Halide-based solid electrolytes and batteries, and methods of making and use thereof

Abstract

Disclosed herein are halide-based solid electrolytes with high ionic conductivity for all-solid-state sodium ion batteries. For example, disclosed herein are solid electrolytes comprising: ABCλ-2x-zDx+y, wherein: A is chosen from Li, Na, K, Mg, Ca, Zn, Al, In, Fe, and combinations thereof; B is chosen from Ca, Mg, Zn, In, V, Nb, Ta, Mn, Ti, Zr, Hf, Fe, Co, Ni, Al, Ga, and combinations thereof; C is chosen from F, Cl, Br, I, and combinations thereof; D is chosen from O, S, Se, Te, and combinations thereof; λ is an integer chosen from 4, 5, and 6, such that the solid electrolyte is charge neutral; 0 < x < 1; 0 < z < 2; and 0 < y < 1.

Description

HALIDE-BASED SOLID ELECTROLYTES AND BATTERIES, AND METHODS OF MAKING AND USE THEREOFCROSS-REFERENCE TO RELATED APPLICATIONSThis application claims the benefit of priority to U.S. Provisional Application No. 63 / 626,232 filed January 29, 2024, which is hereby incorporated herein by reference in its entirety.BACKGROUNDAll-solid-state batteries (ASSBs) are becoming a promising energy storage technology as they bring the safety of state-of-the-art batteries to the next level by replacing the flaming organic liquid electrolytes with nonflammable solid electrolytes (SEs). Inorganic halide-based solid electrolytes have emerged as a game changer because of their fast-conducting characteristics, adequate thermodynamic stability, great deformability, and good oxidative stability. Moreover, solid halide electrolytes have good oxidation stability, based on their high oxidation potential. However, most of the studied halide-based solid electrolytes are based on the Li-ion system, with only a few based on the Na-ion system. Moreover, despite halide-based Na solid electrolytes theoretically having high ionic conductivity, experimentally obtained samples have much lower ionic conductivities compared to their Li counterparts (usually < 0. 1 mS cm-1). Therefore, developing halide-based solid electrolytes with high Na+ionic conductivity is crucial for Na all-solid-state batteries. The compositions, devices, and methods discussed herein address these and other needs.SUMMARYIn accordance with the purposes of the disclosed compositions, devices, and methods as embodied and broadly described herein, the disclosed subject matter relates to halide-based solid electrolyte with high ionic conductivity for all-solid-state sodium ion batteries. For example, disclosed herein are halide-based solid electrolytes and batteries, and methods of making and use thereof.For example, disclosed herein are solid electrolytes comprising:ABC?i-2x-zDx+y wherein: A is chosen from Li, Na, K, Mg, Ca, Zn, Al, hi, Fe, and combinations thereof; B is chosen from Ca, Mg, Zn, In, V, Nb, Ta, Mn, Ti, Zr, Hf, Fe, Co, Ni, Al, Ga, and combinations thereof; C is chosen from F, Cl, Br, I, and combinations thereof; D is chosen from O, S, Se, Te, and combinations thereof; A. is an integer chosen from 4, 5, and 6, such that the solid electrolyte is charge neutral; 0 < x < l; 0 < z < 2; and 0 < y < 1.In some examples, A is chosen from Li, Na, and K; B is chosen from V, Nb, and Ta; and wherein X is 6. In some examples, A is chosen from Li, Na, and K; B is chosen from Mn, Ti, Zr, and Hf; and wherein X is 5. In some examples, A is chosen from Li, Na, and K; B is chosen from Fe, Co, Ni, Al, Ga, and I; and wherein X is 4. In some examples, B is a combination of two of Ca, Mg, Zn, In, V, Nb, Ta, Mn, Ti, Zr, Hf, Fe, Co, Ni, Al, and Ga.In some examples, the solid electrolyte comprises:NaNbaC15a-iO where a is 0.6 to 1.15, such as from 1.0 to 1.15 or from 1.0 to 1.1.In some examples, a is 1, 1.015, 1.030, 1.035, 1.070, or 1.110.In some examples, the solid electrolyte comprises NaNbo.eChO, NaNbo.7Cl2.5O, NaNbo.sChO, NaNbo.85Ch.25O, NaNbo.9Cl3.5O, NaNbo.95Cl3.75O, NaNbCLO, NaNb1.015Cl4.075O, NaNb1.030Cl4.150O, NaNb1.035Cl4.175O, NaNb1.070Cl4.350O, NaNb1.noCl4.550O, or a combination thereof. In some examples, the solid electrolyte comprises NaNbCLO, NaNb1.07Q4.35O, or a combination thereof. In some examples, the solid electrolyte comprises NaNbCLO. In some examples, the solid electrolyte comprises NaNb1.07Cl4.35O.In some examples, wherein the solid electrolyte comprisesNa(NbbTai-b)aC15a-iO where 0 < b < 1 and 0.6 < a < 1. 15.In some examples, b is 0.6, 0.5, 0.4, or 0. In some examples, a is 1. In some examples, a is 1 and b is 0.6, 0.5, 0.4, or 0.In some examples, the solid electrolyte comprises NaNbo.6Tao.4Q4O, NaNbo.5Tao.5G4O, NaNbo.4Tao.6Q4O, NaTaCLO, or a combination thereof. In some examples, the solid electrolyte comprises NaTaCLO.In some examples, the solid electrolyte has been heat treated.In some examples, the solid electrolyte has a Na+ionic conductivity at 30°C of from 1 x 10"3mS cm-1to 20 mS cm1. In some examples, the solid electrolyte has a Na+ionic conductivity at 30°C of 0.5 mS cm1or more. In some examples, the solid electrolyte has a Na+ionic conductivity at 30°C of 1 mS cm'1or more.In some examples, the solid electrolyte has an activation energy of from 0 to 0.7 eV. In some examples, the solid electrolyte has an activation energy 0.3 eV or less. In some examples, the solid electrolyte has an activation energy of 0.25 eV or less.In some examples, the solid electrolyte has an electrochemical stability window of from 2.0 to 4.5 V vs. Na / Na+.Also disclosed herein are methods of making any of the solid electrolytes disclosed herein.In some examples, the method comprises combining a plurality of precursors to form a mixture and ball milling the mixture to form the solid electrolyte. In some examples, the ball milling is performed at a rate of from 100 to 2000 rpm for an amount of time of from 10 minutes to 100 hours. In some examples, the ball milling is performed at a rate of from 250 to 750 rpm for an amount of time of from 1 hour to 24 hours.In some examples, the method further comprises heat treating the solid electrolyte, wherein heat treating comprises heating the solid electrolyte at a temperature for an amount of time. In some examples, the temperature is from 50°C to 500°C, such as from 100°C to 400°C. In some examples, the amount of time is from 1 minute to 100 hours, such as from 1 minute to 24 hours.In some examples, the method further comprises ball milling after heat treatment. In some examples, the ball milling is performed at a rate of from 100 to 2000 rpm for an amount of time of from 10 minutes to 100 hours.In some examples, the method comprises combining a plurality of precursors to form a mixture, and heat treating the mixture in an inert environment to form the solid electrolyte. In some examples, heat treating the mixture comprises heating the mixture at a temperature for an amount of time. In some examples, the temperature is from 50°C to 500°C, such as from 100°C to 400°C. In some examples, the amount of time is from 1 minute to 100 hours, such as from 1 minute to 24 hours. In some examples, the method further comprises ball milling after heat treatment. In some examples, the ball milling is performed at a rate of from 100 to 2000 rpm for an amount of time of from 10 minutes to 100 hours.Also disclosed herein are systems comprising any of the solid electrolytes disclosed herein.Also disclosed herein are articles comprising any of the solid electrolytes disclosed herein.Also disclosed herein are devices comprising any of the solid electrolytes disclosed herein. In some examples, the device is an energy storage device, such as a battery. In some examples, the device is a battery, such as a solid state battery. In some examples, the device is a capacitor or a supercapacitor. In some examples, the device is an electrochemical cell.Also disclosed herein are electrochemical cells comprising any of the solid electrolytes disclosed herein.Also disclosed herein are electrochemical cells comprising a first solid-state electrolyte comprising:AB C A-2x-z D.x+ , wherein: A is chosen from Li, Na, K, Mg, Ca, Zn, Al, In, Fe, and combinations thereof; B is chosen from Ca, Mg, Zn, In, V, Nb, Ta, Mn, Ti, Zr, Hf, Fe, Co, Ni, Al, Ga, and combinations thereof; C is chosen from F, Cl, Br, I, and combinations thereof; D is chosen from O, S, Se, Te, and combinations thereof; A is an integer chosen from 4, 5, and 6, such that the first solid-state electrolyte is charge neutral; 0 < x < l; 0 < z < 2; and 0 < y < 1. In some examples, A is chosen from Li, Na, and K; B is chosen from V, Nb, and Ta; and wherein A, is 6. In some examples, A is chosen from Li, Na, and K; B is chosen from Mn, Ti, Zr, and Hf; and wherein A is 5. In some examples, A is chosen from Li, Na, and K; B is chosen from Fe, Co, Ni, Al, Ga, and I; and wherein is 4. In some examples, B is a combination of two of Ca, Mg, Zn, In, V, Nb, Ta, Mn, Ti, Zr, Hf, Fe, Co, Ni, Al, and Ga.In some examples, the first solid-state electrolyte comprises any of the solid electrolytes disclosed herein.In some examples, the electrochemical cell further comprises an anode material. In some examples, the anode material includes Li, Na, K, Zn, Mg, Al, Si, Ag, Li alloys, Li intermetallics, Li compounds, Na alloys, Na intermetallics, Na compounds, K alloys, K intermetallics, K compounds, Al alloys, Al intermetallics, Al compounds, Si alloys, Si intermetallics, Si compounds, Ag alloys, Ag intermetallics, Ag compounds, or any combination thereof. In some examples, the anode material comprises Li, Na, K, Zn, Mg, Li alloys, Li intermetallics, Li compounds, Na alloys, Na intermetallics, Na compounds, K alloys, K intermetallics, K compounds, or any combination thereof. In some examples, the anode material includes MqSn, wherein M is chosen from Li, Na, K, Zn, and Mg, and where q is from 0.5 to 3. In some examples, the anode material comprises MySn wherein M is chosen from Li, Na, K, Zn, and Mg.In some examples, the electrochemical cell further comprises a cathode material. In some examples, the cathode material is a metal, a ceramic, or a composite. In some examples, the cathode material comprises Cu, C, graphite, Na, K, Li, Mg, Ca, Al, layered oxides, vanadium- based cathode, sulfur-based cathode, spinels, olivines, or any combination thereof. In some examples, the cathode material comprises MCrCF wherein M is chosen from Li, Na, K. Zn and Mg. In some examples, the cathode material includes MxTMC , wherein 0.6 < x < 1, and M is chosen from Li, Na, K, Zn, and Mg, and TM is a transition metal such as Ti, Nb, Ni, Mn, Co, Fe, Al, Cr, Zr and their mixture. In some examples, the cathode material includes MxTM xO ,wherein 0 < x < 2, and TM is a transition metal such as Ti, Nb, Ni, Mn, Co, Fe, Al, Cr, Zr and their mixture.In some examples, the electrochemical cell further comprises a second solid-state electrolyte comprising an anolyte. In some examples, the second solid-state electrolyte comprises MPSC1, wherein M is chosen from Li, Na, K. Zn and Mg. In some examples, the second solid electrolyte includes MxPSyClz, wherein x, y, and z are each independently from 0 to 7, M is chosen from Li, Na, K. Zn and Mg. In some examples, MPSC1 comprises Na2.9PS3.9Clo.!.In some examples, the first solid-state electrolyte further comprises a conductive paste.In some examples, the electrochemical cell is a battery, such as a solid-state battery.In some examples, the electrochemical cell is a solid-state battery, such as an all-solid- state battery.In some examples, the electrochemical cell exhibits a coulombic efficiency of 99% or more for 100 cycles or more. In some examples, the electrochemical cell exhibits a coulombic efficiency of 99% or more for 500 cycles or more.In some examples, the electrochemical cell exhibits a capacity retention of 70% or more for 500 cycles or more. In some examples, the electrochemical cell exhibits a capacity retention of 70% or more for 1000 cycles or more. In some examples, the electrochemical cell exhibits a capacity retention of 80% or more for 500 cycles or more.In some examples, the electrochemical cell exhibits rate capacity retention of 20% or more at 1C compared to C / 10 rate.Also disclosed herein are systems comprising one or more of the electrochemical cells disclosed herein. In some examples, the system is an energy storage system.Also disclosed herein are articles comprising one or more of the electrochemical cells disclosed herein. In some examples, the article is a vehicle, such as a hybrid electric vehicle or an all-electric vehicle. In some examples, the article is a vehicle, such as an electric bike, an electric scooter, an electric drone, or an electric airplane. In some examples, the article comprises an electronic device, such as a portable electronic device, a laptop, a watch, a cell phone, or a medical device. In some examples, the article is an energy storage device.Additional advantages of the disclosed compositions, devices, and methods will be set forth in part in the description which follows, and in part will be obvious from the description. The advantages of the disclosed compositions, devices, and methods will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosedsystems and methods, as claimed.The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.BRIEF DESCRIPTION OF THE FIGURESThe accompanying figures, which are incorporated in and constitute a part of this specification, illustrate several aspects of the disclosure, and together with the description, serve to explain the principles of the disclosure.Figure lA-Figure IE. Synthesis of Na solid-state electrolytes with high ionic conductivities. (Figure 1 A) A picture of the synthesized product after ball-milling for 10 hours. (Figure IB, Figure 1C) The impedance spectroscopy of the O-doped NaNbCle with different molar ratios of the two precursors. (Figure ID) The calculated room temperature ionic conductivity of different samples. (Figure IE) The temperature-dependent ionic conductivities of a few selected samples with decent room temperature ionic conductivities. The activation energies are calculated and listed.Figure 2A-Figure 2D. Synthesizing O2-doped NaNbCle solid-state electrolytes with high ionic conductivities. (Figure 2A) A picture of the synthesized product after ball-milling for 10 hours. (Figure 2B) Electrochemical impedance spectroscopy of the NaNbCle with and without O2-doping. (Figure 2C) The room temperature ionic conductivity of solid-state electrolytes with different amounts of O2-doping. (Figure 2D) The temperature-dependent ionic conductivities of a few selected samples with decent room temperature ionic conductivities. The smallest activation energy is 0.23 eV.Figure 3A-Figure 3B. (Figure 3 A) XRD pattern of the two synthesized solid-state electrolytes. A standard XRD pattern of NaNbCle is shown for comparison. (Figure 3B) The evolution of XRD pattern of NaNbCEO during heating.Figure 4A-Figure 4D. Characterization of the stability of NaNbCUO. (Figure 4A, Figure 4B) The cyclic voltammetry curves with a scan rate of 0.5 mV / s. (Figure 4C) The impedance of NaNbCEO before and after storing test at 70 °C for half an hour. (Figure 4D) The impedance of NaNbCUO and NaPSCl (Na2.9PS3.9Clo.!) composite before and after storing for 24 hours.Figure 5A-Figure 5F. Materials characterization of lab-synthesized NaNbCle and NaNb1.07Cl4.35O powders. (Figure 5A) Crystal structure schematic of NaNbCle. (Figure 5B) A SEM image of NaNb1.07Cl4.35O powder. (Figure 5C) XRD pattern of the three types of solid-state electrolyte powders. A standard NaNbCle XRD card (PDF#34-0929) was inserted for comparison. (Figure 5D)1H chemical shifts of the NaNb1.07Q4.35O sample before and after heattreatment, and (Figure 5E)23Na chemical shifts of the three solid-state electrolyte powders measured by solid-state NMR. (Figure 5F) Raman spectra of the three solid-state electrolyte samples collected under inert conditions with a 532 nm laser.Figure 6A-Figure 6D. Electrochemical evaluation of NaNbCle and NaNb1.07Cl4.35O. (Figure 6A) Nyquist plot of NaNbCle (NNC), NaNb1.07Q4.35O (NNCO), and heat treated- NaNb1 07Cl435O (NNCO-HT) solid-state electrolytes measured at 30 °C. (Figure 6B) The ionic conductivity of NaNb1.07Cl4.35O after heat treatment at different temperatures. The NaNb1.07Cl4.35O sample was held at each temperature for lOh, and the impedances were measured at 30 °C. (Figure 6C) Arrhenius plot of the three solid-state electrolytes. Impedances were measured at five different temperatures, and the activation energies can be extracted. (Figure 6D) Ionic conductivity and activation energy of sodium halide solid-state electrolytes reported in the last decade.Figure 7A-Figure 7B. Energy distribution for Na+ions on different interstitial sites in (Figure 7A) NbCh and (Figure 7B) the NbCh structure with 20% of Cl’ sites substituted with O2(NbCUO), as estimated using the PLMF model. For the undoped system, the standard deviation of the energy distribution is 28.5 meV / atom, while that for the O2’-doped system is 16.3 meV / atom. Inset panels show the NbCb and NbCUO structures and interstitial sites.Figure 8A-Figure 8E. The electrochemical performance of solid-state batteries using the NaNb1.07Cl4.35O solid-state electrolytes. (Figure 8A) The schematic of the solid-state batteries with all components highlighted. (Figure 8B) The LSV curves of the heat treated- NaNb1.07Q4.35O solid-state electrolyte at a scan rate of 0.5 mV s-1. (Figure 8C) The rate capability of the all-solid-state battery tested at room temperature. The voltage range is from 2.5 V - 4.3 V. (Figure 8D) The charge and discharge curves of the all-solid-state battery after different number of cycles. (Figure 8E) The capacity retention and Coulombic efficiency of the solid-state batteries during cycling. The NaNb1.07Q4.35O solid-state electrolytes before and after heating were both tested for comparison.Figure 9A-Figure 9B. (Figure 9A) The impedance of NaNbxClsx iO with x is from 1.000 to 1.110. (Figure 9B) The ionic conductivity of NaNbxClsx iO with x from 0.67 to 1.5.Figure 10. In-situ XRD of NaNb1.07Cl4.35O at various temperatures.Figure 11. The activation energy of NaNbxClsx iO with x from 1.000 to 1.070.Figure 12. Electronic conductivity measurement for the NaNb1.07Cl4.35O solid-state electrolyte sample.Figure 13. The comparison of the electronic conductivity of the synthesized NaNb1.07Cl4.35O solid-state electrolyte with other halide-based Na+solid-state electrolytes.Figure 14. Nyquist plot of NaNbxTai-xCEO before (indicated in blue) and after (indicated in pink) heat treatment at 70 °C for Ih with different x ratios (x = 0.6, 0.5, 0.4, and 0).Figure 15. Nyquist plot of NaNbxTai-xC O before (indicated in blue) and after (indicated in pink) heat treatment at 100 °C for Ih with different x ratios (x = 0.6, 0.5, 0.4, and 0).Figure 16. Arrhenius plot of NaNbxTai-xChO before heat treatment with different x ratios (x = 0.6, 0.5, 0.4, and 0).Figure 17. The impedance of NaNb1.07Cl4.35O before and after exposure to air for 24h.Figure 18A-Figure 18B. The impedance of NaNb1.07Cl4.35O before and after heat treatment under 50 °C and 70 °C for half an hour.Figure 19A-Figure 19F. Nyquist plots of Na2Sn and NasPS4 two layers before and after contact for 1 week (Figure 19A and Figure 19D), Na3PS4 and heat treated-NaNb1.07Cl4.35O two layers before and after contact for 1 week (Figure 19B and Figure 19E), and heat treated- NaNb1.07Cl4.35O and doped-Na2 / 3Nii / 3Mn2 / 3O2 two layers before and after contact for 1 week (Figure 19C and Figure 19F).Figure 20. Cycle performance of all-solid-state batteries using the NaNb1.07Cl4.35O and heat treated-NaNb1.07Cl4.35O as the solid-state electrolytes.Figure 21. C lx, O lx, Cl 2p, Nb 3d, and Na lx XPS spectra of cathode composite with NaNb1.07Cl4.35O and heat treated- NaNb1.07Cl4.35O solid electrolytes at the initial state and after three cycles in all solid state batteries.DETAILED DESCRIPTIONThe compositions, devices, and methods described herein may be understood more readily by reference to the following detailed description of specific aspects of the disclosed subject matter and the Examples included therein.Before the present compositions, devices, and methods are disclosed and described, it is to be understood that the aspects described below are not limited to specific synthetic methods or specific reagents, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting.Also, throughout this specification, various publications are referenced. The disclosures of these publications in their entireties are hereby incorporated by reference into this application in order to more fully describe the state of the art to which the disclosed matter pertains. The references disclosed are also individually and specifically incorporated by reference herein for the material contained in them that is discussed in the sentence in which the reference is relied upon.General DefinitionsIn this specification and in the claims that follow, reference will be made to a number of terms, which shall be defined to have the following meanings.Throughout the description and claims of this specification, the word “comprise” and other forms of the word, such as “comprising” and “comprises,” means including but not limited to, and is not intended to exclude, for example, other additives, components, integers, or steps.As used in the description and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a composition” includes mixtures of two or more such compositions, reference to “an agent” includes mixtures of two or more such agents, reference to “the component” includes mixtures of two or more such components, and the like.“Optional” or “optionally” means that the subsequently described event or circumstance can or cannot occur, and that the description includes instances where the event or circumstance occurs and instances where it does not.Ranges can be expressed herein as from “about” one particular value, and / or to “about” another particular value. By “about” is meant within 5% of the value, e.g., within 4, 3, 2, or 1% of the value. When such a range is expressed, another aspect includes from the one particular value and / or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another aspect.It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint. Similarly, numerical ranges recited herein by endpoints include subranges subsumed within that range (e.g., 1 to 5 includes 1-1.5, 1.5-2, 2-2.75, 2.75-3, 3-3.90, 3.90-4, 4-4.24, 4.24-5, 2-5, 3-5, 1-4, 2-4, etc.).Values can be expressed herein as an “average” value. “Average” generally refers to the statistical mean value.As used herein, the term "substantially" means that the subsequently described event or circumstance completely occurs or that the subsequently described event or circumstance generally, typically, or approximately occurs.Still further, the term “substantially” can in some aspects refer to at least about 80 %, at least about 85 %, at least about 90 %, at least about 91 %, at least about 92 %, at least about 93 %, at least about 94 %, at least about 95 %, at least about 96 %, at least about 97 %, at least about 98 %, at least about 99 %, or about 100 % of the stated property, component, composition,or other condition for which substantially is used to characterize or otherwise quantify an amount.In other aspects, as used herein, the term “substantially free,” when used in the context of a composition or component of a composition that is substantially absent, is intended to refer to an amount that is then about 1 % by weight, e.g., less than about 0.5 % by weight, less than about 0.1 % by weight, less than about 0.05 % by weight, or less than about 0.01 % by weight of the stated material, based on the total weight of the composition.As used herein, the terms “substantially identical reference composition,” “substantially identical reference article,” or “substantially identical reference electrochemical cell” refer to a reference composition, article, or electrochemical cell comprising substantially identical components in the absence of an inventive component. In another exemplary aspect, the term "substantially," in, for example, the context "substantially identical reference composition," or “substantially identical reference article,” or “substantially identical reference electrochemical cell” refers to a reference composition, article, or an electrochemical cell comprising substantially identical components and wherein an inventive component is substituted with a common in the art component.“Exemplary” means “an example of’ and is not intended to convey an indication of a preferred or ideal embodiment. “Such as” is not used in a restrictive sense, but for explanatory purposes.It is understood that throughout this specification the identifiers “first” and “second” are used solely to aid in distinguishing the various components and steps of the disclosed subject matter. The identifiers “first” and “second” are not intended to imply any particular order, amount, preference, or importance to the components or steps modified by these terms.References in the specification and concluding claims to parts by weight of a particular element or component in a composition denotes the weight relationship between the element or component and any other elements or components in the composition or article for which a part by weight is expressed. Thus, in a compound containing 2 parts by weight of component X and 5 parts by weight component Y, X and Y are present at a weight ratio of 2:5, and are present in such ratio regardless of whether additional components are contained in the compound.A weight percent (wt. %) of a component, unless specifically stated to the contrary, is based on the total weight of the formulation or composition in which the component is included.The term “or combinations thereof” as used herein refers to all permutations and combinations of the listed items preceding the term. For example, “A, B, C, or combinations thereof’ is intended to include at least one of: A, B, C, AB, AC, BC, or ABC, and if order isimportant in a particular context, also BA, CA, CB, CBA, BCA, ACB, BAC, or CAB. Continuing with this example, expressly included are combinations that contain repeats of one or more item or term, such as BB, AAA, AB, BBC, AAABCCCC, CBBAAA, CAB ABB, and so forth. The skilled artisan will understand that typically there is no limit on the number of items or terms in any combination, unless otherwise apparent from the context.Some references, which may include various patents, patent applications, and publications, are cited in a reference list and discussed in the disclosure provided herein. The citation and / or discussion of such references is provided merely to clarify the description of the present disclosure and is not an admission that any such reference is “prior art” to any aspects of the present disclosure described herein. In terms of notation, “[n]” corresponds to the nQ1reference in the list. All references cited and discussed in this specification are incorporated herein by reference in their entireties and to the same extent as if each reference was individually incorporated by reference.In describing example embodiments, terminology will be resorted to for the sake of clarity. It is intended that each term contemplates its broadest meaning as understood by those skilled in the art and includes all technical equivalents that operate in a similar manner to accomplish a similar purpose. It is also to be understood that the mention of one or more steps of a method does not preclude the presence of additional method steps or intervening method steps between those steps expressly identified. Steps of a method may be performed in a different order than those described herein without departing from the scope of the present disclosure. Similarly, it is also to be understood that the mention of one or more components in a device or system does not preclude the presence of additional components or intervening components between those components expressly identified.The expressions "ambient temperature" and "room temperature" as used herein are understood in the art and refer generally to a temperature from 20°C to 35 °C.As used herein, the term “composition” is intended to encompass a product comprising the specified ingredients in the specified amounts, as well as any product which results, directly or indirectly, from a combination of the specified ingredients in the specified amounts.It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or intervening elements may be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements present. Other words used to describe the relationship between elements or layers should beinterpreted in a like fashion (e.g., "between" versus "directly between," "adjacent" versus "directly adjacent," "on" versus "directly on").While aspects can be described and claimed in a particular statutory class, such as the system statutory class, this is for convenience only and one of ordinary skill in the art will understand that each aspect of the present invention can be described and claimed in any statutory class. Unless otherwise expressly stated, it is in no way intended that any method or aspect set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not specifically state in the claims or descriptions that the steps are to be limited to a specific order, it is in no way intended that an order be inferred in any respect. This holds for any possible non-express basis for interpretation, including matters of logic with respect to arrangement of steps or operational flow, plain meaning derived from grammatical organization or punctuation, or the number or type of aspects described in the specification.In view of the described processes and compositions, hereinbelow are described certain more particularly described aspects of the inventions. These particularly recited aspects should not, however, be interpreted to have any limiting effect on any different claims containing different or more general teachings described herein, or that the “particular” aspects are somehow limited in some way other than the inherent meanings of the language and formulas literally used therein.Solid ElectrolytesDescribed herein is the addition of second-phase mechanical toughening agents to the bulk of LLZO and other inorganic solid-state electrolytes (SSEs) to prevent fracture and dendrite growth during service. The agents also aid in the densification of the solid-state electrolyte during sintering resulting in higher final compact density for a given processing regiment. The additives also improve the ionic conductivity of the solid-state electrolyte as a result of the denser structure with less pores and other deleterious interfaces.Solid state electrolytes are prone to fracture and growth of dendrites during service, leading to early failure. The approach described herein solves this problem.Disclosed herein is a solid electrolyte composition that exhibits increased sodium ionic conductivity of known solid electrolytes by mixing different types of anions. The composition is developed based on the understanding that the energy of mobile ions (Li+, Na+, K+, etc.) at the tetrahedral site and octahedral site depends on the anion in the crystal structure. For example, when the anion is S2‘, the energy of mobile ions at octahedral sites is higher than that at tetrahedral sites. By comparison, when the anion is CT, the energy of mobile ions at octahedralsites is lower than that at tetrahedral sites. As a mobile ion generally transports between the octahedral site and the tetrahedral site, reducing the energy difference between them will reduce the ion transport energy barrier and thus increase the ionic conductivity.The developed strategy has the potential to be applied to other halide-based solid-state electrolytes to improve their ionic conductivity, promoting the development of all solid-state batteries.In some examples, the solid electrolyte includes: ABCz-2x-zDx+y, wherein: A is chosen from Li, Na, K, Mg, Ca, Zn, Al, In, Fe, and combinations thereof, B is chosen from Ca, Mg, Zn, In, V, Nb, Ta, Mn, Ti, Zr, Hf, Fe, Co, Ni, Al, Ga, and combinations thereof, C is chosen from F, Cl, Br, I, and combinations thereof, D is chosen from O, S, Se, Te, and combinations thereof, A is an integer chosen from 4, 5, and 6, such that the solid electrolyte is charge neutral, 0 < x < 1, 0 < z < 2, and 0 < y < 1.In some examples, A is chosen from Li, Na, and K; B is chosen from V, Nb, and Ta; and wherein A is 6.In some examples, A is chosen from Li, Na, and K; B is chosen from Mn, Ti, Zr, and Hf; and wherein A is 5.In some examples, A is chosen from Li, Na, and K; B is chosen from Fe, Co, Ni, Al, Ga, and I; and wherein A is 4.In some examples, B is a combination of two of Ca, Mg, Zn, In, V, Nb, Ta, Mn, Ti, Zr, Hf, Fe, Co, Ni, Al, and Ga.Examples include general formulas of various halide-based solid electrolytes for all solid-state batteries (ASSBs). The general formula of such solid-state electrolytes can be:(1) ABC6-2x-zDx+y(0 < x < 1, 0 < z < 2, 0 < I < y) where A can be Li, Na, and K; B can be V, Nb, and Ta; C can be F, Cl, Br, and I; D can be O, S, Se, and Te;(2) ABC5-2x-zDx+y(0 < x < l, 0 < z < 2, 0 < l < y) where A can be Li, Na, and K; B can be Mn, Ti, Zr, and Hf; C can be F, Cl, Br, and I; D can be O, S, Se, and Te;(3) ABC4-2x-zDx+y(0 < x < l, 0 < z < 2, 0 < l < y) where A can be Li, Na, and K; B can be Fe, Co, Ni, Al, Ga, and I; C can be F, Cl, Br, and I; D can be O, S, Se, and Te; wherein mobile ion (A) can also be Mg2+, Ca2+, Zn2+, Al3+, In3+, and Fe2+. The stoichiometric ratio of B, C, and D (listed in (1) - (3)) may be adjusted accordingly to help maintain the charge neutrality of the synthesized materials.In some examples, the solid electrolyte comprises:NaNbaC15-iO where a is from 1.0 to 1.15.For example, a can be 0.6 or more (e.g., 0.65 or more, 0.70 or more, 0.75 or more, 0.80 or more, 0.85 or more, 0.90 or more, 0.95 or more, 1.0 or more, 1 .005 or more, 1.010 or more,1.015 or more, 1.020 or more, 1.025 or more, 1.030 or more, 1.035 or more, 1.040 or more,1.045 or more, 1.050 or more, 1.055 or more, 1.060 or more, 1.065 or more, 1.070 or more,1.075 or more, 1.080 or more, 1.085 or more, 1.090 or more, 1.095 or more, 1.10 or more, 1.11 or more, 1.12 or more, or 1.13 or more). In some examples, a can be 1.15 or less (e.g., 1.14 or less, 1.13 or less, 1.12 or less, 1.11 or less, 1.10 or less, 1.095 or less, 1.090 or less, 1.085 or less,1.080 or less, 1.075 or less, 1.070 or less, 1.065 or less, 1.060 or less, 1.055 or less, 1.050 or less, 1.045 or less, 1.040 or less, 1.035 or less, 1.030 or less, 1.025 or less, 1.020 or less, 1.015 or less, 1.010 or less, 1.0 or less, 0.95 or less, 0.90 or less, 0.85 or less, 0.80 or less, 0.75 or less, or 0.70 or less). The value of a can range from any of the minimum values described above to any of the maximum values described above. For example, a can be from 0.6 to 1.15 (e.g., from 0.6 to 0.9, from 0.9 to 1.15, from 0.6 to 0.8, from 0.8 to 1.0, from 1.0 to 1.15, from 0.6 to 1.10, from 0.65 to 1.15, or from 0.65 to 1.10). In some examples, a is from 1.0 to 1.15. In some examples, a is from 1.0 to 1.1. In some examples, a is 1, 1.015, 1.030, 1.035, 1.070, or 1.110.In some examples, the solid electrolyte comprises NaNbo.eChO, NaNbo.7Cl2.5O, NaNbo.sChO, NaNbo.s5Cl3.25O, NaNbo.9Cl3.5O, NaNbo.95Cl3.75O, NaNbCl4O, NaNb1.015Cl4.075O, NaNb1.030Cl4.150O, N Nb1.035Cl4.175O, NaNb1.070Cl4.350O, NaNb1.noCl4.550O, or a combination thereof. In some examples, the solid electrolyte comprises NaNbCUO, NaNb1.07Cl4.35O, or a combination thereof. In some examples, the solid electrolyte comprises NaNbCUO. In some examples, the solid electrolyte comprises NaNb1.07Cl4.35O.In some examples, the solid electrolyte comprises:Na(NbbTai-b)aC15a-iO where 0 < b < 1 and 0.6 < a < 1.15.For example, a can be 0.6 or more (e.g., 0.65 or more, 0.70 or more, 0.75 or more, 0.80 or more, 0.85 or more, 0.90 or more, 0.95 or more, 1.0 or more, 1.005 or more, 1.010 or more,1.015 or more, 1.020 or more, 1.025 or more, 1.030 or more, 1.035 or more, 1.040 or more,1.045 or more, 1.050 or more, 1.055 or more, 1.060 or more, 1.065 or more, 1.070 or more,1.075 or more, 1.080 or more, 1.085 or more, 1.090 or more, 1.095 or more, 1.10 or more, 1.11 or more, 1.12 or more, or 1.13 or more). In some examples, a can be 1.15 or less (e.g., 1.14 or less, 1.13 or less, 1.12 or less, 1.11 or less, 1.10 or less, 1.095 or less, 1.090 or less, 1.085 or less,1.080 or less, 1.075 or less, 1.070 or less, 1.065 or less, 1.060 or less, 1.055 or less, 1.050 or less,1.045 or less, 1.040 or less, 1.035 or less, 1.030 or less, 1.025 or less, 1.020 or less, 1.015 or less,1.010 or less, 1.0 or less, 0.95 or less, 0.90 or less, 0.85 or less, 0.80 or less, 0.75 or less, or 0.70or less). The value of a can range from any of the minimum values described above to any of the maximum values described above. For example, a can be from 0.6 to 1.15 (e.g., from 0.6 to 0.9, from 0.9 to 1.15, from 0.6 to 0.8, from 0.8 to 1.0, from 1.0 to 1.15, from 0.6 to 1.10, from 0.65 to 1.15, or from 0.65 to 1.10). In some examples, a is 1.For example, b can be 0 or more (e.g., 0.01 or more, 0.05 or more, 0.1 or more, 0.15 or more, 0.2 or more, 0.25 or more, 0.3 or more, 0.35 or more, 0.4 or more, 0.45 or more, 0.5 or more, 0.55 or more, 0.6 or more, 0.65 or more, 0.7 or more, 0.75 or more, 0.8 or more, 0.85 or more, or 0.9 or more). In some examples, b is 1 or less (e.g., 0.95 or less, 0.9 or less, 0.85 or less, 0.8 or less, 0.75 or less, 0.7 or less, 0.65 or less, 0.6 or less, 0.55 or less, 0.5 or less, 0.45 or less, 0.4 or less, 0.35 or less, 0.3 or less, 0.25 or less, 0.2 or less, 0.15 or less, 0.1 or less, or 0.05 or less). The value of b can range from any of the minimum values described above to any of the maximum values described above. For example, b can be from 0 to 1 (e.g., from 0 to 0.5, from 0.5 to 1, from 0 to 0.2, from 0.2 to 0.4, from 0.4 to 0.6, from 0.6 to 0.8, from 0.8 to 1, from 0.1 to 1, from 0 to 0.9, or from 0.1 to 0.9). In some examples, b is 0.6, 0.5, 0.4, or 0. In some examples, a is 1 and b is 0.6, 0.5, 0.4, or 0.In some examples, the solid electrolyte comprises NaNbo.6Tao.4Q4O, NaNbo.5Tao.5G4O, NaNbo.4Tao.6Q4O, NaTaCFO, or a combination thereof. In some examples, the solid electrolyte comprises NaTaCUO.In some examples, the solid electrolyte has been heat treated.In some examples, the solid electrolyte has a Na+ionic conductivity at 30°C of 1 x 10"3mS cm-1or more (e.g., 2 x 10"3mS cm-1or more, 3 x 10"3mS cm-1or more, 4 x 10"3mS cm-1or more, 5 x 10'3mS cm-1or more, 6 x 10'3mS cm-1or more, 7 x 10"3mS cm-1or more, 8 x 10’3mS cm-1or more, 9 x IO-3mS cm-1or more, 1 x IO-2mS cm-1or more, 2 x 10‘2mS cm-1or more, 3 x 10‘2mS cm-1or more, 4 x 10’2mS cm-1or more, 5 x 10’2mS cm-1or more, 6 x 10’2mS cm-1or more, 7 x 10'2mS cm-1or more, 8 x 10'2mS cm-1or more, 9 x 10"2mS cm-1or more, 0.1 mS cm-1or more, 0.2 mS cm-1or more, 0.3 mS cm-1or more, 0.4 mS cm-1or more, 0.5 mS cm1or more, 0.6 mS cm or more, 0.7 mSor more, 0.8 mS cm1or more, 0.9 mS cm-1or more, 1 mS cm-1or more, 2 mS cm-1or more, 3 mS cm-1or more, 4 mS cm-1or more, 5 mS cm-1or more, 6 mS cm-1or more, 7 mS cm-1or more, 8 mS cm-1or more, 9 mS cm-1or more, 10 mS cm-1or more, 11 mS cm-1or more, 12 mS cm-1or more, 13 mS cm-1or more, 14 mS cm-1or more, 15 mS cm-1or more, 16 mS cm-1or more, 17 mS cm-1or more, or 18 mS cm-1or more). In some examples, the solid electrolyte has a Na+ionic conductivity at 30°C of 20 mS cm-1or less (e.g., 19 mS cm-1or less, 18 mS cm-1or less, 17 mS cm-1or less, 16 mS cm-1or less, 15 mS cm-1or less, 14 mS cm-1or less, 13 mS cm-1or less, 12 mS cm-1or less, 11 mS cm"1or less, 10 mS cm-1or less, 9 mS cm-1or less, 8 mS cm-1or less, 7 mS cm-1or less, 6 mS cm-1or less, 5 mS cm-1or less, 4 mS cm-1or less, 3 mS cm-1or less, 2 mS cm-1or less, 1 mS cm-1or less, 0.9 mS cm-1or less, 0.8 mS cm-1or less, 0.7 mS cm-1or less, 0.6 mS cm-1or less, 0.5 mS cm-1or less, 0.4 mS cm-1or less, 0.3 mS cm-1or less, 0.2 mS cm-1or less, 0.1 mS cm-1or less, 9 x 10‘2mS cm-1or less, 8 x 10‘2mS cm-1or less, 7 x 10‘2mS cm-1or less, 6 x 10'2mS cm-1or less, 5 x 10'2mS cm-1or less, 4 x 10’2mS cm-1or less, 3 x 10’2mS cm-1or less, 2 x 10’2mS cm-1or less, 1 x 10"2mS cm-1or less, 9 x 10"3mS cm-1or less, 8 x 10"3mS cm-1or less, 7 x 10"3mS cm-1or less, 6 x 10"3mS cm-1or less, 5 x 10"3mS cm-1or less, 4 x 10"3mS cm-1or less, 3 x 10'3mS cm-1or less, or 2 x 10'3mS cm-1or less). The Na+ionic conductivity at 30°C of the solid electrolyte can range from any of the minimum values described above to any of the maximum values described above. For example, the solid electrolyte can have a Na+ionic conductivity at 30°C of from 1 x 10'3mS cm-1to 20 mS cm'1(e.g., from 1 x 10'3to 1 x 101mS cm1, from 1 x 101to 20 mS cm1, from 1 x 10'3to 1 x 10'2mS cm1, from 1 x 10'2to 1 x 101mS cm1, from 1 x 10'1to 1 mS cm1, from 1 to 20 mS cm1, from 5 x 10‘3to 20 mS cm1, from 1 x 10'3to 20 mS cm1, from 5 x 10'2to 20 mS cm1, from 1 x 101to 20 mS cm1, from 5 x 101to 20 mS cm1, from 1 x 10'3to 15 mS cm1, from 5 x 10'3to 15 mS cm1, or from 9 x 10'3to 10 mS cm1). In some examples, the solid electrolyte has a Na+ionic conductivity at 30°C of 0.5 mS cm'1or more. In some examples, the solid electrolyte has a Na+ionic conductivity at 30°C of 1 mS cm'1or more.In some examples, the solid electrolyte has an activation energy of 0 eV or more (e.g., 0.05 eV or more, 0.1 eV or more, 0.15 eV or more, 0.2 eV or more, 0.25 eV or more, 0.3 eV or more, 0.35 eV or more, 0.4 eV or more, 0.45 eV or more, 0.5 eV or more, 0.55 eV or more, or 0.6 eV or more). In some examples, the solid electrolyte has an activation energy of 0.7 eV or less (e.g., 0.65 eV or less, 0.6 eV or less, 0.55 eV or less, 0.5 eV or less, 0.45 eV or less, 0.4 eV or less, 0.35 eV or less, 0.3 eV or less, 0.25 eV or less, 0.2 eV or less, 0.15 eV or less, or 0.1 eV or less). The activation energy of the solid electrolyte can range from any of the minimum values described above to any of the maximum values described above. For example, the solid electrolyte can have an activation energy of from 0 to 0.7 eV (e.g., from 0 to 0.35 eV, from 0.35 to 0.7 eV, from 0 to 0.25 eV, from 0.25 to 0.5 eV, from 0.5 to 0.75 eV, from 0 to 0.6 eV, from 0 to 0.5 eV, from 0 to 0.4 eV, from 0 to 0.3 eV, from 0 to 0.2 eV, from 0 to 0.1 eV, from 0.05 to 0.7 eV, or from 0.05 to 0.6 eV). In some examples, the solid electrolyte has an activation energy 0.3 eV or less. In some examples, the solid electrolyte has an activation energy of 0.25 eV or less.In some examples, the solid electrolyte has an activation energy of from 0 to 0.3 eV. In some examples, the solid electrolyte has an activation energy of from 0 to 0.25 eV.In some examples, the solid electrolyte has an electrochemical stability window of 2.0 V or more vs. Na / Na+(e.g., 2.25 V or more, 2.5 V or more, 2.75 V or more, 3 V or more, 3.25 V or more, 3.5 V or more, 3.75 V or more, 4 V or more, or 4.25 V or more). In some examples, the solid electrolyte has an electrochemical stability window of 4.5 V or less vs. Na / Na+(e.g., 4.25 V or less, 4 V or less, 3.75 V or less, 3.5 V or less, 3.25 V or less, 3 V or less, 2.75 V or less, or 2.5 V or less). The electrochemical stability window of the solid electrolyte can range from any of the minimum values described above to any of the maximum values described above. For example, the solid electrolyte can have an electrochemical stability window of from 2.0 to 4.5 V vs. Na / Na+(e.g., from 2.0 to 3.25 V, from 3.25 to 4.5 V, from 2 to 2.5 V, from 2.5 to 3 V, from 3 to 3.5 V, from 3.5 to 4 V, from 4 to 4.5 V, from 2 to 4.25 V, from 2.25 to 4.5 V, or from 2.25 to 4.25 V).Methods of Making and Use of the Solid ElectrolyteAlso disclosed herein are methods of making any of the solid electrolytes described herein. For example, the methods can comprise a mechanochemical synthesis. In some examples, the method comprises combining a plurality of precursors to form a mixture and ball milling the mixture to form the solid electrolyte.In some examples, the ball milling is performed at a rate of 100 rpm or more (e.g., 150 rpm or more, 200 rpm or more, 250 rpm or more, 300 rpm or more, 350 rpm or more, 400 rpm or more, 450 rpm or more, 500 rpm or more, 600 rpm or more, 700 rpm or more, 800 rpm or more, 900 rpm or more, 1000 rpm or more, 1250 rpm or more, 1500 rpm or more, or 1750 rpm or more). In some examples, the ball milling is performed at a rate of 2000 rpm or less (e.g., 1750 rpm or less, 1500 rpm or less, 1250 rpm or less, 1000 rpm or less, 900 rpm or less, 800 rpm or less, 700 rpm or less, 600 rpm or less, 500 rpm or less, 450 rpm or less, 400 rpm or less, 350 rpm or less, 300 rpm or less, 250 rpm or less, 200 rpm or less, or 150 rpm or less). The rate of the ball milling can range from any of the minimum values described above to any of the maximum values described above. For example, the ball milling can be performed at a rate of from 100 to 2000 rpm (e.g., from 100 to 1000 rpm, from 1000 to 2000 rpm, from 100 to 500 rpm, from 500 to 1000 rpm, from 1000 to 1500 rpm, from 1500 to 2000 rpm, from 150 to 2000 rpm, from 100 to 1750 rpm, from 150 to 1750 rpm, from 175 to 1250 rpm, from 200 to 1000 rpm, or from 100 to 750 rpm). In some examples, the ball milling is performed at a rate of from 250 to 750 rpm.In some examples, the ball milling is performed for an amount of time of 10 minutes or more (e.g., 15 minutes or more, 20 minutes or more, 25 minutes or more, 30 minutes or more, 40 minutes or more, 50 minutes or more, 1 hour or more, 1.5 hours or more, 2 hours or more, 2.5 hours or more, 3 hours or more, 3.5 hours or more, 4 hours or more, 4.5 hours or more, 5 hours or more, 5.5 hours or more, 6 hours or more, 7 hours or more, 8 hours or more, 9 hours or more, 10 hours or more, 12 hours or more, 14 hours or more, 16 hours or more, 18 hours or more, 20 hours or more, 22 hours or more, 24 hours or more, 30 hours or more, 36 hours or more, 42 hours or more, 48 hours or more, 60 hours or more, 72 hours or more, 84 hours or more, or 96 hours or more). In some examples, the ball milling is performed for an amount of time of 100 hours or less (e.g., 96 hours or less, 84 hours or less, 72 hours or less, 60 hours or less, 48 hours or less, 42 hours or less, 36 hours or less, 30 hours or less, 24 hours or less, 22 hours or less, 20 hours or less, 18 hours or less, 16 hours or less, 14 hours or less, 12 hours or less, 10 hours or less, 9 hours or less, 8 hours or less, 7 hours or less, 6 hours or less, 5.5 hours or less, 5 hours or less, 4.5 hours or less, 4 hours or less, 3.5 hours or less, 3 hours or less, 2.5 hours or less, 2 hours or less, 1.5 hours or less, 1 hour or less, 50 minutes or less, 40 minutes or less, 30 minutes or less, 25 minutes or less, or 20 minutes or less). The amount of time that the ball milling is performed can range from any of the minimum values described above to any of the maximum values described above. For example, the ball milling can be performed for an amount of time of from 10 minutes to 100 hours (e.g., from 10 minutes to 48 hours, from 48 hours to 100 hours, from 10 minutes to 1 hour, from 1 hour to 10 hours, from 10 hours to 100 hours, from 15 minutes to 100 hours, from 30 minutes to 100 hours, from 1 hour to 100 hours, from 10 minutes to 96 hours, from 10 minutes to 72 hours, from 10 minutes to 48 hours, from 10 minutes to 24 hours, from 15 minutes to 96 hours, or from 1 hour to 24 hours). In some examples, the ball milling can be performed for an amount of time of from 1 hour to 24 hours.In some examples, the ball milling is performed at a rate of from 100 to 2000 rpm for an amount of time of from 10 minutes to 100 hours.In some examples, the ball milling is performed at a rate of from 250 to 750 rpm for an amount of time of from 1 hour to 24 hours.In some examples, the method further comprises heat treating the solid electrolyte, wherein heat treating comprises heating the solid electrolyte at a temperature for an amount of time.In some examples, the heat treatment temperature is 50°C or more (e.g., 75°C or more, 100°C or more, 125 °C or more, 150°C or more, 175°C or more, 200°C or more, 225 °C or more, 250°C or more, 275°C or more, 300°C or more, 325°C or more, 350°C or more, 375°C or more,400°C or more, 425°C or more, or 450°C or more). In some examples, the heat treatment temperature is 500°C or less (e.g., 475°C or less, 450°C or less, 425°C or less, 400°C or less, 375°C or less, 350°C or less, 325°C or less, 300°C or less, 275°C or less, 250°C or less, 225°C or less, 200°C or less, 175°C or less, 150°C or less, 125°C or less, or 100°C or less). The heat treatment temperature can range from any of the minimum values described above to any of the maximum values described above. For example, the heat treatment temperature can be from 50°C to 500°C (e.g., from 50°C to 275°C, from 275°C to 500°C, from 50°C to 150°C, from 150°C to 250°C, from 250°C to 35O°C, from 350°C to 500°C, from 100°C to 500°C, from 50°C to 450°C, from 100°C to 450°C, or from 100°C to 400°C). In some examples, the heat treatment temperature can be from 100°C to 400°C.In some examples, the amount of time the solid electrolyte is heat treated is 1 minute or more (e.g., 2 minutes or more, 3 minutes or more, 4 minutes or more, 5 minutes or more, 10 minutes or more, 15 minutes or more, 20 minutes or more, 25 minutes or more, 30 minutes or more, 40 minutes or more, 50 minutes or more, 1 hour or more, 1.5 hours or more, 2 hours or more, 2.5 hours or more, 3 hours or more, 3.5 hours or more, 4 hours or more, 4.5 hours or more, 5 hours or more, 5.5 hours or more, 6 hours or more, 7 hours or more, 8 hours or more, 9 hours or more, 10 hours or more, 12 hours or more, 14 hours or more, 16 hours or more, 18 hours or more, 20 hours or more, 22 hours or more, 24 hours or more, 30 hours or more, 36 hours or more, 42 hours or more, 48 hours or more, 60 hours or more, 72 hours or more, 84 hours or more, or 96 hours or more). In some examples, the amount of time the solid electrolyte is heat treated is 100 hours or less (e.g., 96 hours or less, 84 hours or less, 72 hours or less, 60 hours or less, 48 hours or less, 42 hours or less, 36 hours or less, 30 hours or less, 24 hours or less, 22 hours or less, 20 hours or less, 18 hours or less, 16 hours or less, 14 hours or less, 12 hours or less, 10 hours or less, 9 hours or less, 8 hours or less, 7 hours or less, 6 hours or less, 5.5 hours or less, 5 hours or less, 4.5 hours or less, 4 hours or less, 3.5 hours or less, 3 hours or less, 2.5 hours or less, 2 hours or less, 1.5 hours or less, 1 hour or less, 50 minutes or less, 40 minutes or less, 30 minutes or less, 25 minutes or less, 20 minutes or less, 15 minutes or less, 10 minutes or less, or 5 minutes or less). The amount of time that the solid electrolyte is heat treated can range from any of the minimum values described above to any of the maximum values described above. For example, the amount of time that the solid electrolyte is heat treated can be from 1 minute to 100 hours (e.g., from 1 minute to 48 hours, from 48 hours to 100 hours, from 1 minute to 1 hour, from 1 hour to 10 hours, from 10 hours to 100 hours, from 5 minutes to 100 hours, from 15 minutes to 100 hours, from 30 minutes to 100 hours, from 1 hour to 100 hours, from 1 minute to 96 hours, from 1 minutes to 72 hour, from 1 minute to 48 hours, from 1 minute to 24 hours, from1 minutes to 96 hours, or from 10 minutes to 24 hours). In some examples, the amount of time that the solid electrolyte is heat treated can be from 1 minute to 24 hours.In some examples, the solid electrolyte is heat treated at a temperature of from 50°C to 500°C for an amount of time of from 1 minute to 100 hours. In some examples, the solid electrolyte is heat treated at a temperature of from 100°C to 400°C for an amount of time of from 1 minute to 24 hours.In some examples, the method further comprises ball milling after heat treatment. The ball milling after heat treatment can, for example, be performed at a rate of from 100 to 2000 rpm for an amount of time of from 10 minutes to 100 hours.In some examples, the method can comprise a solid-state synthesis. In some examples, the method comprises combining a plurality of precursors to form a mixture, and heat treating the mixture in an inert environment to form the solid electrolyte.In some examples, the method comprises heat treating the mixture, wherein heat treating comprises heating the mixture at a temperature for an amount of time. In some examples, the temperature is from 50°C to 500°C, such as from 100°C to 400°C. In some examples, the amount of time is from 1 minute to 100 hours, such as from 1 minutes to 24 hours.In some examples, the method further comprises ball milling after heating treatment. The ball milling can, for example, be performed at a rate of from 100 to 2000 rpm for an amount of time of from 10 minutes to 100 hours.Also disclosed herein are methods of use of any of the solid electrolytes described herein. For example, also disclosed herein are methods of use of any of the solid electrolytes described herein, for example in a system, an article, and / or a device.Also disclosed herein are systems, articles, and / or devices comprising any of the solid electrolytes disclosed herein. For example, the device can be an energy storage device, such as a battery. In some examples, the device is a battery, such as a solid state battery.In some examples, the device is an electrochemical cell.In some examples, the device is a capacitor or a supercapacitor.Electrochemical CellsAlso disclosed herein are electrochemical cells, for example comprising any of the solid electrolytes described herein.Also disclosed herein are electrochemical cells including: a first solid electrolyte including: ABC -2x-zDx+y, wherein: A is chosen from Li, Na, K, Mg, Ca, Zn, Al, In, Fe, and combinations thereof, B is chosen from Ca, Mg, Zn, In, V, Nb, Ta, Mn, Ti, Zr, Hf, Fe, Co, Ni, Al, Ga, and combinations thereof, C is chosen from F, Cl, Br, I, and combinations thereof, D ischosen from O, S, Se, Te, and combinations thereof, X is an integer chosen from 4, 5, and 6, such that the solid electrolyte is charge neutral, 0 < x < l, 0 < z < 2, and 0 < y < 1. In some examples, A is chosen from Li, Na, and K; B is chosen from V, Nb, and Ta; and wherein X is 6. In some examples, A is chosen from Li, Na, and K; B is chosen from Mn, Ti, Zr, and Hf; and wherein X is 5. In some examples, A is chosen from Li, Na, and K; B is chosen from Fe, Co, Ni, Al, Ga, and I; and wherein X is 4. In some examples, B is a combination of two of Ca, Mg, Zn, In, V, Nb, Ta, Mn, Ti, Zr, Hf, Fe, Co, Ni, Al, and Ga.In some examples, the first solid electrolyte comprises any of the solid electrolytes described herein.In some examples, the electrochemical cell further includes an anode material. In some examples, the anode material includes Li, Na, K, Zn, Mg, Al, Si, Ag, Li alloys, Li intermetallics, Li compounds, Na alloys, Na intermetallics, Na compounds, K alloys, K intermetallics, K compounds, Al alloys, Al intermetallics, Al compounds, Si alloys, Si intermetallics, Si compounds, Ag alloys, Ag intermetallics, Ag compounds, or any combination thereof. The anode material includes Li, Na, K, Zn, Mg, Li alloys, Li intermetallics, Li compounds, Na alloys, Na intermetallics, Na compounds, K alloys, K intermetallics, K compounds, or any combination thereof.In some examples, the anode material includes MqSn, wherein M is chosen from Li, Na, K, Zn, and Mg, and where q is from 0.5 to 3. For example, q can be 0.5 or more (e.g., 1 or more, 1.5 or more, 2 or more, or 2.5 or more). In some examples, q can be 3 or less (e.g., 2.5 or less, 2 or less, 1.5 or less, or 1 or less). In some examples, q is 2.In some examples, the anode material includes M2Sn wherein M is chosen from Li, Na, K, Zn, and Mg.In some examples, the electrochemical cell further includes a cathode material. The cathode material is a metal, a ceramic, or a composite. In some examples, the cathode material includes Cu, C, graphite, Na, K, Li, Mg, Ca, Al, layered oxides, vanadium-based cathode, sulfurbased cathode, spinels, olivines, or any combination thereof. In some examples, the cathode material includes MCrO2, wherein M is chosen from Li, Na, K, Zn and Mg. In some examples, the cathode material includes MxTMCL, wherein 0.6 < x < 1, and M is chosen from Li, Na, K, Zn, and Mg, and TM is a transition metal such as Ti, Nb, Ni, Mn, Co, Fe, Al, Cr, Zr and their mixture. In some examples, the cathode material includes MXTM2-XO2, wherein 0 < x < 2, and TM is a transition metal such as Ti, Nb, Ni, Mn, Co, Fe, Al, Cr, Zr and their mixture.In some examples, the electrochemical cell further includes a second solid electrolyte including an anolyte. In some examples, the second solid electrolyte includes MPSC1, whereinM is chosen from Li, Na, K. Zn and Mg. In some examples, the second solid electrolyte includes MxPSyCL, wherein x, y, and z are each independently from 0 to 7, M is chosen from Li, Na, K. Zn and Mg. In some examples, MPSC1 includes Na2.9PS3.9Clo.!.In some examples, the first solid electrolyte further includes a conductive paste.In some examples, the electrochemical cell includes a first solid electrolyte, an anode material, and a cathode material.In some examples, the electrochemical cell includes a first solid electrolyte, a second solid electrolyte, an anode material, and a cathode material.In some examples, the electrochemical cell is a battery, such as a solid-state battery. In some examples, the electrochemical cell is a solid-state battery, such as an all-solid-state battery.In some examples, the electrochemical cell exhibits a coulombic efficiency of 99% or more (e.g., 99.1% or more, 99.2% or more, 99.3% or more, 99.4% or more, 99.5% or more, 99.6% or more, 99.7% or more, 99.8% or more, or 99.9% or more) for 100 cycles or more. In some examples, the electrochemical cell exhibits a coulombic efficiency of 99% or more (e.g., 99.1% or more, 99.2% or more, 99.3% or more, 99.4% or more, 99.5% or more, 99.6% or more, 99.7% or more, 99.8% or more, or 99.9% or more) for 500 cycles or more.In some examples, the electrochemical cell exhibits a capacity retention of 70% or more (e.g., 75% or more, 80% or more, 85% or more, 90% or more, 95% or more, or 99% or more) for 500 cycles or more. In some examples, the electrochemical cell exhibits a capacity retention of 70% or more (e.g., 75% or more, 80% or more, 85% or more, 90% or more, 95% or more, or 99% or more) for 1000 cycles or more. In some examples, the electrochemical cell exhibits a capacity retention of 80% or more (e.g., 85% or more, 90% or more, 95% or more, or 99% or more) for 500 cycles or more.In some examples, the electrochemical cell exhibits rate capacity retention of 20% or more at 1C compared to C / 10 rate (e.g., 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, or 90% or more).Methods of Making and Use of the Electrochemical CellsAlso disclosed herein are methods of making and use of any of the electrochemical cells disclosed herein.For example, the method can comprise making an all-solid-state battery, the all solid- state battery comprising a cathode, an anode, an anolyte, and a catholyte. In some examples, the method can comprise assembling the all solid-state battery by stacking together the cathode, the anode, the anolyte, and the catholyte. In some examples, the method can further comprise copressing the cathode, the anode, the anolyte, and the catholyte. In some examples, the methodscan further comprise making the cathode, the anode, the anolyte, the catholyte, or a combination thereof.Also disclosed herein are systems comprising one or more of the electrochemical cells described herein. For example, the system can be an energy storage system.Also disclosed herein are articles (e.g., articles of manufacture) comprising one or more of the electrochemical cells described herein. In some examples, the article is a vehicle, such as a hybrid electric vehicle or an all-electric vehicle. In some examples, the article is a vehicle, such as an electric bike, an electric scooter, an electric drone, or an electric airplane. In some examples, the article comprises an electronic device, such as a portable electronic device, a laptop, a watch, a cell phone, or a medical device. In some examples, the article is an energy storage device.A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims.The examples below are intended to further illustrate certain aspects of the systems and methods described herein and are not intended to limit the scope of the claims.EXAMPLESThe following examples are set forth below to illustrate the methods and results according to the disclosed subject matter. These examples are not intended to be inclusive of all aspects of the subject matter disclosed herein, but rather to illustrate representative methods and results. These examples are not intended to exclude equivalents and variations of the present invention, which are apparent to one skilled in the art.Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperature, etc.) but some errors and deviations should be accounted for. Unless indicated otherwise, parts are parts by weight, temperature is in °C or is at ambient temperature, and pressure is at or near atmospheric. There are numerous variations and combinations of measurement conditions, e.g., component concentrations, temperatures, pressures and other measurement ranges and conditions that can be used to optimize the described process.Example 1All-solid-state batteries (ASSBs) are becoming a promising energy storage technology as they bring the safety of state-of-the-art batteries to the next level by replacing the flaming organic liquid electrolytes with nonflammable solid electrolytes (SEs). Inorganic halide-based solid electrolytes have emerged as a game changer because of their fast-conductingcharacteristics, adequate thermodynamic stability, great deformability, and good oxidative stability. Moreover, solid halide electrolytes have good oxidation stability, based on their high oxidation potential. However, most of the studied halide-based solid electrolytes are based on the Li-ion system, with only a few based on the Na-ion system. Moreover, despite halide-based Na solid electrolytes theoretically having high ionic conductivity, experimentally obtained samples have much lower ionic conductivities compared to their Li counterparts (usually < 0.1 mS cm-1). Therefore, developing halide-based solid electrolytes with high Na+ionic conductivity is crucial for Na all-solid-state batteries. In addition, most halide solid-state electrolytes are unstable against moisture and would decompose in air.Herein, a strategy is disclosed to significantly increase the sodium ionic conductivity of solid electrolytes by mixing different types of anions, especially the mixing anions of X7O2", X" / S2" (X = halides). The strategy is developed based on the understanding that the energy of mobile ions (Li+, Na+, K+, etc. ) at different sites in the solid structures largely determined by the surrounding chemical environment, that is the anion type, number and the bond length etc. For example, when the anion is S2‘, the energy of Li+ions at octahedral sites is higher than that at tetrahedral sites. By comparison, when the anion is Cl", the energy of Li+ions at octahedral sites is lower than that at tetrahedral sites. The mixing of S2" and Cl" would reduce the energy difference between octahedral sites and tetrahedral sites. As Li+ion generally transports between the octahedral site and the tetrahedral site, reducing the energy difference between them will reduce the ion transport energy barrier and thus increase the ionic conductivity. When the mobile ions change, the energy at the same site would change but mixing anions still minimizes the site energy difference at different sites and thus reduce the ion transport energy barrier. Furthermore, when halides were replaced with O2, the stability against moisture can be enhanced, due to the stronger bond energy between transition metal ions Mm+and O2".Based on the above-mentioned principle, in the forthcoming example, NaNbCls is used as the baseline material. By doping Cl with O in NaNbCls, the ionic conductivity of this halide- based solid electrolyte was largely increased. O-doped NaNbCls was synthesized using NbCls and NaOH as the precursors. When the molar ratio is 1 : 1 , the proposed reaction mechanism is NbCls+NaOH — >NaNbC14O+HCl. Figure 1 A shows a picture of the product of mixing NbCls and NaOH with a molar ratio of 1: 1 after ball-milling at a speed of 550 rpm for 10 hours. By tailoring the ratio of NbCls and NaOH, a series of O-doped NaNbCls solid electrolytes were synthesized. Figure IB-Figure 1C displays the electrochemical impedance spectroscopy of these solid electrolytes. Their ionic conductivities are compared in Figure ID with a maximum ionic conductivity of 1.1 mS cm"1when the mole ratio of Nads and NaOH reaches 1.07. In addition, afew samples with decent room-temperature ionic conductivities were further tested at different temperatures to measure their Na+transport active energies. Figure IE shows that the sample with the highest room temperature ionic conductivity has an activity energy as low as 0.23 eV. It is worth noting that only a few Na solid electrolytes have been synthesized and explored so far, and most of them have low ionic conductivity (Table 1).Table 1. Comparative experimental ionic conductivities of Na halide-based solid electrolytes.Based on the promising experimental results, it is believed that the proposed methodology is general and can help develop various halide-based solid electrolytes for all- solid-state batteries. The general formula of such solid electrolytes can be:(1) AI-SBC6-2X-SDX (0 < x < 2, -0.5 < 5 < 0.5) where A can be Li, Na, and K; B can be V5+, Nb5+, Ta5+, or a mixture of them; C can be F", Cl", Br", I", or a mixture of them; D can be O2", S2", Se2", Te2", or a mixture of them;(2) Ai-gBCs-zx-sDx (0 < x < 2, -0.5 < 5 < 0.5) where A can be Li, Na, and K; B can be Mn4+, Ti4+, Zr4+, Hf4L or a mixture of them; C can be F", Cl", Br", I", or a mixture of them; D can be O2, S2", Se2", Te2", or a mixture of them;(3) AI-8BC4-2X-5DX(0 < x < 2, -0.5 < 5 < 0.5) where A can be Li, Na, and K; B can be Fe3+, Al3+, Ga3+, In3+, Y3+, La3+, Sm3+, Pm3+, Ce3+or a mixture of them; C can be F", Cl", Br", I , or a mixture of them; D can be O2‘, S2‘, Se2", Te2", or a mixture of them;(4) Ai-sBCxDy (2 < x < 6, 0 < y < 2, -0.5 < 8 < 0.5), where A can be Li, Na, and K. B can be V5+, Nb5+, Ta5+, Mn4+, Ti4+, Zr4+, Hf4+, Fe3+, Al3+, Ga3+, In3+, Y3+, La3+, Sm3+, Pm3+, Ce3+, or a mixture of them; C can be F", Cl", Br", I", or a mixture of them; D can be O2, S2", Se2", Te2", or a mixture of them.The stoichiometric ratio of A, C, and D (listed in (1) - (4)) will be adjusted accordingly to help maintain the charge neutrality of the synthesized materials.The developed strategy has the potential to be applied to other halide-based SEs to improve their ionic conductivity, promoting the development of all-solid-state batteries.Example 2 - Halide-based Solid Electrolyte with High Ionic Conductivity for All-solidstate Sodium-ion BatteriesAbstract. In the realm of advanced battery technologies, sodium-ion batteries present a compelling prospect due to their cost-effectiveness, comparable energy density to lithium-ion counterparts, and heightened safety features. Nonetheless, overcoming impediments related to achieving high ionic conductivity of solid-state electrolytes (SEs), resolving electrode-electrolyte interface intricacies, and managing material compatibility remain critical challenges. Here, a strategy is reported that is aimed at augmenting the ionic conductivity of halide-based solid-state electrolytes by mixing different types of anions for developing sodium solid-state batteries. NaNbCEO (NNCO) is synthesized with a noteworthy room temperature ionic conductivity of 1.10 mS cm-1and an exceptionally low activation energy of 0.23 eV. Additionally, NaNbCEO demonstrated remarkable electrochemical stability up to 4.3 V vs. Na / Na+and exhibited robust chemical compatibility against cathodes. The practical application of the developed NaNbCEO solid-state electrolyte is demonstrated in a solid-state sodium-ion battery, integrating a NaCrOz + NaNbCEO + SP composite cathode, NaNbCEO + Na2.9PS3.9Q01 electrolyte, and Na-Sn anode. These findings underscore the considerable potential for the practical implementation of sodium solid electrolytes in cutting-edge battery technologies.Introduction. Solid-state electrolytes (SEs) have attracted increasing attention in the past few years as they provide enhanced safety due to their non-flammable nature and reduced leakage risks, ensuring a safer battery environment [1-4]. Their compatibility with high-energy- density electrode materials enables the creation of batteries with higher energy densities and long lifespans. Compared with lithium, sodium offers advantages over its abundance, costeffectiveness, lower interfacial resistance, and potential for reduced dendrite formation, presenting a promising avenue for sustainable and efficient energy storage solutions [5]. Developing sodium-ion solid-state batteries (SSBs) can exploit these advantages of sodium for energy storage. However, the main challenge for adopting sodium-ion solid-state electrolytes lies in achieving sufficiently high ionic conductivity at room temperature for practical application in high-performance sodium-ion batteries.Despite the tremendous progress that has been made in the past decades, the progress and application of sodium solid-state batteries are still in the infancy due to the inherent properties, interface complications, and fabrication of solid-state electrolytes [6]. Inorganic halide-basedsolid-state electrolytes are attracting increasing attention because of their fast-conducting characteristics, adequate thermodynamic stability, great deformability, and good oxidative stability [7]. Moreover, halide-based solid-state electrolytes are generally stable against moisture owing to their positive hydrolysis reaction energy [8]. However, most of the studied halide-based solid-state electrolytes are based on the Li-ion system, with only a few based on the Na-ion system, and most Na halide solid-state electrolytes are less conductive. For example, Na2ZrCle (l*10-2mS cm-1), NasYXe (0.77 and 0.44 mS cm-1for X = Cl and Br), NasXL (0.36, 0.35, and 0.2 mS cm-1for X = Sc, Y, and La, respectively), NasMCk (3.09 and 11.54 mS cm-1for M = Sc and In), Na3-xMi-xZrxCle (6.6* 10-2and 0.04 mS cm-1for M = Y and Er), and NaAlCL (3.9* 10-3mS cm-1) [9-13]. Moreover, most of these reported ionic conductivities, especially for those with high ionic conductivities such as Na3MC16 (3.09 and 11.54 mS cm-1for M = Sc and In), are theoretically predicted. Thus, developing new halide-based solid-state electrolytes with high ionic conductivity for the Na-ion system is crucial.In this study, anion mixing is introduced as an effective strategy to increase the ionic conductivity of sodium solid-state electrolytes. NaNbCle (NNC) is selected as the benchmark material with a room temperature ionic conductivity of 9 * 10"3mS cm-1. By doping the material with O2, NaNbCLO (NNCO) shows notably high room temperature ionic conductivity of 1. 10 mS cm-1alongside a low activation energy of 0.23 eV. It was observed that the ionic conductivity of NaNbCLO decreases with the increase of its crystallinity during annealing, suggesting that the disordered structure (amorphous phase) contributes to the high ionic conductivity. In addition, NaNbCLO exhibits remarkable electrochemical and chemical stability, showcasing an elevated oxidation limit of approximately 4.3 V vs. Na / Na+. The anion mixing strategy can be applied to various types of solid-state electrolytes to improve their ionic conductivity and electrochemical stability, opening a new path for the design of solid-state electrolytes.Results and Discussion.Synthesizing O2' -doped NaNbC with High Ionic Conductivity. NaNbCle was chosen as the benchmark material and O2' doping was applied to demonstrate the hypothesis that anion mixing can change the energy level of Na+at different sites in a solid-state electrolyte by increasing the energy at the octahedral site and reducing the energy at the tetrahedral site. The benchmark material (NaNbCle) was synthesized through ball milling of NbCh and NaCl with a 1: 1 molar ratio (NbCl5+ NaCl -> NaNbCl6). The O2‘ doping was introduced via NaOH precursor with a proposed reaction mechanism of NbCl5+ NaOH -> NaNbCl40 + HCl. Figure 2A shows a picture of the product of mixing NbCb and NaOH with a molar ratio of 1 : 1 afterball milling at a speed of 550 rpm for 10 hours. Electrochemical impedance spectroscopy was applied to measure the ionic conductivity of two solid-state electrolyte pellets sandwiched between two stainless steel rods. The conductivity can be calculated through Equation 1 : L< = — (1)A-R where L is the thickness of the pellet, A is the surface area, and R is the measured ohmic resistance.Figure 2B suggests that the O2' doping NaNbCEO solid-state electrolyte has a much smaller impedance than the undoped NaNbCle solid-state electrolyte, indicating that the O2’ doping can significantly increase the Na+conductivity. The result supports the central hypothesis herein.To further optimize the ionic conductivity, the amount of O2-doping in NaNbCle was tailored by varying the molar ratio of NbCIs and NaOH. The maximum room temperature Na+ionic conductivity was reached at 1.10 mS cm-1when the mole ratio of NaCI and NaOH precursors were 1.07 (Figure 2C). Such a high ionic conductivity is already comparable to some advanced liquid electrolytes.In addition, the activation energy for Na+transport in solid-state electrolyte was investigated for a few samples with decent room-temperature ionic conductivities. Figure 2D shows the temperature-dependent ionic conductivity. The activation can then be calculated based on the Arrhenius relationship. The lowest activation energy reached 0.23 eV, which is the lowest activation energy for a halide-based Na solid-state electrolyte. The low activation energy indicates that synthesized solid-state electrolyte has the potential to enable the low-temperature application of solid-state batteries.Structure Characterization through X-ray Diffraction. To understand the high Na ionic conductivity in the O-doped NaNbCle sample, the XRD pattern of the undoped sample (NaNbCle) and the O2-doped sample (NaNbCUO) were measured, as shown in Figure 3A. A standard NaNbCle XRD card (PDF#34-0929) is also shown to demonstrate the successful synthesis of NaNbCle. The main peaks of the synthesized NaNbCle match well with the standard PDF card. A few mismatched peaks at high 2-theta values could be from the impurities or side products formed during the synthesis, where NbCh and NaCl were used as the precursors. Interestingly, there are only a few broad peaks at small 2-theta values in the O-doped sample, which indicates that the NaNbCkO solid-state electrolyte is mainly amorphous without long- range structural ordering.To evaluate the impact of the crystalline of NaNbCUO solid-state electrolyte on its ionic conductivity, the sample was heated to various temperatures, during which its XRD pattern was collected. Figure 3B shows that the XRD pattern does not change significantly with increasing temperature. The two peaks at around 25° of the 2-theta value become sharper with increased intensities when the temperature reaches 90°C. The intensities of the two peaks further increase with the increase of the temperature, indicating an increased crystallinity of the NaNbCUO solid- state electrolyte. The ionic conductivity of the solid-state electrolyte after high-temperature treatment was also measured, and the result suggests that the ionic conductivity decreases. Thus, the formation of an amorphous-dominated product could be correlated to its high roomtemperature ionic conductivity. However, it is still unclear how the amorphous phase affects the Na ionic conductivity in the sample. Further, the exact short-range ordering in the NaNbCl iC) sample is unknown, and how this short-range ordering affects the ionic conductivity is also unknown.Investigation of the Stability of the NaNbC O Solid-State Electrolyte. The electrochemical stability of the synthesized NaNbCUO solid-state electrolyte was evaluated using a cyclic voltammetry (CV) test in the range of 0 - 5 V. NaNbCUO blended with 30% super P conductive agent, served as the cathode, while Na2.9PS3.9Clo.! functioned as the solid-state electrolyte, and Na2Sn acted as the anode. These components were individually pressed under 300 MPa in a cylinder cell with a 12 mm diameter. Figure 4A-Figure 4B suggests that the solid- state electrolyte is stable within the voltage range of 2.2 - 4.3 V (vs. Na+ / Na). The stability at 4.3 V indicates that the O2-doped solid-state electrolyte is promising to be used in practical solid- state batteries with high-voltage cathode materials. However, the solid-state electrolyte is still not compatible with the anode side due to its limited low- voltage stability that can be seen from a reduction peak at around 2.0 V. Thus, the solid-state electrolyte cannot be used as an anolyte for Na solid-state batteries, and a more stable solid-state electrolyte is needed to be placed in between the anode and NaNbCUO solid-state electrolyte.To evaluate the robustness of NaNbCUO solid-state electrolyte at high temperatures, the solid-state electrolyte was stored at 70°C for half an hour. Impedance was measured to study the change of the ionic conductivity during the high-temperature storage. Figure 4C suggests that there are no obvious changes in the impedance during the storage, indicating good stability of the solid-state electrolyte at high temperatures. In addition, to apply NaNbCUO in a Na solid- state battery, an anolyte that is compatible with anodes is needed because of the poor anodic stability of the NaNbCUO solid-state electrolyte. As sulfide solid-state electrolytes (NaPSCl, Na2.9PS3.9Clo.!) are usually used as an anolyte for solid-state batteries, the compatibility ofNaNbCUO against NaPSCl was further tested. Figure 4D shows the change in the impedance of NaNbCUO and NaPSCl composite during storage. After 24 hours of storage, there are negligible changes in the impedance, suggesting a good compatibility between the two solid-state electrolytes. Therefore, a combination of NaNbCUO solid-state electrolyte (catholyte) and NaPSCl solid-state electrolyte (anolyte) is expected to work for developing sodium solid-state batteries.Conclusion. In summary, reported herein is an approach to increase the ionic conductivity of solid-state electrolytes through an anion mixing strategy. In the case of sodium- ion solid-state electrolyte: NaNbCU, the doped oxygen ions reduce the migration distance between Na+ions, concurrently increasing the available sites for Na+within the electrolyte. This strategic modulation facilitates a more favorable diffusion of Na+in the electrolyte, greatly improving the ionic conductivity of the resulting material: NaNbCUO. Subsequent tests have demonstrated that the anion-doped electrolyte not only exhibits high ionic conductivity but also manifests commendable electrochemical and high-temperature stability. This methodology of combining rational design and experimental verification, as exemplified in this study, stands as an effective way to enhance the overall performance of solid-state electrolytes for developing practical sodium-based solid-state batteries.Experimental SectionMaterials synthesis. All fabrication processes were conducted in an Ar- filled glovebox (Mikrouna, H2O < 0.1 ppm, O2 < 0.1 ppm). NbCU (Aladdin) and NaCl (Sinopharm) with a molar ratio of 1 : 1 were used to synthesize NaNbCU, while NbCU (Aladdin) and NaOH (Aladdin) with a molar ratio of 1.07: 1 were used to synthesize NaNbCUO. The mixture was ball milled (QM- 3SP2, Nanda Instruments) at 550 rpm for lOh in a 50 ml ZrO2 jar under an Ar environment. To synthesize NaCrO2 cathode electrode material, a mixture of Na2CO < (Aladdin) and C O-, (Sinopharm) with a molar ratio of 1.05: 1.00 was ball milled at 550 rpm for 10 h. The product was then heated at 900 °C for 10 h (OTF-1200X, HF-Kejing) under an Ar environment. Na2.9PS3.9Clo.! powders were prepared by ball-milling a stoichiometric mixture of Na2S (Sigma Aldrich), P2S5 (Sigma Aldrich), and NaCl (Sinopharm) at 550 rpm for 2 h, followed by heat treatment at 300 °C for 2 h under Ar environment. For the preparation of NasSn, Na metal, and Sn powder were mixed in a steel jar under an Ar environment. The mixture was then ball milled at 300 rpm for 10 h to obtain the homogenous product.Materials Characterization. Powder XRD experiments were conducted on a Philips X’Pert powder diffractometer (D / MAX2500VL / PC, Rigaku) operating at 45 kV and 40 mA, utilizing Cu-K„ radiation ( , = 1.5406 A). The samples, secured in a zero-background holder andshielded with a Kapton film to prevent air exposure, were subjected to data collection at room temperature over a 20 range of 10 to 80°. The X-ray diffractometer (X'pert Pro-MPD, PANalytical, Netherlands) with a super-energy detector was utilized for the in-situ XRD analysis, employing Cu-Ka radiation (X, = 1.5406 A) at a generator voltage of 45 kV and a tube current of 40 mA. The measurements were performed within a temperature range of 30-130 °C, holding for approximately 30 minutes at each temperature, and utilizing a scanning range of 10- 80°.Electrochemical Characterization. The ionic conductivity of NaNbCUO was assessed at 30 °C through electrochemical impedance spectroscopy (EIS) over a frequency range spanning 1 MHz to 1 Hz, employing a potential perturbation of 50 mV (Biologic SP-200). To determine the activation energy, variable-temperature impedance measurements were performed from 30 to 70 °C within a microclimate chamber. The as-synthesized NaNbCUO powders were compacted into 12 mm diameter pellets under a pressure of 260 MPa, sandwiched between two steel rods for all measurements.For the electrochemical stability analysis of NaNbCUO, cyclic voltammetry was employed. NaNbCUO blended with 30% SP, served as the cathode, while Na2.9PS3.9d01 functioned as the solid-state electrolyte, and Na2Sn acted as the anode. These components were individually pressed under 300 MPa in a cylinder cell with a 12 mm diameter. Cyclic voltammetry experiments were conducted on Biologic SP-200 with a scan rate of 0.5 mV / s and a voltage window of 0-5 V.The fabrication process of the all-solid-state NaCrCF II NaNbCUO II Na2.9PS3.9Clo.! II Na2Sn battery involved the following steps. The composite cathode was created by ball milling a mixture of NaCrO2, NaNbCUO, and SP (in a weight ratio of 50:50:3) at 200 rpm for 1 h. Subsequently, the all-solid-state battery was assembled by co-pressing the components in the following order: Na2Sn anode (50 mg), Na2.9PS3.9Clo.! anolyte (70 mg), NaNbCUO catholyte (70 mg), and NaCrO2 composite cathode (10 mg), applying a pressure of 300 MPa.References1. Kamaya N et al. Nature Materials, 201 1, 10(9): 682-686.2. Gao H et al. Chem, 2018, 4(4): 833-844.3. Kim JK et al. Energy & Environmental Science, 2015, 8(12): 3589-3596.4. Hou W et al. Nano Energy, 2018, 52: 279-291.5. Zhang Z et al. Advanced Energy Materials, 2017, 7(4): 1601196.6. Vasudevan S et al. International Journal of Applied Ceramic Technology, 2023, 20(2): 563-584.7. Huang J et al. Chemical Society Reviews, 2023, 52(15): 4933-4995.8. Zhu Y et al. Angewandte Chemie International Edition, 2020, 59(40): 17472- 17476.9. Kwak H et al. Energy Storage Materials, 2021, 37: 47-54.10. Qie Y et al. The Journal of Physical Chemistry Letters, 2020, 11(9): 3376-3383.11. Huang H et al. ACS Applied Materials & Interfaces, 2022, 14(32): 36864-36874.12. Lian Y et al. Journal of Materials Chemistry A, 2023, 11(4): 1906-1919.13. Park J et al. ACS Energy Letters, 2022, 7(10): 3293-3301.14. Ma M et al. Advanced Functional Materials, 2021, 31(25): 2100278.15. Zhou W et al. ACS Central Science, 2017, 3(1): 52-57.16. Famprikis T et al. Nature Materials, 2019, 18(12): 1278-1291.17. Manthiram A et al. Nature Reviews Materials, 2017, 2(4): 1-16.18. Feng X et al. Angewandte Chemie, 2021, 133(50): 26362-26370.19. Thompson T et al. ACS Energy Letters, 2017, 2(2): 462-468.20. Binninger T et al. Journal of Materials Chemistry A, 2020, 8(3): 1347-1359.Example 3 - Enabling Halide-based Solid Electrolyte with High Na+Ionic Conductivity via an Anion Mixing StrategyAbstract. In the realm of advanced battery technologies, sodium solid-state batteries present a compelling prospect due to their cost-effectiveness, comparable energy density to lithium-ion counterparts, and heightened safety features. Nonetheless, overcoming impediments related to achieving high ionic conductivity of solid-state electrolytes (SEs), resolving electrodeelectrolyte interface intricacies, and managing material compatibility remain critical challenges. Here, an anion mixing strategy was applied that significantly increases the transport kinetics of Na+in halide-based solid-state electrolytes. Compared to the crystalline NaNbCk baseline solid- state electrolyte, the glassy O2-doped NaNbxCbx-iO (NNCO, x is close to 1) shows a largely increased Na+ionic conductivity at 30°C by a few orders of magnitude to over 1 mS cm Moreover, the activation energy of the developed NaNb1.07Q4.35O is as low as 0.23 eV. In addition, NaNb1.07O4.35O solid-state electrolyte shows remarkable electrochemical stability up to 4.3 V vs. Na+ / Na and exhibits robust chemical compatibility against sulfide-based anolyte and cathode-active material. The practical application of the developed NaNb1.07Cl4.35O solid-state electrolytes was demonstrated in a solid-state sodium-ion battery, integrating a doped- Na2 / 3Nii / 3Mn2 / 3O2 + NaNb1.07Cl4.35O + SP composite cathode, NaNb1.07Cl4.35O + NasPS electrolyte, and Na2Sn anode, with an initial capacity of 95 mAh g-1and 73% capacity retentionafter 1000 cycles at 0.3C. These findings underscore the potential for the practical implementation of halide-based sodium solid-state electrolytes in cutting-edge battery technologies.Introduction. Solid-state electrolytes (SEs) have attracted increasing attention in the past few years as they provide enhanced safety due to their non-flammable nature and reduced leakage risks, ensuring a safer battery environment [A1-A4], Their compatibility with high- energy-density electrode materials enables the creation of batteries with higher energy densities and long lifespans. Compared with lithium, sodium offers advantages over its abundance, costeffectiveness, lower interfacial resistance, and potential for reduced dendrite formation, presenting a promising avenue for sustainable and efficient energy storage solutions [ A5] . Developing sodium-ion solid-state batteries (SSBs) can exploit these advantages of sodium for energy storage. However, the main challenge for adopting sodium-ion solid-state electrolytes lies in achieving sufficiently high ionic conductivity at room temperature for practical application in high-performance sodium-ion batteries.Despite the tremendous progress that has been made in the past decades, the progress and application of sodium solid-state batteries are still in their infancy due to the inherent properties, interface complications, and fabrication of solid-state electrolytes [A6] . Inorganic halide-based solid-state electrolytes are attracting increasing attention because of their fast-conducting characteristics, adequate thermodynamic stability, great deformability, and good oxidative stability [A7]. Moreover, halide-based solid-state electrolytes are generally stable against moisture owing to their positive hydrolysis reaction energy [ A8] . However, most of the studied halide-based solid-state electrolytes are based on the Li-ion system, with only a few based on the Na-ion system, and most Na halide solid-state electrolytes have much lower ionic conductivities compared to their Li counterparts, such as Na2ZrCle (IxlO-2mS cm-1), NasYXr, (0.77 and 0.44 mS cm-1for X = Cl and Br), NasXIe (0.36, 0.35, and 0.2 mS cm-1for X = Sc, Y, and La, respectively), NaiMCL (3.09 and 11.54 mS cm-1for M - Sc and In), Na3-xMi-xZrxC16 (6.6xl0-2and 0.04 mS cm-1for M = Y and Er), and NaAlCh (3.9xl0-3mS cm-1) [A9-A13]. Moreover, most of these reported ionic conductivities, especially for those with high ionic conductivities such as Na-.MCk, (3.09 and 11.54 mS cm-1for M = Sc and In), are theoretically predicted. The experimentally obtained samples usually result in a much lower ionic conductivity at the level of 10"2to IO"7mS cm-1.Typical halide electrolytes are composed of X<> (M = Y3+, In3+, Zr4+, Sc3+, etc, X = F", CT, Br", I , etc.) octahedron frames, and alkali metal ions (Li+, Na+) are distributed in the interstitial sites. Compared to Li+with a cation size of 76 pm, Na+has a much larger cation size(106 pm) that requires a significantly larger diffusion channel for fast ion transport I A14|. Although anions and cations with large sizes can be applied to broaden the diffusion channel, their application will simultaneously increase the Na+ion hopping distance from one site to its adjacent site. Moreover, synthesizing the desired crystal structure of Na solid-state electrolytes is not trivial, and the experimentally obtained samples usually deviate from the theoretical crystal structures calculated based on their Li-ion counterparts [Al 5]. Thus, developing halide-based solid-state electrolytes with experimentally high room temperature ionic conductivity for the Na- ion system is crucial.In this study, anion mixing is introduced as an effective strategy to increase the ionic conductivity of sodium solid-state electrolytes. NaNbCL (NNC) was selected as the benchmark material with a room temperature ionic conductivity of 9xl0-3mS cm-1. By doping the material with O2-, NaNb1.07Cl4.35O (NNCO) showed notably higher room temperature ionic conductivity beyond 1.0 mS cm-1alongside a low activation energy of 0.23 eV. In addition, NaNb1.07Cl4.35O exhibited remarkable electrochemical and chemical stability, showcasing an elevated oxidation limit of approximately 4.3 V vs. Na / Na+. When the NaNb1.07Cl4.35O electrolyte is directly paired with a layered oxide doped- Na2 / 3Nii / 3Mn2 / 3O2 cathode without additional surface coating, the resulting all-solid-state battery exhibits a remarkable rate performance and cycling stability over 500 cycles with 80% capacity retention at 0.3 C. The anion mixing strategy can be extended to various types of solid-state electrolytes to improve their ionic conductivity and electrochemical stability, opening a new path for the design of solid-state electrolytes.Results and DiscussionAnion mixing strategy for the conductivity improvement of solid-state electrolytes. In solid-state electrolytes, mobile ions migrate within fixed crystal structures. Key positions within these structures include tetrahedral and octahedral sites, which are geometrically defined by the surrounding anion clusters. The tetrahedral site (T-site) is typically surrounded by four anions, forming a smaller space, while the octahedral site (O-site) is typically surrounded by six anions, forming a larger space. According to Marcus's theory, the mobility rate k can be expressed as: k = Aexp( - kgT ), where A is the pre-exponential factor, AG* is the activation energy, kv, is theBoltzmann constant, and T is the temperature [Al 6, A17]. The activation energy can be further expressed as: where AEsiterepresents the energy differencebetween two sites. It shows the minimization of the energy difference between two mobile ion sites, which means the T-site and O-site, can optimize the ionic conductivity.The cation energy can be expressed as E (r) = — which is determined by thetypes (charges, Z Zj) of anions and the cation-anion distance (r), where E0is the dielectric constant, and B and n (n is usually larger than 6) are constant. In a Li -based solid-state electrolyte, the Li+energy in a tetrahedral site is usually higher than that in an octahedral site when the anion is a halide (X-, where X can be F‘, CL, I', Br ). In contrast, the Li+energy in a tetrahedral site is usually lower than that in an octahedral site when the anion is S2-[Al 8]. Thus, a mixture of X7S2" can theoretically reduce the energy barrier for cation transport in a solid-state electrolyte. Thus, devised herein is a strategy to increase ionic conductivity by mixing appropriate anions in halide solid-state electrolytes to reduce the energy difference of mobile ions at different sites.Synthesizing O2' doped NaNbCh with High Ionic Conductivity. NaNbCf, was selected as the benchmark material and O2' doping was introduced to demonstrate that anion mixing is an effective strategy for improving Na+ionic conductivity by reducing the Na+energy difference at different sites in an solid-state electrolyte. The NaNbCL, was synthesized through ball milling of NbCls and NaCl with a 1: 1 molar ratio (NbCl5+ NaCl -» NaNbCl6). The O2doping was introduced via NaOH precursor with a proposed reaction mechanism of xNbCl5+ NaOH -> NaNbxCl5x-O + HCl, where x is close to 1.Figure 5A shows the crystal structure of NaNbCle with a P2i / c space group. The P2i / c space group inorganic crystals have potential outstanding performance as solid-state electrolytes because their monoclinic system structure includes a two-fold screw axis and glide plane parallel to the c-axis, which can form effective ion channels facilitating the migration of bigger ions like sodium ions compared with lithium ions [A19J. This structure typically offers large lattice gaps and suitable ionic radius matching, enhancing ionic conductivity. Na+ions partly occupy the octahedral sites along the a-axis, with a distance of 4.36 A between two neighbored sites [A20, A21]. In many high-performing solid electrolytes, ionic conductivity is enhanced by the presence of lattice defects, such as vacancies or interstitial sites, which act as pathways for ion migration [A22, A23]. The structural stability of NaNbCle, as indicated by its energy above the hull (0.000 eV / atom) and low formation energy, suggests a highly ordered, defect-free structure [A24, A25]. This stability, while beneficial for preventing degradation, results in insufficient defects or vacancies to facilitate Na+hopping, leading to low ionic conductivity. Oxygen substitution for chloride creates local distortions, forming vacancies and defect complexes that facilitate Na+transport. Additionally, oxygen doping weakens the Coulombic interactions between sodium ions and surrounding anions, lowering the energy barriers for ion migration andenhancing the structural flexibility of the lattice. These combined effects lead to improved Na+conductivity while maintaining the material's stability, making oxy gen-doped NaNbCh a more efficient solid-state electrolyte.The morphology of the synthesized NaNb1.07Cl4.35O solid-state electrolyte powder was characterized through scanning electron microscopy (SEM, Figure 5B). The particles exhibit a relatively regular shape with the presence of cubic-like subunits, indicating that some degree of crystallinity is retained even after ball milling. The observed secondary particle size is in the micrometer range (around 2 pm), typical for solid electrolyte materials after mechanical processing [A26, A27], Additionally, significant particle agglomeration is evident, suggesting that smaller particles are clustering together, which may affect the homogeneity and ionic transport pathways within the material. The surface of the particles appears rough, which could provide additional sites for ion migration; however, excessive roughness may increase interfacial resistance, potentially hindering overall electrochemical performance.The X-ray diffraction (XRD) pattern of the NaNbCE, the O2-doped sample (NaNb1.07Q4.35O, NNCO), and NaNb1.07Q4.35O after heat treatment (NNCO-HT) measured via lab X-ray (Cu Ka) are shown in Figure 5C. The reason for applying heat treatment for the NaNb1.07Cl4.35O sample is to remove H+in the synthesized sample, as suggested by the solid- state nuclear magnetic resonance (NMR) spectra. Figure 5D suggests that the heat treatment process removes some of the residual H+ions in the NaNb1.07Q4.35O sample that originate from the precursor NaOH. The elimination of these H+mitigates potential side reactions and parasitic processes at the electrode-electrolyte interface during cycling that can potentially improve electrochemical stability. It is worth noting that some portion of H+still exists in the sample heat-treated at 300°C for 0.5 hours. This finding is different from recent literature that claims H+does not exist in a NaNbCUO sample when NaOH was used as the precursor [A28],Figure 5C shows that the main peaks at 14, 16, 19, 31, 32, and 38 degrees of the synthesized NaNbCE match well with the standard NaNbC , XRD card (PDF#34-0929), indicating a high degree of crystallinity and structural order. A few mismatched peaks at 43, 45, 52, and 56 degrees with low intensities could be from the impurities or side products formed during the synthesis, where NbCls and NaCl were used as the precursors. In contrast, the NaNb1.07Cl4.35O and heat treated-NaNb1.07Cl4.35O samples show broader peaks with low intensities, suggesting a lower crystallinity and the presence of an amorphous phase. While the peak positions of NaNb1.07Q4.35O and heat treated-NaNb1.07Q4.35O remain consistent, the increased peak intensity observed in heat treated-NaNb1.07Cl4.35O suggests an enhanced degree of crystallinity compared to NaNb1.07Cl4.35O.Solid-state NMR was further applied to study the chemical environment of Na ions in the three solid-state electrolytes. Figure 5E shows that a NaCl impurity is present in the NaNbClo and NaNb1.07Cl4.35O samples, as indicated by the23Na peak at around 7.5 ppm. The intensity of the peak is significantly reduced in the heat treated-NaNb1.07Cl4.35O, indicating that the heat treatment can not only help remove H+in the NaNb1.07Q4.35O but also remove the NaCl impurity. The23Na main peak at around -9 ppm in the NaNbClo sample exhibits a primary peak with a noticeable shoulder, indicative of multiple sodium environments or slight structural heterogeneity. This suggests that, while NaNbCle largely retains a crystalline structure with relatively uniform Na+coordination, there are subtle variations in the local sodium environment, likely arising from the coexistence of slightly different coordination sites or structural distortions. The23Na main peak in the NaNb1.07O4.35O and heat treated-NaNb1.07Cl4.35O sample is shifted to the right compared to that in the NaNbClo sample. The upfield shift means that there is an increased shield by electrons for Na+in the NaNb1.07Cl4.35O and heat treated- NaNb1.07Cl4.35O samples. Thus, the transport of Na+in the anion framework is theoretically easier because of the lowered interaction between them. In addition, the23Na main peak in NaNb1.07Cl4.35O exhibits a similar sharp peak with no significant broadening compared to the NaNbCle sample, suggesting a relatively homogeneous local sodium environment. This indicates that oxygen doping does not dramatically disrupt the local coordination of Na+, possibly due to the presence of short-range order or fast ion dynamics averaging out variations in the local environment. By comparison, a slight broadening of the23Na peak is observed in the heat treated-NaNb1.07Q4.35O sample, which suggests a minor increase in local structural disorder or complexity. However, the overall Na+coordination remains consistent across all samples, suggesting that while oxygen doping and heat treatment introduce some degree of structural modification, the local Na+environments are still relatively uniform.Raman spectra of NaNbClo, NaNb1.07Cl4.35O, and heat treated-NaNb1.07Cl4.35O were further taken which offer valuable insights into the structural transformations of Nb-based polyhedral units. Figure 5F shows that the prominent peaks at 365 cm and 421 cm in the NaNbClo sample correspond to the vi (Eg) and V2 (Alg) modes of NbClo" octahedra, respectively, indicating a highly ordered octahedral structure. Additionally, a weaker peak at 174 cm-1is attributed to 5(NbClo ), representing the bending vibrations of the NbClo" anion. By comparison, the intensities of these characteristic peaks in the NaNb1.07Cl4.35O and heat treated- NaNb1.07Cl4.35O samples decrease. A new peak at 788 cm-1appears that can be associated with Nb-O-Nb bonding. This suggests partial oxidation and polymerization of the NbClo" units that lead to the formation of NbCl4O" chains. The heat treatment reduces the width of the Nb-O-Nbpeak at 788 cm-1, indicating an increase in structural order and uniformity that is consistent with the XRD results, where a higher crystallinity is observed in NaNb1.07O4.35O after heat treatment. The increase in structural order enhances connectivity in the Nb-O-Nb network, which can potentially improve the stability of the solid-state electrolyte.Electrochemical Performance Measurement. NaNbxChx-iO was synthesized with x from 1.0 to 1.1. Electrochemical impedance spectroscopy (EIS) was applied to measure the ionic conductivities of the synthesized solid-state electrolytes. Figure 6A suggests that the O2-doped NaNbxChx-iO solid-state electrolytes have a much smaller impedance (64 and 68 ohms) than the undoped NaNbCE solid-state electrolyte (7746 ohms). Their ionic conductivity can be calculated through <7 =where L is the thickness of the pellet, A is the surface area, and R is the resistance measured from EIS. The investigation into the ratio of NaOH and NbCE precursors during the synthesis revealed a strong correlation between reactant ratios and the resultant Na+conductivity (Figure 9A-Figure 9B), and NaNb1.07Cl4.35O (NNCO) exhibited the highest Na+conductivity of 1.02 mS cm-1(Figure 6A). Thus, selecting an appropriate ratio between NaOH and NbCls precursors is critical in optimizing the Na+ionic conductivity in the synthesized product, and NaNb1.07Q4.35O was selected in the later investigations.The calculated Na+ionic conductivities are 9.0 x 10'3mS cm-1, 1.02 mS cm-1, and 1.17 mS cm-1respectively for NaNbCE, NaNb1.07Cl4.35O, and heat treated-NaNb1.07Q4.35O. NaNbClo exhibits significantly lower Na+conductivity due to its highly ordered and defect-free structure that lacks sufficient pathways for ion migration. The O2doping in NaNbClo can significantly increase the Na+ionic conductivity to a value that is comparable to some liquid electrolytes [A29]. Interestingly, the Na+ionic conductivity of the solid electrolytes herein is an order of magnitude higher than that in the NaNbCkO reported by Kmiec et al. (0.1 mS cm1) [A30]. The relatively lower ionic conductivity of NaNbCkO in Kmiec’ s study could be from its high crystallinity. Thus, a comparison between the results herein and Kmiec’s work indicates that the glassy phase of NaNb1.07Cl4.35O is beneficial to its Na+ionic conductivity, which has been found in some lithium solid electrolytes [A31-A33].It is worth noting that a ball milling process (550 rpm for lOh) was applied to the heat treated-NaNb1.07Q4.35O sample after heat treatment to obtain a high Na+conductivity. Without the ball milling process, the ionic conductivity of the NaNb1.07Cl4.35O sample decreases significantly. Figure 6B shows that the ionic conductivity of NaNb1.07Cl4.35O solid-state electrolyte decreases after the heat treatment at different temperatures for lOh. The higher the heat treatment temperature, the lower the room-temperature Na+ionic conductivity. This finding agrees with the trend found in some lithium-based solid-state electrolytes, such as EisZrCkI A34|. To understand such a phenomenon, in-situ XRD measurements were conducted. The NaNb1.07O4.35O solid-state electrolyte sample was heated to various temperatures, during which its XRD pattern was collected. Figure 10 shows that the XRD pattern of NaNb1.07O4.35O does not change significantly with the increase of temperature. The two peaks at around 25° of the 2- theta value become sharper with increased intensities when the temperature reaches 90 °C. The intensities of the two peaks further increase with the increase of the temperature, indicating an increased crystallinity of the NaNb1.07O4.35O solid-state electrolyte. Thus, it is believed that the formation of an amorphous-dominated NaNb1.07Cl4.35O material could be beneficial to its roomtemperature Na+ionic conductivity. More characterizations to uncover the structure-property relationship of the NaNb1.07Q4.35O solid-state electrolyte warrants further exploration.The activation energy of solid-state electrolytes is calculated by measuring their ionic conductivity at different temperatures, and the NaNb1.07Q4.35O sample shows the lowest activation energy of 0.23 eV among all the NaNbxCFx-iO samples (Figure 6C and Figure 11). To the best of the authors knowledge, 0.23 eV is the lowest activation energy for a halide-based Na solid-state electrolyte that has been reported in the literature (Figure 6C). The slightly increased activation energy of NaNb1.07Cl4.35O after heat treatment (0.25 eV) suggests minimal structural rearrangements in the sample. The low activation energy of a solid-state electrolyte is crucial for its application at low temperatures, making it more suitable for practical applications in solid- state batteries. The electronic conductivity of NaNb1.07Cl4.35O was measured to be as low as 4.57 x 10"10S cm-1(Figure 12), indicating that NaNb1.07Cl4.35O primarily functions as an ionic conductor with negligible electronic contribution. This low electronic conductivity is advantageous in solid-state electrolytes, as it minimizes the risk of internal short-circuiting and parasitic electron transport, which can degrade the electrochemical performance of solid-state batteries [A35-A37]. Furthermore, low electronic conductivity helps preserve the electrochemical stability of the electrolyte under high-voltage conditions, preventing undesired side reactions or electronic leakage, which could otherwise reduce the cycling stability and energy efficiency of the battery system. Figure 6D and Figure 13 compare the properties of our NaNb1 07Cl435O and heat treated- NaNbi.ovCk 35 O solid-state electrolytes with other halide-based solid-state electrolytes reported in the literature [A14, A38-A43]. The solid-state electrolytes show high ionic conductivities, low electronic conductivities, and low activation energy, which warrants them to be ideal for developing sodium-ion solid-state batteries.To highlight the applicability of O2' doping as a general strategy for developing halide- based solid electrolytes, NaTaCUO and NaNbxTai.xC14O (0 < x < 1) were synthesized and studied (Figure 14 - Figure 16). The Na+ionic conductivity in NaTaCUO is around 0.5 mS cm-1.The same ball-milling conditions as the NaNbCUO were used for synthesizing NaTaCUO because the latter is used as an example to demonstrate the applicability of the O27Q' anion mixing strategy in developing halide-based solid-state electrolytes. The Na+ionic conductivity could be further increased if the ball-milling conditions were optimized for NaTaCUO, which warrants further investigation. Moreover, the synthesized NaNbxTai-xChO solid-state electrolytes, with varying Nb and Ta ratios, all show decent Na+conductivities and low activation energy (-0.25 eV). Similarly, their synthesis conditions need to be further optimized which can potentially increase their conductivity. These results indicate that the O2 / C1‘ anion mixing strategy is a general strategy in developing halide-based solid-state electrolytes with high Na+ionic conductivity [A43, A44],A notable difference between NaNbxChx 10 (x is close to 1) and NaNbxTai xCUO (0 < x < 1) solid-state electrolytes is their response to the heat treatment. During the heat treatment, the NaNbxChx-iO solid-state electrolyte shows reduced ionic conductivity, while the NaNbxTai- xCUO (0 < x < 1) shows increased ionic conductivity after 1 -hour heat treatments at both 70 °C and 100 °C (Figure 14 and Figure 1 ). The result suggests that Ta doping stabilizes the structure and potentially alters the Na+local coordination environment, mitigating the adverse structural changes observed in NaNbxClsx-iO during thermal processing. Thus, the incorporation of both Ta and oxygen doping in NaNbCle appears to be an effective strategy for developing solid-state electrolytes with high Na+conductivity, low activation energy, and good thermal stability.Theoretical Calculations to Understand High Na+Conductivity in the NaNbxClsx-iO solid-state electrolyte. To investigate the effect of O2-doping on the Na+transport kinetics in the NaNbCle solid-state electrolyte, density functional theory (DFT) calculations combined with machine-learning predictions were applied to investigate the energetics of the Na-Nb-Cl and Na- Nb-Cl-0 systems [A45, A46]. It was chosen to calculate the NaNbCUO (x = 1 in NaNbxCl5-xO ) instead of the NNCO (x = 1.07) that was experimentally characterized to simplify the modeling of the Na-Nb-Cl-0 system. It is worth noting that the NaNbCUO also has high Na+ionic conductivity at room temperature (Figure 11), and thus a theoretical calculation of this material will be useful to help understand the impact of O2-doping on the Na+transport kinetics in the NaNbCle solid-state electrolyte.First, the Na-Nb-Cl system was investigated. Starting from the monoclinic NbCls structure (AFLOW prototype A5B_mP24_14_5e_e, Pearson symbol mP24, space group 14), the AFLOW “cages” module was used to identify interstitial positions in the lattice: a total of 82 unique (symmetrically inequivalent) positions were identified [A47, A48]. These positions were then decorated with Na+ions: for each position, a single Na+ion was inserted in the structure,and then the energy for that structure was estimated using the PLMF model available through the AFLOW-ML API [A49, A50]. The distribution of energies corresponding to the different sites is plotted in the histogram in Figure 7A. To investigate the Na-Nb-Cl-0 system, 20% of the Cl' ions were replaced with O2' ions to represent the NaNbCLO structure. 130 unique interstitial sites were identified in the NaNbCLO structure. The same step as the Na-Nb-Cl system was applied to calculate the energy at each interstitial site. The distribution of energies corresponding to the different sites is plotted in the histogram in Figure 7B.The results show that there is a clear energy gap between the lower energy sites and the higher energy ones for the Na-Nb-Cl system (Figure 7A). By comparison, Figure 7B suggests that the energies for the Na-Nb-Cl-0 system are more evenly distributed. The standard deviations for this energy distribution are 28.5 meV / atom for NaNbCle and 16.3 meV / atom for NaNbCUO. Moreover, the energy distribution range in NaNbCUO (60 meV / atom) is much smaller than that in NaNbCle (90 meV / atom), which suggests that Na+has a smaller migration barrier in the Na-Nb-Cl-0 system. In addition, there are more available Na+sites after the O2' doping in NaNbxClsx iO solid-state electrolyte, which reduces the hopping distance between two adjacent Na+ions, leading to a smaller energy barrier for Na+transport. Therefore, the DFT calculation results indicate that O2'-doping can reduce the Na+transport barrier from one site to its adjacent site in the Na-Nb-Cl system, enhancing its room-temperature ionic conductivity.The Stability and Compatibility of the Developed Solid-State Electrolyte against Electrode Materials. The synthesized NaNb1.07O4.35O solid-state electrolyte exhibited great air stability and high-temperature stability. After 24 hours of exposure to dry air, the conductivity decreased from 1.02 mS cm'1to 1.00 mS cm'1(Figure 17). After high- temperature hold at 50 °C and 70 °C for half an hour, the conductivity decreased by 12.5% and 14.1%, respectively (Figure 18A-Figure 18B). The electrochemical stability of the synthesized heat treated-NaNb1.07Cl4.35O solid-state electrolyte was evaluated using a linear sweep voltammetry (LSV) test in the range of 0.3 V to 5.3 V vs. Na+ / Na (Figure 8B). The LSV data reveals that the heat treated- NaNb1.07Cl4.35O solid-state electrolyte is stable up to 4.3 V (ys. Na / Na+), indicating a good high- voltage stability of the solid-state electrolyte that is crucial for enabling the use of high-voltage cathode materials for developing high-energy -density sodium-ion batteries. However, the reductive stability of the solid-state electrolyte is not as good, and an anolyte layer is needed to physically separate the heat treated-NaNb1.07Cl4.35O solid-state electrolyte and Na metal anode to avoid side reactions.Na3PS4 was selected as the anolyte in this study for testing the NaNb1.07Cl4.35O solid-state electrolytes in solid-state batteries, and NaoSn and Na2 / 3Nii / 3Mn2 / 3O2 were selected as the anodeand cathode materials. To test the chemical compatibility of them, the evolution of the Na2Sn / NasPS4 interface (Figure 19A and Figure 19D), Na^PS i / heat treated-NaNb1.07Cl4.35O interface (Figure 19B and Figure 19E), and heat treated-NaNb1.07Q4.35O / Na2 / 3Ni1 / 3Mn2 / 3O2 interface (Figure 19C and Figure 19F) were monitored using EIS. The results show that all three interfaces are stable with negligible impedance growth during one-week storage, demonstrating robust interfacial compatibility and negligible degradation which is crucial for the long-term performance and efficiency of the solid-state batteries.Solid-state batteries with a configuration shown in Figure 8A were made to evaluate the performance of the developed solid-state electrolytes. Figure 8C shows the rate capability of the all-solid-state battery using the heat treated-NaNb1.07Cl4.35O as the solid-state electrolyte. At a low rate of 0.1 C, the cell exhibits a high specific capacity of 166 mAh g-1, indicating effective utilization of the Na2 / 3Nii / 3Mn2 / 3O2 active material. The all-solid-state battery maintains relatively good capacity retention at high rates, suggesting that the heat treated-NaNb1.07Q4.35O solid-state electrolyte supports efficient Na+transport under fast charge-discharge conditions. Moreover, when the rate is returned to 0.1 C, the capacity recovers to its initial value, highlighting the excellent reversibility of the cell. Figure 8D-Figure 8E shows the cycling stability of the solid-state batteries at 0.3C. The charge-discharge curves (Figure 8D) of the heat treated-NaNbi.07C14.35O-based all-solid-state battery exhibit a faster change in the first 100 cycles and a slower change in the later 400 cycles. The fast change of the cycling curves in the first 100 cycles could be from the formation of protective interface layers that increase the internal resistance and interface polarization.Figure 8E compares the cycling performance of solid-state batteries using NaNb1.07Q4.35O and heat treated-NaNb1.07Cl4.35O solid-state electrolytes. The all-solid-state battery with heat treated-NaNb1.07Cl4.35O solid-state electrolyte exhibits higher initial capacity and better capacity retention compared to the one with NaNb1.07Cl4.35O solid-state electrolyte. The heat treated-NaNb1.07Q4.35O -based all-solid-state battery shows a capacity retention of 80%, while the one with NaNb1.07Q4.35O has only 42% capacity retention after 500 cycles. Both cells were cycled up to 1000 cycles, and the all- solid- state battery with the heat treated- NaNb1.07O4.35O solid-state electrolyte maintains 73% of its initial capacity (Figure 20), indicating excellent cycling stability. Moreover, the average CE of the heat treated- NaNbi.o7C14.350-based all-solid-state battery is 99.9% in the first 500 cycles, demonstrating highly reversible electrochemical reactions with minimal side reactions at the interfaces.The higher specific capacity and better capacity retention for the all-solid-state battery using heat treated-NaNb1.07O4.35O can be attributed to the reduction of H+content achievedthrough heat treatment. The removal of H+mitigates unwanted side reactions at the electrodeelectrolyte interface, such as the formation of passivation layers or gas evolution, which would otherwise increase interfacial resistance and degrade the performance of solid-state batteries. In contrast, the presence of H+in NaNb1.07Cl4.35O likely leads to more side reactions, which result in faster capacity decay and lower CE. Thus, a heating treatment step of the NaNb1.07Cl4.35O solid-state electrolyte synthesized using the NaOH precursor is crucial for its application in solid-state batteries.Postmortem Analysis of Solid Electrolytes via XPS. The XPS analysis of the NaNb1.07Cl4.35O and heat treated-NaNb1.07Cl4.35O samples before and after cycling provides valuable insights into their chemical and electrochemical stability against cathodes. Figure 21 displays the C Is, O Is, Cl 2p, Nb 3d, and Na Is spectra of the four samples before and after Ar+sputting (10 keV) for 10 mins. The C Is spectra can be allocated to C-C, C-O-C, and C=O bonds for all samples. The C-C peak is corrected to 284.8 eV to address the surface charge of all the other elements. The O ls spectra indicate the coexistence of bridging oxygen (Nb-O-Nb, at - 532.5 eV) and non-bridging oxygen (O=Nb, at -530.8 eV), which agrees with recent literature [A51]. For both NaNb1.07Cl4.35O and heat treated-NaNb1.07Cl4.35O samples, the ratios of the peak intensity between Nb-O-Nb and Nb=O reduce, suggesting that there are some side reactions at the surface of the two solid electrolytes which lead to structural rearrangements. Interestingly, a weak peak at around 536 eV is observed that does not agree with other literature [A51 ]. The peak at such a high energy can be attributed to the H-0 bond, indicating the existence of residual hydrogen in the samples that agrees with the NMR data shown in Figure 5d [A52].The Cl 2p spectra in all four samples show one major chemical environment with two spin-orbit splitting peaks. However, the NaNb1.07Q4.35O sample exhibits a small new peak at a higher binding energy after cycling, corresponding to oxidized Cl species (Clx) that suggests the degradation of the solid electrolyte [A28]. Similarly, new Nb4+peaks are identified in the NaNb1.07Cl4.35O sample after cycling, while they are not found in the heat treated- NaNb1.07Cl4.35O sample of the Nb 3d spectra. Thus, the analysis of Cl 2p and Nb 3d spectra suggests that the heat treated- NaNb1 07Cl435O is more stable than the NaNb1.07Cl4.35O solid electrolyte during cycling, which agrees with the different cycling stabilities of all solid state batteries made with the two solid electrolytes.Conclusion. In this study, O2-doping was demonstrated as an effective strategy in regulating the Na+conductivity in NaNbCE. The O2-doped NaNbxChx-iO solid-state electrolytes achieve high ionic conductivities (>1.0 mS cm-1) and low activation energies (< 0.25 eV) that outperform most of the halide-based solid-state electrolytes reported in the literature.The improved properties can be attributed to the reduced energy barrier and shortened distance for Na+transport at different sites by O2doping. Moreover, the O2-doped NaNbxClsx-iO solid- state electrolytes are amorphous dominated, which could be another reason for fast Na+conductivity in the solid-state electrolytes. Moreover, the developed NaNbxClsx-iO solid-state electrolytes have high oxidative stability (4.3 V v . Na+ / Na) and excellent compatibility with Na3PS4 anolyte and high-voltage cathode materials. These properties enable an excellent cycling performance of solid-state batteries made with the NaNbxChx-iO solid-state electrolyte, retaining 73% of its capacity after 1000 cycles and maintaining an average CE near 100%. These results underscore the potential of applying NaNbxClsx-iO as a solid-state electrolyte for next-generation sodium-ion solid-state batteries. Although only O2 / Cl' anion mixing is investigated in this study, other types of anion mixing warrant further investigation to demonstrate the applicability of such a strategy in developing new solid-state electrolytes.ExperimentalMaterials: NbCls (Aladdin) and NaCl (Sinopharm) with a molar ratio of 1 : 1 were used to synthesize NaNbCle, while NbCls (Aladdin) and NaOH (Aladdin) with a molar ratio between 0.670:1 to 1.110:1 were used to synthesize NaNbxClsx-iO. To synthesize NaNbxTai-xCUO, a certain amount of TaCls (Aladdin) was used to replace NbCls to achieve the desired stoichiometric ratio between Nb and Ta in the product. The mixture was ball milled (QM-3SP2, Nanda Instruments) at 550 rpm for lOh in a 50 ml ZrCF jar under an Ar environment. NasPS4 powders were prepared by ball-milling a stoichiometric mixture of Na2S (Sigma Aldrich) and P2S5 (Sigma Aldrich) at 500 rpm for 12 h, followed by heat treatment at 280 °C for 1 h under Ar environment. For the preparation of Na2Sn, Na metal, and Sn powder were mixed in a steel jar under an Ar environment. The mixture was then ball milled at 300 rpm for 10 h to obtain the homogenous product. All precursors were handled in an Ar-filled glovebox (Mikrouna, H2O < 0.5 ppm, O2 < 0.5 ppm).Materials characterization: Powder XRD experiments were conducted on a Philips X’Pert powder diffractometer (D / MAX2500VL / PC, Rigaku) operating at 45 kV and 40 mA, utilizing Cu-Ka radiation (7. = 1.5406 A). The samples, secured in a zero-background holder and shielded with a Kapton film to prevent air exposure, were subjected to data collection at room temperature over a 20 range of 10° to 80°. The X-ray diffractometer (X’pert Pro-MPD, PANalytical, Netherlands) with a super-energy detector was utilized for the in-situ XRD analysis, employing Cu-Ka radiation (A, = 1.5406 A) at a generator voltage of 45 kV and a tube current of 40 mA. The measurements were performed within a temperature range of 30-130 °C,holding for approximately 30 minutes at each temperature, and utilizing a scanning range of 10- 80°.Electrochemical Characterization: The ionic conductivity of solid-state electrolytes was assessed at 30 °C through electrochemical impedance spectroscopy (EIS) over a frequency range spanning 1 MHz to 1 Hz, employing a potential perturbation of 10 mV (Biologic SP-200). To determine the activation energy, variable-temperature impedance measurements were performed from 30 to 70 °C within a microclimate chamber. The as-synthesized NaNbCUO powders were compacted into 12 mm diameter pellets under a pressure of 300 MPa, sandwiched between two steel rods for all measurements.For the electrochemical stability analysis of NaNbCUO, cyclic voltammetry was employed. NaNbCUO blended with 30% super P carbon black, served as the cathode, while Na PSa functioned as the solid-state electrolyte, and Na2Sn acted as the anode. These components were individually pressed under 300 MPa in a cylinder cell with a 12 mm diameter. Cyclic voltammetry experiments were conducted on Biologic SP-200 with a scan rate of 0.5 mV / s and a voltage window of 0-5 V.The fabrication process of the all-solid-state Na2 / 3Nii / 3Mn2 / 30i II NaNb1.07CU.35O II NaiPS4 II Na2Sn battery involved the following steps. The composite cathode was created by ball milling a mixture of doped-Na2 / 3Nii / 3Mn2 / 3O2, NaNb1.07CU.35O, and SP (in a weight ratio of 50:50:3) at 200 rpm for 1 h. Subsequently, the all-solid-state battery was assembled by copressing the components in the following order: Na2Sn anode (50 mg), NaiPS4 anolyte (70 mg), NaNb1.07C .35O catholyte (70 mg), and doped-Na2 / 3Nii / 3Mn2 / 3O2 composite cathode (10 mg), applying a pressure of 300 MPa.References[Al] N. Kamaya et al. Nat Mater 2011, 10, 682.[A2] H. Gao et al. Chem 2018, 4, 833.[A3] J. K. Kim et al. Energy Environ Sci 2015, 8, 3589.[A4] W. Hou et al. Nano Energy, 2018, 52, 279-291.[A5] Z. Zhang et al. Adv Energy Mater 2017, 7, 1601196.[A6] S. Vasudevan et al. Int J Appl Ceram Technol 2023, 20, 563.[A7] J. Huang et al. Chem. Soc. Rev. 2023, 52, 4933-4995.[A8] Y. Zhu et al. Angewandte Chemie Int. Ed. 2020, 59, 17472.[A9] H. Kwak et al. Energy Storage Mater 2021, 37, 47.[A10] Y. Qie et al. Journal of Physical Chemistry Letters 2020, 11 , 3376.[Al l] H. Huang et al. ACS Appl Mater Interfaces 2022, 14, 36864.I Al 2] Y. Lian et al. J Mater Chem A Mater 2023, 11, 1906.[Al 3] J. Park et al. ACS Energy Lett 2022, 7, 3293.[A14] C. Fu et al. Nat Commun 2024, 15, 4315.[A15] E. A. Wu et al. Nat Commun 2021, 12, 1256.[A16] R. A. Marcus, J Chem Phys 1956, 24, 966.[A17] R. A. Marcus, Discussions of Faraday Society, 1960, 29, 21-31[A18] Y. Wang et al. Nature Materials 2015 14:10 2015, 14, 1026.[A19] H Henke. Zeitschrift f ur Kristallographie, 1992, 198, 1.[A20] X. Martinez de Irujo-Labalde et al. J Mater Chem A Mater 2024, 63(10), 5184- 5191.[A21] H. Henke et al. Zeitschrift fur Kristallographie-Crystalline Materials, 2010, 225, 217.[A22] T. Ogawa et al. J Mater Chem A Mater 2024, 12, 31173-31184.[A23] Y. Luo et al. Energy and Environmen. Sci. 2024, 17, 7543-7565.[A24] J. Kim et al. ACS Appl Mater Interfaces 2023, 15(45), 52427-52435.[A25] S. H. Janget al. 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[0052] B. Zhang et al. Int J Biol Macromol 2022, 216, 882.EXEMPLARY ASPECTSIn view of the described compositions and methods, herein below are described certain more particularly described aspects of the inventions. The particularly recited aspects should not, however, be interpreted to have any limiting effect on any different claims containing different or more general teaching described herein or that the “particular” aspects are somehow limited in some way other than the inherent meanings of the language and formulas literally used therein.Example 1: A solid electrolyte comprising: ABC?. zDx+y, wherein: A is chosen from Li, Na, K, Mg, Ca, Zn, Al, In, Fe, and combinations thereof; B is chosen from Ca, Mg, Zn, In, V, Nb, Ta, Mn, Ti, Zr, Hf, Fe, Co, Ni, Al, Ga, and combinations thereof; C is chosen from F, Cl, Br, I, and combinations thereof; D is chosen from O, S, Se, Te, and combinations thereof; is an integer chosen from 4, 5, and 6, such that the solid electrolyte is charge neutral; 0 < x < l ; 0 < z < 2; and 0 < y < 1.Example 2: The solid electrolyte of any examples herein, particularly example 1, wherein A is chosen from Li, Na, and K; B is chosen from V, Nb, and Ta; and wherein X is 6.Example 3: The solid electrolyte of any examples herein, particularly example 1 , wherein A is chosen from Li, Na, and K; B is chosen from Mn, Ti, Zr, and Hf; and wherein X is 5.Example 4: The solid electrolyte of any examples herein, particularly example 1, wherein A is chosen from Li, Na, and K; B is chosen from Fe, Co, Ni, Al, Ga, and I; and wherein X is 4.Example 5: The solid electrolyte of any examples herein, particularly examples 1-4, wherein B is a combination of two of Ca, Mg, Zn, In, V, Nb, Ta, Mn, Ti, Zr, Hf, Fe, Co, Ni, Al, and Ga.Example 6: The solid electrolyte of any examples herein, particularly examples 1-5, wherein the solid electrolyte comprises: NaNbaClsa-iO, where a is 0.6 to 1.15, such as from 1.0 to 1.15 or from 1.0 to 1.1.Example 7: The solid electrolyte of any examples herein, particularly example 6, where a is 1, 1.015, 1.030, 1.035, 1.070, or 1.110.Example 8: The solid electrolyte of any examples herein, particularly example 6 or example 7, wherein the solid electrolyte comprises NaNbo.eChO, NaNbo.7Cl250, NaNbo.sChO, NaNbo.85Cl3.25O, NaNbo.9Cl3.5O, NaNbo.95Cl3.75O, NaNbCEO, NaNb1.015Cl4.075O, NaNb1 030Cl4150O, NaNb1 035Cl4175O, NaNb1 070Cl4350O, NaNb1 noCl4550O, or a combination thereof.Example 9: The solid electrolyte of any examples herein, particularly examples 6-8, wherein the solid electrolyte comprises NaNbCLiO, NaNb1.07Cl4.35O, or a combination thereof.Example 10: The solid electrolyte of any examples herein, particularly examples 6-9, wherein the solid electrolyte comprises NaNbCl iO.Example 11 : The solid electrolyte of any examples herein, particularly examples 6-10, wherein the solid electrolyte comprises NaNb1.07Cl4.35O.Example 12: The solid electrolyte of any examples herein, particularly examples 1-11, wherein the solid electrolyte comprises Na(NbbTai-b)aC15a-iO, where 0 < b < 1 and 0.6 < a < 1.15.Example 13: The solid electrolyte of any examples herein, particularly example 12, wherein b is 0.6, 0.5, 0.4, or 0.Example 14: The solid electrolyte of any examples herein, particularly example 12 or example 13, wherein a is 1.Example 15: The solid electrolyte of any examples herein, particularly examples 12-14, wherein a is 1 and b is 0.6, 0.5, 0.4, or 0.Example 16: The solid electrolyte of any examples herein, particularly examples 12-15, wherein the solid electrolyte comprises NaNbo.6Tao.4d4O, NaNbo.5Tao.5Q4O, NaNbo.4Tao.6Q4O, NaTaChO, or a combination thereof.Example 17: The solid electrolyte of any examples herein, particularly examples 12-16, wherein the solid electrolyte comprises NaTaChO.Example 18: The solid electrolyte of any examples herein, particularly examples 1-17, wherein the solid electrolyte has been heat treated.Example 19: The solid electrolyte of any examples herein, particularly examples 1-18, wherein the solid electrolyte has a Na+ionic conductivity at 30°C of from 1 x 10'3mS cm-1to 20 mS cm1.Example 20: The solid electrolyte of any examples herein, particularly examples 1-19, wherein the solid electrolyte has a Na+ionic conductivity at 30°C of 0.5 mS cm'1or more.Example 21 : The solid electrolyte of any examples herein, particularly examples 1-20, wherein the solid electrolyte has a Na+ionic conductivity at 30°C of 1 mS cm'1or more.Example 22: The solid electrolyte of any examples herein, particularly examples 1-21, wherein the solid electrolyte has an activation energy of from 0 to 0.7 eV.Example 23: The solid electrolyte of any examples herein, particularly examples 1-22, wherein the solid electrolyte has an activation energy 0.3 eV or less.Example 24: The solid electrolyte of any examples herein, particularly examples 1-23, wherein the solid electrolyte has an activation energy of 0.25 eV or less.Example 25: The solid electrolyte of any examples herein, particularly examples 1-24, wherein the solid electrolyte has an electrochemical stability window of from 2.0 to 4.5 V vs. Na / Na+.Example 26: A method of making the solid electrolyte of any examples herein, particularly examples 1-25.Example 27: The method of any examples herein, particularly example 26, wherein the method comprises combining a plurality of precursors to form a mixture and ball milling the mixture to form the solid electrolyte.Example 28: The method of any examples herein, particularly example 27, wherein the ball milling is performed at a rate of from 100 to 2000 rpm for an amount of time of from 10 minutes to 100 hours.Example 29: The method of any examples herein, particularly example 27 or example 28, wherein the ball milling is performed at a rate of from 250 to 750 rpm for an amount of time of from 1 hour to 24 hours.Example 30: The method of any examples herein, particularly examples 27-29, wherein the method further comprises heat treating the solid electrolyte, wherein heat treating comprises heating the solid electrolyte at a temperature for an amount of time.Example 31 : The method of any examples herein, particularly example 30, wherein the temperature is from 50°C to 500°C, such as from 100°C to 400°C.Example 32: The method of any examples herein, particularly example 30 or example 31, wherein the amount of time is from 1 minute to 100 hours, such as from 1 minute to 24 hours.Example 33: The method of any examples herein, particularly examples 30-32, wherein the method further comprises ball milling after heat treatment.Example 34: The method of any examples herein, particularly example 33, wherein the ball milling is performed at a rate of from 100 to 2000 rpm for an amount of time of from 10 minutes to 100 hours.Example 35: The method of any examples herein, particularly example 26, wherein the method comprises combining a plurality of precursors to form a mixture, and heat treating the mixture in an inert environment to form the solid electrolyte.Example 36: The method of any examples herein, particularly example 35, wherein heat treating the mixture comprises heating the mixture at a temperature for an amount of time.Example 37: The method of any examples herein, particularly example 36, wherein the temperature is from 50°C to 500°C, such as from 100°C to 400°C.Example 38: The method of any examples herein, particularly example 36 or example 37, wherein the amount of time is from 1 minute to 100 hours, such as from 1 minute to 24 hours.Example 39: The method of any examples herein, particularly examples 36-38, wherein the method further comprises ball milling after heat treatment.Example 40: The method of any examples herein, particularly example 39, wherein the ball milling is performed at a rate of from 100 to 2000 rpm for an amount of time of from 10 minutes to 100 hours.Example 41 : A system comprising the solid electrolyte of any examples herein, particularly examples 1-25.Example 42: An article comprising the solid electrolyte of any examples herein, particularly examples 1-25.Example 43 : A device comprising the solid electrolyte of any examples herein, particularly examples 1-25.Example 44: The device of any examples herein, particularly example 43, wherein the device is an energy storage device, such as a battery.Example 45: The device of any examples herein, particularly example 43 or example 44, wherein the device is a battery, such as a solid state battery.Example 46: The device of any examples herein, particularly examples 43-45, wherein the device is a capacitor or a supercapacitor.Example 47: The device of any examples herein, particularly examples 43-46, wherein the device is an electrochemical cell.Example 48: An electrochemical cell comprising the solid electrolyte of any examples herein, particularly examples 1-25.Example 49: An electrochemical cell comprising: a first solid-state electrolyte comprising: ABCA-2x-zDx+y, wherein: A is chosen from Li, Na, K, Mg, Ca, Zn, Al, In, Fe, and combinations thereof; B is chosen from Ca, Mg, Zn, In, V, Nb, Ta, Mn, Ti, Zr, Hf, Fe, Co, Ni, Al, Ga, and combinations thereof; C is chosen from F, Cl, Br, I, and combinations thereof; D ischosen from O, S, Se, Te, and combinations thereof; A is an integer chosen from 4, 5, and 6, such that the first solid-state electrolyte is charge neutral; 0 < x < l; 0 < z < 2; and 0 < y < 1.Example 50: The electrochemical cell of any examples herein, particularly example 49, wherein the first solid-state electrolyte comprises the solid electrolyte of any examples herein, particularly examples 1-25.Example 51 : The electrochemical cell of any examples herein, particularly examples 47- 50, further comprising an anode material.Example 52: The electrochemical cell of any examples herein, particularly example 51, wherein the anode material includes Li, Na, K, Zn, Mg, Al, Si, Ag, Li alloys, Li intermetallics, Li compounds, Na alloys, Na intermetallics, Na compounds, K alloys, K intermetallics, K compounds, Al alloys, Al intermetallics, Al compounds, Si alloys, Si intermetallics, Si compounds, Ag alloys, Ag intermetallics, Ag compounds, or any combination thereofExample 53: The electrochemical cell of any examples herein, particularly example 51 or example 52, wherein the anode material comprises Li, Na, K, Zn, Mg, Li alloys, Li intermetallics, Li compounds, Na alloys, Na intermetallics, Na compounds, K alloys, K intermetallics, K compounds, or any combination thereof.Example 54: The electrochemical cell of any examples herein, particularly examples 51-53, wherein the anode material includes MqSn, wherein M is chosen from Li, Na, K, Zn, and Mg, and where q is from 0.5 to 3.Example 55: The electrochemical cell of any examples herein, particularly examples 51-54, wherein the anode material comprises MzSn wherein M is chosen from Li, Na, K, Zn, and Mg.Example 56: The electrochemical cell of any examples herein, particularly examples 47-55, further comprising a cathode material.Example 57 : The electrochemical cell of any examples herein, particularly example 56, wherein the cathode material is a metal, a ceramic, or a composite.Example 58: The electrochemical cell of any examples herein, particularly examples 56-57, wherein the cathode material comprises Cu, C, graphite, Na, K, Li, Mg, Ca, Al, layered oxides, vanadium-based cathode, sulfur-based cathode, spinels, olivines, or any combination thereof.Example 59: The electrochemical cell of any examples herein, particularly examples 56-58, wherein the cathode material comprises MCrC , wherein M is chosen from Li, Na, K. Zn and Mg.Example 60: The electrochemical cell of any examples herein, particularly examples SOSO, wherein the cathode material includes MxTM02, wherein 0.6 < x < 1, and M is chosen from Li, Na, K, Zn, and Mg, and TM is a transition metal such as Ti, Nb, Ni, Mn, Co, Fe, Al, Cr, Zr and their mixture.Example 61 : The electrochemical cell of any examples herein, particularly examples 56-60, wherein the cathode material includes MXTM2-XC>2, wherein 0 < x < 2, and TM is a transition metal such as Ti, Nb, Ni, Mn, Co, Fe, Al, Cr, Zr and their mixture.Example 62: The electrochemical cell of any examples herein, particularly examples 47-61, further comprising a second solid-state electrolyte comprising an anolyte.Example 63 : The electrochemical cell of any examples herein, particularly example 62, wherein the second solid-state electrolyte comprises MPSC1, wherein M is chosen from Li, Na, K. Zn and Mg.Example 64: The electrochemical cell of any examples herein, particularly example 63, wherein the second solid electrolyte includes MxPSyClz, wherein x, y, and z are each independently from 0 to 7, M is chosen from Li, Na, K. Zn and Mg.Example 65 : The electrochemical cell of any examples herein, particularly example 63 or example 64, wherein MPS Cl comprises Na2.9PS3.9Clo.!.Example 66 : The electrochemical cell of any examples herein, particularly examples 47-65, wherein the first solid-state electrolyte further comprises a conductive paste.Example 67: The electrochemical cell of any examples herein, particularly examples 47-66, wherein A is chosen from Li, Na, and K; B is chosen from V, Nb, and Ta; and wherein A, is 6.Example 68: The electrochemical cell of any examples herein, particularly examples 47- 66, wherein A is chosen from Li, Na, and K; B is chosen from Mn, Ti, Zr, and Hf; and wherein k is 5.Example 69: The electrochemical cell of any examples herein, particularly examples 47- 66, wherein A is chosen from Li, Na, and K; B is chosen from Fe, Co, Ni, Al, Ga, and I; and wherein k is 4.Example 70: The electrochemical cell of any examples herein, particularly examples 47-69, wherein B is a combination of two of Ca, Mg, Zn, In, V, Nb, Ta, Mn, Ti, Zr, Hf, Fe, Co, Ni, Al, and Ga.Example 71 : The electrochemical cell of any examples herein, particularly examples 47-70, wherein the electrochemical cell is a battery, such as a solid-state battery.Example 72: The electrochemical cell of any examples herein, particularly examples 47-71, wherein the electrochemical cell is a solid-state battery, such as an all-solid-state battery.Example 73: The electrochemical cell of any examples herein, particularly examples 47-72, wherein the electrochemical cell exhibits a coulombic efficiency of 99% or more for 100 cycles or more.Example 74: The electrochemical cell of any examples herein, particularly examples 47-73, wherein the electrochemical cell exhibits a coulombic efficiency of 99% or more for 500 cycles or more.Example 75: The electrochemical cell of any examples herein, particularly examples 47-74, wherein the electrochemical cell exhibits a capacity retention of 70% or more for 500 cycles or more.Example 76: The electrochemical cell of any examples herein, particularly examples 47-75, wherein the electrochemical cell exhibits a capacity retention of 70% or more for 1000 cycles or more.Example 77: The electrochemical cell of any examples herein, particularly examples 47-76, wherein the electrochemical cell exhibits a capacity retention of 80% or more for 500 cycles or more.Example 78: The electrochemical cell of any examples herein, particularly examples 47-77, wherein the electrochemical cell exhibits rate capacity retention of 20% or more at 1C compared to C / 10 rate.Example 79: A system comprising one or more of the electrochemical cells of any examples herein, particularly examples 47-78.Example 80: The system of any examples herein, particularly example 79, wherein the system is an energy storage system.Example 81 : An article comprising one or more of the electrochemical cells of any examples herein, particularly examples 47-78.Example 82: The article of any examples herein, particularly example 81, wherein the article is a vehicle, such as a hybrid electric vehicle or an all-electric vehicle.Example 83 : The article of any examples herein, particularly example 81 or example 82, wherein the article is a vehicle, such as an electric bike, an electric scooter, an electric drone, or an electric airplane.Example 84: The article of any examples herein, particularly example 81, wherein the article comprises an electronic device, such as a portable electronic device, a laptop, a watch, a cell phone, or a medical device.Example 85: The article of any examples herein, particularly example 81, wherein the article is an energy storage device.Other advantages which are obvious and which are inherent to the invention will be evident to one skilled in the art. It will be understood that certain features and sub-combinations are of utility and may be employed without reference to other features and sub-combinations. This is contemplated by and is within the scope of the claims. Since many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.The methods of the appended claims are not limited in scope by the specific methods described herein, which are intended as illustrations of a few aspects of the claims and any methods that are functionally equivalent are intended to fall within the scope of the claims. Various modifications of the methods in addition to those shown and described herein are intended to fall within the scope of the appended claims. Further, while only certain representative method steps disclosed herein are specifically described, other combinations of the method steps also are intended to fall within the scope of the appended claims, even if not specifically recited. Thus, a combination of steps, elements, components, or constituents may be explicitly mentioned herein or less, however, other combinations of steps, elements, components, and constituents are included, even though not explicitly stated.

Claims

CLAIMSWhat is claimed is:

1. A solid electrolyte comprising:ABCA -2x-zDx+y, wherein:A is chosen from Li, Na, K, Mg, Ca, Zn, Al, In, Fe, and combinations thereof,B is chosen from Ca, Mg, Zn, In, V, Nb, Ta, Mn, Ti, Zr, Hf, Fe, Co, Ni, Al, Ga, and combinations thereof,C is chosen from F, Cl, Br, I, and combinations thereof,D is chosen from 0, S, Se, Te, and combinations thereof,A is an integer chosen from 4, 5, and 6, such that the solid electrolyte is charge neutral, 0 < x < 1, 0 < z < 2, and 0 < y < 1.

2. The solid electrolyte of claim 1, wherein A is chosen from Li, Na, and K; B is chosen from V, Nb, and Ta; and wherein A is 6.

3. The solid electrolyte of claim 1, wherein A is chosen from Li, Na, and K; B is chosen from Mn, Ti, Zr, and Hf; and wherein A is 5.

4. The solid electrolyte of claim 1, wherein A is chosen from Li, Na, and K; B is chosen from Fe, Co, Ni, Al, Ga, and I; and wherein A is 4.

5. The solid electrolyte of any one of claims 1-4, wherein B is a combination of two of Ca, Mg, Zn, In, V, Nb, Ta, Mn, Ti, Zr, Hf, Fe, Co, Ni, Al, and Ga.

6. The solid electrolyte of any one of claims 1-5, wherein the solid electrolyte comprises:NaNbaCLa-iO where a is 0.6 to 1.15, such as from 1.0 to 1.15 or from 1.0 to 1.1.

7. The solid electrolyte of claim 6, where a is 1, 1.015, 1.030, 1.035, 1.070, or 1.1 10.

8. The solid electrolyte of claim 6 or claim 7, wherein the solid electrolyte comprises NaNbo.eCLO, NaNbo.7Cl2.5O, NaNbo.sChO, NaNbo.85Cl3.25O, NaNbo.9Cl3.5O, NaNbo.95Cl3.75O, NaNbCLO, NaNb1.015Cl4.075O, NaNb1.030Cl4.150O, NaNb1.035Cl4.175O, NaNb1.070Cl4.350O, NaNb1.n0Cl4.550O, or a combination thereof.

9. The solid electrolyte of any one of claims 6-8, wherein the solid electrolyte comprisesNaNbCUO, NaNb1.07Q4.35O, or a combination thereof.

10. The solid electrolyte of any one of claims 6-9, wherein the solid electrolyte comprises NaNbCUO.

11. The solid electrolyte of any one of claims 6-10, wherein the solid electrolyte comprises NaNb1.07Cl4.35O.

12. The solid electrolyte of any one of claims 1-11, wherein the solid electrolyte comprisesNa(NbbTai-b)aCl5a-iO where 0 fi b < 1 and 0.6 < a < 1.15.

13. The solid electrolyte of claim 12, wherein b is 0.6, 0.5, 0.4, or 0.

14. The solid electrolyte of claim 12 or claim 13, wherein a is 1.

15. The solid electrolyte of any one of claims 12-14, wherein a is 1 and b is 0.6, 0.5, 0.4, or0.

16. The solid electrolyte of any one of claims 12-15, wherein the solid electrolyte comprises NaNbo.6Tao.4Q4O, NaNbo sTao sCLiO, NaNbo.4Tao.6G4O, NaTaCkO, or a combination thereof.

17. The solid electrolyte of any one of claims 12-16, wherein the solid electrolyte comprises NaTaChO.

18. The solid electrolyte of any one of claims 1-17, wherein the solid electrolyte has been heat treated.

19. The solid electrolyte of any one of claims 1-18, wherein the solid electrolyte has a Na+ionic conductivity at 30°C of from 1 x 10‘3mS cm-1to 20 mS cm1.

20. The solid electrolyte of any one of claims 1-19, wherein the solid electrolyte has a Na+ionic conductivity at 30°C of 0.5 mS cm’1or more.

21. The solid electrolyte of any one of claims 1-20, wherein the solid electrolyte has a Na+ionic conductivity at 30°C of 1 mS cm’1or more.

22. The solid electrolyte of any one of claims 1-21, wherein the solid electrolyte has an activation energy of from 0 to 0.7 eV.

23. The solid electrolyte of any one of claims 1-22, wherein the solid electrolyte has an activation energy 0.3 eV or less.

24. The solid electrolyte of any one of claims 1-23, wherein the solid electrolyte has an activation energy of 0.25 eV or less.

25. The solid electrolyte of any one of claims 1-24, wherein the solid electrolyte has an electrochemical stability window of from 2.0 to 4.5 V vs. Na / Na+.

26. A method of making the solid electrolyte of any one of claims 1-25.

27. The method of claim 26, wherein the method comprises combining a plurality of precursors to form a mixture and ball milling the mixture to form the solid electrolyte.

28. The method of claim 27, wherein the ball milling is performed at a rate of from 100 to 2000 rpm for an amount of time of from 10 minutes to 100 hours.

29. The method of claim 27 or claim 28, wherein the ball milling is performed at a rate of from 250 to 750 rpm for an amount of time of from 1 hour to 24 hours.

30. The method of any one of claims 27-29, wherein the method further comprises heat treating the solid electrolyte, wherein heat treating comprises heating the solid electrolyte at a temperature for an amount of time.31 . The method of claim 30, wherein the temperature is from 50°C to 500°C, such as from 100°C to 400°C.

32. The method of claim 30 or claim 31, wherein the amount of time is from 1 minute to 100 hours, such as from 1 minute to 24 hours.

33. The method of any one of claims 30-32, wherein the method further comprises ball milling after heat treatment.

34. The method of claim 33, wherein the ball milling is performed at a rate of from 100 to 2000 rpm for an amount of time of from 10 minutes to 100 hours.

35. The method of claim 26, wherein the method comprises combining a plurality of precursors to form a mixture, and heat treating the mixture in an inert environment to form the solid electrolyte.

36. The method of claim 35, wherein heat treating the mixture comprises heating the mixture at a temperature for an amount of time.

37. The method of claim 36, wherein the temperature is from 50°C to 500°C, such as from 100°C to 400°C.

38. The method of claim 36 or claim 37, wherein the amount of time is from 1 minute to 100 hours, such as from 1 minute to 24 hours.

39. The method of any one of claims 36-38, wherein the method further comprises ball milling after heat treatment.

40. The method of claim 39, wherein the ball milling is performed at a rate of from 100 to 2000 rpm for an amount of time of from 10 minutes to 100 hours.

41. A system comprising the solid electrolyte of any one of claims 1-25.

42. An article comprising the solid electrolyte of any one of claims 1-25.

43. A device comprising the solid electrolyte of any one of claims 1-25.

44. The device of claim 43, wherein the device is an energy storage device, such as a battery.

45. The device of claim 43 or claim 44, wherein the device is a battery, such as a solid state battery.

46. The device of any one of claims 43-45, wherein the device is a capacitor or a supercapacitor.

47. The device of any one of claims 43-46, wherein the device is an electrochemical cell.

48. An electrochemical cell comprising the solid electrolyte of any one of claims 1 -25.

49. An electrochemical cell comprising: a first solid-state electrolyte comprising:ABCA -2x-zDx+y, wherein:A is chosen from Li, Na, K, Mg, Ca, Zn, Al, In, Fe, and combinations thereof,B is chosen from Ca, Mg, Zn, In, V, Nb, Ta, Mn, Ti, Zr, Hf, Fe, Co, Ni, Al, Ga, and combinations thereof,C is chosen from F, Cl, Br, I, and combinations thereof,D is chosen from O, S, Se, Te, and combinations thereof,A is an integer chosen from 4, 5, and 6, such that the first solid-state electrolyte is charge neutral, 0 < x < 1, 0 < z < 2, and 0 < y < 1.

50. The electrochemical cell of claim 49, wherein the first solid-state electrolyte comprises the solid electrolyte of any one of claims 1-25.

51. The electrochemical cell of any one of claims 47-50, further comprising an anode material.

52. The electrochemical cell of claim 51 , wherein the anode material includes Li, Na, K, Zn, Mg, Al, Si, Ag, Li alloys, Li intermetallics, Li compounds, Na alloys, Na intermetallics, Na compounds, K alloys, K intermetallics, K compounds, Al alloys, Al intermetallics, Al compounds, Si alloys, Si intermetallics, Si compounds, Ag alloys, Ag intermetallics, Ag compounds, or any combination thereof.

53. The electrochemical cell of claim 51 or claim 52, wherein the anode material comprises Li, Na, K, Zn, Mg, Li alloys, Li intermetallics, Li compounds, Na alloys, Na intermetallics, Na compounds, K alloys, K intermetallics, K compounds, or any combination thereof.

54. The electrochemical cell of any one of claims 51-53, wherein the anode material includes MqSn, wherein M is chosen from Li, Na, K, Zn, and Mg, and where q is from 0.5 to 3.

55. The electrochemical cell of any one of claims 51-54, wherein the anode material comprises M2Sn wherein M is chosen from Li, Na, K, Zn, and Mg.

56. The electrochemical cell of any one of claims 47-55, further comprising a cathode material.

57. The electrochemical cell of claim 56, wherein the cathode material is a metal, a ceramic, or a composite.

58. The electrochemical cell of any one of claims 56-57, wherein the cathode material comprises Cu, C, graphite, Na, K, Li, Mg, Ca, Al, layered oxides, vanadium-based cathode, sulfur-based cathode, spinels, olivines, or any combination thereof.

59. The electrochemical cell of any one of claims 56-58, wherein the cathode materialcomprises MCrCL. wherein M is chosen from Li, Na, K. Zn and Mg.

60. The electrochemical cell of any one of claims 56-59, wherein the cathode material includes MxTM02, wherein 0.6 < x < 1, and M is chosen from Li, Na, K, Zn, and Mg, and TM is a transition metal such as Ti, Nb, Ni, Mn, Co, Fe, Al, Cr, Zr and their mixture.

61. The electrochemical cell of any one of claims 56-60, wherein the cathode material includes MXTM2-XC>2, wherein 0 < x < 2, and TM is a transition metal such as Ti, Nb, Ni, Mn, Co, Fe, Al, Cr, Zr and their mixture.

62. The electrochemical cell of any one of claims 47-61, further comprising a second solid- state electrolyte comprising an anolyte.

63. The electrochemical cell of claim 62, wherein the second solid-state electrolyte comprises MPSC1, wherein M is chosen from Li, Na, K. Zn and Mg.

64. The electrochemical cell of claim 63, wherein the second solid electrolyte includes MxPSyCL, wherein x, y, and z are each independently from 0 to 7, M is chosen from Li, Na, K. Zn and Mg.

65. The electrochemical cell of claim 63 or claim 64, wherein MPSC1 comprises Na2.9PS3.9Clo.!.

66. The electrochemical cell of any one of claims 47-65, wherein the first solid-state electrolyte further comprises a conductive paste.

67. The electrochemical cell of any one of claims 47-66, wherein A is chosen from Li, Na, and K; B is chosen from V, Nb, and Ta; and wherein Z is 6.

68. The electrochemical cell of any one of claims 47-66, wherein A is chosen from Li, Na, and K; B is chosen from Mn, Ti, Zr, and Hf; and wherein A, is 5.

69. The electrochemical cell of any one of claims 47-66, wherein A is chosen from Li, Na, and K; B is chosen from Fe, Co, Ni, Al, Ga, and I; and wherein A is 4.

70. The electrochemical cell of any one of claims 47-69, wherein B is a combination of two of Ca, Mg, Zn, In, V, Nb, Ta, Mn, Ti, Zr, Hf, Fe, Co, Ni, Al, and Ga.

71. The electrochemical cell of any one of claims 47-70, wherein the electrochemical cell is a battery, such as a solid-state battery.

72. The electrochemical cell of any one of claims 47-71, wherein the electrochemical cell is a solid-state battery, such as an all-solid-state battery.

73. The electrochemical cell of any one of claims 47-72, wherein the electrochemical cell exhibits a coulombic efficiency of 99% or more for 100 cycles or more.

74. The electrochemical cell of any one of claims 47-73, wherein the electrochemical cell exhibits a coulombic efficiency of 99% or more for 500 cycles or more.

75. The electrochemical cell of any one of claims 47-74, wherein the electrochemical cell exhibits a capacity retention of 70% or more for 500 cycles or more.

76. The electrochemical cell of any one of claims 47-75, wherein the electrochemical cell exhibits a capacity retention of 70% or more for 1000 cycles or more.

77. The electrochemical cell of any one of claims 47-76, wherein the electrochemical cell exhibits a capacity retention of 80% or more for 500 cycles or more.

78. The electrochemical cell of any one of claims 47-77, wherein the electrochemical cell exhibits rate capacity retention of 20% or more at 1C compared to C / 10 rate.

79. A system comprising one or more of the electrochemical cells of any one of claims 47- 78.

80. The system of claim 79, wherein the system is an energy storage system.

81. An article comprising one or more of the electrochemical cells of any one of claims 47- 78.

82. The article of claim 81 , wherein the article is a vehicle, such as a hybrid electric vehicle or an all-electric vehicle.

83. The article of claim 81 or claim 82, wherein the article is a vehicle, such as an electric bike, an electric scooter, an electric drone, or an electric airplane.

84. The article of claim 81 , wherein the article comprises an electronic device, such as a portable electronic device, a laptop, a watch, a cell phone, or a medical device.

85. The article of claim 81, wherein the article is an energy storage device.

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