WO2024081391A1

WO2024081391A1 - Solid-state lithium-sulfur battery compositions and devices

Info

Publication number: WO2024081391A1
Application number: PCT/US2023/035085
Authority: WO
Inventors: Linda F. Nazar; Zhuo YU
Original assignee: Conamix Inc.; University Of Waterloo
Priority date: 2022-10-14
Filing date: 2023-10-13
Publication date: 2024-04-18

Abstract

The present disclosure provides, inter aha, compositions for lithium-sulfur batteries and methods of forming those compositions. In some embodiments, a composition includes an inorganic sulfide-based solid material. The inorganic sulfide-based solid material may be an argyrodite-type compound. The composition may include a structure that includes a graphene, such as, for example, N-doped graphene, and a carbon nitride, such as, for example, graphitic carbon nitride (g-C3N4). The structure may be disposed in (e.g., dispersed in) the inorganic sulfide-based solid material. The structure can act as a sulfur host. The structure may be in direct physical contact with the material in the composition. Thus, a composition may be used in a hybrid cathode for an all-solid-state lithium-sulfur battery'. Such a hybrid cathode may exhibit (i) high electrical and ionic conductivity, (ii) a porous structure to accommodate high sulfur loading, (hi) suppression of Li5.5PS4 5CI1.5 electrolyte degradation pathways, or (iv) a combination of (i)-(iii).

Description

SOLID-STATE LITHIUM-SULFUR BATTERY COMPOSITIONS AND DEVICES

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority to U.S. Provisional Patent Application No. 63/416,222, filed on October 14, 2022. the entirety of which is hereby incorporated by reference.

FIELD

[0002] The present disclosure relates generally to lithium-sulfur batteries, and in particular to solid-state lithium-sulfur batteries.

BACKGROUND

[0003] Lithium-sulfur batteries (Li-S batteries) are rechargeable batteries that are promising candidates for next-generation energy storage systems due to their high theoretical volumetric energy density (2600 Wh L , compared to about 680 Wh L for lithium-ion batteries), the high abundance of sulfur on earth, and the low atomic weight of sulfur that can result in lightweight batteries. Li-S batteries have high energy density, high power density, and low weight that make them attractive for consumer electronics and electric vehicles. In a typical Li-S battery, the anode is a Li-containing metal where dissolution of metallic lithium occurs, and the cathode is a S-containing compound where sulfur is reduced to lithium sulfide (Li2S). Energy is typically stored in the cathode using elemental Ss. Conventional Li-S batteries often have liquid ether-based electrolytes that undergo unwanted reactions and are flammable.

[0004] One of the major limitations of current Li-S battery technology is known as the “shuttle effect,” where material gradually leaks from the cathode due to dissolution of polysulfides in the liquid ether-based electrolyte. This effect leads to poor sulfur utilization and a rapid decay in battery capacity, and thus significantly hinders practical applications of Li-S batteries. The intrinsic shuttle effect cannot be completely eliminated in ty pical Li-S batteries, although many efforts have been made to suppress it. Examples of such efforts include cathode confinement, separator coatings, and electrolyte regulation.

[0005] Accordingly, all-solid-state Li-S batteries (ASSLSBs) using inorganic sulfide-based solid electrolytes, such as LisPS4 and LiePS.sCl, have been proposed. Generally, in ASSLSBs, sulfur is directly converted into lithium sulfide without any formation of poly sulfides during the charge-discharge process and only one sloping discharge plateau is obtained. Argyrodite-type solid electrolytes (LiePSsX, X = Cl, Br, I) have been proposed for ASSLSBs due to their high ionic conductivity and good deformability.

[0006] Nevertheless, there are still several challenges faced by argyrodite-type electrolytes. A common problem for all sulfide electrolytes is their air sensitivity and tendency to decompose by reaction with H2O and O2, so that inert atmospheres are required for their synthesis. In addition, argyrodite-type electrolytes usually have a narrow window of electrochemical stability. For example, the thermodynamic stability window of LifiPS.sCl has been calculated to be only 1.71 - 2.01 V, and was experimentally measured to be 1.08 - 2.24 V with an indirect two-step decomposition pathway, forming the intermediates LiiPSsCl on oxidation and LiiiPSsCl on reduction. Outside this window, LiePSsCl is oxidized to a mixture of LiCl and other products, which have poor conductivity and can cause capacity loss and interfacial passivation.

[0007] Sulfur hosts should provide sufficient electronic conductivity to favor the mutual electrochemical conversion of insulating sulfur and lithium sulfide, and possess good interfacial compatibility with sulfur and solid electrolytes. Sulfide compounds such as FeS2 and VS2 have been shown to have good Li⁺ diffusion and stable cycling performance, but the sulfur content in these materials is quite low (less than 40%) and vanadium is toxic. In general, higher sulfur loadings are desirable to achieve high energy density. In many ASSLSBs, low sulfur content or loading, and poor cyclability due to conductivity requirements and electrolyte degradation severely hinder their practical applications.

[0008] Carbon-based materials such as graphene, activated carbon, and CMK-3 (a type of ordered mesoporous carbon) are the most commonly used host materials in ASSLSBs. These types of carbon-based materials usually have high electronic conductivities and large pore volumes to accommodate high sulfur content and to alleviate volume expansion upon the conversion of sulfur into lithium sulfide (Li2S). Although carbon-based materials can effectively compensate for the intrinsic insulating nature of sulfur and lithium sulfide, direct contact between carbon and argyrodite-type electrolytes can accelerate the decomposition of the electrolyte. [0009] Therefore, existing ASSLSBs all suffer from one or more shortcomings that ultimately lead to less than optimal performance. Accordingly, there is a need for new ASSLSBs, incorporating a solid electrolyte and sulfur host, that have improved battery⁷ performance and mitigate shortcomings of existing ASSLSBs.

SUMMARY

[0010] The present disclosure provides, inter alia, compositions for ASSLSBs and methods of their formation. A composition may include a combination of an inorganic sulfide-based solid material (e.g.. electrolyte), such as an argyrodite-type compound and a structure that includes a graphene and a carbon nitride (e.g., in a stacked-sheet arrangement). The particular combination of such a structure and an inorganic sulfide-based solid material can lead to a battery w ith improved performance, for example at mildly elevated temperatures (e.g., about 60 °C), and/or mitigate one or more problems with existing ASSLSB materials, such as electrolyte degradation.

[0011] In some embodiments, an ASSLSB includes a sulfur host that includes a continuous conductive netw ork formed by hybridizing graphitic carbon nitride sheets (g- CsNr) (CN) and conducting N-doped graphene (NG) to form a (e.g., porous) composite material (CN-NG) and highly ion-conductive argyrodite-type Li5.sPS45CI1.5 that together form a hybrid CN-NG/S/ Li5.5PS4.5Ch.5 cathode that may provide large sulfur accommodation, and fast electron and ion transport in multiple channels, so that a high sulfur content of up to 69 wt% may be achieved. The CN-NG composite material may suppress decomposition of the Lis.5PS45CI1.5 solid electrolyte during oxidation, which may lead to improved electrochemical performance of these ASSLSBs. A battery fabricated with these compositions may deliver a capacity of 1139.4 mAh g'¹ under a sulfur loading of 1.66 mg cm'², and a capacity of 4.94 mAh g'¹ for a sulfur loading of 6.8 mg cm'² operating at room temperature. A similar battery may deliver a capacity of 11.3 mAh cm'² and a capacity retention of 91.7% for a sulfur loading of 7.63 mg cm'² operating at 60°C, with an initial conversion efficiency of up to 96.7%. The hybrid material in these embodiments features a combination of preventing electrolyte degradation and forming a continuous conductive net ork to improve ASSLSB performance.

[0012] In some aspects, the present disclosure is directed to a lithium-sulfur battery (e.g., an all-solid-state Li-S battery). The batten may include an inorganic sulfide-based solid electrolyte. The battery may further include a structure (e.g., a porous structure) including a graphene (e.g., N-doped graphene) and a carbon nitride (e.g., graphitic carbon nitride (g-CiN-t)). A mass ratio of the electrolyte and the structure may be between 1:2 and 2: 1, e.g., about 1 : 1. The batten- may further include an anode including lithium (e.g., a lithium-indium (Li/In) alloy). The battery may be preferably used (e.g., charged and/or discharged) while the battery is at a temperature of between 50 °C and 70 °C (e.g., about 60 °C), for example thereby optimizing performance.

[0013] In some embodiments, the inorganic sulfide-based solid electrolyte includes (e.g., is made of) an argyrodite-type compound. In some embodiments, the inorganic sulfide-based solid electrolyte includes (e.g., is made of) LiniPtoSniXni, where X = Cl, Br, or 1, and where each of nl, n2, n3, and n4 is > 0. In some embodiments, the LiniPn2Sn3Xn4 is Li₇-xPS6-xXx (e.g., where x = 1.5) (e.g., and wherein X = Cl).

[0014] In some embodiments, the structure includes graphitic carbon nitride/N- doped graphene (CN-NG) sheets (e.g., wherein the sheets are porous). In some embodiments, the structure includes stacked sheets of the graphene and the carbon nitride (e.g., wherein the stacked sheets include three or more layers of alternating sheets of the graphene and the carbon nitride) (e g., wherein the sheets are porous). In some embodiments, the structure forms a continuous conductive network. In some embodiments, the graphene and the carbon nitride are hybridized together.

[0015] In some embodiments, the structure is a sulfur host in the battery- (e.g., wherein the structure allows the structure, or cathode comprising the structure, to have a high sulfur content, e.g., > 50 wt%. e.g., > 55 wt%, e.g., > 60 wt%, e.g., > 65 wt%, e.g.. about 69 wt%). In some embodiments, the battery further includes sulfur hosted in the structure (e.g., sulfur in an elemental form and/or in a lithium sulfide) [e.g., wherein a loading of the sulfur in the structure, or cathode comprising the structure, is > 50 wt%, > 55 wt%, > 60 wt%, or > 65 wt% (e.g., and no more than 80 wt%)].

[0016] In some embodiments, the battery includes a cathode (e.g., a hybrid cathode) including the structure (e.g., and at least a portion of the electrolyte if a hybrid cathode). [0017] In some embodiments, the structure is in direct physical contact with the electrolyte. In some embodiments, the structure includes a particle (e.g., flake) (e.g., microparticle or nanoparticle) including the graphene and the carbon nitride. In some embodiments, the structure is disposed in (e.g., dispersed in) the electrolyte. [0018] In some embodiments, the battery includes a solid separator. In some embodiments, the separator includes an inorganic sulfide-based solid material. In some embodiments, the inorganic sulfide-based solid material is made of an argy rodite-type compound [e.g., wherein the inorganic sulfide-based solid material includes LiniPn2Sn3Xn4, where X = Cl. Br, or 1, and where each of nl, n2. n3, and n4 is > 0 (e.g., wherein the LiniPn2Sn3Xn4 is Liv-xPSe-xXx (e.g., where x = 1.5) (e g., and wherein X = Cl))].

[0019] A characteristic binding energy between the structure and the inorganic sulfide-based solid material may be at least -2 meV/(atom*A²) (e.g., at least -3 meV/(atom*A²) or at least -3.5 meV/(atom*A²)). A characteristic distance between a surface of the inorganic sulfide-based solid material and the structure may be no more than 2.5 A (e.g., no more than 2 A).

[0020] In some aspects, the present disclosure is directed to a solid (e.g., powder) composition for a hybrid cathode. The composition may include an inorganic sulfide-based solid material (e.g., electrolyte) (e.g., made of an argyrodite-type compound). The composition may further include a structure (e.g., a porous structure) [e.g., including a particle (e.g., a flake) (e.g., a micro-particle or nanoparticle)] including a graphene (e.g., N- doped graphene) and a carbon nitride (e.g., graphitic carbon nitride (g-CsNA). The structure may be disposed in (e.g., dispersed in) the inorganic sulfide-based solid material. A mass ratio of the material and the structure may be between 1 :2 and 2: 1 , e.g., about 1 :1. A hybrid cathode may be made with the composition. The hybrid cathode may be included in an allsolid-state lithium-sulfur battery'. The inorganic sulfide-based solid material may be a powder. The composition may be a powder mixture (e.g., that can be pressed into a layer or pellet). The composition may be in a layer (e.g., for use in, or in, a lithium-sulfur batter) or a pellet. The layer or pellet may have been pressed together. A characteristic binding energy' between the structure and the inorganic sulfide-based solid material may be at least - 2 meV/(atom*A²) (e.g.. at least -3 meV/(atom*A²) or at least -3.5 meV/(atom*A²)). for example when the composition has been pressed into a pellet or layer. A characteristic distance between a surface of the inorganic sulfide-based solid material and the structure may be no more than 2.5 A (e.g., no more than 2 A), for example when the composition has been pressed into a pellet or layer.

[0021] In some aspects, the present disclosure is directed to a lithium-sulfur battery (e.g., an all-solid-state Li-S battery) that includes a cathode composition having a porous structure (e.g., sheets) that hosts sulfur, said cathode composition (e.g., said sheets) including a graphene (e.g., N-doped graphene) and a carbon nitride (g-CsN4) (e.g., a cathode including CN-NG sheets); a solid electrolyte (e.g., and separator) including an inorganic argyrodite-type compound [e.g., Li?-xPS6-xXx (e.g., where x = 1.5) (e.g., and wherein X = Cl)]; and an anode including lithium (e.g., a lithium-containing alloy, e.g., a Li/In alloy). The cathode composition may suppress decomposition of the inorganic sulfide-based solid electrolyte yet has high electrical conductivity [e.g., > 7 S/cm (Siemens per centimeter), e.g., > 10 S/cm, e.g., about 11.4 S/cm],

[0022] In some aspects, the present disclosure is directed to a method of making a composition for a battery (e.g., a lithium-sulfur battery). The method may include combining [e.g., by grinding (e.g., hand grinding) and/or pulverizing] (i) a structure including a graphene and a carbon nitride and (ii) an inorganic sulfide-based solid material (e.g., in a mass ratio of between 1:2 and 2: 1, e.g., about 1: 1) to form the composition. The structure and the material may be in direct physical contact in the composition.

[0023] The method may include forming the structure prior to the combining. Forming the structure may include pyrolyzing a carbon-nitride precursor and a graphene precursor together. A mixture of the carbon-nitride precursor and the graphene precursor may be formed (e.g., as a slurry or paste) and freeze dried before the pyrolizing. The carbon-nitride precursor may be dicyandiamide. The graphene precursor may be graphene oxide. The pyrolyzing may dope the graphene (e.g., N-dope the graphene). The pyrolyzing may hybridize the graphene and the carbon nitride. In some embodiments, forming the structure includes loading (e.g.. melt-diffusing) sulfur into the structure.

[0024] In some embodiments, the method includes disposing (e.g., spreading) the composition on a first side of a substrate (e.g., a separator). The substrate may be an inorganic sulfide-based solid material, e.g., made of an argyrodite-type compound (e.g., including LiniPnrSniXi , where X = Cl, Br, or I, and where each of nl, n2, n3, and n4 is > 0). The method may include pressing the composition disposed on the first side of the substrate [e.g., at a pressure of at least one ton (e.g., at least two tons or at least three tons) (e.g., for at least a minute)] . The method may include forming the substrate, wherein forming the substrate includes pressing an inorganic sulfide-based solid material [e.g., at a pressure of at least one ton (e.g., at least two tons) (e.g., for at least 30 seconds)]. The method may include contacting (e.g., pressing) an anode including lithium (e.g., a lithium-indium alloy) to a second side of the substrate that is opposite the first side of the substrate. The method may include forming a battery that includes the composition, the substrate, and the anode (e.g., wherein the substrate is a separator and the battery includes a hybrid cathode that includes the composition, wherein the structure in the composition acts as a cathode and the material in the composition acts as an electrolyte).

[0025] In some aspects, the present disclosure is directed to a composition for a hybrid cathode (e.g., for use in, or included in, an all-solid-state Li-S battery ), the composition including: an inorganic sulfide-based solid material (e.g., electrolyte); and a plurality of particles (e.g., porous particles) (e.g.. flakes) (e.g., micro-particles and/or nanoparticles) each comprising a graphene (e.g., N-doped graphene) and a carbon nitride (e.g., graphitic carbon nitride (g-CsNi)). A mass ratio of the material and the plurality' of particles may be between 1 :2 and 2: 1, e.g., about 1: 1. The inorganic sulfide-based solid material may include (e.g., be made of) an argyrodite-type compound. A characteristic binding energy between the particles and the inorganic sulfide-based solid material may be at least -2 meV/(atom*A²) (e.g., at least -3 meV/(atom*A²) or at least -3.5 meV/(atom*A²)). A characteristic distance between a surface of the inorganic sulfide-based solid material and each of the particles may be no more than 2.5 A (e g., no more than 2 A). The graphene and the carbon nitride may be hybridized together. Each particle may include sheets (e.g., stacked sheets) of the graphene and the carbon nitride (e g., at least one sheet of the graphene and at least one sheet of the carbon nitride in an alternating stack).

[0026] Any two or more of the features described in this specification, including in this summary section, may be combined to form implementations of the disclosure, whether specifically expressly described as a separate combination in this specification or not.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present teachings described herein will be more fully understood from the following description of various illustrative embodiments, when read together with the accompanying drawings. It should be understood that the drawing described below is for illustration purposes only and is not intended to limit the scope of the present teachings in any way. The foregoing and other objects, aspects, features, and advantages of the disclosure will become more apparent and may be better understood by referring to the following description taken in conjunction with the accompanying drawings, in which: [0028] FIG. 1 is a schematic illustration of synthesis of g-CsNr/N-doped graphene (CN-NG) and CN-NG/S, according to illustrative embodiments of the present disclosure;

[0029] FIG. 2 is a plot showing a thermogravimetric analysis (TGA) curve of CN- NG/S, according to illustrative embodiments of the present disclosure;

[0030] FIG. 3A is a plot showing voltage profiles of all-solid-state Li-S battery (ASSLSB) with CN-NG/S cathode at discharge rate of C/10 and at S loading of 1.66 mg cm'², at room temperature, according to illustrative embodiments of the present disclosure;

[0031] FIG. 3B is a plot showing cycling performance of ASSLSB with CN-NG/S cathode at discharge rate of 0. 1 C and at S loading of 1.66 mg cm'², at room temperature, according to illustrative embodiments of the present disclosure;

[0032] FIG. 4 is a plot showing cycling performance of ASSLSB with CN/NG-S cathode at discharge rate of 0. 1 C and at S loading of 3.44 mg cm'², at room temperature, according to illustrative embodiments of the present disclosure;

[0033] FIG. 5A is a plot showing voltage profiles of ASSLSB with CN-NG/S cathode at discharge rate of C/20 and with S loading of 6.8 mg cm'², at room temperature, according to illustrative embodiments of the present disclosure;

[0034] FIG. 5B is a plot showing cycling performance of ASSLSB with CN-NG/S cathode at discharge rate of C/20 and with S loading of 6.8 mg cm'², at room temperature, according to illustrative embodiments of the present disclosure;

[0035] FIG. 6A is a plot show ing voltage profiles of ASSLSB with CN-NG/S cathode at discharge rate of C/20 and with S loading of 7.63 mg cm'² operating at 60°C, according to illustrative embodiments of the present disclosure; [0036] FIG. 6B is a plot showing cycling performance of ASSLSB with CN-NG/S cathode at discharge rate of C/20 and with S loading of 7.63 mg cm'² operating at 60°C, according to illustrative embodiments of the present disclosure;

[0037] FIG. 7A is a plot showing direct initial charge voltage profiles of ASSLSBs with CN-NG, NG and Vulcan carbon (VC) at discharge rate of C/20, at room temperature, according to illustrative embodiments of the present disclosure;

[0038] FIG. 7B is a plot showing differential capacity analysis of ASSLSBs with CN-NG, NG, and VC, at room temperature, according to illustrative embodiments of the present disclosure.

[0039] FIG. 8 is a flowchart showing a method for synthesizing CN-NG and CN- NG/S, according to illustrative embodiments of the present disclosure;

[0040] FIG. 9 is a flowchart showing a method for synthesizing Lis.sPS sCli.s, according to illustrative embodiments of the present disclosure;

[0041] FIG. 10 is a flowchart showing a method for assembling an ASSLSB, according to illustrative embodiments of the present disclosure;

[0042] FIG. 11 is a schematic illustration of an assembled ASSLSB, according to illustrative embodiments of the present disclosure;

[0043] FIGs. 12A-12C are plots showing voltage profiles of an assembled ASSLSB with CN-NG/S cathode at discharge rate of C/20 and with S loading of 7.46 mg cm'², operating at 45°C, where FIG. 12A shows the initial discharge, 1^st cycle, and 2^nd cycle, FIG. 12B shows the 6^th cycle, and FIG. 12C shows the 1^st - 21^st cycles, according to illustrative embodiments of the present disclosure;

[0044] FIG. 13 is a scanning electron microscopy (SEM) micrograph of a structure that includes graphene and carbon nitride exhibiting flake like characteristics, according to illustrative embodiments of the present disclosure; and

[0045] FIG. 14A is a plot of voltage profiles of an ASSLSB with a NG/S cathode cycled at C/10 and FIG. 14B is a plot of cycling performance of the ASSLSB cycled at C/10, with sulfur loading of 1.59 mg cm'², according to illustrative embodiments of the present disclosure. DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

[0046] In this application, unless otherwise clear from context or otherwise explicitly stated, (i) the term “a” may be understood to mean “at least one”; (ii) the term “or” may be understood to mean “and/or”; (iii) the terms “comprising” and “including” may be understood to encompass itemized components or steps whether presented by themselves or together with one or more additional components or steps; (iv) the terms “about” and “approximately” may be understood to permit standard variation as would be understood by those of ordinary skill in the relevant art; and (v) where ranges are provided, endpoints are included. In certain embodiments, the term "approximately" or "about" refers to a range of values that fall within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, or less in either direction (greater than or less than) of the stated reference value unless otherw ise stated or otherwise evident from the context (except where such number would exceed 100% of a possible value).

[0047] The present disclosure provides, inter alia, compositions for electrochemical cells (e.g., batteries), such as lithium-based batteries, for example lithium-sulfur batteries; electrochemical cells (e.g., batteries) and components therefor (e.g., cathodes) that include them; and methods of forming those compositions, cells (e.g., batteries), and components. In some embodiments, a composition includes a solid material, in certain embodiments, an inorganic sulfide-based solid material. The inorganic sulfide-based solid material may be an argyrodite-type compound. The material may act as an electrolyte in an electrochemical cell, such as a battery. The composition may further include a structure that includes a graphene, such as, for example. N-doped graphene, and a carbon nitride, such as, for example, graphitic carbon nitride (g-CsNr). The structure may be included in a cathode in an electrochemical cell, such as a battery. The structure may be disposed in (e.g., dispersed in) the inorganic sulfide-based solid material. The structure can act as a conversion material host, such as a sulfur host, for example due to its porosity. Accordingly, a hybrid cathode for a lithium-sulfur battery may be formed from a combination of the material and the structure, for example by grinding and pressing the constituents together. The structure may be in direct physical contact with the material, which can limit degradation of the material (e.g., electrolyte) observed in conventional ASSLSBs, for example during charging, as discussed further subsequently. The structure may form a continuous conductive network (e.g., in a hybrid cathode). For example, a continuous conductive network may exist at least in each discrete particle comprising a carbon nitride and a graphene (e.g., that are hybridized together). In some embodiments, a continuous conductive network extends further, for example across at least a portion of a hybrid cathode (e.g., across a hybrid cathode). Such a continuous conductive network may extend further by extending across multiple particles that include a (e.g., hybridized) graphene and carbon nitride material, for example where such particles are disposed in (e.g., dispersed in) a solid electrolyte, such as an inorganic sulfide-based solid electrolyte.

[0048] In addition to an inorganic sulfide-based solid material and graphene/carbon nitride-including structure, a battery may include (i) an anode, such as, for example, a lithium indium (Li/In) anode; (ii) a separator, such as, for example, one that includes (e.g., is made from) an inorganic sulfide-based solid material; or (iii) both (i) and (ii). Thus, in some embodiments, a lithium-sulfur battery includes an anode, a solid separator, and a hybrid cathode that includes an inorganic sulfide-based solid electrolyte and a structure that includes a graphene and a carbon nitride. These components may each form a layer in a cell that may be packaged (e.g., encased). Generally, batteries disclosed herein may use any suitable form factor, such as a coin cell or cylindrical cell.

[0049] In some embodiments, a composition (e.g., hybrid cathode composition) for a lithium-sulfur battery includes a plurality of particles (e.g.. flakes) (e.g.. micro-particles and/or nanoparticles) that include a graphene (e g., N-doped graphene) and a carbon nitride (e.g., g-CsNty The particles may be disposed in (e.g., dispersed in) an inorganic sulfide- based solid material (e.g., electrolyte). The composition may be included in a hybrid cathode in a lithium-sulfur battery, for example that further includes an anode and/or separator. The cathode composition may suppress decomposition of the inorganic sulfide- based solid material yet have high electrical conductivity [e.g., > 7 S/cm (Siemens per centimeter), e.g., > 10 S/cm, e.g., about 11.4 S/cm], An electrochemical cell, such as a batteiyy that includes a structure and an inorganic sulfide-based solid material (e.g., electrolyte) may have optimal performance at elevated temperature, for example between 50 °C and 70 °C (e.g., at about 60 °C).

[0050] An inorganic sulfide-based solid material may be used as an electrolyte and/or separator. An inorganic sulfide-based solid material used as an electrolyte may have a same or different composition (e.g., stoichiometry) as an inorganic sulfide-based solid material used as a separator. An inorganic sulfide-based solid material may comprise (e.g., be) an argyrodite-type compound. For example, an inorganic sulfide-based solid material may have a composition of LiniPiuSniXnr, where X = Cl, Br, or I, and where each of nl, n2, n3, and n4 is > 0. In some embodiments, LiniPn2Sn3Xn4 is Li?-xPS6-xXx, optionally x may be 1.5 and independently, optionally, X may be Cl. The inorganic sulfide-based solid material may be present in a composition as a powder, for example prior to forming a hybrid cathode or separator (e.g., by pressing). Examples of suitable inorganic sulfide-based solid materials (and methods of forming) can be found in and/or adapted from materials (and processes) found in Zhou, et al., “Innovative Approaches to Li-Argyrodite Solid Electrolytes for All- Solid-State Lithium Batteries,” Acc. Chem. Res., 54(12): 2717-2728 (2021).

[0051] A structure may include a graphene and a carbon nitride. The graphene may be N-doped graphene. The carbon nitride may be a graphitic carbon nitride (g-CsNr). The structure may include a particle, such as a flake, that includes a graphene and a carbon nitride. The particle may be a micro-particle and/or nanoparticle (e.g., nanoflake). The structure may include sheets of the carbon nitride and graphene, for example stacked sheets. Stacked sheets may be alternating layers (e.g., three or more) of a graphene and a carbon nitride. For example, there may be at least one sheet of a graphene and at least one sheet of a carbon nitride disposed in an alternating manner (e.g., wherein adjacent sheets of the graphene and the carbon nitride are hybridized together). Stacked two-dimensional sheets of a graphene and a carbon nitride may form a three-dimensional structure. The sheets may be porous, for example sufficiently porous to act as a conversion material host, for example a sulfur host. The graphene and the carbon nitride may be hybridized together, for example due. at least in part, to having a stacked sheet configuration. A pyrolysis of a graphene precursor and a carbon-nitride precursor may result in N-doping of a graphene and/or hybridization of a graphene and a carbon nitride. In some embodiments, a particle or particles include sheets (e.g., stacked sheets) of a graphene and a carbon nitride. The structure may be porous, for example due to porosity in a graphene (e.g., N-doped graphene) and/or a carbon nitride (e.g., graphitic carbon nitride). The structure can act as a conversion material host, such as a sulfur host, for example due to its porosity. The structure may be in direct physical contact with the material (e.g., electrolyte) in the hybrid cathode. The structure may be present in a composition as a powder, for example prior to forming a hybrid cathode or separator (e.g., by pressing). Examples of suitable structures that include a carbon nitride and a graphene can be found in and/or adapted from structures found in Pang, et al. “A Comprehensive Approach Towards Stable Lithium-Sulfur Batteries with High Volumetric Energy Density,” Adv. Energy Mater., 7: 1601630 - 1601638 (2017). [0052] FIG. 13 is an SEM micrograph of a structure that includes a graphene and a carbon nitride, in this case CN-NG. The structure shown in FIG. 13 may be incorporated into a hybrid cathode, for example by combining with a solid electrolyte, such as an inorganic sulfide-based solid electrolyte. The combined solid electrolyte and structure may be ground (e.g., hand ground) together and pressed to form the hybrid cathode.

[0053] In some embodiments, a loading of a conversion material, such as sulfur, in a structure (or in a cathode that includes a structure) can be > 50 wt%. > 55 wt%, > 60 wt%, or > 65 wt%, e.g., about 69 wt%, and, in some embodiments, no more than 80 wt%. In some embodiments, a structure (or cathode that includes a structure) has a low loading of a conversion material, such as sulfur, (e.g., < 3 mg/cm²). In some embodiments, a structure (or cathode that includes a structure) has a high loading of sulfur (e.g.. > 3 mg/cm²). Accordingly, a structure may be included in (e.g., form, when loaded with a conversion material) a cathode for a lithium-sulfur battery. In some embodiments, sulfur hosted is in a structure that includes a graphene and a carbon nitride included in a cathode of a battery', where the sulfur converts between elemental sulfur and a lithium sulfide during electrochemical cycling of the battery’.

[0054] In some embodiments, a structure is included in a hybrid cathode that further includes an inorganic sulfide-based solid material (e.g., electrolyte). In various embodiments, a hybrid cathode includes a cathode, such as a graphene and carbon nitride material loaded with sulfur (e.g., CN-NG/S), and an electrolyte, such as an argyrodite-type compound like Liy-xPSe-xXx (where X = Cl, Br, or I). A hybrid cathode may be made of a cathode and an electrolyte. A cathode may be made of a graphene and a carbon nitride material (e.g., a hybridized carbon nitride and graphene) (e.g., in the form of sheets of a carbon nitride and a graphene) loaded with a conversion material, such as sulfur (e.g.. CN- NG/S).

[0055] A graphene and a carbon nitride may be hybridized together in a structure, for example as a result of a formation process used, such as pyrolysis. A (e.g., hybridized) graphene and carbon nitride structure may be bonded to an inorganic sulfide-based solid material (e.g.. electrolyte), such as an argyrodite-type compound. In some embodiments, a characteristic binding energy between a structure including a carbon nitride and a graphene and an inorganic sulfide-based solid material (e.g., electrolyte) is at least -2 meV/(atom*A²), for example at least -3 meV/(atom*A²) or at least -3.5 meV/(atom*A²). In some embodiments, a characteristic distance between a surface of an inorganic sulfide-based solid material and a structure including a carbon nitride and a graphene is no more than 2.5 A (e.g., no more than 2 A). In some embodiments, a characteristic binding energy between particles each including a carbon nitride and a graphene and an inorganic sulfide-based solid material (e.g., electrolyte) is at least -2 meV/(atom*A²), for example at least -3 meV/(atom*A²) or at least -3.5 meV/(atom*A²). In some embodiments, a characteristic distance between a surface of an inorganic sulfide-based solid material and particles each including a carbon nitride and a graphene is no more than 2.5 A (e.g., no more than 2 A). Without wishing to be bound to any particular theory', tight electronic binding and/or close physical proximity' (in direct physical contact) of a structure that includes a carbon nitride and a graphene may contribute to reduced inorganic sulfide-based solid material (e.g., electrolyte) degradation (e.g., oxidation), for example during electrochemical cycling. [0056] In various embodiments, a graphene includes an atomically thin sheet of carbon arranged in primarily a honeycomb lattice. A graphene may be doped, for example doped with an element, such as nitrogen. There may be one or more oxygen- and/or hydrogen-containing functional groups throughout the lattice. Examples of these functional groups include carbonyl, carboxyl, hydroxide, and epoxide groups.

[0057] In various embodiments, a carbon nitride is a compound containing carbon and nitrogen with a two-dimensional sheet-like morphology and polycyclic aromatic structure. Thus, a graphene and/or a carbon nitride included in a structure may each be considered to be individually two-dimensional in some embodiments. In some embodiments, a carbon nitride is graphitic carbon nitride. Graphitic carbon nitride (g-ChN-i) can be formed by, for example, polymerization of various compounds such as cyanamide, dicyandiamide, and melamine.

[0058] Compositions that include a structure that includes a graphene and a carbon nitride and an inorganic sulfide-based solid material may be formed by combining the structure and the material together. The combining may result in the structure and the material being in direct physical contact. For example, the structure may be disposed in (e.g., dispersed in) the material. The combining may include grinding (e.g.. hand grinding) and/or pulverizing (e.g., simultaneously) the structure and the material, for example by providing precursor material (e.g., of a larger size) together.

[0059] A structure may be formed by pyrolyzing a carbon-nitride precursor, such as, for example, dicyandiamide, together with a graphene precursor, such as, for example, graphene oxide. The precursors may be mixed (e.g., in a slurry or paste) and freeze dned before pyrolizing. In some embodiments, the pyrolyzing results in a carbon-nitride precursor doping a graphene (e.g., dicyandiamide releasing ammonia that N dopes a graphene). The pyrolyzing may hybridize a graphene and a carbon nitride together (e.g., in a stacked sheet configuration). Forming the structure may include loading sulfur into the structure, for example using melt-diffusion. An inorganic sulfide-based solid material may be formed by combining (e.g., by grinding) precursors, such as, for example, lithium sulfide, phosphorus pentasulfide, and lithium chloride, at a target ratio (e.g., under inert atmosphere, such as Ar atmosphere). The precursors may then be pressed into a pellet (e.g., under vacuum) and sintered (e.g., at at least 200 °C, at least 300 °C, at least 400 °C, or at least 500 °C) for a period of time (e.g., at least 1 h, at least 2 h, at least 3 h, at least 5 h, or at least 7 h). A ramp rate for the sintering may be at least 0. 1 °C/min and no more than 1 °C/min.

[0060] A method of making battery may include spreading a composition resulting from combining a structure that includes a graphene and a carbon nitride and an inorganic sulfide-based solid material on a first side of a substrate (e g., a separator). The composition and substrate may then be pressed together. For example, such pressing may occur at a pressure of at least one ton (e g., at least two tons or at least three tons) for a period of time (e.g., for at least a minute, at least two minutes, at least three minutes, or at least five minutes). A substrate, such as a separator made of an inorganic sulfide-based solid material, may be formed by pressing the material (e.g., originally in particle form). For example, such pressing may occur at a pressure of at least one ton (e.g., at least two tons) for a period of time (e.g., for at least 30 seconds or at least one minute). The method may further include contacting (e.g., pressing) an anode (e.g., comprising lithium, such as, for example, a lithium-indium alloy) to a second side of the substrate that is opposite the first side of the substrate. The resulting structure may be encased, for example thereby forming a coin cell.

Materials Compositions and Structures [0061] Graphitic carbon nitride (g-CsNr) is a promising material used in Li-S batteries due to its interaction with sulfur species. Graphitic carbon nitride’s typical electrical conductivity alone may not satisfy the requirements of battery operation. Accordingly, it may be combined with other conductive agents. As shown in FIG. 1, g-CslSU and N -doped graphene both have two-dimensional nanosheet structures. By stacking and combining both ty pes of nanosheets, a three-dimensional, continuous, conductive network can be obtained, according to illustrative embodiments of the present disclosure. In some embodiments, g-CsISh 10 and N-graphene 12 may be stacked to form CN-NG 14. In some embodiments, adding sulfur and applying a melt-diffusion method results in CN-NG/S 16. [0062] In some embodiments, a composite material combining g-CsNr and N-doped graphene (CN-NG) may be synthesized through pyrolysis of precursors (i.e., uniformly mixed dicyandiamide and graphene oxide). In some embodiments, during a high- temperature treatment, such as pyrolysis, polymerization of dicyandiamide may release ammonia which may in turn dope N into graphene. In some embodiments, mixing the resulting CN-NG composite with sulfur and applying a melt-diffusion method may result in CN-NG/S.

Synthesis and Assembly Methods

Synthesis of Graphene and Carbon Nitride Structure and Sulfur Loading

[0063] FIG. 8 is a flow chart illustrating an exemplary method 20 for synthesizing CN-NG 14 and CN-NG/S 16, according to illustrative embodiments of the present disclosure. In step 22, dicyandiamide and silica colloidal solution are added to a graphene oxide aqueous solution. For example, the quantity of dicyandiamide may be between 500 mg and 1500 mg, for example about 900 mg. For example, the silica colloidal solution may comprise AS-30 colloid solution or may comprise a colloidal solution of silica particles suspended in water at between 10 wt% and 50 wt% loading, for example about a 30 wt% loading, where the silica particles have a diameter of approximately between 5 nm and 30 nm, for example about 12 nm. For example, the quantity of silica colloidal solution may be between 5 g and 20 g, for example about 9.6 g. For example, the graphene oxide aqueous solution may have a concentration of between 0.1 mg/mL and 10 mg/mL, for example about 1 mg/mL, and the quantity of graphene oxide aqueous solution may be between 200 mL and 600 mL, for example about 400 mL. [0064] Referring still to FIG. 8, in step 24 the mixture formed in step 22 may be sonicated. For example, the sonication time may be about 2 h. In step 26, the sonicated mixture is stirred. For example the stirring time may be about 5 h. In step 28, the stirred mixture may be heated to evaporate enough of the water content to form a thick paste. For example, after the heating step, the proportion of water that may be evaporated may be about 80%. In step 30, the paste is freeze-dried to obtain a precursor. In step 32, the freeze-dried precursor may be annealed. For example, the annealing temperature may be between 400 °C and 700 °C, such as about 550 °C; the temperature ramping rate may be between 1°C min'¹ and 10°C min'¹, such as about 4 °C min'¹; and the annealing time may be between 1 h and 6 h, such as about 4 h. In step 34, the annealed precursor is etched with HF and dried. In step 36, CN-NG is obtained. In step 38, CN-NG is mixed with sulfur (e.g., elemental sulfur powder) and heated. For example, the heating temperature may be between 120°C and 200°C, such as about 155 °C; the heating time may be between 10 h and 24 h, such as about 18 h. In step 40, CN-NG/S is obtained.

[0065] Examples of suitable synthesis methods for structures that include a carbon nitride (e.g., g-CsN4) and a graphene (e.g., N-doped graphene) are found in and/or can be adapted from processes found in Pang, et al. “A Comprehensive Approach Towards Stable Lithium-Sulfur Batteries with High Volumetric Energy Density/’ Adv. Energy Mater., 7: 1601630 - 1601638 (2017).

Synthesis of Argyrodite-Type Compounds

[0066] FIG. 9 is a flow chart showing a method 50 for synthesizing an argyroditetype compound, such as Li5.5PS4.5Cl15, according to illustrative embodiments of the present disclosure. In step 52, a mixture may be formed by combining lithium sulfide, phosphorus pentasulfide, and lithium chloride. In step 54, the mixture may be ground in a mortar at a target ratio under Ar atmosphere to form the desired compound. In step 56, the ground mixture may be pressed into a pellet under Ar atmosphere. In step 58, the pellet may be sealed under vacuum. In step 60, the pellet may be sintered. For example, the sintering temperature may be between 400 °C and 700 °C, such as about 550°C; the heating ramp rate may be betw een 0.1 °C min'¹ and 2 °C min'¹, such as about 0.5 °C min'¹; and the sintering time may be between 5 h and 10 h, such as about 7 h. In step 62, Li5.5PS45CI1.5 may be obtained. Assembly of All-Solid-State Lithium-Sulfur Battery

[0067] FIG. 10 is a flow chart illustrating an exemplary' method 70 for assembling an ASSLSB, according to illustrative embodiments of the present disclosure. In step 72, CN- NG/S and Li5.5PS4.5Ch 5 may be combined to form a mixture in a particular mass ratio. For example, the mass ratio may be between 1 :2 and 2:1, such as about 1 : 1. In step 74, the mixture formed in step 72 may be subjected to hand grinding. For example, hand grinding may occur for a duration of between 60 min and 120 min, such as about 90 min. In step 76, a CN-NG/S / Li5.5PS4.5Cli.5 composition (e.g., powder) for a hybrid cathode may be obtained. In step 78, a mass of Lis 5PS45CI1 5 may be pressed into a pellet. For example, the mass of L15.5PS4.5CI1.5 may be between 50 mg and 100 mg, such as about 70 mg. For example, the mass of Li5.5PS4.5Cli.5 may be pressed in a die with diameter between 5 mm and 25 mm, such as a 10 mm die; the force of pressing may be between 1 ton and 5 tons, such as about 2 tons; and the duration of pressing may be between 30 seconds and 5 min, such as about 1 min. In step 80, a Lis.sPS .sCli.s separator may be obtained.

[0068] Referring still to FIG. 10, in step 82 the CN-NG/S / Li5.5PS4.5d15 hybrid cathode composition (e.g., powder) may be spread on a surface of the Li5.5PS4.5Cl1.5 separator. For example, the spreading step may be achieved using a manual tool or a mechanical tool or an automated tool. In step 84, the hybrid cathode composition and separator may be pressed together to form a hybrid cathode disposed on a separator. For example, the pressing may be at a force of between 1 ton and 5 tons, such as about 3 tons; the duration of pressing may be between 2 min and 10 min, such as about 5 min. In step 86, a piece of Li/In alloy that may be used as an anode may be attached on an opposite side of the Li5.5PS4.5Cli.5 separator and may be pressed together. For example, the pressing may be at a force of between 0.5 tons and 5 tons, such as about 1 ton. In step 88, the die may be sealed in a stainless steel casing. In step 90, screws are fastened on the casing by applying torque. For example, the torque may be between 5 Nm and 15 Nm, such as 10.7 Nm. In step 92, an all-solid state LiS battery is obtained.

[0069] FIG. 11 is a schematic illustration of an assembled ASSLSB 100, according to illustrative embodiments of the present disclosure. In some embodiments, a hybrid cathode 102 may include a CN-NG/S / Li5.5PS4.5Q1 5 composite; a separator and electrolyte 104 may include Li5.5PS4.5d15; and an anode 106 may include a Li/In alloy; or any combination thereof. In certain embodiments, Li/In alloys have a molar ratio in a range of 0.4-0.8. In certain embodiments, an Li/In anode has a potential of about 0.6 V vs. Li/Li+ (e.g., due to a molar ratio in a range of 0.4-0.8. An Li/In anode may have a thickness of, for example, 10 pm to 300 pm (e.g., 100 pm to 200 pm. e.g., 125 pm - 175 pm). In some embodiments, the cathode 102 and anode 106 are connected to a circuit with a device 108 for charging and/or discharging the ASSLSB 100. In some embodiments, the assembled ASSLSB 100 illustrated in FIG. 11 may be assembled using the steps show n in FIG. 10. Total thickness of an ASSLSB (exclusive of casing) may be. for example, in a range of 50 pm to 1 mm (e.g.. 250 pm to 750 pm) (e.g., 500 pm to 700 pm). A hybrid cathode may- have a thickness, for example, in a range of 20 pm to 300 pm (e.g., 50 pm to 250 pm). An ASSLSB, anode, and/or hybrid cathode may have a thickness that is greater or less than these respective ranges.

Performance of All-Solid-State Lithium-Sulfur Batteries

[0070] In some embodiments, ASSLSBs may be assembled using CN-NG/S as cathode, Li5.5PS4.5d15 as electrolyte and separator, and Li/In alloy as anode (0.6 V versus Li/Li⁺). In some embodiments, the steps shown in FIG. 10 may be used to assemble a similar ASSLSB with a resulting structure similar to the one shown in FIG. 11.

[0071] An assembled ASSLSB may be tested for its performance as a battery by conducting galvanostatic cycling. For example, galvanostatic cycling may be conducted in the voltage range of 1.4 - 3.1 V vs. Li/Li⁺, or in the voltage range of 1.0 - 3.5 V vs. Li/Li⁺. For example, galvanostatic cycling may be conducted using a BioLogic VMP3 electrochemical work station, or on another electrochemical work station.

EXAMPLES

[0072] In order that the application may be more fully understood, the following examples are set forth. It should be understood that these examples are for illustrative purposes only' and are not to be construed as limiting in any manner.

Example 1: Elemental Analysis and Composition of CN-NG/S

[0073] The present example describes elemental analysis and composition of a sample of CN-NG/S synthesized using the method summarized in FIG. 1. [0074] FIG. 2 is a plot showing a thermogravimetric analysis (TGA) curve of CN- NG/S, according to illustrative embodiments of the present disclosure. The TGA plot shows weight loss as a function of temperature from room temperature to just below 600°C. There is a steep decrease in mass between about 150°C and about 250°C corresponding to loss of sulfur, indicating that sulfur content in CN-NG/S may be as high as 69 wt%.

Example 2: Performance of ASSLSB with 1.66 mg cm'² Sulfur Loading

[0075] The present example describes the electrochemical performance of an ASSLSB with sulfur loading of 1.66 mg cm'² at C/10. In this example, sulfur loading is calculated using mass ratio of sulfur to structure that includes a graphene (N-doped graphene in this example) and a carbon nitride (g-CsN-i in this example) (CN-NG/S in this example). [0076] The ASSLSB in this example was fabricated using CN-NG/S as the cathode, Li5.5PS45Cl1.5 as the electrolyte and separator, and Li/In alloy as the anode (0.6 V vs.

Li/Li⁺). At the cathodic side, CN-NG/S was thoroughly mixed with Lis 5PS45CI1.5 at a mass ratio of 1 : 1. In FIGs. 3A-B, the electrochemical performance of this ASSLSB with sulfur loading of 1.66 mg cm'² at a rate of C/10 is shown. FIG. 3 A shows voltage profiles of this ASSLSB for different discharge cycles, and FIG. 3B shows its cycling performance, with the capacity for charge and discharge cycles plotted on the left vertical axis, and the Coulombic efficiency on the right vertical axis. The horizontal axis shows the number of cycles. The results show the ASSLSB delivers stable charge and discharge plateaus w ith an initial discharge capacity of 888.3 mAh g'¹. The capacity initially increases, up to a maximum of 1134.9 mAh g ¹, which may be ascribed to the redistribution and utilization of large sulfur particles initially found in the composite after synthesis. After 53 cycles, the battery still maintained a capacity⁷ of 988.3 mAh g'¹, indicating stable performance at high sulfur content.

Example 3: Performance of ASSLSB with 3.44 mg cm'² Sulfur Loading

[0077] The present example describes electrochemical performance of an ASSLSB with 3.44 mg cm'² sulfur loading and cycling at 0.1 C. In this example, sulfur loading is calculated using mass ratio of sulfur to structure that includes a graphene (N-doped graphene in this example) and a carbon nitride (g-CsN4 in this example) (CN-NG/S in this example). [0078] The ASSLSB in this example was fabricated using CN-NG/S as the cathode, Li5.5PS4.5d15 as the electrolyte and separator, and Li/In alloy as the anode (0.6 V vs.

Li/Li⁺). The long-term cycling performance was evaluated under an elevated sulfur loading of 3.44 mg cm'² as shown in FIG. 4. The capacity for charging and discharging is plotted on the left vertical axis, and the Coulombic efficiency on the right vertical axis. The horizontal axis shows the number of cycles. The cycling performance shows that this battery can deliver a high initial areal capacity of 2.62 mAh cm'², with a similar increasing trend. After 180 cycles, a capacity of 1.78 mAh cm'² is maintained, suggesting good cyclability.

Example 4: Performance of ASSLSB with 6.8 mg cm'² and 7.63 mg cm'² Sulfur Loading

[0079] The present example describes electrochemical performance of an ASSLSB with 6.8 mg cm'² sulfur loading and cycling at C/20. In this example, sulfur loading is calculated using mass ratio of sulfur to structure that includes a graphene (N-doped graphene in this example) and a carbon nitride (g-CsN 4 in this example) (CN-NG/S in this example). [0080] For practical applications, battery performance at high sulfur loading is desirable for achieving high energy density. In this example, the ASSLSB was fabricated with 6.8 mg cm'² sulfur loading and was tested by cycling at a rate of C/20. As shown in FIG. 5A, the cell demonstrates a similar one-plateau discharge voltage profile as was seen in the case of 1.66 mg cm'² sulfur loading (see FIG. 3 A). This plot is a typical discharge curve for an ASSLSB in which Li2S is directly formed by sulfur without any formation of polysulfides. The cycling performance data is shown in FIG. 5B, where the capacity at charging and discharging cycles are plotted on the left vertical axis, the Coulombic efficiency is plotted on the right vertical axis, and the horizontal axis shows cycle number. These results indicate that this battery can deliver 4.94 mAh cm'² at the initial discharge, with good capacity retention over 50 cycles.

Example 5: Performance of ASSLSB with 7.63 mg cm'² Sulfur Loading at 60°C [0081] The present example describes electrochemical performance of an ASSLSB with 7.63 mg cm'² sulfur loading and cycling at C/20 and 60°C temperature. In this example, sulfur loading is calculated using mass ratio of sulfur to structure that includes a graphene (N-doped graphene in this example) and a carbon nitride (g-C3N4 in this example) (CN-NG/S in this example).

[0082] Further testing of a battery with 7.63 mg cm'² sulfur loading was performed at 60°C. as shown in FIGs. 6A-B. The battery showed much better electrochemical performance at 60°C, due to the enhanced Li⁺ diffusion and reaction kinetics, as compared to an equivalent battery at room temperature. FIG. 6A shows voltage profiles, while FIG. 6B shows cycling performance. This battery' demonstrated smaller polarization (difference between charge and discharge plateaus) and higher initial conversion efficiency of 96.7%, as compared to an equivalent battery at room temperature. This battery’ can deliver 11.3 mAh cm'² at the initial cycle, and an excellent capacity' retention of 91.7% over 39 cycles (calculated based on the first cycle), which is higher than previously reported solid-state Li- S batteries.

Example 6: Comparison of ASSLSBs with Different Cathode Materials and the Effect on Electrolyte Degradation

[0083] The present example describes electrochemical performance for three different ASSLSBs. each fabricated with a different cathode material, to demonstrate the suppression of electrolyte degradation when compared to batteries with conventional cathode materials.

[0084] The electrochemical performance of the ASSLSBs fabricated with CN-NG cathodes derives not only from the highly electron-conductive networked based on CN-NG and the high ionic conductivity of Li5.5PS4.5Cl1.5, but also from the effective suppression of electrolyte degradation by CN-NG during the oxidation process (i.e., during the charging process). To investigate the role of suppressing electrolyte decomposition, fresh ASSLSB cells were directly charged to 3.5 V vs. Li/In (i.e., 4. 1 V vs. Li/Li⁺) in order to eliminate the capacity contribution of sulfur, which can only provide capacity during the discharge process. ASSLSBs were fabricated using CN-NG, NG, and VC as the cathodes, using similar methods as described above, and tested for their electrochemical performance using similar procedures as described above.

[0085] FIG. 7A shows the direct initial charge profiles of the three batteries (i.e., with CN-NG, NG, and VC as the cathodes). These results indicate that the cell with the CN- NG composite cathode shows the highest charge plateau and the lowest decomposition capacity of argyrodite-type Li5.5PS4.5Cl 1.5.

[0086] FIG. 7B shows the differential capacity analysis of the three batteries, which provides more details on the electrolyte decomposition process and demonstrates a stronger contrast between the CN-NG cathode and the other two materials, NG and VC. In this plot, the Li5.5PS4.5Cli.5 electrolyte in the batteries with NG and VC cathodes both experience a two-step decomposition process with two differential capacity peaks. Additionally, the Li_5.5PS45CI1.5 in the battery with the VC cathode shows the lowest oxidation potential and highest capacity, indicating it can easily decompose on the surface of porous carbon. The first peak (which occurs at 2.42 V for VC and 2.52 V for NG) corresponds to Li5.5PS4.5Cl 1.5 decomposing into LisPS4, LiCl and S. The second peak (which occurs at 2.94 V for VC and 2.95 V for NG) corresponds to LisPSr further oxidizing to S and PzS?⁴’. However, in the case of the battery with the CN-NG composite cathode, there is only one wide and weak peak at 2.90 V, demonstrating very slow oxidation kinetics, and thus strong suppression of the degradation of Li5.5PS4.5d15, which are both beneficial to ASSLSB cycling.

[0087] FIGs. 14A-B illustrate performance of an ASSLSB that includes a hybrid cathode including simple NG/S and an electrolyte made of an argyrodite-type compound, with a sulfur loading of 1.59 mg cm’² cycled at C/10. As can be seen in FIG. 14A in particular, electrolyte decomposition has already begun by the 10^th cycle. Without wishing to be bound by any particular theory, this rapid decomposition of the electrolyte occurs at least in part due to weak binding energy between the argyrodite-type compound and the NG. Such degradation has not been observed in hybrid cathodes that utilize carbon nitride and graphene structures as disclosed herein.

Example 7: Performance of ASSLSB with 7.46 mg cm’² Sulfur Loading at 45°C

[0088] The present example describes electrochemical performance of an ASSLSB with 7.46 mg cm’² sulfur loading and cycling at C/20 and 45°C. In this example, sulfur loading is calculated using mass ratio of sulfur to structure that includes a graphene (N- doped graphene in this example) and a carbon nitride (g-CsN in this example) (CN-NG/S in this example).

[0089] Further testing of a battery’ assembled with CN-NG/S cathodes and 7.46 mg cm’² sulfur loading was performed at C/20 cycling and 45 °C operating temperature, as shown in FIGs. 12A-C. The ratio between the CN-NG/S and Lis 5PS45CI1.5 was 50:50. The plot in FIG. 12A shows voltage profiles for the initial discharge, and 1^st and 2^nd cycles. The plot in FIG. 12B shows a voltage profile for the 6^th cycle. The plot in FIG. 12C shows voltage profiles for the 1^st - 21^st cycles. In general, this battery ran well in the first 5 cycles, but a steep voltage drop occurred at the end of discharge starting from the 6^th cycle, and then proceeded to a fast decay.

Example 8: Binding of Inorganic Sulfide-Based Solid Materials and Graphene and Carbon Nitride Structures

[0090] Modeling has shown that a characteristic binding energy between Li TSsCl and a CN-NG may be as high as -3.8 meV/(atom*A²) vs. only -1.71 for LiePSsCl and a simple graphitic carbon. These specific values are given for a (010) face of LiePSsCl but other faces showed similar results, within about 5%. The same modeling has shown a characteristic distance between LiePSsCl and a CN-NG of as low as 1.88 A vs. 2.62 A for a simple graphitic carbon. Without wishing to be bound by any particular theory, tighter binding with CN-NG reduces or prevents oxidation of argyrodite-type compounds (e.g., during electrochemical cycling).

[0091] It is contemplated that methods, compositions, and processes of the disclosure encompass variations and adaptations developed using information from the embodiments described herein. Adaptation and/or modification of the methods, compositions, and processes described herein may be performed, as contemplated by this description.

[0092] Throughout the description, where methods, compositions, and processes are described as having, including, or comprising specific components, or where processes and methods are described as having, including, or comprising specific steps, it is contemplated that, additionally, there are compositions of the present disclosure that consist essentially of, or consist of, the recited components, and that there are processes and methods according to the present disclosure that consist essentially of, or consist of, the recited steps.

[0093] It should be understood that the order of steps or order for performing certain action is immaterial so long as operability is not lost. Moreover, two or more steps or actions may be conducted simultaneously. [0094] The mention herein of any publication, for example, in the Background section, is not an admission that the publication, or description thereof, serves as prior art wi th respect to any of the claims presented herein.

[0095] Documents are incorporated herein by reference as noted. Where there is any discrepancy in the meaning of a particular term, the meaning provided in the Definition section above is controlling.

[0096] Headers have been provided for the convenience of the reader; the presence and/or placement of a header is not intended to limit the scope of the subject matter described herein.

[0097] Certain embodiments of the present disclosure were described above. It is, however, expressly noted that the present disclosure is not limited to those embodiments, but rather the intention is that additions and modifications to what was expressly described in the present disclosure are also included within the scope of the disclosure. Moreover, it is to be understood that the features of the various embodiments described in the present disclosure were not mutually exclusive and can exist in various combinations and permutations, even if such combinations or permutations were not made express, without departing from the spirit and scope of the disclosure. The disclosure has been described in detail with particular reference to certain embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the claimed invention.

Claims

What is claimed:

1. A lithium-sulfur battery (e.g., an all-solid-state Li-S battery ) comprising: an inorganic sulfide-based solid electrolyte; and a structure (e.g., a porous structure) comprising a graphene (e.g., N-doped graphene) and a carbon nitride (e g., graphitic carbon nitride (g-ONfi) (e.g., wherein a mass ratio of the electrolyte and the structure is between 1 :2 and 2: 1, e.g., about 1: 1).

2. The battery of claim 1, further comprising an anode comprising lithium (e.g., a lithium-indium (Li/In) alloy).

3. The battery⁷ of claim 1 or 2, wherein the inorganic sulfide-based solid electrolyte comprises an argyrodite-type compound.

4. The battery of any one of the preceding claims, wherein the inorganic sulfide-based solid electrolyte comprises LiniPn2Sn3Xn4, where X = Cl, Br, or I, and where each of nl, n2, n3, and n4 is > 0.

5. The battery of claim 4, wherein the LiniPn2Sn3Xn4 is Li7-xPS6-_xX_x (e.g., where x = 1.5) (e.g., and wherein X = Cl).

6. The battery of any one of the preceding claims, wherein the structure comprises carbon nitride/N-doped graphene (CN-NG) sheets (e.g., wherein the sheets are porous).

7. The battery⁷ of any one of the preceding claims, wherein the structure comprises stacked sheets of the graphene and the carbon nitride (e.g., wherein the stacked sheets comprise three or more layers of alternating sheets of the graphene and the carbon nitride) (e.g., wherein the sheets are porous).

8. The battery of any one of the preceding claims, wherein the structure forms a continuous conductive network.

9. The batery⁷ of any one of the preceding claims, wherein the graphene and the carbon nitride are hybridized together.

10. The batery of any one of the preceding claims, wherein the structure is a sulfur host in the batery' (e.g., wherein the structure allows the structure to have a high sulfur content, e.g., > 50 wt%, e.g., > 55 wt%, e.g., > 60 wt%, e.g., > 65 wt%, e.g., about 69 wt%) (e.g., wherein the structure is comprised in a cathode and the structure allows the cathode to have a high sulfur content, e.g., > 50 wt%, e.g., > 55 wt%, e.g., > 60 wt%, e.g., > 65 wt%, e.g., about 69 wt%).

11. The batery of any one of the preceding claims, further comprising sulfur hosted in the structure (e.g., sulfur in an elemental form and/or in a lithium sulfide) [e.g., wherein a loading of the sulfur in the structure is > 50 wt%, > 55 wt%, > 60 wt%, or > 65 \\1% (e.g., and no more than 80 wt%)] (e.g., wherein the structure is comprised in a cathode and the cathode has a high sulfur content, e.g., > 50 wt%, e.g., > 55 wt%, e.g., > 60 wt%, e.g., > 65 wt%, e.g.. about 69 wt%).

12. The batery of any one of the preceding claims, comprising a cathode (e.g., a hybrid cathode) comprising the structure (e.g., and at least a portion of the electrolyte if a hybrid cathode).

13. The batery of any one of the preceding claims, wherein the structure is in direct physical contact with the electrolyte.

14. The batery of any one of the preceding claims, wherein the structure comprises a particle (e.g., flake) (e.g., micro-particle or nanoparticle) comprising the graphene and the carbon nitride.

15. The batery of any one of the preceding claims, wherein the structure is disposed in (e.g., dispersed in) the electrolyte.

16. The batery of any one of the preceding claims, comprising a solid separator.

17. The batery⁷ of claim 16, wherein the separator comprises an inorganic sulfide-based solid material.

18. The batery of claim 17, wherein the inorganic sulfide-based solid material is made of an argyrodite-type compound [e.g., wherein the inorganic sulfide-based solid material comprises LiniPn2Sn3Xn4, where X = Cl, Br, or I, and where each of nl, n2, n3, and n4 is > 0 (e.g., wherein the LiniPn2Sn3Xn4 is Li7-_xPSe-_xX_x (e.g., where x = 1.5) (e.g., and wherein X = Cl))].

19. A solid composition for a hybrid cathode, the composition comprising: an inorganic sulfide-based solid material (e.g., electrolyte) (e.g., made of an argyrodite-type compound); and a structure (e.g., a porous structure) [e.g., comprising a particle (e.g., a flake) (e.g., a micro-particle or nanoparticle)] comprising a graphene (e.g., N-doped graphene) and a carbon nitride (e.g., graphitic carbon nitride (g-CsNr))

[e.g., wherein the structure is disposed in (e.g., dispersed in) the inorganic sulfide- based solid electrolyte (e.g., wherein a mass ratio of the material and the structure is between 1 :2 and 2: 1, e.g., about 1 : 1)] [e.g., wherein the composition is a mixture comprising the structure and the material (e.g., a powder)].

20. An all-solid-state lithium-sulfur batery comprising a hybrid cathode made with the composition of claim 19.

21. A lithium-sulfur batery (e.g., an all-solid-state Li-S batery’) comprising: a cathode composition having a porous structure (e.g., sheets) that hosts sulfur, said cathode composition (e.g., said sheets) comprising a graphene (e.g., N-doped graphene) and a carbon nitride (g-CsNr) (e.g., a cathode comprising CN-NG sheets); a solid electrolyte (e.g., and separator) comprising an inorganic argyrodite-ty pe compound [e.g., Li7-_xPSe-_xX_x (e.g., where x = 1.5) (e.g., and wherein X = Cl)]; and an anode comprising lithium (e.g., a lithium-containing alloy, e g., a Li/In alloy).

22. The batery of claim 21, wherein the cathode composition suppresses decomposition of the inorganic sulfide-based solid electrolyte yet has high electrical conductivity [e.g., > 7 S/cm (Siemens per centimeter), e.g., > 10 S/cm, e.g.. about 11.4 S/cm],

23. A method of making a composition for a batery (e.g., a lithium-sulfur batery), the method comprising: combining [e.g.. by grinding (e.g., hand grinding) and/or pulverizing] (i) a structure (e.g., a porous structure) (e.g., sheets, e.g., stacked sheets) comprising a graphene (e.g., N- doped graphene) and a carbon nitride (e.g., graphitic carbon nitride (g-CsNr)) (e.g., in a mass ratio of between 1:2 and 2: 1, e.g., about 1: 1) and (ii) an inorganic sulfide-based solid material such that the structure and the material are in direct physical contact, thereby forming the composition.

24. The method of claim 23, comprising forming the structure prior to the combining, wherein forming the structure comprises pyrolyzing a carbon-nitride precursor and a graphene precursor together (e.g., after freeze dry ing a mixture of the carbon-nitride precursor and the graphene precursor) (e.g., wherein the carbon-nitride precursor is dicyandiamide) (e.g., wherein the graphene precursor is graphene oxide) (e.g., wherein the pyrolyzing dopes the graphene).

25. The method of claim 24, wherein forming the structure comprises loading (e.g., melt-diffusing) sulfur into the structure.

26. The method of any one of claims 23-25, yvherein the inorganic sulfide-based solid material is made of an argyrodite-type compound [e.g., comprises Li_niPn2Sn3Xn4, where X = Cl, Br, or I, and where each of nl, n2, n3, and n4 is > 0 (e.g., Li7-xPSe-xXx (e.g., where x = 1.5) (e.g., and wherein X = Cl))].

27. The method of any one of claims 23-26, comprising disposing (e.g., spreading) the composition on a first side of a substrate (e.g., a separator) [e.g.. wherein the substrate is an inorganic sulfide-based solid material, e.g., made of an argyrodite-type compound (e.g., comprising LiniPn2Sn3Xn4, where X = CL Br, or I, and where each of nl, n2, n3, and n4 is > 0 (e.g., Li₇-xPS6-_xXx (e.g., where x = 1.5) (e.g., and wherein X = Cl)))].

28. The method of claim 27, comprising pressing the composition disposed on the first side of the substrate [e.g., at a pressure of at least one ton (e.g., at least two tons or at least three tons) (e.g., for at least a minute)].

29. The method of claim 27 or claim 28, comprising forming the substrate, wherein forming the substrate comprises pressing an inorganic sulfide-based solid material [e.g., made of an argyrodite-type compound (e.g., comprising LiniPn2SniXn4, where X = Cl, Br, or I, and where each of nl, n2, n3, and n4 is > 0 (e.g., Li7-_xPS6-xX (e.g., where x = 1.5) (e.g., and wherein X = Cl)))] [e.g., at a pressure of at least one ton (e.g., at least two tons) (e.g., for at least 30 seconds)].

30. The method of any one of claims 27-29, comprising contacting (e.g., pressing) an anode comprising lithium (e.g., a lithium-indium alloy) to a second side of the substrate that is opposite the first side of the substrate.

31. The method of claim 30, comprising forming a battery that comprises the composition, the substrate, and the anode (e.g., wherein the substrate is a separator and the batten' comprises a hybrid cathode that comprises the composition, wherein the structure acts as a cathode and the material acts as an electrolyte).

32. A method of using a battery of any one of claims 1-18, 20, and 21, the method comprising charging and/or discharging the battery while the battery is at a temperature of between 50 °C and 70 °C (e.g., about 60 °C).

33. A composition for a hybrid cathode (e g., for use in, or included in, an all-solid-state Li-S battery), the composition comprising: an inorganic sulfide-based solid material (e.g., electrolyte); and a plurality of particles (e.g., porous particles) (e.g., flakes) (e.g., micro-particles and/or nanoparticles) each comprising a graphene (e.g., N-doped graphene) and a carbon nitride (e.g., graphitic carbon nitride (g-CsNf)).

34. The composition of claim 33, wherein a mass ratio of the material and the plurality of particles may be between 1:2 and 2: 1 (e.g., about 1: 1).

35. The composition of claim 33 or claim 34, wherein the inorganic sulfide-based solid material comprises (e.g., is made of) an argyrodite-type compound.

36. The composition of any one of claims 33-35, wherein (i) a characteristic binding energy between the particles and the inorganic sulfide-based solid material is at least -2 meV/(atom*A²) (e.g.. at least -3 meV/(atom*A²) or at least -3.5 meV/(atom*A²)): (ii) a characteristic distance between a surface of the inorganic sulfide-based solid material and each of the particles is no more than 2.5 A (e.g., no more than 2 A); or (iii) both (i) and (ii).

37. The composition of any one of claims 33-36, wherein the graphene and the carbon nitride are hybridized together.

38. The composition of any one of claims 33-37, wherein each of the particles comprises sheets (e.g., stacked sheets) of the graphene and the carbon nitride (e.g., at least one sheet of the graphene and at least one sheet of the carbon nitride in an alternating stack).