation and precipitation, resulting in composite entities characterized by a unique wrapping structure wherein the 3D entities are encased by layers formed from the 2D materials.

[0069] An important aspect of this synthesis method is the strong intermolecular forces between the 2D and 3D entities that facilitate their aggregation and enable the formation of the composite's distinct architecture. The method offers flexibility in selecting the 3D material entities, which can include but are not limited to the following:• Group 1 alkali metals such as lithium (including lithium alloys, lithium salts, lithium compounds such as lithium cobalt oxide and lithium iron phosphate), sodium (and its alloys, salts, and compounds), among others.• Group 2 alkaline earth metals, including beryllium (with its alloys and salts) and magnesium (along with its alloys, salts, and compounds).• Transition metals such as titanium (including oxides), vanadium (and its oxides), chromium (with chromium oxides), iron (and its oxides and phosphates), cobalt (with its oxides), nickel, manganese oxides, zinc, aluminum, and gallium.• Semi-metals, including silicon (with monoxide, dioxide, nitride, carbide, and alloys) and germanium; tin and its alloys are also applicable.• Nonmetals such as carbon (including graphite, hard carbon, and compounds) and sulfur (and its compounds).

[0070] The method further accommodates the use of various two- dimensional materials such as, but not limited to, graphene, graphene oxide, borophene, borocarbonitrides, boron nitride, MXenes, or transition metal dichalcogenides. Post-synthesis reduction techniques are available to modify the composite material properties: light exposure can be used for reduction; thermal reduction is achieved by heating at temperatures ranging from 100 °C to 600 °C over periods of 5 to 1440 minutes in either gaseous or non-gaseous environments; and chemical reduction methods are also applicable. This comprehensive approach enables the creation of composite materials with tailored properties suitable for a wide range of applications.

[0071] It is contemplated that any of the foregoing aspects, and / or various separate aspects and features as described herein, may be combined for additional advantage. Any of the various embodiments as disclosed herein may be combined with one or more other disclosed embodiments unless indicated to the contrary herein.

[0072] Those skilled in the art will recognize improvements and modifications to the preferred embodiments of the present disclosure. All such improvements and modifications are considered within the scope of the concepts disclosed herein and the claims that follow.

Claims

ClaimsWhat is claimed is:1 . A method of synthesizing silicon-graphene composite material comprising:• mixing a dispersion of graphene oxide (GO) and silicon microparticles (SiMPs) in solvent to form a dispersion; and• injecting the combined dispersion into antisolvent, wherein the GO and SiMPs aggregate and precipitate, creating a plurality of SiMPs each having a wrapping structure comprised of carbon layers formed from the GO.

2. The method of synthesizing the silicon-graphene composite material of claim 1 wherein SiMPs have an average diameter of between 10 nanometers and 50 micrometers.

3. The method of synthesizing the silicon-graphene composite material of claim 1 wherein the GO has a thickness between 0.5 nanometers and 1 micrometer, and has an average flake diameter of between 1 nanometer and 1000 micrometers.

4. The method of synthesizing the silicon-graphene composite material of claim 1 further comprising drying the resulting SiMP / GO material.

5. The method of synthesizing the silicon-graphene composite material of claim 4 wherein the silicon-graphene composite material is thermally treated.

6. The method of synthesizing the silicon-graphene composite material of claims 4 and 5 further comprising reducing the resulting SiMP / GO material to SiMP / reduced GO (SiMP / rGO).

7. The method of synthesizing the silicon-graphene composite material of claims 4-6 wherein reducing the resulting SiMP / GO material to SiMP / LSG is achieved by laser scribing the SiMP / GO material.

8. The method of synthesizing the silicon-graphene composite material of claims 6 and 7 further comprising forming silicon oxide (SiOx) and silicon carbide (SiC) protection layers on the SiMPs.

9. The method of synthesizing the silicon-graphene composite material of claim 7 wherein the laser scribing is conducted a plurality of times until a predetermined electrical conductivity is achieved in a gaseous or non- gaseous environment.

10. The method of synthesizing the silicon-graphene composite material of claim 7 wherein the reducing the resulting SiMP / GO material to SiMP / reduced GO (rGO) is achieved by thermal reduction at a temperature of 100 °C to 600 °C for 5-1440 minutes in a gaseous or non-gaseous environment.11 . The method of synthesizing the silicon-graphene composite material of claims 9 and 10 wherein the gaseous environment is substantially air, vacuum, inert gas, or other gaseous environment.

12. The method of synthesizing the silicon-graphene composite material of claims 5, 6, 7, and 8 wherein the SiMP / GO composite material is configured as an electrode material.

13. The method of synthesizing the silicon-graphene composite material of claim 12 wherein the SiMP / rGO composite material is configured as an anode electrode material.

14. A silicon-graphene composite material comprising a plurality of SiMPs each wrapped in at least one layer of GO.

15. A battery comprising: an anode comprised of a silicon-graphene composite material; a cathode separated from the anode; and an electrolyte dispersed between the anode and the cathode.

16. The battery of claim 15 wherein the silicon-graphene composite material comprises a plurality of SiMPs each wrapped in at least one layer of GO.

17. The battery of claim 15 wherein the silicon-graphene composite material is dispersed onto a copper current collector.

18. The battery of claim 16 having a specific discharge capacity that ranges between 1 milliampere hours / gram (mAh / g) and 4000 mAh / g after at least 25 discharge cycles.

19. The battery of claim 18 wherein the GO is laser scribed graphene.

20. A method of producing silicon / graphene oxide composites comprising:• preparing a silicon particle-graphene oxide (Si-GO) tetrahydrofuran solution;• adding the Si-GO solution into n-hexane, thereby producing Si-GO particles;• thermally treating the Si-GO particles at a predetermined temperature for a predetermined time.21 . The method of producing silicon / graphene oxide composites of claim 20 further incorporating the heat-treated particles into a battery slurry to create an electrode for lithium-ion batteries.

22. The method of producing silicon / graphene oxide composites of claim 20 wherein the predetermined temperature is at least 100 °C and the predetermined time is at least 1 hour.

23. The method of producing silicon / graphene oxide composites of claim 20 wherein the predetermined temperature is at least 600 °C and the predetermined time is no more than 5 minutes.

24. The method of producing silicon / graphene oxide composites of claim 20 wherein the step of thermally treating the Si-GO particles occurs under atmospheric pressure.

25. The method of producing the silicon / graphene oxide composites of claim 20 wherein the step of thermally treating the Si-GO particles occurs in an inert atmosphere.

26. The method of producing the silicon / graphene oxide composites of claim 20 wherein the step of thermally treating the Si-GO particles occurs in a vacuum.

27. The method of producing the silicon / graphene oxide composites of claim 20 wherein the step of thermally treating the Si-GO particles occurs in any other gaseous atmosphere.

28. The method of producing the silicon / graphene oxide composites of claim 20 wherein the step of thermally treating the Si-GO particles occurs in a liquid environment.

29. The method of producing the silicon / graphene oxide composites of claim 20 further comprising using a laser-scribing technique to convert graphene oxide into laser-scribed graphene (LSG) during the thermal treatment step.

30. The method of producing the silicon / graphene oxide composites of claim 20 further comprising using a laser-scribing technique to convert graphene oxide into LSG after the thermal treatment step.31 . A method of synthesizing a composite material comprising:• mixing a dispersion of two-dimensional material entities and three- dimensional material entities in solvent to form a dispersion; and• injecting the dispersion into antisolvent, wherein the two-dimensional material entities and three-dimensional material entities aggregate andprecipitate, creating a plurality of composite entities each having a wrapping structure comprised of two-dimensional layers formed from the two-dimensional material entities.

32. The method of synthesizing the composite material of claim 31 wherein there is a strong intermolecular force between both the three-dimensional material entities and two-dimensional material entities to drive the aggregation and wrapping of the two-dimensional material entities around the 3- dimensional material entities.

33. The method of synthesizing the composite material of claim 32 wherein the three-dimensional material entities are members of group 1 alkali metals.

34. The method of synthesizing the composite material of claim 32 wherein the three-dimensional material entities are members of group 1 alkali metalcontaining compounds / composites.

35. The method of synthesizing the composite material of claim 32 wherein the three-dimensional material entities are members of group 2 alkaline earth metals.

36. The method of synthesizing the -composite material of claim 32 wherein the three-dimensional material entities are members of group 2 alkaline earth metal-containing compounds / composites.

37. The method of synthesizing the composite material of claim 32 wherein the three-dimensional material entities are members of transition metals.38 The method of synthesizing the composite material of claim 32 wherein the three-dimensional material entities are members of transition metalcontaining compounds / composites.

39. The method of synthesizing the composite material of claim 32 wherein the three-dimensional material entities are members of semi-metals.

40. The method of synthesizing the composite material of claim 32 wherein the three-dimensional material entities are members of semi-metal-containing compounds / composites.41 . The method of synthesizing the composite material of claim 32 wherein the three-dimensional material entities are members of non-metals.

42. The method of synthesizing the composite material of claim 32 wherein the three-dimensional material entities are members of non-metal-containing compounds / composites.

43. The method of synthesizing the composite material of claim 32 wherein the two-dimensional material entities are from the group consisting of graphene, graphene oxide, borophene, borocarbonitrides, boron nitride, MXenes, and transition metal dichalcogenides.

44. The method of synthesizing the composite material of claim 32 further comprising reducing the resulting composite material by light exposure.

45. The method of synthesizing the composite material of claim 32 further comprising reducing the resulting composite material by thermal reduction at a temperature of 100 °C to 600 °C for 5-1440 minutes in a gaseous or non- gaseous environment.

46. The method of synthesizing the composite material of claim 32 further comprising reducing the resulting composite material by chemical reduction.

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