Lithium-magnesium alloy anodes for lithium-sulfur batteries

Abstract

Lithium-magnesium alloy anodes and fluorinated ether electrolytes for lithium-sulfur batteries. The lithium-magnesium alloy anode may include lithium-magnesium-boron alloys. The lithium-magnesium-boron alloys may include one or more of a Li2B5 alloy phase or a Li5B4 alloy phase. The lithium-magnesium-boron alloys may include a carbon-based material including flaky graphene and nodular graphene (three-dimensional graphene carbons or 3DG carbons). The 3DG carbons may include titanium dioxide (TiO2) nanoparticles disposed on one or more surfaces of the 3DG carbons or within the 3DG carbons. Methods for forming lithium-magnesium-boron alloys using a single-step exothermic melt process. The lithium-magnesium-boron alloy anodes may be freestanding. The freestanding lithium alloy anodes may include at least one anode protective layer.

Description

LITHIUM-MAGNESIUM ALLOY ANODES FOR LITHIUM-SULFUR BATTERIES RELATED APPLICATIONS

[0001] This Patent Application claims priority to U.S. Provisional Patent Application No.63 / 773,076 entitled “LITHIUM-ALLOY ANODES FOR LITHIUM-SULFUR BATTERIES” and filed on March 17, 2025, to U.S. Provisional Patent Application No. 63 / 874,129 entitled “LITHIUM-ALLOY ANODES FOR LITHIUM-SULFUR BATTERIES” and filed on September 02, 2025, and to U.S. Provisional Patent Application No. 63 / 949,992 entitled “LITHIUM-MAGNESIUM ALLOY COMPOSITE ANODES FOR LITHIUM-SULFUR BATTERIES” and filed on December 29, 2025, all of which are assigned to the assignee hereof. The disclosures of all prior Applications are considered part of and are incorporated by reference in this Patent Application in each of their respective entireties.TECHNICAL FIELD

[0002] This disclosure relates generally to batteries, and, more particularly, to lithiumsulfur batteries that can provide high specific energy and energy density combined with long cycle life.DESCRIPTION OF RELATED ART

[0003] Recent developments in batteries allow consumers to use high-specific energy batteries such as Li-sulfur batteries in many new applications. However, further improvements in battery technology are desirable.SUMMARY

[0004] This summary is provided to introduce in a simplified form a selection of concepts that are further described below in the Detailed Description section. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to limit the scope of the claimed subject matter.

[0005] In some implementations, an alloy associated with a lithium-sulfur battery anode may include a lithium-magnesium-boron (“Li-Mg-B”) alloy and a carbon-based material including flaky graphene and nodular graphene (also referred to herein as “three-dimensional graphene carbons” or “3DG carbons”). In some instances, the Li-Mg-B alloy may include a lithium-boron (“Li-B”) alloy phase. In some other instances, the carbon-based material may further include titanium dioxide (TiCL) nanoparticles disposed on one or more surfaces of thecarbon-based material or within the carbon-based material. In some examples, the carbonbased material may further include graphitic carbon.

[0006] In some implementations, the Li-B alloy phase may include one or more of a Li2Bs alloy phase or a U5B4 alloy phase. In some instances, the amount of boron in the alloy is between approximately 1 wt% and approximately 15 wt%. In some other instances, the amount of boron in the alloy may be approximately 10 wt%. In some examples, the amount of magnesium in the alloy may be between approximately 5 wt% and approximately 15 wt%. In some other examples, the amount of the carbon-based material in the alloy may be between approximately 5 wt% and approximately 20 wt%.

[0007] In various implementations, the Brunauer-Emmett-Teller (“BET") surface area of the carbon-based material measured using nitrogen gas may be between approximately 50 m2 / g and approximately 300 m2 / g. In some examples, the carbon-based material may be characterized by a Raman spectroscopy signature having an ID / IG ratio between approximately 0.35 and approximately 0.56. In some other examples, the carbon-based material may be characterized by a Raman spectroscopy signature having an ED / IG ratio between approximately 0.53 and approximately 0.7. In some instances, the carbon-based material may be characterized by a Raman spectroscopy signature having an ID / IG ratio between approximately 0.35 and approximately 0.56, and an ED / IG ratio between approximately 0.53 and approximately 0.7.

[0008] In some implementations, the flaky graphene associated with the carbon-based material may include a plurality of graphene layers. In some examples, the number of graphene layers in the plurality of graphene layers may be between 5 and 15. In some other examples, the plurality of graphene layers may include one or more of few layer graphene (“FLG”) or many layer graphene (“MLG"). In some instances, the graphene layers may be arranged as one or more stacks connected to each other and defining a three-dimensional (“3D”) porous scaffold structure including mesopores. In some other instances, at least some of the flaky graphene may be characterized by a linear dimension of between approximately 50 nm and 200 nm.

[0009] In some other implementations, the nodular graphene associated with the carbonbased material may include a plurality of carbon nano-onions (“CNOs”). In some instances, the nodular graphene may include porous carbon agglomerates of porous carbon primary nanoparticles. In some other instances, a respective porous carbon primary nanoparticle may include an inner porous shell disposed about a center of the respective porous carbon primary nanoparticle and enclosing an inner porous carbon region, an outer porous shell enclosing anouter porous carbon region disposed between the inner porous shell and the outer porous shell, and an interconnected porous network disposed in and in fluid communication with the inner and outer porous carbon regions. In some examples, the inner porous carbon region and the outer porous carbon region may be characterized by an average pore size and an average pore density associated with each region. In some other examples, the average pore size may decrease along a radial direction from the center of the respective porous carbon primary nanoparticle to the outer porous shell of the respective porous carbon primary nanoparticle. In some instances, the porous carbon primary nanoparticle may further include one or more intermediate porous shells disposed between the inner porous shell and the outer porous shell of the respective porous carbon primary nanoparticle, wherein each of the intemrediate porous shells encloses a corresponding intermediate porous carbon region.

[0010] In some implementations, the carbon-based material may further include one or more oxygen containing functional groups disposed on one or more surfaces of the 3DG carbons or within the 3DG carbons. In some instances, the oxygen containing functional groups may include one or more of epoxide (C-O-C), hydroxyl (-OH), ether (C-O-C), ketone (O-C=O), or carboxylic acid (-COOH) groups.

[0011] In various implementations, an anode associated with a lithium-sulfur battery may include a lithium-magnesium-boron (“Li-Mg-B”) alloy including a lithium-boron (“Li-B”) alloy phase and a carbon-based material including flaky graphene and nodular graphene (“3DG carbons”). In some instances, the carbon-based material may further include titanium dioxide (TiCL) nanoparticles disposed on one or more surfaces of the carbon-based material or within the carbon-based material. In some other instances, the Li-B alloy phase may include one or more of a Li2Bs alloy phase or a LisB4 alloy phase. In some examples, the carbon-based material may further include graphitic carbon.

[0012] In some other implementations, the amount of boron in the Li-Mg-B alloy may be between approximately 1 wt% and approximately 15 wt%. In some instances, the amount of boron in the Li-Mg-B alloy may be approximately 10 wt%. In some other instances, the amount of magnesium in the Li-Mg-B alloy may be between approximately 5 wt% and approximately 15 wt%. In some examples, the amount of the carbon-based material in the Li-Mg-B alloy may be between approximately 5 wt% and approximately 20 wt%. In some examples, the anode may further include a polymer coating disposed on the anode. In some instances, the polymer coating may include one or more of poly vinylidene fluoride (“PVDF”), pentaerythritol tetraacrylate (“PETEA”), or polyethylene glycol dimethacrylate (“PEGDMA”).

[0013] In some implementations, a lithium- sulfur battery may include a lithium-magnesium-boron (“Li-Mg-B”) alloy and a fluorinated ether electrolyte. In some instances, the Li-Mg-B alloy may include a lithium-boron (“Li-B”) alloy phase and a carbon-based material including flaky graphene and nodular graphene (“3DG carbons”). In some examples, the Li-B alloy phase may include one or more of a Li2Bs alloy phase or a L1 B4 alloy phase. In some other examples, the amount of boron in the Li-Mg-B alloy may be between approximately 1 wt% and approximately 15 wt%. In some instances, the carbonbased material may further include titanium dioxide (T1O2) nanoparticles disposed on one or more surfaces of the carbon-based material or within the carbon-based material. In some other instances, the carbon-based material may further include graphitic carbon.

[0014] In various implementations, the fluorinated ether electrolyte may include approximately 50:25:25 (vol%) 1 ,2-dimethoxyethane (“DME”): 1,3-dioxolane (“DOL”): bis (2,2,2-trifluoroethyl) ether (“BTFE”) and including approximately 0.4 M lithium bis (trifluoromethanesulfonyl) (“LiTFSI”) and approximately 2 wt% Li NO.?.

[0015] In some implementations, the fluorinated ether electrolyte may include approximately 50:25:25 (vol%) DME : DOL: 1,1, 2, 2-tetraethoxy ethane (“TEE”) and including approximately 0.4 M LiTFSI and approximately 2 wt% LiNO .

[0016] In some other implementations, the fluorinated ether electrolyte may include approximately 50:25:25 (vol%) DME : DOL: 1,1,2,2-tetrafluoroethyl 2,2,2-trifluoroethyl ether (“TFETFE”) and including approximately 0.4 M LiTFSI and approximately 2 wt% LiNO3.

[0017] In some other implementations, the fluorinated ether electrolyte may include approximately 60:20:10:10 (vol%) DME : DOL: TEE: TFETFE and including approximately 0.4 M LiTFSI and approximately 2 wt% LiNO?.

[0018] In various implementations, the fluorinated ether electrolyte may include approximately 50:25:25 (vol%) DME : DOL: l.l,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (“TTE”) and including approximately 0.4M LiTFSI and approximately 2 wt% LiNOs.

[0019] In some implementations, the fluorinated ether electrolyte may include approximately 50:25:25 (vol%) DME : DOL: 1 fluorinated 1,4-dimethoxylbutane (“FDMB”) including approximately 0.4 M LiTFSI and approximately 2 wt% LiNO?.

[0020] In some other implementations, the fluorinated ether electrolyte may include approximately 1.0 M LiTFSI in approximately 50:50 (vol%) DOL: BTFE. In some instances,the fluorinated ether electrolyte may include approximately 50:25:25 (vol%) DME: DOL: BTFE and including between approximately 0.6 M and approximately 0.8M LiTFSI, between approximately 0.5M and approximately 0.7M EiNCK and between approximately 0.15M and approximately 0.2M dicyandiamide (“DCDA”).

[0021] In some implementations, the lithium- sulfur battery may further include a polymer coating disposed on the anode as an anode protective layer. In some examples, the polymer coating may include one or more of polyvinylidene fluoride (“PVDF”), pentaerythritol tetraacrylate (“PETEA”), or polyethylene glycol dimethacrylate (“PEGDMA”).

[0022] In some implementations, a method of forming a lithium-magnesium-boron (“Li-Mg-B”) alloy may include producing a lithium-magnesium (“Li-Mg”) alloy melt by melting a Ei-Mg alloy at a process temperature, producing a Ei-Mg-B melt by adding powdered boron to the Li-Mg alloy melt at the process temperature, and soaking the Li-Mg-B alloy melt for a soak time at the process temperature. In some instances, the Li-Mg-B alloy may include one or more of a Li2Bs alloy phase or a L1 B4 alloy phase. In some other instances, the method may further include adding a carbon-based material including flaky graphene and nodular graphene (“3DG carbons”) to the Li-Mg alloy melt at the process temperature. In some examples, the carbon-based material may further include titanium dioxide (TiO2) nanoparticles disposed on one or more surfaces of the carbon-based material or within the carbon-based material. In some other examples, the method of forming a lithium-magnesium-boron (“Li-Mg-B”) alloy may further include confirming the presence of the LisB4 alloy phase or the I J2B5 alloy phase by analyzing the Li-Mg-B alloy layer using X-ray diffraction (“XRD”). In some instances, the carbon-based material may further include graphitic carbon.

[0023] In some implementations, the process temperature may be between approximately 550 °C and approximately 750 °C. In some instances, the process temperature may be approximately 700 °C. In some other instances, the soak time may be between approximately 2 minutes and approximately 30 minutes. In some examples, the soak time may be approximately 5 minutes. In some other examples, the lithium-magnesium alloy may include a 90 wt% lithium - 10 wt% magnesium alloy.

[0024] In some implementations, another method of forming a lithium-magnesium-boron (“Li-Mg-B”) alloy associated with a lithium-sulfur battery anode may include producing a Li-Mg alloy melt by melting a Li-Mg alloy at a process temperature, adding a carbon-based material doped with boron to the Li-Mg alloy melt, and soaking the Li-Mg alloy meltincluding the carbon-based material doped with boron at a soaking temperature. The Li-Mg-B alloy may include a lithium-boron (“Li-B”) alloy phase. In some instances, the carbonbased material may include flaky graphene and nodular graphene. In some instances, the carbon-based material may further include graphitic carbon. In some other instances, the method may further include forming an ingot by cooling the Li-Mg-B. In some examples, the temperature associated with the adding operation is approximately equal to the process temperature. In some other examples, the soaking temperature is approximately equal to the process temperature.

[0025] In some other implementations, the Li-B alloy phase may include one or more of a Li2Bs alloy phase or a I .idL alloy phase. In some instances, the amount of magnesium in the alloy may be between approximately 5 wt% and approximately 20 wt%. In some other instances, the carbon-based material may further include graphitic carbon. In some examples, the process temperature may be between approximately 550 °C and approximately 750 °C. In some other examples, the soaking time associated with the soaking operation is between approximately 2 minutes and approximately 30 minutes.

[0026] In some implementations, the geometrical shape of any one of the lithium- sulfur batteries described herein may be cylindrical. The cylindrical battery may be approximately 18 mm in diameter and approximately 65 mm in length. In some implementations, the cylindrical battery may be approximately 21 mm in diameter and approximately 70 mm in length. In some implementations, the cylindrical battery may be approximately 46 mm in diameter and approximately 80 mm in length.

[0027] Details of one or more implementations of the subject matter described in this disclosure are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages will become apparent from the description, the drawings, and the claims. Note that the relative dimensions of the following figures may not be drawn to scale.BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1A shows a flow chart depicting a single-step exothermic operation associated with forming a lithium-magnesium-boron alloy (Li-Mg-B) anode, according to some implementations.

[0029] Figure IB shows a flow chart depicting an example operation associated with forming a lithium-magnesium-boron alloy (Li-Mg-B) anode including three-dimensional graphene carbons (3DG carbons), according to some implementations.

[0030] Figure 2A shows a schematic diagram of a porous carbon primary nanoparticle, according to some implementations.

[0031] Figure 2B shows a transmission electron microscopy (TEM) image showing aggregates of porous carbon primary nanoparticles, according to some implementations.

[0032] Figure 2C shows a TEM image of agglomerates of porous carbon primary nanoparticles, according to some implementations.

[0033] Figure 2D shows a TEM image of surface etched agglomerates of porous carbon primary nanoparticles, according to some implementations.

[0034] Figure 2E shows a schematic diagram of another porous carbon primary nanoparticle, according to some implementations.

[0035] Figure 3A shows a schematic diagram of agglomerates of porous carbon primary nanoparticles, according to some implementations.

[0036] Figure 3B shows a scanning electron microscopy (SEM) micrograph of agglomerates of porous carbon primary nanoparticles, according to some implementations.

[0037] Figure 3C shows a TEM micrograph of agglomerates of porous carbon primary nanoparticles, according to some implementations.

[0038] Figures 3D-3E show SEM micrographs of 3DG carbons including flaky graphene and nodular graphene, according to some implementations.

[0039] Figures 3F-3I show TEM micrographs of 3DG carbons including flaky graphene and nodular graphene, according to some implementations.

[0040] Figure 4 shows a schematic diagram depicting a lithium- sulfur cylindrical battery, according to some implementations.

[0041] Figure 5 shows a TEM micrograph of a carbon-based material including flaky graphene, nodular graphene, and graphitic carbon, according to some implementations.

[0042] Figures 6A-6B show electron energy loss spectroscopy (EELS) spectra of a carbon-based material including flaky graphene, nodular graphene, and graphitic carbon, according to some implementations.

[0043] Figure 7 shows a flow chart depicting an example operation associated with forming a lithium-magnesium alloy including a doped carbon-based material, according to some implementations.

[0044] Figure 8A shows a SEM micrograph of a doped carbon-based material, according to some implementations.

[0045] Figures 8B-8C show SEM-energy dispersive X-ray spectroscopy (EDS) elemental dispersion images of a doped carbon-based material, according to some implementations.

[0046] Figure 8D shows a TEM micrograph of a doped carbon-based material, according to some implementations.

[0047] Figure 8E shows an X-ray photoelectron spectroscopy (XPS) image of a doped carbon-based material, according to some implementations.

[0048] Figure 8F shows an X-ray diffraction (XRD) pattern of a Li-Mg-B alloy formed using the process described with reference to Figure 7, according to some implementations.

[0049] Figures 9A-9B show SEM micrographs of a boron-doped carbon-based material, according to some implementations.

[0050] Figures 9C-9E show SEM-energy dispersive X-ray spectroscopy (EDS) elemental dispersion images of a boron-doped carbon-based material, according to some implementations.

[0051] Figure 10 shows an X-ray diffraction (XRD) pattern of a lithium-magnesium-boron alloy formed by a single step exothermic melt process, according to some implementations.

[0052] Figure 11 shows a SEM micrograph of a lithium-magnesium-boron alloy (Li-Mg-B) formed by a single step exothermic melt process, according to some implementations.

[0053] Figure 12 shows a plot illustrating cathode discharge capacity and capacity retention of lithium- sulfur coin cells including lithium-magnesium-boron alloy anodes, according to some implementations.

[0054] Figure 13A shows an SEM micrograph of a Li-Mg-B alloy including 3DG carbons, according to some implementations.

[0055] Figures 13B-13C show SEM-energy dispersive X-ray spectroscopy (EDS) elemental dispersion images of a Li-Mg-B alloy including 3DG carbons, according to some implementations.

[0056] Figure 14 shows a plot illustrating cathode discharge capacity and capacity retention of lithium- sulfur coin cells including lithium-magnesium-boron alloy anodes, according to some implementations.

[0057] Figures 15A-15B show plots illustrating cathode discharge capacity and capacity retention of lithium- sulfur coin cells assembled with Li-Mg-B alloy anodes including a doped carbon-based material, according to some implementations.

[0058] Figure 15C shows a plot illustrating columbic efficiency of lithium-sulfur coin cells assembled with a Li-Mg-B alloy anode including a doped carbon-based material, according to some implementations.

[0059] Figure 16A-16B shows plots illustrating cathode discharge capacity and capacity retention of lithium-sulfur coin cells assembled with another Li-Mg-B alloy anode including doped a carbon-based material, according to some implementations.

[0060] Figures 17A-17B show plots illustrating cathode discharge capacity and columbic efficiency of lithium-sulfur coin cells assembled with another Li-Mg-B alloy anode including a doped carbon-based material, according to some implementations.

[0061] Like reference numbers and designations in the various drawings indicate like elements.DETAILED DESCRIPTION

[0062] The following description is directed to some example implementations for the purpose of describing the innovative aspects of this disclosure. However, a person having ordinary skill in the art will readily recognize that the teachings herein can be applied in a multitude of different ways. The implementations described can be implemented in batteries for a variety of applications and may be tailored to compensate for various performance related deficiencies. As such, the disclosed implementations are not to be limited by the examples provided herein, but rather encompass all implementations contemplated by the attached claims. Additionally, well-known elements of the disclosure will not be described in detail or will be omitted so as not to obscure the relevant details of the disclosure.

[0063] Various aspects of the novel compositions and methods are described more fully herein with reference to the accompanying drawings. These aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Although some examples and aspects are described herein, many variations and permutations of these examples fall within the scope of the disclosure.Although some benefits and advantages of the various aspects are mentioned, the scope of the disclosure is not intended to be limited to benefits, uses, or objectives. The detailed description and drawings are merely illustrative of the disclosure rather than limiting, the scope of the disclosure being defined by the appended claims and equivalents thereof.

[0064] In this disclosure, a “three-dimensional graphene carbons’’ (also referred to herein as “3DG carbons”) includes flaky graphene and nodular graphene. In some instances, the 3DG carbons also include graphitic carbons. In some examples, the 3DG carbons may also include amorphous carbon. As such, the 3DG carbons may be referred to as “mixed morphology" carbons. Graphitic carbon is characterized by a layered three-dimensional structure including many graphene layers, for example, more than 30 graphene layers. In this disclosure, few layer graphene (“FLG”) includes flaky graphene characterized by 5 to 10 graphene layers, and many layer graphene (“MLG”) includes flaky graphene characterized by 10-to-30-layer graphene layers.

[0065] The mixed morphology carbons may include agglomerates of primary carbon nanoparticles. A primary carbon particle may be considered as a spheroidal shaped, non-discreet component of an aggregate that is separable from the aggregate only by fracturing. A plurality of primary carbon nanoparticles may be coalesced or joined to form carbon aggregates including primary carbon nanoparticles. An aggregate may be considered as a discrete, colloidal entity that is the smallest dispersible unit composed of coalesced primary carbon nanoparticlcs. The primary carbon particles may be connected together by one or more of Van der Waals forces, covalent bonds, ionic bonds, metallic bonds, or by other physical or chemical interactions. Additionally, a plurality of carbon aggregates may be considered as carbon agglomerates. Since carbon aggregates of at least 1 pm in size may be considered as agglomerates, the term “carbon aggregates" also includes “carbon agglomerates” in this disclosure.

[0066] The carbon nanoparticles may include three-dimensional (“3D”) mesoporous carbon nanoparticles. A mesoporous material, as generally understood and as referred to herein, includes a material containing pores with diameters between 2 nm and 50 nm, according to the International Union of Pure and Applied Chemistry (“IUPAC”) nomenclature. For the purposes of comparison, IUPAC defines microporous material as a material having pores smaller than 2 nm in diameter and defines macroporous material as a material having pores larger than 50 nm in diameter.

[0067] Those skilled in the art would recognize that “graphene” refers to an allotrope of carbon in the form of a two-dimensional, atomic-scale, hexagonal lattice in which one atom forms each vertex. The carbon atoms in graphene may be sp2hybridized carbon atoms. Additionally, pristine graphene has a Raman spectrum with two main peaks: a G-mode at approximately 1580 cm'1and a D mode at approximately 1350 cm'1(when using a 532 nm excitation laser). In contrast, the 3DG carbons disclosed herein are characterized by a distinct morphological structure as described below in this disclosure with reference to Figures 2A-2E, 3A-3I, 5, and 6A-6B.

[0068] In some implementations, flaky graphene associated with the 3DG carbons may be covalently linked or welded or fused to nodular graphene by one or more of microwave radiation, direct current discharge, low temperature non-equilibrium plasma, thermal equilibrium plasma, plasma generated at an intermediate temperature below thermal equilibrium temperature during chemical processing of one or more hydrocarbon feedstocks to produce the 3DG carbons.

[0069] Commercialization of lithium- sulfur (“Li-S”) batteries has been hampered by limited discharge / charge cycling of less than approximately 100 cycles. Root cause analysis suggests that lithium-metal anode failure is a primary reason for cell failure. During cycling, the lithium-metal anode experiences significant volume change caused by repeated stripping (during discharge) and plating (during charge) of lithium. This volume change negatively impacts anode stability, and in particular, the stability of unsupported (or freestanding) lithium-metal anodes. In a freestanding lithium-metal anode, the anode is not supported on a metal substrate including a copper current collector. Anode stability is further impacted by an unstable electrode-electrolyte interface and pulverization of the anode caused by volume changes during cycling, because lithium has a high oxidation potential (approximately 3.04V) and can react with almost any electrolyte solution, either in a solvent or in a salt form, to form a solid electrolyte interphase (“SEI”) layer.

[0070] The SEI layer is electronically insulating but ionically conductive to Li+ions. As such, once the SEI layer is formed, additional undesirable reaction between the Li-metal anode and electrolyte may be blocked or partially blocked by the SEI layer. However, the SEI layer is generally non-uniform, which results in non-uniform current distribution during plating, and may cause uneven (or non-uniform) lithium deposition and anode cracking during cycling. Fresh lithium-metal anodes may be exposed to the electrolyte resulting in the undesirable consumption of lithium for re- formation of the SEI layer. The localized non-uniform lithium deposition and stripping may manifest as dendrites during plating and pits during stripping at the anode during charge / discharge cycles. Dendrites may cause serious safety problems and reduce the cyclability of lithium-ion batteries. Additionally, dendrites may be dislodged from the anode to form ‘dead’ zones of lithium. Lithium dendrites may penetrate through polyolefin separators or even polymer / solid electrolyte separators disposed between the anode and the cathode of a battery and negatively impact the safety and performance of lithium-ion batteries.

[0071] The above problems are further exacerbated in lithium-sulfur batteries, which include sulfur confined in a porous carbon cathode as the active cathode material. Sulfur reacts with lithium ions forming poly sulfides. During the discharge cycle, lithium ions migrate from the anode to the cathode through the electrolyte where sulfur is reduced to lithium sulfide (Li2S). The sulfur reduction to Li2S is complex and may involve the formation of several intermediate lithium-polysulfides (LizSx, 8 < x < 1). Polysulfides (“Li-PS”) may be formed during the battery discharge cycle as:Ss —> Li2Ss LizSe Li2S4 Li2S3~ * [.1282^ LizS

[0072] Ideally, the Li-PS compounds oxidize back to sulfur during the charge cycle. In practice, Li-PS compounds leak out from the porous carbon cathode as they are highly soluble in the electrolyte, which results in loss of sulfur and reduction in cathode capacity. While sulfur and Li2S are relatively insoluble in most electrolytes, many intermediate polysulfides are soluble and cause irreversible loss of active sulfur from the cathode. The dissolution of Li-PS in the electrolyte requires a large amount of electrolyte (E / S > 3), which reduces battery specific energy. The higher polysulfides ( LizSs and Li2Se) may diffuse to the anode and may get reduced to lower polysulfides (I^Se and IJ2S4), which subsequently get oxidized at the cathode. At the anode, the polysulfides participate in SEI formation, increase the unevenness of SEI, and aggravate the corrosion of the lithium-metal anode. This cyclic process commonly known as the polysulfide “shuttle effect” results in poor coulombic efficiency, and progressive leakage of active sulfur material from the cathode which also reduces the life cycle of the battery. Further, the conversion of elemental sulfur to Li2Sxsulfur compounds is accompanied by large volumetric expansion at the cathode (which could be as high as 80%), which subjects the cathode to significant mechanical stresses resulting in rapid cathode degradation.

[0073] Additionally, the “shuttle effect” is responsible for self-discharge of lithium-sulfur batteries, because of the slow dissolution of Li-PS during battery dormancy. Battery self-discharge reduces battery life and causes safety issues. The repeated volume change and the corrosion reactions at the anode continuously consume active Li and form massive “dead Li,” which may be detached during cycling, leading to poor recyclability of a lithium-sulfur battery. As previously noted, often the anode contributes to cell failure, either via electrolyte consumption of Li due to corrosion or its depletion during cycling. These challenges limit the commercial viability of high-specific energy lithium-sulfur batteries having dense cathodes, limited electrolyte, and limited anode capacity (or low N / P ratio). The N / P ratio may be defined as the ratio of reversible capacity (mAh) of the negative electrode (anode) to that of the positive electrode (cathode) assuming complete utilization of sulfur.

[0074] Accordingly, to mitigate the loss of conductivity due to dissolved Li-PS an excess amount of electrolyte is used in lithium- sulfur batteries. Additionally, to mitigate lithium-metal loss due to SEI formation, pitting, and dendrite formation, an excess of lithium-metal is required at the anode. These requirements frustrate attempts to reach or exceed the specific energy target of 500 W-h / kg in lithium-sulfur batteries. Lithium-sulfur batteries require an electrolyte to sulfur ratio (“E / S ratio”) of approximately 5 pL / mgS, and a N / P ratio of greater than 2. For comparison, the N / P ratio in commercial lithium-ion batteries is between approximately 1.03 and 1.2. While the N / P ratio is important to offset the higher loss of anode material during cycling, the areal capacity (mAh / cm2) is also critical to reduce the current density and hence failure rate on the anode.

[0075] Lithium- sulfur battery anodes may include a current collector such as copper as an anode support. Copper adds significant weight to lithium-sulfur batteries and reduces the specific energy of the battery. Copper is also susceptible to corrosion by polysulfides.Accordingly, there is significant interest in developing substrate-free or freestanding anodes. However, freestanding anode in lithium- sulfur batteries is challenging due to the morphological and instability issues with the lithium-metal (“pure lithium”) anode.Freestanding anode alloy compositions that are stable under cyclic conditions in lithiumsulfur batteries and at low E / S ratios of less than or equal to 5 for coin cells, and less than or equal to 3 for pouch cells are needed. Freestanding anode compositions that are stable under cyclic conditions in lithium- sulfur batteries and at N / P ratios of approximately less than 2 to realize battery specific energy of 500 W-h / kg are also needed.

[0076] In some implementations, lithium-alloys may be used as freestanding anodes instead of pure-lithium metal anodes to overcome the previously described anode instability issues related to volume change during cycling, and the high reactivity of the lithium-metalanodes with the electrolyte and with polysulfides. Lithium may alloy with several metals including one or more of silicon, tin, magnesium, or aluminum. Lithium-alloy anodes may be characterized by higher electrode potential compared to lithium and may hinder corrosion at the anode caused by reactions between the anode and poly sulfides and electrolytes.Meanwhile, the alloying element may function as a lithium host for lithium deposition or plating (during the charge cycle) absorb volume changes during cycling and help to stabilize the anode. The alloying element may form a stable surface film over the anode, which may reduce the non-uniform deposition of lithium during plating.

[0077] In some implementations, alloying lithium with small amounts of magnesium (Mg) may improve the stability of lithium-sulfur battery anodes to reactions with the electrolyte and polysulfides and increase battery cycle life. In lithium-magnesium (“Li-Mg”) alloy anodes, the magnesium alloying element may provide structural integrity to the anode during volume changes associated with battery cycling, because magnesium does not undergo stripping and plating at the anode. Additionally, alloying lithium with small amounts of magnesium permits a free-standing anode design (without the need for a copper current collector substrate), which also increases battery specific energy.

[0078] Li and Mg have comparable atomic radii and form an extended single solid phase (body centered cubic structure or BCC) alloy over a wide composition range of approximately 11.5-100 wt% lithium in Li-Mg alloys. Therefore, the capacity of a Li-Mg alloy anode may be tuned over a broad range free of any alloy phase change considerations. The Li-Mg alloy may provide a scaffold-like structure, which may facilitate insertion and removal of Li+ions during the charge / discharge cycling of a lithium-sulfur battery. The volume change related to the insertion of one mole of Li into Mg may be approximately 80% as calculated using Li-Mg alloy lattice parameters, which is much lower than the volume change related to the interaction of lithium with other alloying elements such as silicon, tin, and antimony. Li-Mg alloys are very ductile, which permit straightforward fabrication of electrodes by rolling and annealing. At Li-rich compositions of approximately 90%, no loss in battery voltage may be observed when replacing a Li-anode (100% lithium) with a Li-Mg anode, because lithium stripping and plating may occur close to 0 V. Additionally, as magnesium is lithiophilic, dispersed magnesium in Li-Mg anodes may serve as nucleation sites for uniform lithium deposition during the charge cycle.

[0079] Since Li-Mg alloy anodes form relatively stable SEI interface (compared to Li-anodes), a comparatively smooth anode surface morphology may be realized during thecyclic operation of a lithium- sulfur battery. Additionally, a Li-Mg alloy matrix, poor in lithium, and with high electric and ionic conductivity, may be formed after Li stripping to provide an excellent anode current collector and host for subsequent Li plating. Accordingly, Li-Mg alloy anodes may be freestanding and may not require a separate anode current collector.

[0080] As previously described, lithium has a high oxidation potential (of approximately 3.04V) and can react with almost any electrolyte solution, either in a solvent or in a salt form, to form a solid electrolyte interphase (“SEI”) layer. Lithium anode stability is further impacted by an unstable electrode-electrolyte interface and pulverization of the anode caused by volume changes during cycling. Alloying lithium with metals including magnesium may reduce the life of the anode in lithium-sulfur cells, but this increased stability often requires an increase in the number of formation cycles required to reach a target cathode discharge capacity.

[0081] In some other implementations, a cathode discharge capacity of approximately 600 mAh / g may be realized in lithium-sulfur batteries without sacrificing anode stability and cell formation cycle time using a lithium-magnesium (“Li-Mg”) alloy anode. In some implementations, a freestanding anode associated with a lithium- sulfur battery may include a lithium-magnesium alloy or a lithium-magnesium-boron alloy, as described below in this disclosure, and a lithium-ion conducting material.

[0082] In some implementations, the lithium-ion conducting material may include one or more of lithium titanate (“LTO”), lithium lanthanum zirconium oxide (“LLZO”), lithium nitride (LisN), or lithium phosphide (LisP). In some examples, a freestanding Li-Mg alloy anode may further include one or more of alumina (AI2O3) or titanium dioxide (TiCL). In some instances, the amount of the lithium-ion conducting material in the freestanding Li-Mg alloy or lithium-magnesium-boron alloy anode may be between approximately 10 wt% and approximately 40 wt%. In some other instances, the weight ratio of the Li-Mg alloy anode to the lithium-ion conducting material may be between approximately 1 and approximately 9. Without being bound by any particular theory the lithium-ion conducting materials may help in controlling the grain size of Li-Mg in the Li-Mg alloy and facilitate lithium-ion diffusion across grain boundaries.

[0083] In some implementations, lithium- sulfur batteries including freestanding Li-Mg alloy or lithium-magnesium-boron alloy anodes may be subject to sluggish activation that requires several activation cycles to achieve rated discharge capacity. In some instances,prolonged activation may be observed when the Mg content in Li-Mg alloys is greater than approximately 10 wt%. Prolonged battery activation is not suitable for commercial lithiumsulfur battery applications. To mitigate sluggish activation, Li-Mg alloys or lithium-magnesium-boron alloys may include one or more of lithium-ion conducting materials or electron conducting materials, or a combination thereof, lithium-ion conducting materials may include one of lithium titanate (“LTO”), lithium lanthanum zirconium oxide (“LLZO”), lithium nitride (Li?N), or lithium phosphide (I d?P), or similar lithium-ion conducting materials including ceramic materials. Electron conducting materials may include one or more of carbon, aluminum, or silicon, or other similar electron conducting materials. The enhanced lithium-ionic conductivity or electron conductivity of the Li-Mg alloys including lithium-ion conducting materials or electron conducting materials may improve lithium utilization by reducing impedance associated with charge transfer during plating. Increasing the Mg content in Li-Mg alloys may also reduce material costs associated with the anode and improve the safety of lithium- sulfur batteries.

[0084] Without being bound by any particular theory, the lithium-ion conducting materials or electron conducting materials may disperse in the bulk alloy and reduce the grain size of Li-Mg domains or reduce the diffusion length of Li+ions in the Li-Mg or the lithium-magnesium-boron alloy bulk alloy to facilitate faster lithium-ion diffusion across grain boundaries. With faster lithium-ion diffusion, lithium-ion plating / stripping during charge / discharge cycles in lithium-ion batteries may be more uniform and mitigate dendrite growth. Dendrites may penetrate the polymeric or ceramic separators in lithium-ion batteries and create a short circuit within a battery resulting in fire hazards.

[0085] In some implementations, a diffusion coefficient of lithium in Li-Mg / LTO or Li-Mg-B / LTO alloys may be approximately 2.3 x 10'8cm2 / s, which is approximately an order of magnitude greater than the diffusion coefficient of lithium in Li-Mg alloys of approximately 3.8 x 10‘9cm2 / s. Magnesium in Li-Mg / LTO alloys primarily controls the reactivity or stability of the alloy, and LTO reduces the size of Li-Mg domains and improves lithium-ion diffusivity. As such, improved lithium- sulfur battery cycle life and discharge capacities and a reduction in the N / P ratio to less than 2 may be possible with Li-Mg alloys including up to approximately 28 wt% Mg and an LTO content of up to approximately 40 wt%.Accordingly, the lithium content in the Li-Mg / LTO alloys may be reduced to between approximately 40 wt% and approximately 45 wt%, which in turn reduces material costs associated with the lithium-ion battery anode.

[0086] Additionally, the melting point of a Li-Mg / LTO alloy is approximately 210 °C, which is greater than the melting point of lithium of approximately 180 °C. Battery safety is enhanced because the thermal runaway onset point in lithium- sulfur batteries increases from approximately 126 °C for a 90 wt% Li - 10 wt% Mg alloy to approximately 236 °C for a Li-Mg / LTO alloy, thereby increasing the temperature at which lithium-sulfur batteries associated with various aspects of the implementations disclosed herein can be safely used to approximately 110 °C.

[0087] In some implementations, the magnesium content in a freestanding Li-Mg alloy or a lithium-magnesium-boron alloy anode including a lithium-ion conducting material may be between approximately 10 wt% and approximately 28 wt%. As previously noted, lithium-ion conducting materials may include one of lithium titanate (“LTO”), lithium lanthanum zirconium oxide (“LLZO”), lithium nitride (LiaN), or lithium phosphide (Li P). In some instances, the amount of the lithium-ion conducting material in a freestanding Li-Mg alloy anode may be between approximately 10 wt% and approximately 40 wt%. In some other instances, the weight ratio of the Li-Mg alloy to the lithium-ion conducting material may be between approximately 1 and approximately 9. In some other instances, the weight ratio of the Li-Mg alloy to the lithium-ion conducting material may be approximately 1.5.

[0088] As previously described herein, lithium-magnesium alloy anodes may include lithium-ion conducting materials in an amount between approximately 10 wt% and approximately 40 wt%. Examples of lithium ion conducting materials may include one or more of lithium titanate (“LTO”), lithium lanthanum zirconium oxide (LLZO), lithium nitride (LisN), or lithium phosphide (LisP).

[0089] In some implementations, lithium-magnesium alloy anodes including at least 10 wt% of one or more lithium-ion conducting materials may be characterized by an undesirable increase in the weight of the anode. An increase in the weight of the anode would decrease the specific capacity (mAh / g) or specific energy (Wh / kg) of lithium-sulfur batteries. For example, in some implementations, increasing the LTO content in lithium-magnesium alloy anodes from approximately 10 wt% to approximately 50 wt% may decrease the specific capacity of lithium-sulfur batteries from approximately 2800 mAh / g to approximately 1400 mAh / g.

[0090] Without being bound by any particular theory, lithium-magnesium alloy anodes including nanosized ionic fillers may increase cycle life of lithium- sulfur batteries or reduce the number of activation cycles without incurring a penalty in the specific capacity associatedwith lithium sulfur batteries. Accordingly, in some implementations, a freestanding anode associated with a lithium- sulfur battery may include a Li-Mg alloy and one or more of a lithium-ion conducting material, an electron conducting material, or an ionic filler.

[0091] In some implementations, lithium-magnesium alloy anodes may include an ionic filler including one or more of alumina or titanium oxide (TiCh) nanoparticles having an average particle size (dso) of less than 50 nm as ionic fillers. In some other instances, lithium-magnesium alloy anodes may include an ionic filler including one or more of alumina or titanium oxide (TiCh) nanoparticles having an average particle size (dso) of between approximately 10 nm and approximately 50 nm. As referred to herein in this disclosure, an ionic filler is an ionic compound that includes positively charged metal ions and negatively charged non-metal ions. As referred to herein, an ionic filler is generally not considered to be a lithium ion-conducting material.

[0092] In some implementations, lithium-magnesium alloy anodes associated with lithium-sulfur cells may include one or more of approximately 10 wt% LTO or approximately 10 wt% TiCk. A lithium-magnesium alloy may include a 90 wt% Li-10 wt% Mg alloy.

[0093] In some implementations, the amount of a lithium-ion conducting material in lithium-magnesium alloy anodes may be between approximately 10 wt% and approximately 40 wt%.

[0094] In some other implementations, an amount of an ionic filler in lithium-magnesium alloy anodes may be between approximately 10 wt% and approximately 40 wt%. In some other implementations, the amount of an ionic filler in lithium-magnesium alloy anodes may be approximately 10 wt%.

[0095] In some implementations, a lithium-magnesium alloy anode may include approximately 80 wt% Li-Mg alloy or lithium-magnesium-boron alloy, approximately 10 wt% LTO, and approximately 10 wt% TiO2. A lithium-magnesium alloy may include a 90 wt% Li- 10 wt% Mg alloy.

[0096] In some other implementations, a lithium-magnesium alloy anode may include approximately 62 wt% Li, approximately 18 wt% Mg, approximately 10 wt% LTO and approximately 10 wt% TiO2. In some examples, a Li-Mg alloy may include approximately 90 wt% Li and approximately 10 wt% Mg.

[0097] In some implementations, lithium-magnesium alloy anodes may include a lithium-ion conducting material having an average particle size (dso) of between approximately 0.5pm and approximately 2 pm. As previously described herein, lithium ion conducting materials may include one or more of LTO, lithium lanthanum zirconium oxide (“LLZO”), lithium nitride (Li?N), or lithium phosphide (LLP).

[0098] In some implementations, the electron conducting materials included in lithiummagnesium alloy freestanding anodes may include one or more of carbon, aluminum, or silicon. In some instances, carbon may include graphite. In some examples, the lithiummagnesium alloy associated with a lithium-magnesium alloy freestanding anode may include a lithium-magnesium-tin alloy as described below in this disclosure. In some other examples, the lithium-magnesium alloy associated with a freestanding lithium-magnesium alloy anode may include a lithium-magnesium-aluminum alloy as described below in this disclosure.

[0099] In some implementations, a grain size of Li-Mg domains in any one of the Li-Mg alloys previously described herein may be manipulated via annealing or rapid quenching operations associated with the thermal treatment and mechanical processing of Li-Mg alloys. For example, Li-Mg domain grain growth may be mitigated by annealing Li-Mg alloys at 70% of the melting point of the alloy. In some implementations, annealing Li-Mg alloys associated with lithium-sulfur battery anodes at approximately 150 °C may improve the capacity retention and columbic efficiency of lithium-sulfur batteries. Annealing or rapid quenching may also alter the orientation of body centered cubic (“BCC”) crystalline grain structure in Li-Mg alloys to preferred orientations, for example, the (110) plane or the (200) plane. In some implementations, the grain size of Li-Mg domains in Li-Mg alloys or any one of the Li-Mg composite alloys describe herein after annealing may be less than approximately 175 pm.

[0100] In some implementations, the lithium-magnesium alloys described herein may include a carbon-based porous material including flaky graphene and nodular graphene (referred to herein as three-dimensional graphene carbons or “3DG carbons”). In some instances, the alloy may further include a lithium-carbon phase. In some instances, the lithium-carbon phase may include one or more of LiCi2 or LiCe. In some examples, the amount of the carbon-based porous material in the alloy may be between approximately 5 wt% and approximately 20 wt%. Examples of carbon-based porous materials are described in this disclosure with reference to Figures 2A-2E and Figures 3A-3I.

[0101] In some implementations, an anode associated with a lithium- sulfur battery may include a lithium-magnesium-boron (“Li-Mg-B”) ternary alloy or a lithium-boron (“Li-B”) binary alloy. Li-B binary alloys are conventionally made using a two-step exothermic meltprocess. Li-B phase formation may be accompanied by exothermic reactions at about 350 °C (also referred to herein as the first exothermic step) and subsequently, at about 550 °C (also referred to herein as the second exothermic step). When molten lithium is contacted with boron below 300 °C, no alloying is observed. At about 350 °C, an exothermic reaction between lithium and boron occurs and as the temperature is increased to about 550 °C, the viscosity of the melt increases due to the formation of an intermetallic phase, for example LivBe. Careful control of processing parameters including temperature and the alloying sequence is needed. For example, vigorous stirring of the melt is generally required upon formation of the intermetallic phase. Regarding the formation of Li-Mg-B ternary alloys, magnesium may be added to the melt at about 550 °C. The addition of magnesium prior to both exothermic reactions will impact formation of the Li-Mg-B ternary alloy with desired characteristics. Accordingly, a relatively simple and scalable method for forming Li-Mg-B ternary alloys and Li-B binary alloys is needed.

[0102] In some implementations, an example Li-Mg-B alloy may be formed using a single-step exothermic melt process. Figure 1 A shows a flow chart depicting a single-step exothermic melt operation 100 A associated with forming a Li-Mg-B alloy anode, according to some implementations. In some implementations, operation 100 A may begin at 101 A with producing a lithium-magnesium (“Li-Mg”) alloy melt by melting a Li-Mg alloy at a process temperature. In some instances, the process temperature may be between approximately 550 °C and approximately 750 °C. In some other instances, the process temperature may be approximately 700 °C. In some examples, the lithium-magnesium alloy may include a 90 wt% lithium - 10 wt% magnesium alloy.

[0103] In some implementations, operation 100A may continue at 102A with adding powdered boron to the Li-Mg melt at the process temperature. In some instances, operation 100A may continue at 103 A with soaking the melted Li-Mg alloy including boron powder during a soak time at the process temperature. In some examples, the soak time may be between approximately 2 minutes and approximately 30 minutes. In some other examples, the soak time may be approximately 5 minutes. Those skilled in the art will appreciate that other ranges associated with the soak time may exist without departing from the scope and spirit of the present implementations.

[0104] In some implementations, operation 100A may continue at 104A with cooling the Li-Mg-B alloy and confirming the presence of a LisB4 alloy phase or a Li2Bs alloy phase by analyzing a sample of the Li-Mg-B alloy using X-ray diffraction (“XRD”) or one or moreanalytical tools. As described below with reference to Example 1, the Li JE alloy phase associated with the Li-Mg-B alloys may be uniformly distributed as fibrous structures in the Li-Mg-B alloy.

[0105] At 105A, upon confinnation of desired crystallographic properties of the Li-Mg-B alloy, an anode associated with a lithium- sulfur battery may be fabricated using the Li-Mg-B alloy. In some instances, at 105 A, the Li-Mg-B alloy may be rolled to form one or more Li-Mg-B layers or films. In some examples, the thickness of a rolled Li-Mg-B layer may be approximately 100 pm. Additional details related to Li-Mg-B alloys formed by the single-step exothermic melt process are described below with reference to Example 1.

[0106] In some implementations, the amount of boron associated in the Li-Mg-B alloy may be between approximately 1 wt% and approximately 15 wt%. In some examples, the weight ratio of lithium to magnesium may be between about 8 and about 9. In some other instances, the amount of magnesium in the Li-Mg-B alloy may be between approximately 5 wt.% and approximately 15 wt%.

[0107] In some implementations, an anode associated with a lithium-sulfur battery may include any one of the lithium-magnesium-boron (“Li-Mg-B”) alloys previously described herein. In some instances, the amount of boron in the Li-Mg-B alloy may be between approximately 1 wt% and approximately 15 wt%. In some examples, the Li-Mg-B alloy may include a lithium-boron alloy phase (also referred to herein as a lithium-boron intermetallic compound). In some other examples, the lithium-boron alloy phase may include one or more of a L12B5 alloy phase or a LisBa alloy phase. In some instances, the weight ratio of lithium to magnesium associated with the Li-Mg-B alloy may be between about 8 and about 9. In some other instances, the magnesium content in the Li-Mg-B alloy may be between approximately 5 wt% and approximately 15 wt%.

[0108] In some implementations, any one of the Li-Mg-B anodes previously described herein may further include a polymer coating including one or more of poly vinylidene fluoride (“PVDE”), pentaerythritol tetraacrylate (“PETEA”), or polyethylene glycol dimethacrylate (“PLGDMA”).

[0109] In some implementations, lithium-boron (“Li-B”) binary alloys may also be formed using the single-step exothermic melt process previously described herein with reference to f igure 1 A. In some instances, lithium may be melted at a process temperature, powdered boron may be added to the melt at the process temperature, and the melt including powdered boron may be soaked during a soak time at the process temperature. In someinstances, the process temperature may be between approximately 550 °C and approximately 750 °C. In some other instances, the process temperature may be approximately 700 °C. In some instances, the Li-B binary alloy may include one or more of a one or more of a LisBs alloy phase or a IJ5B4 alloy phase uniformly distributed as fibrous structures in the alloy. X-ray diffraction (“XRD”) patterns and microscopic analysis, for example scanning electron microscopy analysis of the Li-B alloys may be similar to the characteristics of Li-Mg-B alloys described below with reference to Example 1.

[0110] In some implementations, a lithium-sulfur battery may include an anode including a lithium-magnesium-boron (“Li-Mg-B”) alloy and a fluorinated ether electrolyte. In some instances, the Li-Mg-B alloy may include one or more of a Li2Bs alloy phase or a L15B4 alloy phase (also referred to herein as an intermetallic compound). In some instances, the L15B4 alloy phase may be uniformly distributed in the Li-Mg-B alloy. In some instances, the LisB4 alloy phase may be characterized by a fibrous structure in the Li-Mg-B alloy. In some examples, the amount of boron in the Li-Mg-B alloy may be between approximately 1 wt% and approximately 15 wt%.

[0111] In some implementations, a fluorinated ether electrolyte associated with a lithiumsulfur battery may include approximately 50:25:25 (vol%) 1,2-dimethoxyethane (“DME”): 1,3-dioxolane (“DOL”): bis (2,2,2-trifluoroethyl) ether (“BTFE”) and including approximately 0.4 M LiTFSI and approximately 2 wt% LiNO3.

[0112] In some implementations, the fluorinated ether electrolyte may include approximately 50:25:25 (vol%) DME : DOL: 1,1,2,2-tetraethoxyethane (“TEE”) and including approximately 0.4 M LiTFSI and approximately 2 wt% LiNO3.

[0113] In some implementations, the fluorinated ether electrolyte may include approximately 50:25:25 (vol%) DME : DOL: 1,1,2,2-tetrafluoroethyl 2,2,2-trifluoroethyl ether (“TFETFE”) and including approximately 0.4 M LiTFSI and approximately 2 wt% LiNO3.

[0114] In some implementations, the fluorinated ether electrolyte may include approximately 60:20:10:10 (vol%) DME : DOL: TEE: TFETFE and including approximately 0.4 M LiTFSI and approximately 2 wt% LiNO3.

[0115] In some implementations, the fluorinated ether electrolyte may include approximately 50:25:25 (vol%) DME : DOL: l,l,2,2-tetrafluoroethyl-2,2,3,3-tctrafluoropropyl ether (“TTE”) and including approximately 0.4M LiTFSI and approximately 2 wt% LiNO3.

[0116] In some implementations, the fluorinated ether electrolyte may include approximately 50:25:25 (vol%) 1 ,2-dimethoxyethane (“DME”): 1,3-dioxolane (“DOL”): bis (2,2,2-trifluoroethyl) ether (“BTFE”), and including between approximately 0.6 M and approximately 0.8M LiTFSI, between approximately 0.5M and approximately 0.7M LiNCh, and between approximately 0.15M and approximately 0.2M dicyandiamide (“DCDA”).

[0117] In some implementations, the fluorinated ether electrolyte may include approximately 50:25:25 (vol%) DME : DOL: 1 fluorinated 1,4-dimethoxylbutane (“FDMB”) including approximately 0.4 M LiTFSI and approximately 2 wt% I.iNO?.

[0118] In some implementations, the fluorinated ether electrolyte may include approximately 1.0 M LiTFSI in approximately 50:50 (vol%) DOL: BTFE.

[0119] In some implementations, any one of the anodes previously described herein may further include a polymer coating disposed on the anode. In some implementations, an example of a polymer coating may include one or more of poly vinylidene fluoride (“PVDF”), pentaerythritol tetraacrylate (“PETEA”), or polyethylene glycol dimethacrylate (“PEGDMA”).

[0120] Without being bound by any particular theory, additives including lithium nitrate (LiNCL) in a fluorinated ether electrolyte may dissociate to produce lithium cations (Li+). Alternately, additives including LiTFSI in the electrolyte may dissociate to produce lithium cations (Li+) and TFSI anions. Additives in the electrolyte that may dissociate to lithium ions may also include one or more of lithium lanthanum zirconium oxide (“LLZO”), oxinitrides (e.g., lithium phosphorus oxynitride or “LIPON”), NASICON-type conductors (e.g., lithium aluminum titanium phosphate) or lithium tin phosphorus sulfide (“LSPS”).

[0121] In some implementations, an anode including a lithium-magnesium-boron alloy and associated with a lithium-sulfur battery may be disposed as a freestanding anode. In a freestanding anode, the anode is not supported on a metal substrate. An example of an anode metal substrate may include a current collector made of copper.

[0122] In some implementations, a lithium- sulfur battery may include a cathode disposed opposite to the anode. As described below with reference to Figures 2A-2E, in some implementations, the cathode may include one or more porous carbon layers including porous carbon agglomerates of porous carbon primary nanoparticles. In some instances, a respective porous carbon primary nanoparticle may include an inner porous shell disposed about a center of the respective porous carbon primary nanoparticlc and enclosing an inner porous carbon region, an outer porous shell enclosing an outer porous carbon region disposedbetween the inner shell and the outer shell, and an interconnected porous network disposed in and in fluid communication with the inner and outer porous carbon regions.

[0123] In some implementations, the inner carbon region and the outer carbon region of the porous carbon primary nanoparticles may be characterized by an average pore size and an average pore density associated with each region. In some other aspects, the average pore size may decrease along a radial direction from the center to the outer porous shell.

[0124] In some other implementations, at least some of the porous carbon primary nanoparticle as described above may further include one or more intermediate porous shells disposed between the inner porous shell and the outer porous shell, wherein each of the intermediate porous shells encloses a respective intermediate porous carbon region.

[0125] In various implementations, the porous carbon agglomerates may be characterized by a Raman spectroscopy signature with an ID / IG ratio between approximately 0.95 and approximately 1.05. In some other aspects, the porous carbon agglomerates may be characterized by a Brunauer-Emmett-Teller (“BET”) surface area between approximately 50 m2 / g and 300 m2 / g measured using nitrogen gas. In some other aspects, the porous carbon agglomerates may be characterized by an electrical conductivity of between approximately 500 S / m and 20,000 S / m when compressed at a pressure of approximately 12,000 pounds per square inch (psi).

[0126] In some other implementations, an alloy associated with a lithium- sulfur battery anode may include a lithium-magnesium-boron (“Ei-Mg-B”) alloy and a carbon-based material including flaky graphene and nodular graphene (also referred to herein as “three- dimensional graphene carbons” or “3DG carbons”). In some instances, the Li-Mg-B alloy may include a lithium-boron (“Li-B”) alloy phase. In some other instances, the carbon-based material may further include titanium dioxide (TiCh) nanoparticles disposed on one or more surfaces of the carbon-based material or within the carbon-based material. In some examples, the carbon-based material may include graphitic carbon. Examples of 3DG carbons including flaky graphene and nodular graphene are described below with reference to Eigures 3D-31.

[0127] Without being bound by any particular theory, lithium- sulfur battery anodes including the Li-Mg-B alloys including 3DG carbons as described herein may harness the ionic conductivity of titanium dioxide ( I1O2) to improve lithium ion conductivity at the anode. In some instances, the mechanical stability of the anode may be enhanced by the three-dimensional (“3D”) freestanding Li-Mg-B alloy framework formed during cyclicoperation of lithium-sulfur batteries. Additionally, as described below with reference to Examples 1-3, a LisI phase present in the Li-Mg-B alloys as fibrous structures may improve uniform stripping and plating of lithium at the anode during cyclic operation of lithium-sulfur batteries. In some instances, the lithium-magnesium-boron alloys may also include one or more lithium-carbon alloy phases, which may increase both ionic and electronic conductivity at the lithium-sulfur battery anodes.

[0128] In some implementations, the amount of boron in the Li-Mg-B alloy may be between approximately 1 wt% and approximately 15 wt%. In some other examples, the amount of boron in the Li-Mg-B alloy may be approximately 10 wt%. In some instances, a weight ratio of lithium to magnesium in the Li-Mg-B alloy may be between approximately 8 and approximately 9. In some other instances, the amount of magnesium in the Li-Mg-B alloy may be between approximately 5 wt% and approximately 15 wt%. In some examples, the amount of the 3DG carbons in the Li-Mg-B alloy may be between approximately 5 wt% and approximately 20 wt%.

[0129] In some implementations, the flaky graphene associated with the 3DG carbons may include a plurality of graphene layers. Examples of flaky graphene are described below with reference to Figures 3A-3C. In some implementations, nodular graphene associated with the 3DG carbons may include a plurality of carbon nano-onions (“CNOs”). Examples of nodular graphene are described below with reference to Figures 2A-2E.

[0130] In some implementations, the 3DG carbons may include one or more oxygen containing functional groups disposed on one or more surfaces of the 3DG carbons or within the 3DG carbons. In some examples, the oxygen containing functional groups may include one or more of epoxide (C-O-C), hydroxyl (-OH), ether (C-O-C), ketone (O-C=O), or carboxylic acid (-COOH) groups.

[0131] In some implementations, a lithium-sulfur battery may include an anode including a lithium-magnesium-boron (“Li-Mg-B”) alloy and a fluorinated ether electrolyte. As previously described herein, the Li-Mg-B alloys may include a carbon-based material including flaky graphene and nodular graphene (“3DG carbons”) and one or more of a L12B alloy phase or a LisB4 alloy phase. In some other instances, the amount of boron in the Li-Mg-B alloy may be between approximately 1 wt% and approximately 15 wt%. In some instances, the 3DG carbons may further include titanium dioxide (TiCL) nanoparticles disposed on one or more surfaces of the 3DG carbons or within the 3DG carbons. Examples of fluorinated ether electrolytes were previously described herein.

[0132] In some implementations, a lithium-sulfur battery may further include a polymer coating disposed on the anode as an anode protective layer. In some examples, the polymer coating may include one or more of polyvinylidene fluoride (“PVDF”), pentaerythritol tetraacrylate (“PETEA”), or polyethylene glycol dimethacrylate (“PEGDMA”).

[0133] Figure IB shows a flow chart depicting an example operation 100B associated with forming a Li-Mg-B alloy anode including 3DG carbons, according to some implementations. In some implementations, operation 100B may begin at 101B with producing a lithium-magnesium (“Li-Mg”) alloy melt by melting a Li-Mg alloy at a process temperature. In some instances, the process temperature may be between approximately 550 °C and approximately 750 °C. In some other instances, the process temperature may be approximately 700 °C. In some examples, the lithium-magnesium alloy may include a 90 wt% lithium - 10 wt% magnesium alloy.

[0134] In some implementations, operation 100B may continue at 102B with adding a carbon-based material to the Ei-Mg melt. As described below with reference to Figures 3D-31, the carbon-based material may include flaky graphene and nodular graphene (referred io herein as “three-dimensional graphene carbons” or “3DG carbons”). Tn some examples, the carbon-based material may further include graphitic carbon. In some instances, the carbonbased material may be added to the Li-Mg melt at the process temperature. In some other instances, the carbon-based material may be added to the Li-Mg melt at a temperature that is different from the process temperature. In some examples, the carbon-based material may further include titanium dioxide (TiO2) nanoparticles disposed on one or more surfaces of the carbon-based material, or within the carbon-based material. In some other examples, at least some of the carbon-based material may be dispersed in the Li-Mg alloy. In some instances, at least some of the carbon-based material may form a lithium-carbon phase.

[0135] In some implementations, operation 100B may continue at 103B with producing a Li-Mg-B melt by adding powdered boron to the Li-Mg melt. In some instances, powdered boron may be added to the Li-Mg melt at the process temperature. In some other instances, powdered boron may be added to the Li-Mg melt at a temperature that is different from the process temperature. Those skilled in the art will appreciate that the carbon-based material or the powdered boron may be added to the Li-Mg melt in any sequence, or added simultaneously to the Li-Mg melt, and that such variations may exist without departing from the scope and spirit of the present implementations.

[0136] In some instances, operation 100B may continue at 104B with soaking the Li-Mg-B melt including the carbon-based material during a soak time. In some instances, soaking may be conducted at the process temperature. In some other instances, soaking may be conducted at a temperature that is different from the process temperature. In some examples, the soak time may be between approximately 2 minutes and approximately 30 minutes. In some other examples, the soak time may be approximately 5 minutes. Those skilled in the art will appreciate that other ranges associated with the soak time may exist without departing from the scope and spirit of the present implementations.

[0137] In some implementations, operation 100B may continue at 105B with cooling the Li-Mg-B alloy and confirming the presence of a LisB4 alloy phase or a LJ2B5 alloy phase by analyzing a sample of the Li-Mg-B alloy using X-ray diffraction (“XRD”) or one or more analytical tools. As described below with reference to Example 1, the LLB4 alloy phase associated with the Li-Mg-B alloys may be uniformly distributed as fibrous structures in the Li-Mg-B alloy.

[0138] At 106B, upon confirmation of desired crystallographic properties of the Li-Mg-B alloy, an anode associated with a lithium-sulfur battery may be fabricated using the Li-Mg-B alloy. In some instances, at 106B, the Li-Mg-B alloy may be rolled to form one or more Li-Mg-B layers or films. In some examples, the thickness of a rolled Li-Mg-B layer may be approximately 100 pm.

[0139] In some implementations, any one of the anodes previously described herein may further include a polymer coating disposed on the anode. In some implementations, the polymer coating may include one or more of poly vinylidene fluoride (“PVDF’), pcntacrythritol tctraacrylatc (“PETEA”), or polyethylene glycol dimcthacrylatc (“PEGDMA”). Without being bound by any particular theory, PVDF may react with lithium in the freestanding Li-Mg alloy anode to form LiF ions dispersed in a polymeric matrix. The protective layer may improve and / or may be associated with an improvement of lithium ion (Li+) transport from and to the anode during cycling. Reducing lithium-containing dendritic growth from the anode of a lithium-sulfur battery may increase the charge rate, the discharge rate, the energy density, the cycle life, or any combination thereof. The polymeric matrix may partially trap TFSI" anions produced by the dissociation of additives including LiTFSI in the electrolyte.

[0140] In some implementations, a lithium-sulfur battery may include a cathode disposed opposite to the anode. As described below with reference to Figures 2A-2E, in someimplementations, a cathode may include one or more porous carbon layers including porous carbon agglomerates of porous carbon primary nanoparticles. Figure 2A shows a schematic diagram 200A of a porous carbon primary nanoparticle 205, according to some implementations. In some examples, the porous primary carbon nanoparticle 505 may resemble carbon nano-onions (“CNOs”). As shown in the example of Figure 2A, the porous primary carbon nanoparticle 205 may include a core (inner) porous carbon region 211 defined by a first porosity and enclosed within an inner porous shell 213. The inner porous carbon region 211, which may also be referred to herein as the first porosity region, may include a plurality of first pores 201 dispersed therein. An outer porous carbon region 212, which may also be referred to herein as the second porosity region, may be disposed between the inner porous shell 213 and an outer porous shell 210 and may include a plurality of second pores 202 dispersed therein. The inner porous carbon region 211 and the outer porous carbon region 212 may be interconnected by one or more of the first pores 201 or one or more of the second pores 202, thereby interconnecting the first and second porosity regions. That is, the inner porous carbon region 211 may be configured to be in fluid communication with the outer porous carbon region 212 through an interconnected porous network. The inner porous carbon region 211 may be defined by a first pore density, and the outer porous carbon region 212 may be defined by a second pore density that is similar to, or different than, the first pore density.

[0141] In some implementations, porous primary carbon nanoparticle 205 may be characterized by an average size or principal dimension (diameter, length, width) of less than approximately 200 nm. In some implementations, an average pore size may gradually decrease along a radial direction from the center 216 of the nanoparticle 205 to the outer boundary 213 of the nanoparticle 205. In some implementations, porous primary carbon nanoparticle 205 may be characterized by a range of pore sizes and pore distributions in each region. The first pores 201 may be configured to retain polysulfides 220, and the second pores 202 may provide pathways or channels for the transport of lithium ions (not shown for simplicity) into and from the porous primary carbon nanoparticles 205 and for pre-loading sulfur 224 into the nanoparticles.

[0142] Figure 2B shows a transmission electron microscopy (“TEM”) micrograph 200B of aggregates 240 of porous primary nanoparticles 205, according to some implementations. Those skilled in the art will appreciate that the micrographs are shown by way of example only, and that other scales may exist without departing from the scope and spirit of thepresent implementations. The carbon aggregates 240 may include an interconnected porous network disposed between adjacent carbon nanoparticles 205. Aggregate 240 may include a plurality of porous carbon primary nanoparticles 205 and, in some instances, may resemble a “string-of-pearls.” In some implementations, the size or principal dimension of aggregate 240 may be between approximately 50 nm and approximately 500 nm.

[0143] Figure 2C shows a TEM image 200C of agglomerates 245 of porous primary carbon nanoparticles 205, according to some implementations. An agglomerate 245 of porous carbon primary nanoparticles 205 may be characterized by a Brunauer-Emmett-Teller (“BET”) surface area of between approximately 50 m2 / g and approximately 300 m2 / g measured using nitrogen gas. In some implementations, an agglomerate 545 may be spherical in shape. In some implementations, an agglomerate 245 may be of any shape, including one or more of spherical, spheroidal, dumbbell, cylindrical, elongated cylindrical type, rectangular prism, disk, wire, or irregular.

[0144] Figure 2D shows a TEM image 200D of surface etched agglomerates 242 of porous primary carbon nanoparticles, according to some implementations. The agglomerates 245 may be surface etched using methods that include CO2 etching to create pores on the external surface of the agglomerates 245 and to increase the surface area of the carbon agglomerates 245 to yield surface-etched agglomerates 242. After etching, the surface etched agglomerates 242 may include three-dimensional graphene carbons (“3DG carbons”) including graphene layers interconnected as three-dimensional (“3D”) graphene structures (not shown for simplicity). The surface etched agglomerates 242 of porous primary carbon nanoparticles may be characterized by a Raman spectroscopy signature with an 1D / IG ratio of between approximately 0.95 and approximately 1.05. In some instances, the surface etched agglomerates 242 may be assembled as rigid porous carbon agglomerates by processes including spray drying.

[0145] Figure 2E shows a schematic diagram 200E of another porous primary carbon nanoparticle 205, according to some implementations. The tri-zone porous primary nanoparticle 205 may include a first core (inner) carbon zone or region 251, nested within a second intermediate carbon zone or region 252, which in turn is nested within a third outer carbon zone or region 253. The first zone 251 may include pores 261 having an average size or principal dimension (diameter, length width) of less than approximately 40 nm, the second zone 252 may include pores 262 having an average size or principal dimension of less than approximately 35 nm, and the third zone 253 may include pores 263 having an average sizeor principal dimension of less than approximately 30 nm. In some implementations, pores 261 may be characterized as macropores, the pores 262 in the intermediate region 252 may be characterized as mesopores, and the pores 263 in the outer region 252 as micropores.

[0146] In some implementations, the principal dimension DI of first zone 251 may be less than approximately 100 nm, the principal dimension D2 may be less than approximately 150 nm, and the principal dimension D3 of third zone 253 may be approximately 200 nm. The relative dimensions, porosities, and electrical conductivities of the first zone 251, the second zone 252, and the third zone 253 may be tuned to achieve a desired balance between minimizing the polysulfide shuttle effect and maximizing the specific capacity of a host battery. The first zone (inner core zone) 251 may have a density of carbons of less than approximately 1 g / cc. The third zone (outer zone) 253 bounded by the perimeter or outer shell 255 of particle 205 may have a density of carbons of approximately less than between 1 g / cc and 3.5 g / cc. The second zone (intermediate zone) 252 may have a density of carbons of between approximately 0.5 g / cc and 3 g / cc. Each of the zones 251, 252, and 253 may be characterized by an average pore size and an average pore density associated with each region. The average pore size associated with each of zones 251-253 may decrease along a radial direction from the center of the porous primary carbon nanoparticlc 205 to the outer porous shell 255.

[0147] In some implementations, agglomerates of porous primary carbon nanoparticles 505 may be surface etched using methods that include CO2 etching to create pores on the external surface of the agglomerates and to increase the surface area of the carbon agglomerates. In some implementations, the agglomerates porous primary carbon nanoparticles may be produced by thermal cracking of hydrocarbon feedstock as disclosed in commonly owned U.S. Pat. No. 9,862,602, U.S. Pat. No. 10,112,837, U.S. Pat. No.11,053,121, and / or U.S. Pat. Pub. No. 2021 / 0292170, all of which are incorporated by reference herein in each of their entireties.

[0148] The porous carbon agglomerates as described above may be used to produce carbon-sulfur composites (“CSC”) by sulfurizing the carbon agglomerates. The sulfur to carbon weight ratio may be between approximately 1:5 and 10:1. The sulfur to carbon weight ratio may be approximately 3. A slurry including the carbon-sulfur composites and one or more polymeric binders may be cast as one or more layers or films of carbon material on a suitable substrate to form the cathode in a lithium-sulfur battery. The cathode substrate may include a cathode current collector. The cathode current collector may includealuminum. The carbon agglomerates may resist deformation under high shear mixing and therefore produce films or layers of carbon of desired porosity, thickness, and packing density. In some implementations, the cathode may be characterized by a packing density of carbon material on the substrate (including sulfur, binder, and other constituents) of at least approximately 7 mg / cm2, which in turn increases the sulfur loading at the cathode and may reduce the N / P ratio in a lithium-sulfur battery.

[0149] In some implementations, the porous carbon agglomerates may resist deformation under high shear mixing and therefore produce films or layers of carbon of desired porosity, thickness, and packing density. In some implementations, the porous carbon agglomerates may resist deformation at shear rates of at least 500 s'1during mixing of a slurry including the porous carbon agglomerates in a high shear mixer. The slurry may be disposed as one or more porous carbon layers on the cathode substrate (also referred to herein as the cathode current collector).

[0150] In some implementations, as described below with reference to Figures 3A-3C, one or more of the cathode associated with a lithium- sulfur battery or the carbon-based material associated with the anode may include flaky graphene including one or more interconnected bundles of electrically conductive graphene layers. In some examples, the graphene layers may be arranged as one or more stacks connected to each other and defining a three-dimensional (“3D”) porous scaffold structure including mesopores. In some other examples, the one or more stacks may be disposed substantially orthogonal to each other. In some instances, the graphene layers may be characterized by a linear dimension of between approximately 50 nm and 200 nm. In some other instances, the graphene layers may include one or more of single layer graphene (“SLG”), few layer graphene (“FLG”), or many layer graphene (“MLG”).

[0151] Figure 3A shows a schematic diagram of a mesoporous carbon nanoparticle 300A having an interconnected bundle of electrically conductive graphene layers arranged to form a 3D open porous scaffold structure, according to some implementations. Nanoparticle 300A and porous carbon agglomerates including nanoparticles 300A may be produced using a high throughput, low-cost, cracking of a hydrocarbon gas such as natural gas, in an atmospheric microwave plasma reactor. An example of a microwave plasma reactor is disclosed in commonly owned U.S. Pat. No. 9,767,992, which is incorporated by reference herein in its entirety. For example, the porous carbon agglomerates may be formed in-flight and grownby adding additional carbon-based materials derived from incoming carbon-containing gas within a microwave-plasma reaction chamber.

[0152] The carbon nanoparticles 300A may include three-dimensional (“3D”) multimodal mesoporous carbon nanoparticles. A mesoporous material, as generally understood and as referred to herein, includes a material containing pores with diameters between 2 nm and 50 nm, according to International Union of Pure and Applied Chemistry (“IUPAC”) nomenclature. For the purposes of comparison, IUPAC defines microporous material as a material having pores smaller than 2 nm in diameter and defines macroporous material as a material having pores larger than 50 nm in diameter. In some instances, mesoporous carbon particle 300A may be characterized by a three-dimensional (“3D”) hierarchical porous structure including pores 380. In some examples, at least a portion of the hierarchical porous structure may further define a 3D open porous scaffold structure 381.

[0153] In some implementations, the nanoparticle 300A may include one or more interconnected bundles 382 of electrically conductive graphene layers or sheets. Each interconnected bundle 382 may include one or more stacks 383 of graphene layers. Each stack 383 may include a plurality of graphene layers 386 that are generally stacked horizontally as more clearly shown in stack 384. One or more stacks 383 of graphene layers 386 may be arranged to form a 3D porous scaffold structure 381 including mesopores. That is, a plurality of stacks 383 of electrically conductive graphene layers 386 may be sintered together to define the 3D open porous scaffold structure 381 (which includes mesopores 380 in the example of Figure 3A). In some implementations, one or more of the stacks 383 may be connected substantially orthogonal to each other. The open porous scaffold structure 381 may be configured to provide electrical conduction between contact points (not shown for simplicity) of the stacks of graphene layers 386. In some implementations, each graphene layer 386 may be characterized by a diameter or linear dimension (“La”) of between approximately 50 nm to approximately 200 nm. In some implementations, the graphene stack 383 may include few layer graphene (“FLG”), which may be composed of 5 to 15 layers of graphene.

[0154] A plurality of porous carbon primary nanoparticles 300A may be coalesced or joined to form porous carbon agglomerates of porous carbon primary nanoparticles. In this disclosure, three-dimensional graphene carbons (“3DG carbons”) may include mixed morphology carbons including both flaky graphene and nodular graphene, as described herein with respect to Figures 3A-3I. In some instances, the 3DG carbons may also include graphitic carbon. In some implementations, the 3DG carbons described herein may becharacterized by a Bmnauer-Emmett-Teller (“BET”) surface area measured using nitrogen gas of approximately 50 to 300 m2 / g. In some implementations, the 3DG carbons may be characterized by a graphene to amorphous carbon ratio of between approximately 1 % and 95%. In some implementations, the 3DG carbons may be characterized by a carbon purity of at least 99.9%. The 3DG carbons may be characterized by an electrical conductivity of between approximately 500 S / m and approximately 20,000 S / m when compressed at pressure of approximately 12,000 pounds per square inch (“psi”). The open porous scaffold structure 381 , while confining sulfur, may also provide a host scaffold-type structure to manage volume expansion due to the formation of long chain polysulfides.

[0155] In some implementations, sulfur may be confined in the pores 380 of open porous scaffold structure 381. In some implementations, sulfur may also be confined in the scaffold structure spaces 385 formed by orthogonally joined stacks 383 of graphene layers 384.

[0156] In some implementations, the porous carbon primary nanoparticles 300A may include a plurality of interconnected crinkled 3D graphene sheets, a plurality of non-hollow carbon spherical particles (“NHCS”), flat graphene, wrinkled graphene, or a plurality of carbon nano-onions (“CNOs”). In some implementations, the porous carbon primary nanoparticles 300A may include wavy or flexible graphene layers that resemble crinkled paper and may be produced using microwave processes. The graphene layers may be flexible as they may be fused with each other at sp3type defects in a sp2graphene lattice structure.

[0157] Figure 3B shows a SEM micrograph 300B of porous carbon agglomerates 302, according to other implementations. In some instances, plasma-based processing conditions applied or performed in a reactor such as a microwave reactor may be adjusted with a high degree of tunability to achieve of porous carbon agglomerates and graphene-on-graphene densification to yield the complex 3D carbons 302. The porous carbon agglomerates 302 may be surface etched using methods such as CO2 etching to create pores on the external surface of the aggregates and to increase the surface area of the aggregates.

[0158] Figure 3C shows a TEM micrograph 300C of porous carbon agglomerates, according to some implementations. As shown, the 3D few-layer graphene (“FLG”) structure 304 may be considered to be a porous carbon aggregate at a 50 nm scale. Those skilled in the art will appreciate that the micrographs are shown by way of example only, and that other scales may exist without departing from the scope and spirit of the present implementations.

[0159] In some implementations, the three-dimensional graphene carbons (“3DG carbons”) associated with the lithium-sulfur battery anodes or lithium- sulfur battery cathodesmay include agglomerates including both flaky graphene and nodular graphene. In some instances, 3DG carbons may be referred to as a “mixed morphology carbons.” Nodular graphene may include carbon nano-onions (“CNOs”). In some instances, the 3DG carbons may include graphitic carbons. Examples of nodular graphene were previously described herein with respect to Figures 2A-2E. Without being bound by any particular theory, flaky graphene may be characterized by sp2hybridized carbon atoms and are prone to stack via 71 -7i bond interactions. Examples of flaky graphene were previously described herein with respect to Figure 3A. Stacked or localized graphene flakes may hinder uniform dispersion of the 3DG carbons in a cathode slurry, or an anode slurry, associated with the production of a lithium-sulfur battery cathode, or a lithium- sulfur battery anode, respectively. Additionally, nodular graphene is generally spherical, or substantially spherical in shape, and may be characterized by a lower surface area-to-volume ratio than flaky graphene.

[0160] In contrast, 3DG carbons including both flaky graphene and nodular graphene may inhibit stacking and localization of flaky graphene, as flaky graphene may be interleaved with nodular graphene resulting in well dispersed graphene in a cathode slurry or in the carbon-based material associated with Li-Mg alloy anode. 3DG carbons including flaky graphene and nodular graphene may also increase mechanical strength and thermal conductivity of the anode or cathode associated with lithium- sulfur batteries and may reduce residual stresses at the anode or cathode. As previously described herein, the 3DG carbons may include graphitic carbon.

[0161] In some implementations, flaky graphene associated with 3DG carbons may be covalently linked or welded or fused to nodular graphene by one or more of microwave radiation, direct current discharge, low temperature non-equilibrium plasma, thermal equilibrium plasma, plasma generated at an intermediate temperature below thermal equilibrium temperature during chemical processing of one or more hydrocarbon feedstock to produce 3DG carbons, or during post-processing of 3DG carbons.

[0162] Figures 3D-3E show scanning electron microscopy (“SEM”) micrographs 300D- 300E of 3DG carbons including flaky graphene and nodular graphene, according to some implementations. Those skilled in the art will appreciate that the micrographs included in this disclosure are shown by way of example only, and that other scales may exist without departing from the scope and spirit of the present implementations. As can be seen, the 3DG carbons 306 includes a plurality of flaky graphene 302E, nodular graphene 303E, andmesopores 307. Flaky graphene 302E may include one or more graphene layers as previously described herein with reference to Figures 3A.

[0163] Figures 3F-3I show transmission electron microscopy (“TEM”) micrographs 300F-300I of 3DG carbons including flaky graphene and nodular graphene, according to some implementations. In some implementations, at least some of the flaky graphene 302F may be characterized by a linear dimension of between approximately 50 nm and 200 nm. Referring to Figures 3G-3H, in some instances, flaky graphene 302D may include wavy or wrinkled graphene 308. Referring to Figure 3H, in some other instances, at least some of the wavy and / or wrinkled flaky graphene may be joined together to define one or more ridges and valleys 309. At least some of the ridges and valleys 309 may produce areas of increased flexibility within the wavy and / or wrinkled graphene 308. In some implementations, flaky graphene 302D may include wavy or flexible graphene layers that resemble crinkled paper. The graphene layers may be flexible as they may be fused with each other at sp3type defects in a sp2graphene lattice structure. In some instances, as shown in Figure 31, nodular graphene 3031 may be disposed as porous carbon agglomerates 310, which may be arranged as a “string of pearls.”

[0164] In some implementations, a Brunauer-Emmett-Teller (“BET”) surface area measured using nitrogen gas of 3DG carbons including flaky graphene and nodular graphene may be between approximately 50 m2 / g and approximately 300 m2 / g.

[0165] In some implementations, 3DG carbons including flaky graphene and nodular graphene may be characterized by a Raman spectroscopy signature having an ID / IG ratio between approximately 0.35 and approximately 0.56. In some instances, the 3DG carbons may be characterized by a Raman spectroscopy signature having an D / IG ratio between approximately 0.53 and approximately 0.7. An FD / IG ratio less than 2 suggests that flaky graphene associated with the carbon filler includes several layers of graphene.

[0166] In some other instances, 3DG carbons may be characterized by a Raman spectroscopy signature having an ID / IG ratio between approximately 0.35 and approximately 0.56 and an FD IG ratio between approximately 0.53 and approximately 0.7.

[0167] In some implementations, flaky graphene in 3DG carbons may include a plurality of graphene layers. In some instances, the number of graphene layers in the plurality of graphene layers may be between 5 and 15. In some other instances, the plurality of graphene layers may include one or more of few layer graphene (“FLG”) or many layer graphene (“MLG”).

[0168] Any one of the lithium- sulfur battery cathode or anode implementations previously described herein may be configured or disposed for use in cylindrical batteries, prismatic batteries, pouch cells, or any other suitable geometrical shape. A lithium-sulfur cylindrical battery may comport with the dimensions of an 18650 battery (approximately 18 mm diameter x approximately 65 mm length), a 21700 (approximately 21 mm diameter x approximately 70 mm length) battery or a 4680 (approximately 46 mm diameter x approximately 80 mm length) battery. In some implementations, a lithium- sulfur battery may have a prismatic form factor that can comport with the dimensions of a CP3553 battery. For example, a lithium-sulfur battery may have a height between approximately 56 mm and approximately 58 mm, a length between approximately 34 mm and approximately 36 mm, and a width between approximately 6 mm and approximately 8 mm.

[0169] Figure 4 shows a schematic diagram 400 depicting a cylindrical battery 400, according to some implementations. Battery 400 may include a shell 410 and a jelly roll 420. Shell 410 may have a longitude axis indicated as AA’ in Figure 4, and jelly roll 420 may be disposed along the longitudinal axis AA’ within shell 410. Jelly roll 420 may have a cross section in a circle, a rectangle, a square, a triangle, or any other geometric shapes. Jelly roll 420 may include an anode 422, a first barrier layer (or separator layer) 424, a cathode 426, and a second barrier layer 428, each in the form of a rollable sheet. Anode 422, first barrier layer 424, cathode 426, and the second barrier layer 428 may be laminated on top of one another. As such, anode 422 and cathode 426 may be separated by the first and the second barrier layers to avoid undesirable short circuiting within battery 400. In some other implementations, a center pin or mandrel (not shown in Figure 4 for simplicity) may be attached to an inner edge of anode 422, and the lamination of cathode-first barrier layeranode-second barrier layer may be radially wound or rolled around the center pin to form the jelly roll 420. Anode current collector 402 (in the event the anode is not a free-standing anode) and cathode current collectors 404 may be integrated into the anode and cathode layers, respectively.

[0170] In some implementations, anode 422, the first barrier layer 424, cathode 426, and second barrier layer 428 may share the same dimensions, and the sheets may be aligned with one another during the rolling process so that there are no sheets protruding from the jelly roll 420. Either anode 422 or cathode 426 current collectors may include a current collector tab, which may protrude out after the sheets are wounded into the jelly roll 420. Tab 423 may connect the anode 422 or the cathode 426 to a negative or positive terminal (not shown inFigure 4 for simplicity), respectively, via any suitable process including a mechanical welding process. In some implementations, tab 423 may be the cathode current collector tab. The anode current collector (not shown for simplicity) may be disposed at the outer edge of the jelly roll 420, and the cathode current collector tab 423 may be disposed approximately in the center of the jelly roll 420.

[0171] In some implementations, either electrode (e.g., the anode 422 or the cathode 426) may be arranged in a misalignment with the other electrode and the first and the second barrier layers 424 and 428 during the rolling process so that a portion 425 may protrude out of the jelly roll 420. In some examples, an electron conductive glue (not shown in Figure 4 for simplicity) may be disposed within shell 410 at the top and bottom of shell 410. The protruding portion 425 may be connected to the negative or positive terminal of shell 410 via electron conductive glue and thereby eliminates the need for a mechanical welding process. In some implementations, anode 422, anode current collector (not shown), first barrier layer 424, cathode 426, cathode cunent collector 404 and the second barrier layer 428 may be laminated on top of one another. A center pin or mandrel (not shown in Figure 4 for simplicity) may be configured as the cathode terminal and may be attached to the cathode current collector 404. When disposed as a jelly roll, the anode current collector may be disposed at the outer edge of the jelly roll 420, and the cathode current collector 404 may be disposed approximately in the center of the jelly roll 420.

[0172] In various implementations, anode 422 may be any suitable material that is typically used as an anode in a lithium-sulfur battery. For example, anode 422 may be a lithium foil or a lithium substrate. In some instances, anode 422 may include a current collector to support the lithium foil or the lithium substrate. In some examples, the anode 422 may include any one of the free-standing lithium-magnesium alloy anodes described herein.

[0173] In some implementations, cathode 426 may include one or more layers of films or CSC including any of the previously described rigid porous carbon agglomerates including metal nanoparticles. Cathode 426 may be disposed on the current cathode collector 404. The cathode films may coat both sides of a current collector, such as an aluminum foil, to provide the maximum cathode capacity. The cathode CSC including any of the previously described rigid porous carbon agglomerates having metal nanoparticles may include multiple pores to micro-confine sulfur as the cathode electroactive material. The electroactive material (sulfur) may constitute between approximately 60 wt% and approximately 90 wt% of the cathodefilms. The electroactive material of the cathode 426 may include other suitable sulfur-containing materials, such as lithium sulfide.

[0174] In some implementations, battery 400 may have electrolyte (not shown in Figure 4 for simplicity) incorporated into the jelly roll 420. In some implementations, battery 400 may have a liquid electrolyte that may be added to shell 410 after jelly roll 420 is disposed in shell or casing 410. In some other implementations, battery 400 may include a non-aqueous electrolyte such as solid-state electrolyte, gel electrolyte, or polymer film electrolyte incorporated into jelly roll 420. For example, between the first and the second barrier layers 424 and 428, one barrier layer may function as a separator, and the other one may function as a non-aqueous electrolyte film. In some other implementations, each of the first and second barrier layers 424 and 428 may function as both a separator and a non-aqueous electrolyte film. The electrolyte may include any one of the electrolyte compositions previously described herein.

[0175] In some implementations, a microporous monolayer polypropylene membrane may be used as a separator disposed between the anode 422 and the cathode 426. The porosity of a separator (e.g., CelgardR2500) may be approximately 55%. The separator may have a similar ionic conductivity as the electrolyte but may serve to reduce lithium dendrite formation. The separator may be formed from a ceramic containing material that does not chemically react with metallic lithium. As a result, the separator with ceramic containing material may be used to control lithium-ion transport through the pores dispersed across the separator, while concurrently preventing a short-circuit by impeding the flow or passage of electrons through the electrolyte. The separator layer may include a mechanical strength enhancer coated and / or deposited on the anode. The mechanical strength enhancer may provide structural support for the battery, may prevent lithium dendrite formation from the anode, and / or may prevent protrusion of lithium dendrite throughout the battery. In some exemplary implementations, ceramic particles may be impregnated in the microporous monolayer polypropylene membrane. In some exemplary implementations, the separator may include a ceramic coated separator.

[0176] In a cylindrical lithium-ion battery, the dense packing of the various layers in the jelly roll 420 and volume changes during discharge-charge cycling may cause mechanical stress and ageing of the battery 400. As previously described, volume changes may result from non-uniform lithium plating and dendrite formation at the anode, polysulfide “shuttle effect’’ and growth of solid electrolyte interfaces. Dendrites may even cause fires due tolocalized heating. Also, pit formation on the anode 422 leads to non-homogenous transport of Li ions from the anode 422 to the cathode 426 and also to fracture of the protective coating / layers disposed on the anode. Similarly, during the charging cycle, lithium dendrites may be formed on the metal anodes due to non-homogenous transport and deposition of lithium ions from the cathode to the anode. Pitting and / or dendrite formation leads to uneven stress and volumetric expansion of the jelly roll 420, which over time causes the layers of the jelly roll 420 to lose intimate contact with one another to exacerbate these issues and lead to accelerated degradation / capacity fade. Cathodes may include any one of the previously described CSC materials including any of the previously described porous carbon agglomerates. Freestanding anodes may include any one of the alloy compositions described herein. Any one of the previously described electrolyte compositions may mitigate the polysulfide shuttle effect and the effect of mechanical stresses and increase the cycle life of lithium-sulfur batteries.

[0177] In some other implementations, a carbon-based material associated with lithiummagnesium alloy anodes may include flaky graphene, nodular graphene, and graphitic carbon. Figure 5 shows a TEM micrograph 500 of a carbon-based material 500A including flaky graphene, nodular graphene, and graphitic carbon, according to some implementations. As shown in Figure 5, carbon-based material 500A may include flaky graphene 501, nodular graphene 502, and graphitic carbon 503. In some implementations, flaky graphene may be characterized by multiple layers of graphene disposed as a stack of layers. In some other examples, the lateral size (also referred to herein as length) of flaky graphene may be between approximately 10 nm and approximately 100 nm. In some examples, the lateral size of flaky graphene may exceed 100 nm. In some instances, flaky graphene 501 may include a stack of less than ten graphene layers. In some other instances, flaky graphene 501 may include a stack of more than ten graphene layers. In some examples, flaky graphene 501 may be characterized by “irregular-shaped” graphene layers 504. In some other examples, the “irregular-shaped” graphene layers 904 associated with flaky graphene 501 may be folded or bent. Additional details related to flaky graphene were previously described herein with reference to Figures 3A-3C.

[0178] In some implementations, nodular graphene 502 may include a plurality of carbon nano-onions 505 disposed as a “string of pearls.” In some examples, carbon nano-onions 505 may include multiple graphene layers, which may be characterized by defects (also referred to herein as disorder). Defects may include deviations from the hexagonal lattice of carbonatoms associated with single layer graphene. As described below with reference to Figures 6A-6B, defects or disorder in carbon nanostructures including nodular graphene may be caused by one or more of vacancies, grain boundaries, or wrinkles that deviate from the ideal honeycomb lattice of single layer graphene. Additional details related to nodular graphene were previously described herein with reference to Figures 2A-2E.

[0179] In some implementations, graphitic carbon 503 may include curved graphene layers 506. In some examples, curved graphene layers 506 may enclose a volume defined by a core region 507 encapsulated by shell region 508. In some other examples, the core region 507 may include a plurality of graphene layers. In some other examples, shell region 508 may include a plurality of graphene layers. In some instances, the core region 507 may be characterized by a core region porosity. In some other instances, the shell region 508 may be characterized by a shell region porosity. In some instances, the shell region porosity may be greater than the core region porosity.

[0180] In implementations, at least some of the flaky graphene, the nodular graphene, or the graphitic carbon in the carbon-based materials described herein, may include one or more surface functional groups including oxygen. In some instances, the surface functional groups may include one or more of epoxide (C-O-C), hydroxyl (-OH), ether (C-O-C), ketone (O-C=O), or carboxylic acid (-COOH) groups.

[0181] Figures 6A-6B show electron energy loss spectroscopy (“EELS”) spectra 600A-600B of a carbon-based material including flaky graphene, nodular graphene, and graphitic carbon, according to some implementations. In some examples, at least some of the flaky graphene, the nodular graphene, or the graphitic carbon in the carbon-based material may include one or more surface functional groups including oxygen. In some instances, surface functional groups including oxygen may be generated by ozone etching of the carbon-based material. The EELS spectra 600A-600B correspond to the K-shell ionization edge of carbon (also referred to herein as the “core loss edge” or “C-K edge”). The EELS spectra associated with Figure 6A is representative of the core (or central) region of flaky graphene, nodular graphene, and graphitic carbon in the carbon-based material. The EELS spectra associated with Figure 6B is representative of the edge (or peripheral) region of flaky graphene, nodular graphene, and graphitic carbon in the carbon-based material.

[0182] Referring to Figures 6A-6B, the distinct peak at approximately 285 eV corresponds to sp2hybridization and represents 7i* bonding. Additionally, the distinct peak at approximately 293 eV corresponds to sp3hybridization and represents o* bonding. As such,the carbon-based material includes carbon nanostructure or nanoparticles characterized by “mixed bonding,’’ and as such, may be considered as “mixed morphology’’ carbons.

[0183] As shown in Figures 6A-6B, the clear and sharp 71* peaks associated with both graphitic carbon and nodular graphene suggest significant sp2characteristics at both the edge and core regions of these nanoparticles in the carbon-based material. At the core region (Figure 6A), the intensity of the 71* peak of nodular graphene is greater than the intensity of the 71* peak of flaky graphene. Additionally, the intensity of the 71* peak of flaky graphene is greater than the intensity of the n* peak of graphitic carbon. At the edge region (Figure 6B), the intensity of the 71* peak associated with graphitic carbon is substantially similar to the intensity of the n* peak associated with flaky graphene. Additionally, the intensity of the 71* peak associated with nodular graphene is less than the respective intensity of the 71* peak associated with each of graphitic carbon and flaky graphene. These observations associated with the EELS spectra suggest a change in sp2characteristics associated with the transition from the core region to the edge region of the flaky graphene, nodular graphene, and graphitic carbon nanoparticles in the carbon-based material.

[0184] On the other hand, the o* peaks associated with both the core region and edge region of the flaky graphene, nodular graphene, and graphitic carbon nanoparticles are not as well defined as their respective 71* peaks, which suggests the presence of disordered C-C bonds in the carbon nanostructure of flaky graphene, nodular graphene, and graphitic carbon. The o* peak associated with nodular graphene appears to be “smeared out,” with a broad hump and indicates that nodular graphene is characterized by a relatively higher degree of disorder in the carbon nanostructure or high defect concentration. In some examples, nodular graphene may be considered as relatively more amorphous than flaky graphene or graphitic carbon.

[0185] In some implementations, based on the o* peaks associated with the EELS spectra of the carbon-based material including flaky graphene, nodular graphene and graphitic carbon, the degree of disorder associated with the carbon nanostructure in nodular graphene may be greater than the degree of disorder associated with the carbon nanostructure in flaky graphene. Additionally, the degree of disorder associated with the carbon nanostructure in flaky graphene may be greater than the degree of disorder associated with the carbon nanostructure in graphitic carbon. The degree of disorder associated with carbon nanostructures or nanoparticles may also be referred to as a “defect concentration” associated with a respective carbon nanostructure in the carbon-based material. Defects or disorder inthe carbon nanostructures may be caused by one or more of vacancies, grain boundaries, or wrinkles that deviate from the ideal honeycomb lattice nanostructure of single layer graphene. A higher defect concentration indicates greater disorder.

[0186] In some implementations, the degree of disorder associated with nodular graphene in the carbon-based material may be greater than the degree of disorder associated with the flaky graphene. The degree of disorder associated with nodular graphene and flaky graphene corresponds to a defect concentration associated with nodular graphene and flaky graphene, respectively, relative to the honeycomb lattice structure of single layer graphene. In some examples, the degree of disorder associated with flaky graphene may be greater than the degree of disorder associated with graphitic carbon. The degree of disorder associated with flaky graphene and graphitic carbon corresponds to a defect concentration associated with flaky graphene and graphitic carbon, respectively, relative to the honeycomb lattice nanostructure of single layer graphene.

[0187] In some implementations, a lithium-magnesium-boron (“Li-Mg-B”) alloy including a carbon-based material may be formed by adding a carbon-based material doped with boron to a Li-Mg alloy melt. The carbon-based material may include flaky graphene, nodular graphene, and graphitic carbon as previously described herein with references to Figure 5 and Figures 6A-6B.

[0188] Figure 7 shows a flow chart depicting an example operation 700 associated with forming a Li-Mg alloy including a doped carbon-based material, according to some implementations. In some implementations, operation 700 may begin at 701 with forming a Li-Mg alloy melt by melting a Li-Mg alloy at a process temperature. In some examples, the Li-Mg alloy may include a 90 wt% lithium - 10 wt% magnesium alloy. In some instances, the process temperature may be between approximately 550 °C and approximately 750 °C. At 702, operation 700 may continue with forming a Li-Mg-X alloy by adding a doped carbon-based material including a dopant element “X” to the Li-Mg alloy melt while mixing. In some examples, adding the doped carbon-based material may be performed at approximately the process temperature. In some other examples, the dopant element “X” may include one or more of a Group IIIA element associated with the periodic table of elements or a Group VA element associated with the periodic table of elements. In some implementations, the dopant “X” includes boron.

[0189] In some implementations, operation 700 may continue at 703 with soaking the Li-Mg melt including the doped carbon-based material at a soaking temperature to form the Li-Mg-X alloy. In some examples, the soaking temperature may be approximately equal to the process temperature. In some instances, a soaking time associated with soaking at 703 may be between approximately 2 minutes and approximately 30 minutes. In some other examples, operation 700 may further include forming, at 705, an ingot by cooling the Li-Mg-X alloy. In some examples, the ingots may be rolled into Li-Mg-X alloy films or foils.

[0190] In some implementations, a lithium-magnesium-boron (“Li-Mg-B”) alloy produced using the method described with reference to Figure 7 may include one or more of a IJ2B5 alloy phase or a U5B4 alloy phase. In some examples, the amount of magnesium in the Li-Mg-B alloy may be between approximately 5 wt% and approximately 20 wt%. In some other examples, the amount of carbon-based material in the Li-Mg-B alloy may be between approximately 1 wt% and approximately 5 wt%. In some instances, the amount of the boron-doped carbon-based material may be approximately 3 wt% of the weight of the Li-Mg alloy melt. In some other instances, the amount of boron in the boron-doped carbon-based material may be approximately 14 wt% of the weight of the boron-doped carbon-based material.

[0191] Figure 8A shows a scanning electron microscopy (“SEM”) micrograph 800A of doped carbon-based material, according to some implementations. Figures 8B-8C show SEM-energy dispersive X-ray spectroscopy (“EDS”) elemental dispersion images 800B-800C of a doped carbon-based material, according to some implementations. Boron was used as the lithiophilic dopant in the carbon-based material. The carbon-based material was previously described herein with reference to Figures 5 and Figures 6A-6B. The elements examined during EDS analysis included carbon, shown in EDS image 500B (K line), and boron, shown in elemental dispersion image 800C (K line). Referring to micrographs 800 A-800C, a substantially uniform coverage of the carbon surfaces associated with the doped porous carbon agglomerates by boron may be observed. Those skilled in the art will appreciate that the micrographs included in this disclosure are shown by way of example only, and that other scales may exist without departing from the scope and spirit of the present implementations.

[0192] Figure 8D shows a TEM micrograph 800D of doped carbon-based material, according to some implementations. Referring to micrograph 800D, carbon matrix 801 may include discrete particles of boron dopants 802. The boron dopant 802 may be present as boron, or as one or more boron oxides. Figure 8E shows an X-ray photoelectron spectroscopy (XPS) micrograph 800E of doped porous carbon agglomerates including graphene, according to some implementations. As can be seen, boron Is peaks 803 atbinding energies of approximately 182 eV, 185 eV, and 192 eV support the presence of one or more boron oxides in the porous carbon agglomerates. As boron is easily oxidized, XPS spectra often indicate the presence of B2O3 and other oxides, which may be represent by the generic form BxOy. The binding energy of B2C S approximately 193 eV.

[0193] Figure 8F shows an X-ray diffraction (XRD) pattern 800F of a Li-Mg-B alloy, according to some implementations. The Li-Mg alloy was formed using the method previously described herein with reference to Figure 7. XRD analysis was performed using Cu K„ radiation. As can be seen, XRD pattern 800F includes the crystallographic planes corresponding to the body-centered cubic (“BCC") crystalline structure of lithium-metal but also includes a peak corresponding to an intermetallic Li2Bs phase.

[0194] In some implementations, the amount of the doped carbon-based material added to the lilhium-magnesium alloy melt may be between approximately 5 wt% and approximately 15 wt% of the combined weight of the Li-Mg alloy melt and the weight of the doped porous carbon agglomerates. In some instances, the amount of the doped carbon-based material may be approximately 5 wt% of the combined weight of the Li-Mg alloy melt and the weight of the doped carbon-based material.

[0195] Figures 9A-9B show SEM micrographs 900A-900B of a boron-doped carbonbased material, according to some implementations. The layered morphology 901A suggests that the carbon-based material is graphitic. The graphitic carbon-based material may be characterized by a Brunauer-Emmett-Teller (“BET”) surface area of approximately 215 m2 / g measured using nitrogen gas.

[0196] Figures 9C-9E show SEM-energy dispersive X-ray spectroscopy (EDS) elemental dispersion images 900C-900E of a boron-doped carbon-based material, according to some implementations. The boron-doped carbon-based material was previously described with reference to Figures 9A-9B. The elements examined during EDS analysis included carbon, shown in EDS image 900C (K line), boron, shown in elemental dispersion image 900D (K line), and oxygen shown in EDS image 900E (K line). Referring to micrographs 900C-900E, a substantially uniform coverage by boron of the carbon surfaces associated with the boron-doped carbon-based material was observed. Those skilled in the art will appreciate that the micrographs are shown by way of example only, and that other scales may exist without departing from the scope and spirit of the present implementations.

[0197] Any one of the freestanding anode implementations previously described herein may also be used in other lithium-ion battery chemistries including, but not limited to, nickel-manganese-cobalt (“NMC”) batteries, lithium iron phosphate (“LFP”) batteries, or nickel cobalt aluminum oxide (“NCA”) batteries.EXAMPLES

[0198] In the examples described below, the electrolyte used in the lithium-sulfur battery implementations include approximately 50:25:25 (vol%) DME: DOL: BTFE and including approximately 0.4 M LiTFSI and approximately 2 wt% LiNCh.EXAMPLE 1. Formation and characterization of Li-Mg-B alloys.

[0199] As previously described herein with reference to Figures 1A, a lithium-magnesium-boron (“Li-Mg-B”) alloy may be formed by a single-step exothermic melt process including melting a Li-Mg alloy at a process temperature, adding powdered boron to the melt at the process temperature, and soaking during a soak time at the process temperature. A 90 wt% Li - 10 wt% Mg alloy was melted at approximately 700 °C (referred to herein as the process temperature). Powdered boron was added to the melt at approximately 700 °C in an amount corresponding to a boron concentration of 10 wt% in a Li-Mg-B alloy. The melt was soaked at a soak time of approximately 5 minutes to yield an alloy including approximately 81 wt% lithium, 9 wt% magnesium, and 10 wt% boron.

[0200] Figure 10 shows an X-ray diffraction (“XRD”) pattern 1000 of a lithium-magnesium-boron alloy (“Li-Mg-B”) formed by a single-step exothermic process, according to some implementations. XRD analysis was performed using Cu K„ radiation. As can be seen, XRD pattern 1001 associated with the Li-Mg-B alloy formed using the single-step exothermic method and including approximately 10 wt% boron suggests that the Li-Mg-B alloy includes the Li lL phase. In contrast, the XRD pattern 1002 of a Li-Mg-B alloy formed at the first exothermic stage corresponding to about 350 °C and associated with a conventional two-step exothermic melt process does not support the formation of the LisB4 phase and only shows crystallographic planes corresponding to the body-centered cubic (“BCC”) crystalline structure of lithium-metal.

[0201] Figure 11 shows a scanning electron microscopy (“SEM”) micrograph 1100 of a lithium-magnesium-boron (“Li-Mg-B”) alloy formed by a single-step exothermic melt process, according to some implementations. The Li-Mg-B alloy including the L15B4 phase formed using the single-step exothermic melt process, as described above was examined using scanning electron microscopy (“SEM”). As can be seen, the Li-Mg-B alloy wascharacterized by a fibrous structure 1101 associated with the formation of the intermetallic LisB4 phase, in contrast to discrete boron particles distributed in the Li-Mg melt.EXAMPLE 2. Cathode discharge capacity and capacity retention of lithium-sulfur coin cells including lithium-magnesium-boron alloy anodes.

[0202] Eigure 12 shows a plot 1200 illustrating cathode discharge capacity and capacity retention of lithium-sulfur coin cells including lithium-magnesium-boron alloy (“Li-Mg-B”) anodes, according to some implementations. Each coin cell included a Li-Mg-B alloy anode. The Li-Mg-B alloy anode included an approximately 81 wt% lithium-9 wt% magnesium-10 wt% boron alloy formed using the single-step exothermic melt process as described above with reference to Example 1. For comparison, Figure 12 also shows the electrochemical performance of coin cells including 90 wt% lithium-10 wt% magnesium (“Li-Mg”) alloy anodes.

[0203] Cathode discharge capacity at C / 3 charge / discharge rate of the lithium-sulfur coin cells was measured. The electrolyte included a liquid fluorinated ether electrolyte with an approximate composition of 50:25:25 (vol%) 1,2-dimethoxyethane (“DME”): 1,3-dioxolane (“DOL”): bis (2,2,2-trifluoroethyl) ether (“BTFE”) and including approximately 0.4 M LiTFSI and approximately 2 wt% LiNO . The E / S ratio was approximately 5 pL / mgS,

[0204] Referring to Figure 12, cathode discharge capacity associated with coin cells including the Li-Mg-B alloy anode described above was at least 500 mAh / g at approximately 80% capacity retention. Additionally, the cyclic life of coin cells including the Li-Mg-B alloy anode was significantly better than the cycle life of coin cells including the reference Li-Mg anode. Without being bound by any particular theory, the enhanced electrochemical performance of the coin cells including the Li-Mg-B anodes is due to the presence of the Lis B4 phase characterized by a fibrous structure, which may improve uniform plating and etching of lithium alloy anodes during the cyclic discharge / charge process.EXAMPLE 3. Cathode discharge capacity and capacity retention of lithium-sulfur coin cells including lithium-magnesium-boron alloy anodes.

[0205] Lithium-magnesium-boron alloy (“Li-Mg-B”) anodes were produced using the method previously described herein with reference to Figure IB. The Li-Mg-B alloy anodes included approximately 5 wt% boron, and between approximately 4 wt% and approximately 10 wt% 3DG carbons. The 3DG carbons included titanium dioxide (TiO2) nanoparticles disposed on one or more surfaces of the 3DG carbons or within the 3DG carbons. The 3DGcarbons included flaky graphene and nodular graphene as previously described herein with reference to Figures 3D-3I.

[0206] Figure 13A shows a scanning electron microscopy (“SEM”) micrograph 1300A of a cross section of a Li-Mg-B alloy including 3DG carbons, according to some implementations. Figures 13B-13C show SEM-energy dispersive X-ray spectroscopy (“EDS”) elemental dispersion images 13OOB-13OOC of a Li-Mg-B alloy including 3DG carbons, according to some implementations. Referring to Figure 13A, the Li-Mg-B alloy including the 3DG carbons was characterized by a fibrous structure 1301A, which may be associated with the formation of the intermetallic LijB4 phase.

[0207] Referring to Figures 13B-13C, the elements examined during EDS analysis included boron and carbon (shown in EDS image 1300B, K line) and magnesium and titanium (shown in elemental dispersion image 1300C, K line). As can be seen, boron, carbon, magnesium, and titanium are each uniformly distributed across the thickness of the alloy.

[0208] Figure 14 shows a plot 1400 illustrating cathode discharge capacity and capacity retention of lithium-sulfur coin cells including lithium-magnesium-boron alloy (“Li-Mg-B”) anodes, according to some implementations. Each test coin cell included a Li-Mg-B alloy anode including 3DG carbons as described above with reference to Figures 13A-13C. The reference coin cells each included a 90 wt% lithium - 10 wt% magnesium alloy anode.

[0209] Cathode discharge capacity at C / 3 charge / discharge rate of the lithium-sulfur coin cells was measured. Referring to Figure 14, the cathode discharge capacity associated with coin cells including the Li-Mg-B alloy anode including 3DG carbons was at least 500 mAh / g at approximately 80% capacity retention. Additionally, the cyclic life of coin cells including the Li-Mg-B alloy anode including the 3DG carbons was significantly better than the cycle life of coin cells including the reference lithium-magnesium alloy anode. Without being bound by any particular theory, the enhanced electrochemical performance of the coin cells including the Li-Mg-B anodes may be due to the presence of the Li5B4 phase characterized by a fibrous structure, which may improve uniform plating and etching of the lithium alloy anodes during the cyclic discharge / charge process.EXAMPLE 4, Electrochemical performance of lithium- sulfur coin cells assembled with Li- Mg-B alloy anodes including a doped carbon-based material.

[0210] Figures 15A-15C show plots 1500A-1500C illustrating cathode discharge capacity, capacity retention, and columbic efficiency of lithium-sulfur coin cells assembledwith Li-Mg-B alloy anodes including a doped carbon-based material, according to some implementations. The reference anodes included a 90 wt% lithium- 10 wt% magnesium alloy. The lithiophilic dopant included boron.

[0211] The carbon-based material included flaky graphene, nodular graphene, and graphitic carbon as previously described herein. The alloy anode (referred to herein as Alloy “A”) was formed by rolling Li-Mg alloy foils with the doped carbon-based material. The composition of the Ti-Mg alloy was approximately 90 wt% lithium and approximately 10 wt% magnesium. The amount of doped carbon-based material was about 5 wt% based on the combined weight of the Li-Mg alloy foils and the weight of the doped carbon-based material.

[0212] Referring to Figures 15A-15B, a cathode discharge capacity of at least 500 mAh / g was measured using the lithium-sulfur cells with the Alloy “A” anodes over a greater number of charge / discharge cycles compared to that of the cells including the reference freestanding 90 wt% Li - 10 wt% Mg alloy anode. Additionally, the discharge capacity of at least approximately 500 mAh / g was measured at approximately 80% capacity retention.

[0213] Referring to Figure 15C, the cells including the Alloy “A" anode were characterized by improved columbic efficiency compared to the corresponding columbic efficiency of the cells including the reference anodes.EXAMPLE 5. Cathode discharge capacity and capacity retention of lithium-sulfur coin cells assembled with anodes including a Li-Mg-B alloy including a doped carbon-based material.

[0214] Figures 16A-16B show plots 1600A-1600B illustrating cathode discharge capacity and capacity retention of lithium-sulfur coin cells assembled with anodes including a Li-Mg-B alloy including a carbon-based material, according to some implementations. The carbon-based material was doped with boron as the lithiophilic dopant. The carbon-based material included flaky graphene, nodular graphene, and graphitic carbon as previously described herein. The alloy anode (referred to herein as Alloy “B”) was formed by melt infusing Li-Mg alloy into the doped porous carbon agglomerates. The magnesium content in the Li-Mg alloy melt was approximately 20 wt%. The reference anode included an approximately 80 wt% lithium-20 wt% magnesium alloy.

[0215] Referring to Figures 16A-16B, the cathode discharge capacity and capacity retention of the cells including the Alloy “B” anode was each comparable to the cathode discharge capacity and capacity retention of the cells including the reference anode.However, the cells assembled with the reference anodes including approximately 20 wt%magnesium were characterized by undesirable sluggish activation, while the cells including the Alloy “B” anodes was not hampered by slow activation.EXAMPLE 6. Electrochemical performance of lithium- sulfur coin cells assembled with Li- Mg-B alloy anodes including a doped carbon-based material.

[0216] Eigures 17A-17B show plots 1700A-1700B illustrating cathode discharge capacity and columbic efficiency of lithium- sulfur coin cells assembled with Li-Mg-B alloy anodes including a doped carbon-based material, according to some implementations. The reference anodes included a 90 wt% lithium- 10 wt% magnesium alloy

[0217] The Li-Mg-B alloy anode (referred to herein as Alloy “A”) was formed by rolling one or more Li-Mg alloy composite ingots produced using the process described with reference to Figure 7. Details related to boron-doped graphite were previously described herein with reference to Figure 9A-9E. The doped carbon-based material included boron as the dopant. The composition of the Li-Mg alloy was approximately 90 wt% lithium and approximately 10 wt% magnesium. The amount of the boron-doped graphite in the Li-Mg alloy composite was approximately 3 wt% of the weight of the Li-Mg alloy composite. The amount of boron in the boron-doped graphite material was approximately 14 wt% of the weight of the boron-doped graphite material.

[0218] Referring to Figures 17A, a cathode discharge capacity of at least 500 mAh / g was measured using the lithium-sulfur cells with the Alloy “A” anodes over a greater number of charge / discharge cycles compared to that of the cells including the reference freestanding 90 wt% Li - 10 wt% Mg alloy anode.

[0219] Referring to Figure 17B, the cells including the Alloy “A” anode were characterized by improved columbic efficiency compared to the corresponding columbic efficiency of the cells including the reference anodes.

[0220] As used herein, a phrase referring to “at least one of’ or “one or more of’ a list of items refers to any combination of those items, including single members. For example, “at least one of: a, b, or c” is intended to cover the possibilities of: a only, b only, c only, a combination of a and b, a combination of a and c, a combination of b and c, and a combination of a and b and c. Unless otherwise specified in this disclosure, for construing the scope of the tcim “about” or “approximately,” the error bounds associated with the values (dimensions, operating conditions etc.) disclosed is ± 10% of the values indicated in this disclosure. The error bounds associated with the values disclosed as percentages is ± 1% ofthe percentages indicated. The word “substantially” used before a specific word includes the meanings “considerable in extent to that which is specified,” and “largely but not wholly that which is specified.”

[0221] Various modifications to the implementations described in this disclosure may be readily apparent to persons having ordinary skill in the art, and the generic principles defined herein may be applied to other implementations without departing from the spirit or scope of this disclosure. Thus, the claims are not intended to be limited to the implementations shown herein but are to be accorded the widest scope consistent with this disclosure, the principles and the novel features disclosed herein.

[0222] Additionally, various features that are described in this specification in the context of separate implementations can also be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation can also be implemented in multiple implementations separately or in any suitable subcombination. As such, although features may be described above in combination with one another, and even initially claimed as such, one or more features from a claimed combination can in some cases be omitted from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.

[0223] Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. Further, the drawings may schematically depict one more example processes in the form of a flowchart or flow diagram. However, other operations that are not depicted can be incorporated in the example processes that arc schematically illustrated. For example, one or more additional operations can be performed before, after, simultaneously, or between any of the illustrated operations. In some circumstances, multitasking and parallel processing may be advantageous. Moreover, the separation of various system components in the implementations described above should not be understood as requiring such separation in all implementations, and it should be understood that the described program components and systems can generally be integrated together in a single product or packaged into multiple products.

Claims

CLAIMSWhat is claimed is:

1. An alloy associated with a lithium-sulfur battery anode, the alloy including a lithium-magnesium-boron (Li-Mg-B) alloy comprising a lithium-boron (Li-B) alloy phase and a carbon-based material including flaky graphene and nodular graphene.

2. The alloy of claim 1, wherein the carbon-based material further includes graphitic carbon.

3. The alloy of claim 1, wherein the carbon-based material further includes titanium dioxide (TiCh) nanoparticles disposed on one or more surfaces of the carbon-based material or within the carbon-based material.

4. The alloy of claim 1, wherein the Li-B alloy phase includes one or more of a Li?B- alloy phase or a LisB4 alloy phase.

5. The alloy of claim 1, wherein an amount of the boron in the alloy is between approximately 1 wt% and approximately 15 wt%.

6. The alloy of claim 1 , wherein an amount of the boron in the alloy is approximately 10 wt%.

7. The alloy of claim 1, wherein an amount of the magnesium in the alloy is between approximately 5 wt% and approximately 15 wt%.

8. The alloy of claim 1, wherein an amount of the carbon-based material in the alloy is between approximately 5 wt% and approximately 20 wt%.

9. The alloy of claim 1, where a Brunauer-Emmett-Teller (BET) surface area of the carbon-based material measured using nitrogen gas is between approximately 50 m2 / g and approximately 300 m2 / g.

10. The alloy of claim 1, wherein the carbon-based material is characterized by a Raman spectroscopy signature having an ID / IG ratio between approximately 0.35 and approximately 0.56.

11. The alloy of claim 1, wherein the carbon-based material is characterized by a Raman spectroscopy signature having an FD / IG ratio between approximately 0.53 and approximately 0.7.

12. The alloy of claim 1, wherein the carbon-based material is characterized by a Raman spectroscopy signature having an ID / IG ratio between approximately 0.35 and approximately 0.56, and an DD / IG ratio between approximately 0.53 and approximately 0.7.

13. The alloy of claim 1, wherein the flaky graphene includes a plurality of graphene layers.

14. Fhe alloy of claim 13, wherein a number of graphene layers in the plurality of graphene layers is between 5 and 15.

15. The alloy of claim 13, wherein the plurality of graphene layers includes one or more of few layer graphene (FLG) or many layer graphene (MTG).

16. The alloy of claim 13, where the graphene layers are arranged as one or more stacks connected to each other and defining a three-dimensional (3D) porous scaffold structure including mesopores.

17. The alloy of claim 1, wherein at least some of the flaky graphene is characterized by a linear dimension of between approximately 50 nm and 200 nm.

18. The alloy of claim 1, wherein the nodular graphene includes a plurality of carbon nano-onions (CNOs).

19. The alloy of claim 1, wherein the nodular graphene includes porous carbon agglomerates of porous carbon primary nanoparticles, wherein a respective porous carbon primary nanoparticle includes:an inner porous shell disposed about a center of the respective porous carbon primary nanoparticle and enclosing an inner porous carbon region;an outer porous shell enclosing an outer porous carbon region disposed between the inner porous shell and the outer porous shell; andan interconnected porous network disposed in and in fluid communication with the inner and outer porous carbon regions.

20. The alloy of claim 19, wherein the inner porous carbon region and the outer porous carbon region are characterized by an average pore size and an average pore density associated with each region.

21. The alloy of claim 20, wherein the average pore size decreases along a radial direction from the center of the respective porous carbon primary nanoparticle to the outer porous shell of the respective porous carbon primary nanoparticlc.

22. fhe alloy of claim 19, wherein the respective porous carbon primary nanoparticle further includes one or more intermediate porous shells disposed between the inner porous shell and the outer porous shell of the respective porous carbon primary nanoparticle, wherein each of the intermediate porous shells encloses a corresponding intermediate porous carbon region.

23. The alloy of claim 1, wherein the carbon-based material further includes one or more oxygen containing functional groups disposed on one or more surfaces of the carbon¬ based material or within the carbon-based material.

24. The alloy of claim 23, wherein the oxygen containing functional groups include one or more of epoxide (C-O-C), hydroxyl (-OH), ether (C-O-C), ketone (O-C=O), or carboxylic acid (-COOH) groups.

25. An anode associated with a lithium- sulfur battery, the anode including a lithium-magnesium-boron (Li-Mg-B) alloy comprising a lithium-boron (Li-B) alloy phase and a carbon-based material including flaky graphene and nodular graphene.

26. The anode of claim 25, wherein the carbon-based material further includes graphitic carbon.

27. The anode of claim 25, wherein the carbon-based material further includes titanium dioxide (TiCh) nanoparticles disposed on one or more surfaces of the carbon-based material or within the carbon-based material.

28. The anode of claim 25, wherein the Ti-B alloy phase includes one or more of a i2Bs alloy phase or a LisB4 alloy phase.

29. The anode of claim 25, wherein an amount of the boron in the alloy is between approximately 1 wt% and approximately 15 wt%.

30. The anode of claim 25, wherein an amount of the boron in the alloy is approximately 10 wt%.

31. The anode of claim 25, wherein an amount of the magnesium in the alloy is between approximately 5 wt% and approximately 15 wt%.

32. The anode of claim 25, wherein an amount of the carbon-based material in the alloy is between approximately 5 wt% and approximately 20 wt%.

33. The anode of claim 25, further including a polymer coating disposed on the anode, wherein the polymer coating includes one or more of poly vinylidene fluoride (PVDF), pentaerythritol tetraacrylate (PETEA), or polyethylene glycol dimethacrylate (PEGDMA).

34. A lithium-sulfur battery including:an anode including a lithium-magnesium-boron (Ei-Mg-B) alloy comprising a lithium-boron (Li-B) alloy phase and a carbon-based material including flaky graphene and nodular graphene; anda fluorinated ether electrolyte.

35. The lithium-sulfur battery of claim 34, wherein the Ei-B alloy phase includes one or more of a Li2Bs alloy phase or a LisB4 alloy phase.

36. The lithium-sulfur battery of claim 34, wherein an amount of the boron in the alloy is between approximately 1 wt% and approximately 15 wt%.

37. The lithium- sulfur battery of claim 34, wherein the carbon-based material further includes titanium dioxide (TiCh) nanopaiticles disposed on one or more surfaces of the carbon-based material or within the carbon-based material.

38. The lithium-sulfur battery of claim 34, wherein the carbon-based material further includes graphitic carbon.

39. The lithium-sulfur battery of claim 34, wherein the fluorinated ether electrolyte includes one or more of:approximately 50:25:25 (vol%) 1 ,2-dimethoxyethane (DME): 1,3-dioxolane (DOL): bis (2,2,2-trifluorocthyl) ether (BTFE) and including approximately 0.4 M LiTFSI and approximately 2 wt% LiNO3;approximately 50:25:25 (vol%) DME : DOE: 1,1,2,2-tetraethoxyethane (TEE) and including approximately 0.4 M LiTFSI and approximately 2 wt% LiNO3;approximately 50:25:25 (vol%) DME : DOL: 1,1,2,2-tetrafhioroethyl 2,2,2-trifluoroethyl ether (TFETFE) and including approximately 0.4 M LiTFSI and approximately 2 wt% LiNO3;approximately 60:20:10:10 (vol%) DME : DOL: TEE: TFETFE and including approximately 0.4 M LiTFSI and approximately 2 wt% LiNO3;approximately 50:25:25 (vol%) DME : DOL: l,l,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE) and including approximately 0.4M LiTFSI and approximately 2 wt% LiNO3;approximately 50:25:25 (vol%) 1 ,2-dimethoxyethane (DME): 1,3-dioxolane (DOL): bis (2,2,2-trifluoroethyl) ether (BTFE), and including between approximately 0.6 M and approximately 0.8M LiTFSI, between approximately 0.5M and approximately 0.7M LiNO3, and between approximately 0.15M and approximately 0.2M dicyandiamide (DCDA);approximately 50:25:25 (vol%) DME : DOL: 1 fluorinated 1,4-dimethoxylbutane (FDMB) including approximately 0.4 M LiTFSI and approximately 2 wt% LiNO3; or approximately 1.0 M LiTFSI in approximately 50:50 (vol%) DOL: BTFE.

40. The lithium-sulfur battery of claim 34, further including a polymer coating disposed on the lithium-magnesium-boron alloy, wherein the polymer coating includes including one or more of polyvinylidene fluoride (PVDF), pentaerythritol tetraacrylate (PETEA), or polyethylene glycol dimethacrylate (PEGDMA).

41. A method of forming a lithium-magnesium-boron (Li-Mg-B) alloy, the method including:producing a lithium-magnesium (Li-Mg) alloy melt by melting a Ei-Mg alloy at a process temperature;producing a Li-Mg-B melt by adding powdered boron to the Li-Mg alloy melt at the process temperature; andsoaking the Li-Mg-B alloy melt during a soak time at the process temperature, wherein the Li-Mg-B alloy includes one or more of a Li2Bs alloy phase or a 14 B4 alloy phase.

42. Phe method of claim 41, further including adding a carbon-based material including flaky graphene and nodular graphene to the Li-Mg alloy melt at the process temperature.

43. The method of claim 42, wherein the carbon-based material further includes graphitic carbon.

44. The method of claim 42, wherein the carbon-based material further includes titanium dioxide (TiCL) nanoparticles disposed on one or more surfaces of the carbon-based material or within the carbon-based material.

45. The method of claim 41, further including confirming the presence of the Li2Bs alloy phase or the L15B4 alloy phase by analyzing the Li-Mg-B alloy using X-ray diffraction (XRD).

46. The method of claim 41, wherein the process temperature is between approximately 550 °C and approximately 750 °C.

47. The method of claim 41, wherein the process temperature is approximately 700 °C.

48. The method of claim 41 , wherein the soak time is between approximately 2 minutes and approximately 30 minutes.

49. The method of claim 41, wherein the soak time is approximately 5 minutes.

50. The method of claim 41, wherein the lithium-magnesium alloy includes a 90 wt% lithium - 10 wt% magnesium alloy.

51. A method of forming a lithium-magnesium-boron (Li-Mg-B) alloy associated with a lithium- sulfur battery anode, the method including:producing a lithium-magnesium (Li-Mg) alloy melt by melting a Li-Mg alloy at a process temperature;adding a carbon-based material doped with boron to the Li-Mg alloy melt, wherein the carbon-based material includes flaky graphene and nodular graphene; andsoaking the Li-Mg alloy melt including the carbon-based material doped with boron at a soaking temperature, wherein the Li-Mg-B alloy includes a lithium-boron (Li-B) alloy phase.

52. The method of claim 51, wherein the Li-B alloy phase includes one or more of a Li2Bs alloy phase or a LisB4 alloy phase.

53. The method of claim 51, wherein a temperature associated with the adding operation is approximately equal to the process temperature.

54. The method of claim 51, wherein the soaking temperature is approximately equal to the process temperature.

55. The method of claim 51, wherein an amount of the magnesium in the Li-Mg -B alloy is between approximately 5 wt% and approximately 20 wt%.

56. The method of claim 51 , wherein the carbon-based material further includes graphitic carbon.

57. The method of claim 51 , wherein the process temperature is between approximately 550 °C and approximately 750 °C.

58. The method of claim 51 , wherein a soaking time associated with the soaking operation is between approximately 2 minutes and approximately 30 minutes.

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