Compositions and methods of making and use thereof

Abstract

Described herein are compositions and methods of making and use thereof. For example, described herein are high entropy oxides and methods of making and use thereof, for example in electrodes and / or batteries.

Description

[0001] COMPOSITIONS AND METHODS OF MAKING AND USE THEREOF

[0002] CROSS-REFERENCE TO RELATED APPLICATION

[0003] This application claims priority to, and the benefit of U.S. Provisional Application No. 63 / 538,536, filed on September 15, 2023, the content of which is hereby incorporated in its entirety.

[0004] BACKGROUND

[0005] As much as it is important to develop higher energy, higher power, and long stable cycle anode active material for next generation lithium-ion batteries, it is necessary to use relatively abundant elements in order to keep the price of these energy storage devices competitively enough to fossil fuel. Although cobalt is relatively abundant on earth, about 70% of the world supply comes from a single country (Democratic Republic of Congo) (Faraday insights. Building a Responsible Cobalt Supply Chain, issue 7: May 2020. https: / / faraday.ac.uk / wp- content / uploads / 2020 / 05 / Insight-cobalt-supply-chainl.pdf, accessed 04 / 23 / 2021). Due to political instability in this country and around the region, prices and availability fluctuations can devastate the battery industry. The current world supply of cobalt is thus fragile. In addition, as the Li-ion industry grows to 1 TWh of production per year, approximately one million tons of combined cobalt will be required, thereby placing significant strains on the metal resources51. As previously asserted, LiCoCh was the first commercially available cathode active material for lithium-ion batteries and is still used today in commercial batteries. However, with the intense necessity to move away from cobalt-base battery materials, research has led to the layered materials, MNC series and MNA series, which are now the dominant cathode active materials in today’s lithium-ion batteries as detailed above. To echo this same trend, (Sarkar, A., Velasco, L., Wang, D. et al. High entropy oxides for reversible energy storage. Nat Commun 9, 3400 (2018) (“Sarkar et. al ”) who first proposed (MgCoNiZnCu)O as an anode material for lithium-ion batteries, attempted to remove cobalt from the formulation to propose (MgNiZnCu)O, but the material did not show good electrochemical performance as that obtained from the initial formulation. In addition, in order to prove that the high entropy oxide anode active material concept provides great design space to tune the electrochemical properties of this new class of material, Sarkar et. al. also attempted to investigate the effects of each transition metal cation. It is clear from the figure that all five metal cations are necessary for the long-term performance of the HEO material. Specifically, one of the figures displays the role of cobalt in the material, an effect that could discourage the battery community from paying attention to this material. The voltage vs. profile plot shows that the lithiation of the various TM-HEO materials occurs at slightly different potentials, and more importantly, the lithiation of the TM-MEO (-Cu) occurs at significantly lower voltage than the other materials.

[0006] Devices with improved properties are needed. The compositions, methods, and devices discussed herein address these and other needs.

[0007] SUMMARY

[0008] In accordance with the purposes of the disclosed compositions, methods, and devices as embodied and broadly described herein, the disclosed subject matter relates to compositions and methods of making and use thereof. For example, disclosed herein are high entropy oxides and methods of making and use thereof, for example in electrodes and / or batteries.

[0009] Described herein are high entropy oxides including:

[0010] (MgCoNiZnCu)O wherein at least a portion of the Co is substituted (e.g., replaced) with a more abundant element, such as Fe, Ti, Mn, or a combination thereof; at least a portion of the Ni is substituted (e.g., replaced) with a more abundant element, such as Fe, Ti, Mn, or a combination thereof; at least a portion of the Mg is substituted (e.g., replaced) with Ca; or a combination thereof.

[0011] Described herein are also high entropy oxides including:

[0012] ([Mgi-qCaq][Coi-a-b-cFeaTibMnc][Nii-x-y-zFexTiyMnz]ZnCu)O wherein q, a, b, c, x, y, and z are each independently from 0 to 1; a+b+c is from 0 to 1; and x+y+z is from 0 to 1; with the proviso that: when a is greater than 0, then x is 0; when x is greater than 0, then a is 0; when b is greater than 0, then y is 0; when y is greater than 0 then b is 0; when c is greater than 0, then z is 0; and when z is greater than 0 then c is 0; and with the further proviso that: q is greater than 0; a+b+c is greater than 0; x+y+z is greater than 0; or a combination thereof.

[0013] Also described herein are oxyfluorides derived from any of the high entropy oxides described herein. Also described herein are methods of making the oxyfluorides. For example, the methods can include fluorinating any of the high entropy oxides described herein.

[0014] Also described herein are methods of use of any of compositions disclosed herein, for example in a device, a system, and / or an article.

[0015] For example, also disclosed herein are devices, such as an electrode and / or a battery, including any of the compositions disclosed herein.

[0016] Also disclosed herein are electrodes including any of the high entropy oxides and / or oxyfluorides described herein.

[0017] For example, also described herein are anodes including any of the high entropy oxides disclosed herein.

[0018] Also described herein, for example, are cathodes including any of the oxyfluorides disclosed herein.

[0019] In some examples, the electrode, anode, and / or cathode is high capacity, stable, fast charging, or a combination thereof.

[0020] Also described herein are methods of use of any of the electrodes, anodes, and / or cathodes disclosed herein, for example, in a device, a system, and / or an article.

[0021] For example, also described herein are devices, such as a battery, including any of the electrodes, anodes, and / or cathodes disclosed herein.

[0022] Also described herein are batteries including any of the electrodes, anodes, and / or cathodes described herein. In some examples, the battery is a lithium ion battery.

[0023] 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 disclosed devices 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.

[0024] BRIEF DESCRIPTION OF THE FIGURES

[0025] The 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.

[0026] Figures 1A-1C: Material characterization. (1A) XRD (the insert is an XRD of (MgCoNiZnCu)O as reported in the literature Sarkar, et al ), (IB) SEM / EDS (the scale bar is 10pm), (1C) CV of the as prepared (MgCoNiZnCu)O powder at 0.1 mV / s scan rate.

[0027] Figures 2A-2B: (MgMnNiZnCu)O characterization. (2A) Powder XRD of sintered pellet and ball mill sample (the starred peaks represent the expected rock salt). (2B) SEM / EDS of ball mill sample: the scale bar in the image is 20 pm.

[0028] Figures 3A-3B: Electrochemical performance of the (MgMnNiZnCu)O material. (3 A) CV at 0.1 mV / s scan rate. (3B) Specific capacity vs. cycle number and corresponding coulombic efficiency at a current density of lOOmA / g.

[0029] DETAILED DESCRIPTION

[0030] The compositions, methods, and devices 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.

[0031] Before the present compositions, methods, and devices 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.

[0032] 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. In 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.

[0033] 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.

[0034] 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.

[0035] “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.

[0036] 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.

[0037] Values can be expressed herein as an “average” value. “Average” generally refers to the statistical mean value.

[0038] By “substantially” is meant within 5%, e.g., within 4%, 3%, 2%, or 1%.

[0039] “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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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 is important 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.

[0044] As used herein, the terms “active component” and “active material” are used synonymously, and refer to a material that reacts with a working ion (e.g., lithium) under conditions typically encountered during charging and discharging of a battery (e.g., a lithium ion battery). Two or more active components can be present as the majority components of the amorphous glasses described herein.

[0045] As used herein, the terms “inactive component” and “inactive material” are used synonymously, and refer to a material that does not react with a working ion (e.g., lithium) under conditions typically encountered during charging and discharging of a battery (e.g., a lithium ion battery). Two or more inactive components can be present as minority components of the amorphous glasses described herein.

[0046] As used herein, the term “metal” refers to both metals and metalloids such as silicon and germanium. The metal is often in an elemental state.

[0047] As used herein, the term “lithiation” refers to the process of adding lithium to an amorphous glass described herein (i.e., lithium ions are reduced). Likewise, the term “sodiation” refers to an analogous process where sodium is added to an amorphous glass described herein.

[0048] As used herein, the term “delithiation” refers to the process of removing lithium from an amorphous glass described herein (i.e., lithium ions are oxidized). Likewise, the term “desodiation” refers to an analogous process where sodium is removed from an amorphous glass described herein. As used herein, the term “charging” refers to a process of providing electrochemical energy to a battery.

[0049] As used herein, the term “discharging” refers to a process of removing electrochemical energy from a battery (i.e., discharging is a process of using the battery to do useful work).

[0050] As used herein, the term “cathode” refers to the electrode where electrochemical reduction occurs during the discharging process. During discharging, the cathode undergoes lithiation. During charging, lithium atoms are removed from this electrode.

[0051] As used herein, the term “anode” refers to the electrode where electrochemical oxidation occurs during the discharging process. During discharging, the anode undergoes delithiation. During charging, lithium atoms are added to this electrode.

[0052] Compositions and Methods of Making and Use thereof

[0053] Disclosed herein are compositions and methods of making and use thereof. For example, disclosed herein are high entropy oxides and methods of making and use thereof, for example in electrodes and / or batteries.

[0054] For example, described herein are high entropy oxides including:

[0055] (MgCoNiZnCu)O wherein at least a portion of the Co is substituted (e.g., replaced) with a more abundant element, such as Fe, Ti, Mn, or a combination thereof; at least a portion of the Ni is substituted (e.g., replaced) with a more abundant element, such as Fe, Ti, Mn, or a combination thereof; at least a portion of the Mg is substituted (e.g., replaced) with Ca; or a combination thereof.

[0056] In some examples, at least a portion of the Co is substituted (e.g., replaced) with a more abundant element, such as Fe, Ti, Mn, or a combination thereof. In some examples, substantially all of the Co is substituted (e.g., replaced) with a more abundant element, such as Fe, Ti, or Mn.

[0057] In some examples, the amount and nature of the substitution can be independently selected, for example, to select and / or tune the electrochemical properties of the high entropy oxide.

[0058] Also described herein are high entropy oxides including:

[0059] ([Mgi-qCaq][Coi-a-b-cFeaTibMnc][Nii-x-y-zFexTiyMnz]ZnCu)O wherein q, a, b, c, x, y, and z are each independently from 0 to 1; a+b+c is from 0 to 1; and x+y+z is from 0 to 1; with the proviso that: when a is greater than 0, then x is 0; when x is greater than 0, then a is 0; when b is greater than 0, then y is 0; when y is greater than 0 then b is 0; when c is greater than 0, then z is 0; and when z is greater than 0 then c is 0; and with the further proviso that: q is greater than 0; a+b+c is greater than 0; x+y+z is greater than 0; or a combination thereof.

[0060] In some examples, a+b+c is greater than 0.

[0061] In some examples, q, a, b, c, x, y, and z are each independently 0 or 1; a+b+c is 0 or 1; and x+y+z is 0 or 1.

[0062] In some examples, q, a, b, c, x, y, and z can be independently selected, for example, to select and / or tune the electrochemical properties of the high entropy oxide.

[0063] In some examples, the high entropy oxide can include (MgFeNiZnCu)O, (MgTiNiZnCu)O, (MgMnNiZnCu)O, (MgCoFeZnCu)O, (MgCoTiZnCu)O, (MgCoMnZnCu)O, (CaCoNiZnCu)O, (MgFeTiZnCu)O, (MgFeMnZnCu)O, (MgTiFeZnCu)O, (MgTiMnZnCu)O, (MgMnFeZnCu)O, (MgMnTiZnCu)O, (CaFeNiZnCu)O, (CaTiNiZnCu)O, (CaMnNiZnCu)O, (CaCoFeZnCu)O, (CaCoTiZnCu)O, (CaCoMnZnCu)O, (CaFeTiZnCu)O, (CaFeMnZnCu)O, (CaTiFeZnCu)O, (CaTiMnZnCu)O, (CaMnFeZnCu)O, (CaMnTiZnCu)O, or a combination thereof.

[0064] In some examples, the high entropy oxide can include (MgFeNiZnCu)O, (MgTiNiZnCu)O, (MgMnNiZnCu)O, (MgCoFeZnCu)O, (MgCoTiZnCu)O, (MgCoMnZnCu)O, (CaCoNiZnCu)O, or a combination thereof.

[0065] In some examples, the high entropy oxide can include (MgMnNiZnCu)O.

[0066] In some examples, the high entropy oxide can include (MgFeTiZnCu)O, (MgFeMnZnCu)O, (MgTiFeZnCu)O, (MgTiMnZnCu)O, (MgMnFeZnCu)O, (MgMnTiZnCu)O, (CaFeNiZnCu)O, (CaTiNiZnCu)O, (CaMnNiZnCu)O, (CaCoFeZnCu)O, (CaCoTiZnCu)O, (CaCoMnZnCu)O, or a combination thereof.

[0067] In some examples, the high entropy oxide can include (CaFeTiZnCu)O, (CaFeMnZnCu)O, (CaTiFeZnCu)O, (CaTiMnZnCu)O, (CaMnFeZnCu)O, (CaMnTiZnCu)O, or a combination thereof.

[0068] In some examples, the metal cations can be present in a substantially equimolar amount in the high entropy oxide.

[0069] In some examples, the high entropy oxide can be crystalline. In some examples, the high entropy oxide can be single-phase rock salt crystalline material. In some examples, the metal ions occupy random cation sites in the crystal lattice unit cell.

[0070] In some examples, the high entropy oxide is stabilized by configurational entropy.

[0071] In some examples, the high entropy oxide is capable of lithium storage.

[0072] Also disclosed herein are methods of making any of the high entropy oxides described herein. In some examples, the method includes nebulized spray pyrolysis, flame spray pyrolysis, reverse co-precipitation, solid state synthesis, or a combination thereof.

[0073] In some examples, the method can include reverse co-precipitation. In some examples, the reverse co-precipitation method can include: dissolving nitrates of the corresponding metals in substantially equimolar amount in water to make a solution; adjusting the pH of the solution to 10 to form a product; and separating, drying, optionally grinding, and calcining the product. In some examples, the method can further include agitating the solution. Agitating can be accomplished, for example, by mechanical stirring, shaking, vortexing, sonication (e.g., bath sonication, probe sonication, ultrasonication), and the like, or combinations thereof.

[0074] In some examples, the method can include solid state synthesis. In some examples, the solid state synthesis method can include contacting substantially equimolar amounts of binary oxides of the metals to form a mixture; and heating the mixture. In some examples, the method can further include agitating and / or grinding the mixture before, after and / or while heating the mixture. In some examples, the mixture can be heated at a temperature sufficient to overcome the positive enthalpy of mixing in order to obtain a single-phase rock salt structure. In some examples, the method can further include quenching the mixture after heating.

[0075] Also described herein are oxyfluorides derived from any of the high entropy oxides described herein. Also described herein are methods of making the oxyfluorides. For example, the methods can include fluorinating any of the high entropy oxides described herein. Also described herein are methods of use of any of compositions disclosed herein, for example in a device, a system, and / or an article.

[0076] For example, also disclosed herein are devices, such as an electrode and / or a battery, including any of the compositions disclosed herein.

[0077] Also disclosed herein are electrodes including any of the high entropy oxides and / or oxyfluorides described herein.

[0078] For example, also described herein are anodes including any of the high entropy oxides disclosed herein.

[0079] Also described herein, for example, are cathodes including any of the oxyfluorides disclosed herein.

[0080] In some examples, the electrode, anode, and / or cathode is high capacity, stable, fast charging, or a combination thereof.

[0081] Also described herein are methods of use of any of the electrodes, anodes, and / or cathodes disclosed herein, for example, in a device, a system, and / or an article.

[0082] For example, also described herein are devices, such as a battery, including any of the electrodes, anodes, and / or cathodes disclosed herein.

[0083] Also provided are electrochemical cells that include the anodes described herein. For example, provided are electrochemical cells that include an anode described herein, a cathode described herein, and an electrolyte disposed between the anode and the cathode.

[0084] Any suitable electrolyte can be included in the lithium ion battery. The electrolyte can be in the form of a solid or liquid. Exemplary solid electrolytes include polymeric electrolytes such as polyethylene oxide, polytetrafluoroethylene, polyvinylidene fluoride, fluorine-containing copolymers, polyacrylonitrile, or combinations thereof. Exemplary liquid electrolytes include ethylene carbonate, dimethyl carbonate, diethyl carbonate, propylene carbonate, gammabutyrolactone, tetrahydrofuran, 1,2-dimethoxy ethane, di oxolane, or combinations thereof. The electrolyte includes a lithium electrolyte salt such as LiPFe, LiBF4, LiCICh, LiN(SO2CF3)2, LiN(SO2CF2CF3)2, and the like.

[0085] The electrolyte can include a redox shuttle molecule, an electrochemically reversible material that during charging can become oxidized at the cathode, migrate to the anode where it can become reduced to reform the unoxidized (or less-oxidized) shuttle species, and migrate back to the cathode. Suitable redox shuttle molecules include, for example, those described in U.S. Pat. Nos. 5,709,968 (Shimizu), U.S. Pat. No. 5,763,119 (Adachi), U.S. Pat. No. 5,536,599 (Alamgir et al.), U.S. Pat. No. 5,858,573 (Abraham et al.), U.S. Pat. No. 5,882,812 (Visco et al.), U.S. Pat. No. 6,004,698 (Richardson et al.), U.S. Pat. No. 6,045,952 (Kerr et al.), and U.S. Pat. No. 6,387,571 Bl (Lain et al.); and in PCT Published Patent Application No. WO 01 / 29920 Al (Richardson et al.).

[0086] Also described herein are batteries including any of the electrodes, anodes, and / or cathodes described herein. In some examples, the battery is a lithium ion battery.

[0087] Any suitable cathode known for use in lithium ion batteries can be utilized. Some exemplary cathodes in a charged state contain lithium atoms intercalated within a lithium transition metal oxide such as lithium cobalt dioxide, lithium nickel dioxide, and lithium manganese dioxide. Other exemplary cathodes are those disclosed in U.S. Pat. No. 6,680,145 B2 (Obrovac et al.), incorporated herein by reference. That is, the cathode can contain particles that include transition metal grains (e.g., iron, cobalt, chromium, nickel, vanadium, manganese, copper, zinc, zirconium, molybdenum, niobium, or combinations thereof) having a grain size no greater than about 50 nanometers in combination with lithium-containing grains selected from lithium oxides, lithium sulfides, lithium halides (e.g., chlorides, bromides, iodides, or fluorides), or combinations thereof. These particles can be used alone or in combination with a lithium- transition metal oxide material such as lithium cobalt dioxide. In some embodiments, the cathode can be a cathode described herein.

[0088] In some lithium-ion batteries with solid electrolytes, the cathode can include LiVsOs or LiV2Os. In other lithium-ion batteries with liquid electrolytes, the cathode can include LiCoCh, LiCoo.2Nio.8O2, LiMn2O4, LiFePO4, or LiNiO2.

[0089] In some examples, the electrochemical cell can include a lithium ion battery, and the cathode includes a lithium-based cathode (e.g., lithium iron phosphate, LiNii-xMnx / 2Cox / 2O2, wherein x = 0.4 or 0.2, or LiNi0.8Co0.15Al0.05O2).

[0090] In some examples, the electrochemical cell can include a lithium ion battery, and the cathode can be a cathode described herein.

[0091] The lithium-ion batteries can be used as a power supply in a variety of applications. For example, the lithium-ion batteries can be used in power supplies for electronic devices such as computers and various hand-held devices, motor vehicles, power tools, photographic equipment, and telecommunication devices. Multiple lithium-ion batteries can be combined to provide a battery pack.

[0092] In some examples, the battery is rechargeable. In some examples, the battery exhibits a capacity retention of 80% or more (e.g., 90% or more) for 10 cycles or more (e.g., 25 cycles or more, 50 cycles or more, or 100 cycles or more). Also disclosed herein are systems including one or more of the batteries disclosed herein. For example, the system can be an energy storage system.

[0093] Also disclosed herein are articles (e.g., articles of manufacture) including one or more of the batteries disclosed herein. For example, the article can be a vehicle, such as a hybrid electric vehicle or an all-electric vehicle. In some examples, the article can include an electronic device, such as a portable electronic device, a laptop, a watch, a cell phone, etc.

[0094] 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.

[0095] The examples below are intended to further illustrate certain aspects of the devices and methods described herein, and are not intended to limit the scope of the claims.

[0096] EXAMPLES

[0097] The 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.

[0098] 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.

[0099] Example 1 - High Entropy Oxide and Oxyhalides as Anodes and Cathodes

[0100] The compound (MgCoNiZnCu)O is a single-phase rock salt with the metal ions occupying random cations stabilized by configurational entropy, commonly referred to as high entropy oxide. Herein, a series of high capacity, stable and fast charging high entropy oxide anodes are demonstrated by substituting Co and / or Ni with elements that are more abundant, such as such as iron (Fe2+), titanium (Ti2+), and manganese (Mn2+). Magnesium was also replaced with calcium in the (MgCoNiZnCu)O to shed some light on the role of this electrochemically nonactive species. Additionally, the oxide can be fluorinated to form an oxyfluoride to investigate the material as cathode.

[0101] Example 2

[0102] Twenty years after Sony Commercialized the first lithium-ion battery, a Nobel Prize was awarded to its inventors1. The words uttered by the Royal Swedish Academy of Sciences was clear:

[0103] “[...] This lightweight, rechargeable and powerful battery is now used in everything from mobile phones to laptops and electric vehicles. It can also store significant amounts of energy from solar and wind power, making possible a fossil fuel-free society. [...]”

[0104] It is not unreasonable to think that what might have nudged the Nobel Committee to award this prize is the growing need to limit carbon dioxide emissions in order to halt the global temperature increase to no more than 2 °C above pre-industrial level, as endorsed within the Paris Climate Agreement in 20152. In order to reach this goal, a large decrease in annual emission of carbon dioxide equivalents (CCheq) is required, according to the UN Environment Program Emissions Gap Report3. To reach the 2 °C or the 1.5 °C goal by 2030, an ~ 27% or ~50% in global carbon dioxide emissions reduction from the present emission levels need to be achieved, respectively. This cannot be achieved by simply following the Paris Climate Agreement as the projections show. This is thus why the UN Environment Program Emissions Gap is emphasizing the need to intensively change the energy source from coal to renewable3. It is extremely difficult to imagine such a switch without the development of energy storage devices that can efficiently allow for a good management of fluctuating energy sources such as wind energy and photovol taics. In addition, the transportation sector alone was responsible for about 24% of direct CO2 emissions from fuel combustion4. Electric vehicles are therefore highly desirable in this sector, a feat that will require safe, long lasting, and high energy density devices, which so far has only been offered by lithium-ion-based systems.

[0105] Li-ion batteries have gained wide use since its introduction and have been the subject of several research groups for the past 30 years5. These batteries are rechargeable batteries during which lithium ions (Li+) migrate from the cathode to the anode when charging and from the anode to the cathode during discharge. The cathode of these batteries is generally lithium metal oxides, and graphite (C) is generally used as anode material. During charge, the Li-ions stored within the cobalt oxide layered material on the cathode migrate toward the anode to occupy the space within the graphene sheets of the graphite material. Evolution of Cathode Materials for Lithium-Ion Batteries. Since the discovery that layered-metal chalcogenides of the form MX2 could store lithium-ions6, TiS2 / Li rechargeable battery was developed in 1977 by Whittingham and Co-workers7,8and in the subsequent years, MoS2 / Li cell was developed and commercialized by Moli Energy in 1980s9. Because of the low working potential (~ 2.5V vs Li+ / Li) of these cathode materials, the commercialized batteries had low energy density, and as a consequence, there was a growing need to develop new cathode materials with higher working voltage. The replacement of chalcogens in the metal chalcogenides series by oxygen, led to the development of LiCoCh by Goodenough and Coworkers and the working potential of this material was ~ 4V vs Li+ / Li10,11. The spinel-like LiM Ch was also develop by Goodenough and Coworkers12as cheaper alternative to LiCoCh. However, this spinel-like material suffers from capacity loss due to dissolution of the transition metal ion, specially at elevated temperatures13. To remediate this problem, Amine et. al.udeveloped LiNio.5Mm.5O4 which exhibit a working potential greater than 4V vs Li+ / Li. As opposed to LiM O4 where Mn changes oxidation state from an average value of +3.5 to +4 during delithiation, it stays at +4 oxidation state during delithiation in LiNio.5Mm.5O4 which solves the dissolution problem but lowers the material specific capacity15. The quest for higher specific capacity cathode active materials (CAM) led Dahn and co-workers16and Makimura and co-workers17to independently discover LiNii / 3Mm / 3Coi / 3O2 (NMC111 : the letters indicate the transition metal elements while the numbers indicate their ratio in the compound) which is now one of the most used CAM in commercial lithium-ions batteries. Optimization of the NMC cathode active materials series has led to the development of the so-called nickel-rich NMC materials, namely, NMC523, NMC622, and NMC811. Manganese in the NMC series has also been replaced by aluminum to form LiNi0.8Co0.15Al0.05O2 with improved cycling performance and is the cathode active material in the Tesla’s Model S, X, and 318,19. The idea of having multiple metals in cathode active materials that can easily be substituted by other metals is very appealing since it prevents the battery industry from relying on a single metal to produce energy storage devices and also provides a good design platform to tune the electrochemical properties of the material. This idea inspired Lun et. al.™ to investigate a new class of materials called “cation-disordered rock salt-type high entropy materials”. They showed that, by systematically designing a series of compounds such as Lii.3(Mn(III)o.4Tio.3)Oi.7Fo.3, Lii.3(Mn(II)o.2Mn(III)o.2Tio.iNbo.2)Oi.7Fo.3, Lii.3(Mn(II)o.iMn(III)o.iCr(II)o.iCr(III)o.iTio.iNbo.2)Oi.7Fo.3, the energy density, power density, and cycling rate of the cathode active material could be tuned to obtain the desirable electrochemistry.

[0106] Evolution of Anode Materials for Lithium-Ion Batteries. Lithium was the first anode material to be considered as an anode material for lithium-ion batteries due to its low reduction potential. This low reduction potential provided earlier lithium-ion batteries with high energy density, but it was soon realized that the process of lithium plating and stripping during charge and discharge led to the continuous degradation of the electrolyte in the battery. Even more problematic was the inhomogeneous formation of dendritic structures on the lithium surface which grew through the separator and short circuited the battery causing serious safety issues. These safety issues proved impossible to solve and eventually stopped the commercialization of earlier lithium-ion batteries by Exxon and Moli Energy21,22and paved the way to the discovery of graphite which intercalates lithium ions within its graphene sheets and provides a maximum theoretical capacity of 372 mAh / g23,24,25. The combination of low cycling rate, low theoretical capacity, and low conductivity of graphite based anode material has nudged researchers to investigate metallic and semi-metallic elements such as tin and silicon that reversibly form intermetallic compounds with lithium, achieving specific capacities multiple times that of graphite. Among metallic elements such as silicon (Si), tin (Sn), germanium (Ge) of the group IV of the periodic table and their alloys that have been shown to reversibly store lithium- ions27,28, tin has drawn a disproportionately large amount of attention as a plausible new anode material because of its high gravimetric theoretical capacity of 960 mA.h / g, its relatively low potential difference versus Li / Li+pair29, most importantly, its relatively large abundance and electrical conductivity of about 8.7xl04S / cm. The lithium-rich intermetallic phases they form introduce significant volume expansion in the material, leading to electrochemical milling (particle cracking), particle disintegration, continuous lithium inventory losses through electrolyte degradation, and the active material loss of contact with the current collector, all of which result in poor capacity retention30. There have been strong research efforts to remediate these issues, but the methods proposed so far either do not satisfy the long term cyclability required for commercial application31,32,33, or the material synthetic methods are too complicated to be commercially viable34,35. However, since the first report of metallic glass formation by rapid solidification of liquid metallic alloys36, there has been extensive effort to develop methods to easily make these materials. These advances in the field of metallic alloys have encourage researchers to investigate these materials as plausible anode materials for lithium-ion batteries37,38. The mechanism of lithium storage in these metallic glass materials remains elusive. Herein, a silicon, tin, aluminum-based metallic glass material is proposed as a fast charge, long stable cycling materials for lithium-ion battery application.

[0107] Conversion-typed active anode materials such as tin oxides (SnO, SnCh) and transition metal oxides have also been investigated since Fuji introduced the STALION battery39in 1997. The STALION battery had tin oxide as anode material but suffered from significant capacity fade after just a few cycles. The earlier commercial success of the STALION battery and its subsequent failure motivated researchers to investigate the mechanism of lithium storage in this material. Tin oxides anodes were first thought to operate under the same working principles as graphite anodes, but it was later found that the first process involves the irreversible decomposition of the Sn-0 bond in the oxide material to form metallic tin and lithium oxide, followed by the reversible lithiation of the tin metal40. The electrochemical reactions were described as shown in equation 1 and 241’42.

[0108] Transition metal oxides such as CuO, CoO, NiO, CO3O4, Fe20s, FesCh, CrcCh, MnO, M Ch, MnCh, NiO, have also been investigated as plausible anode materials for lithium-ion batteries, with their lithium storage mechanism proposed to be similar to that discussed with tin oxides, with the exception that equation 2 is not observed for most of these transition metals since they do not turn to form intermetallic phases with lithium43. Equation 1 thus is proposed to be reversible for these metal oxides since they display some charge / discharge behaviors43. Recently, a new class of materials called high entropy oxides (HEO) such as (MgCoNiZnCu)O where metal ions occupy a random lattice site to form a single-phase crystalline material has been investigated as possible anode material for lithium-ion storage and available electrochemical data show relatively high capacity and stable cycling performance44,46. Herein, a (MgCoNiZnCu)O material will be prepared, its mechanism of lithium storage will be investigated, and the ability to tune its electrochemical properties by substituting metal ions such as cobalt in this formulation with other transition metals as previously demonstrated with the NMC cathode active material series will be investigated.

[0109] Synthesis, characterization, and study of lithium storage mechanism of the high entropy oxide (MgCoNiZnCu)O. Research in the field of metallic alloys has significantly broadened since it was discovered that enhanced properties such as corrosion resistance, lower grain boundary, and high elasticity, could be achieved with materials called high entropy alloys, formed by rapid solidification of liquid metallic alloys36. This feat in material engineering inspired Rost et. alf5in 2015 to synthesize the compound (MgCoNiZnCu)O which is now commonly referred to as high entropy oxide. The compound is a single-phase rock salt crystalline material with the metal ions occupying random cations sites in the crystal lattice unit cell. Because of this random distribution of metal cations in the unit cell, Rost et. al. hypothesized and experimentally proved that the single-phase crystalline material is stabilized by configurational entropy, thus the name high entropy oxide. The configurational entropy (Sconfig) can be derived from Boltzmann equation to be:

[0110] S(config) )Znx( )Znx where R is the universal gas constant, x(i) is the mole fraction of the ithcation, and x(j) is the mole fraction of the jthanion. From this equation, it is clear that the anion contribution to the configurational entropy in this compound or related similar compounds will be zero since there are exactly only one anion per formula unit, x(j) = 1 and ln(l) is zero. A maximum configurational entropy (1.6R) for this compound and related five cationic system is therefore achieved when the cations are in equimolar amount. Rost et. al. made this compound via solid state synthesis by heating the pelletized, thoroughly mixed equimolar binary oxides (MgO, CuO, ZnO, CoO, NiO) for 2 hours, and then finally quenching the resulting sample in air. Because the binary oxides ZnO and CuO have crystal structures wurtzite and tenorite respectively, which are different from the rock salt structure adopted by CoO, MgO, and NiO, Rost et. al. experimentally demonstrated that there is a critical temperature required to overcome the positive enthalpy of mixing in order to obtain a single-phase rock salt structure as imposed by the thermodynamic expression AGmixing = AHmixing - TAS. In material design therefore, Rost et. al. demonstrated through a series of multiple experiments that in order to minimize the critical temperature required to make a single crystalline phase from these binary oxides, it is necessary to maximize the configurational entropy. Because all the transition metals used in this high entropy compound have been investigated as plausible anode materials for lithium-ion battery, this inspired Sarkar et. al.^ and Qiu et. al.46to study the electrochemical behavior of this material against lithium anode in a half-cell.

[0111] Electrochemical Performance of (MgCoNiZnCu)O and Proposed Mechanism. Qiu et. al. synthesized the high entropy oxide material using the solid-state synthesis as earlier reported by Rost et. al. and characterized the product using XRD to confirm the phase purity, XPS to confirm that the oxidation states of the metals remained +2 after sintering, and STEM-EDS to ensure there was no metal segregation in the material after quenching in air. The resulting material was then used to make slurry containing 70 wt% high entropy active material, 20 wt% carbon black to improve the conductivity of the material, and 10 wt% vinylidene fluoride as binder. The slurry was casted on a copper current collector. The electrode was used to assemble coin cells with lithium metal as counter and reference electrode, 1.0 M LiPFe dissolved in 1 : 1 volume ratio of ethylene carbonate / diethyl carbonate as electrolyte, and a microporous polyethylene film as a separator. Cyclic voltammetry (CV) tests were carried out on the material in the potential range 10 mV-3 V versus Li+ / Li at a scan rate of 0.1 mV / s. Galvanostatic tests were also carried out on the material. The CV first cycle shows a peak at about 0.4 V, which completely disappears in the subsequent circles, a change that Qiu et. al. attributed to a significant structure change in the material. The second and subsequent cycles have a new and highly reproduceable cathodic peak at about 1 V, indicating no further structural changes in the material after the first cycle. The galvanostatic (charge / discharge) long term cycling performance shows long stable cycles of about 900m Ah / g after 300 cycles. The rate capability of the material was also investigated at different current densities and a high capacity of about 500mAh / g was achieved at a very high current density of 3000mA / g. This superior electrochemical performance encouraged Qiu et. al. and Sarkar et. al. to investigate the lithium storage mechanism of this material using high resolution transmission electron microscopy / energy dispersive X-ray spectroscopy (HRTEMZEDS), selected area X-ray electron diffraction (SAED), and operando X- ray diffraction techniques. HRTEMZEDS, and SAED are ex-situ techniques incapable of capturing transient transformation that may be occurring during battery cycling. These ex-situ techniques were used to investigate the transformations occurring in the material at different state of charge, and it was inferred from the SAED data that a new nanosized crystalline phase is formed during lithiation, which the authors indexed the new phase to Li2O. They also observed significant structural transformation after the first lithiation cycle, which they use to explain the cathodic peak shift. Operando XRD was used to hopefully probe the real time lithium interaction with the material but because of the structural transformation that leads to crystallites formation, there was no additional information obtained from this experiment and all the authors observed was a disappearance of the rock salt reflection peaks corresponding to the lithiation of the (MgCoNiZnCu)O material but no additional diffraction peaks were observed. It was thus concluded from these experiments that the mechanism of lithium interaction with this high entropy oxide material is similar to that proposed with binary transition metal oxides as previously discussed. That is, the lithiation of the material involves the formation of Li2O, followed by the reduction of the transition metal ions to form the corresponding metal elements dispersed within the MgO and Li2O matrix. During delithiation therefore, the oxidation of the metallic elements accompanied by the decomposition of Li2O leads to the formation of the metal oxides which is responsible for the anodic peak observed around 2.0 V in the CV diagram. Because this material is a new class of material and is not commercially available, a goal is to first synthesize this high entropy material, characterize it to make sure the material of interest was synthesized, and then study the mechanism of lithium interaction with this material using X- ray photoemission spectroscopy (XPS) at different state of charge and7Li derivative operando (dOp) NMR spectroscopy to probe the real time interaction of lithium with the material.

[0112] Synthesis and Characterization of (MgCoNiZnCu)O. Several synthetic methods such as nebulized spray pyrolysis47, flame spray pyrolysis47, reverse co-precipitation47, and solid state45,46have been shown to yield single phase (MgCoNiZnCu)O material. Because of this, a single method was selected and implemented herein.

[0113] Reverse Co-precipitation. Nitrates of the corresponding metals were dissolved in equimolar amounts in water to make a 0.1 M solution. The prepared solution was added dropwise in a 1% NH3 (29.7%) / H2O mixture at pH 10. The NH3 / H2O solution was added as needed to maintain the pH at 10 and the overall mixture was continuously stirred on a stirring plate. At the end of the addition while continuously stirring, the solution was left sitting for about 5 hours and a gelatinous precipitate was obtained. The precipitate was filtered and dried in an oven at 100 °C overnight, ground the next day, and calcined at 1100 °C for 1 hour. XRD, SEMZEDS, and electrochemical analysis was performed on the as-prepared sample and the results are shown in Figure 1 A-1C. The slurry used for the electrochemical characterization of the material was made by mixing 65 wt% active material, 25 wt% carbon black, 10 wt% PVDF in N-methylpyrrolidone (NMP) and casted on a 9 pm thick copper current collector. The XRD in Figure 1 A shows no extra peaks besides the peaks expected for the material of interest as seen on the insert in the figure obtained from Sarkar et. al.44, confirming a single-phase compound. The SEMZEDS shows a homogenous distribution of the metal cations in the material, suggesting a random distribution of cations in the crystal lattice. The cyclic voltammogram obtained is characteristic of the high entropy oxide as previously reported by Qiu et. al.46and Sarkar et. al.44. Mechanistic Study. XPS and7Li NMR spectroscopy are proposed as primary tools to understand the mechanism of lithium storage and removal in this new class of material.

[0114] XPS Analysis. As previously discussed, it is believed that the mechanism of (de)lithiation involves the formation of Li2O and the reduction of the transition metal cations to form neutral metal species during lithiation, and the decomposition of Li2O accompany by the oxidation of the neutral metals to recover the metallic oxide during delithiation. If this hypothesis is true, then X-ray photoemission spectroscopy (XPS), which is a versatile technique used to probe the oxidation state of elements in a given sample, should show a characteristic biding energy peak shift as the transition metals change oxidation state from +2 to zero during lithiation and back to +2 during delithiation. Since this technique is an ex-situ technique, the material will be investigated at different state of charge (SOC), that is, it will be lithiated to achieve specific voltages and then analyzed to determine the oxidation state of the metal species in the material. This analysis should provide information on which metallic ions are taking place in the electrochemical process.

[0115] Li NMR Spectroscopy.7Li is a spin 3 / 2 NMR active nuclei that has long been used for ex-situ and operando NMR experiments to probe changes in the7Li environment48. In parallel with the XPS experiment, an operando7Li NMR experiment would provide information on the formation and decomposition of the Li2O specie. The high-capacity fade of the (MgCoNiZnCu)O material after the first cycle suggests that the Li2O formed during this cycle is not completely decomposed during delithiation. In addition, the7Li resonance frequency of the Li2O formed during the lithiation of (MgCoNiZnCu)O is likely to overlap with that in the electrolyte and Li2O of the solid electrolyte interface (SEI). It is thus unlikely that useful information will be obtained from the7Li operando NMR. To improve the resolution of the7Li operando experiment, the recently developed derivative operando (dOp) data processing technique initially proposed by Lorie Lopez et. al.49will be used. With this technique, the formation and decomposition of the Li2O formed from the (MgCoNiZnCu)O material should be able to be clearly observed, and time-dependent phenomena can also be isolated from timeindependent ones. It is not unreasonable to think that another mechanism of (de)lithiation might involve the intercalation / insertion of lithium within the material, in which case the presence of paramagnetic cations (Cu2+, Co2+, Ni2+) randomly distributed in the crystal lattice might lead to significant7Li peak broadening due to dipolar interaction. However, this peak broadening will be informative of a mechanism other than conversion. Modification of the high entropy oxide (MgCoNiZnCu)O formulation. As much as it is important to develop higher energy, higher power, and long stable cycle anode active material for next generation lithium-ion batteries, it is necessary to use relatively abundant elements in order to keep the price of these energy storage devices competitively enough to fossil fuel. Although cobalt is relatively abundant on earth, about 70% of the world supply comes from a single country (Democratic Republic of Congo)50. Due to political instability in this country and around the region, prices and availability fluctuations can devastate the battery industry. The current world supply of cobalt is thus fragile. In addition, as the Li-ion industry grows to 1 TWh of production per year, approximately one million tons of combined cobalt will be required, thereby placing significant strains on the metal resources51. As previously asserted, LiCoCh was the first commercially available cathode active material for lithium-ion batteries and is still used today in commercial batteries. However, with the intense necessity to move away from cobalt- base battery materials, research has led to the layered materials, MNC series and MNA series, which are now the dominant cathode active materials in today’s lithium-ion batteries as detailed above. To echo this same trend, Sarkar et. al.^ who first proposed (MgCoNiZnCu)O as an anode material for lithium-ion batteries, attempted to remove cobalt from the formulation to propose (MgNiZnCu)O, but the material did not show good electrochemical performance as that obtained from the initial formulation. In addition, in order to prove that the high entropy oxide anode active material concept provides great design space to tune the electrochemical properties of this new class of material, Sarkar et. al.^ also attempted to investigate the effects of each transition metal cation. It is clear from the figure that all five metal cations are necessary for the long-term performance of the HEO material. Specifically, Figure 2b of Sarkar et al. displays the role of cobalt in the material, an effect that could discourage the battery community from paying attention to this material. The voltage vs. profile plot (Figure 2b of Sarkar, et all) shows that the lithiation of the various TM-HEO materials occurs at slightly different potentials, and more importantly, the lithiation of the TM-MEO (-Cu) occurs at significantly lower voltage than the other materials. This electrochemical tuning has already been discussed in great length in the cathode evolution above. An interesting question to ask would be: what would happen if instead of removing an element like cobalt entirely in the (MgCoNiZnCu)O formulation, the element was substituted with another transition metal cation of the same oxidation state? Additional experiments would therefor investigate this question by replacing cobalt in (MgCoNiZnCu)O by other relatively more abundant transition metal cations such as iron (Fe2+), titanium (Ti2+), and manganese (Mn2+). In addition, replacing magnesium with calcium in the (MgCoNiZnCu)O might shed some light on the role of this electrochemically nonactive species.

[0116] Investigating Redox Incompatibility. The fact that it is necessary to combine the different metal cations in equimolar amount or as close to equimolar amount as possible, in order to minimize the temperature required to sinter the material to a single phase crystalline solid to obtain a single-phase crystalline material has already been discussed. When Lun et. al.™ attempted to make a single phase crystalline high entropy cation-disordered rock salt-type (HE DRX) material with the target composition Lii.3Mn2+o.i5Mn3+o.25Tio.o5Mo4+o.iNbo.i50i.7Fo.3, they failed to obtain a single-phase crystalline material and attributed this failure to a redox incompatibility problem between Mn3+and Mo4+, i.e., when they coexist, Mn3+will be reduced to Mn2+while Mo4+is oxidized to Mo6+, leading to synthesis failure. This failure inspired Lun et. al. to computationally investigate the redox compatibility of some selected metal cations. Red regions in Lun Figure indicate redox-incompatible pairs in which the elements from the horizontal axis will oxidize those from the vertical axis, while green regions indicate redoxincompatible pairs with an opposite direction of charge transfer. Yellow regions denote redoxcompatible pairs. It is clear from these computational calculations that the cations chosen to substitute cobalt in the initial TM-HEO composition should not lead to any redox incompatibility phase segregation issues.

[0117] Preliminary Results with Manganese Substituted sample. The reverse co-precipitation technique that was previously described with (MgCoNiZnCu)O synthesis had a significantly low yield and controlling the metal ratios proved to be almost impossible. So, it was decided to switch to an all-solid state synthesis method. The synthesis of the (MgCoNiZnCu)O initial formulation was repeated using this all-solid state synthetic method for consistency (results not shown).

[0118] Solid State Synthesis of (MgMnNiZnCu)O . The corresponding binary oxides where thoroughly mixed in an equimolar ratio using agate mortar, pelletized, and heated at 1100°C in a platinum crucible for 3 hours. The corresponding pellets were ground and ball mill in isopropanol for about 2 hours, dried at 100°C in a vacuum oven overnight. The sample was characterized using XRD and SEMZEDS for phase purity and the results are shown in Figures 2A-2B. The starred XRD peaks in Figure 2 A represent the expected single phase rock salt structure. It is clear from Figure 2A that the sample is not a single-phase material. The extra peaks are likely not coming from the ball milling step since there are also present in the as- sintered pellet. These extra-peaks are likely from the unreacted manganese oxide since EDS shows some manganese segregation. Future heating time will be increased to test this hypothesis.

[0119] Electrochemical Performance of (MgMnNiZnCu)O. The electrochemical performance of the ball mill sample was evaluated to get an insight on the behavior of this new material toward lithium. The electrodes were made as previously described above, i.e., the slurry was made by mixing 65 wt% (MgMnNiZnCu)O, 25% wt carbon black, and 10 wt% PVDF in NMP. The resulting slurry was casted on an ~9 pm thick copper current collector and dried in a vacuum oven at 100°C overnight. Coin cells were made in an argon glovebox using lithium metal as reference and counter electrode. Cyclic voltammogram and galvanostatic experiments were conducted on using the coin cells and the results are shown in Figures 3A-3B. The electrochemistry of this new material with manganese is quite similar to that observed with the original material with cobalt using the same synthetic procedure in our laboratory (results not shown). These electrochemical results indicate that cobalt is not particularly the reason why this class of material have relatively higher capacity and long cycling period as previously thought. The mechanism of lithium interaction with this sample is likely similar to that proposed with the cobalt sample. Iron, titanium, and calcium substituted samples can also be made, and the hypothesis is that they should also have similar electrochemical performance.

[0120] References

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[0176] 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.

[0177] 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 high entropy oxide comprising:(MgCoNiZnCu)O wherein at least a portion of the Co is substituted (e.g., replaced) with a more abundant element, such as Fe, Ti, Mn, or a combination thereof; at least a portion of the Ni is substituted (e.g., replaced) with a more abundant element, such as Fe, Ti, Mn, or a combination thereof; at least a portion of the Mg is substituted (e.g., replaced) with Ca; or a combination thereof.

2. The high entropy oxide of claim 1, wherein at least a portion of the Co is substituted (e.g., replaced) with a more abundant element, such as Fe, Ti, Mn, or a combination thereof.

3. The high entropy oxide of claim 1 or claim 2, wherein substantially all of the Co is substituted (e.g., replaced) with a more abundant element, such as Fe, Ti, or Mn.

4. A high entropy oxide comprising:([Mgi-qCaq][Coi-a-b-cFeaTibMnc][Nii-x-y-zFexTiyMnz]ZnCu)O wherein q, a, b, c, x, y, and z are each independently from 0 to 1; a+b+c is from 0 to 1; and x+y+z is from 0 to 1; with the proviso that: when a is greater than 0, then x is 0; when x is greater than 0, then a is 0; when b is greater than 0, then y is 0; when y is greater than 0 then b is 0; when c is greater than 0, then z is 0; and when z is greater than 0 then c is 0; and with the further proviso that: q is greater than 0; a+b+c is greater than 0; x+y+z is greater than 0;or a combination thereof.

5. The high entropy oxide of claim 4, wherein a+b+c is greater than 0.

6. The high entropy oxide of claim 4 or claim 5, wherein: q, a, b, c, x, y, and z are each independently 0 or 1; a+b+c is 0 or 1; and x+y+z is 0 or 1.

7. The high entropy oxide of any one of claims 4-6, wherein q, a, b, c, x, y, and z can be selected, for example, to select and / or tune the electrochemical properties of the high entropy oxide.

8. The high entropy oxide of any one of claims 1-7, wherein the high entropy oxide comprises (MgFeNiZnCu)O, (MgTiNiZnCu)O, (MgMnNiZnCu)O, (MgCoFeZnCu)O, (MgCoTiZnCu)O, (MgCoMnZnCu)O, (CaCoNiZnCu)O, (MgFeTiZnCu)O, (MgFeMnZnCu)O, (MgTiFeZnCu)O, (MgTiMnZnCu)O, (MgMnFeZnCu)O, (MgMnTiZnCu)O, (CaFeNiZnCu)O, (CaTiNiZnCu)O, (CaMnNiZnCu)O, (CaCoFeZnCu)O, (CaCoTiZnCu)O, (CaCoMnZnCu)O, (CaFeTiZnCu)O, (CaFeMnZnCu)O, (CaTiFeZnCu)O, (CaTiMnZnCu)O, (CaMnFeZnCu)O, (CaMnTiZnCu)O, or a combination thereof.

9. The high entropy oxide of any one of claims 1-8, wherein the high entropy oxide comprises (MgFeNiZnCu)O, (MgTiNiZnCu)O, (MgMnNiZnCu)O, (MgCoFeZnCu)O, (MgCoTiZnCu)O, (MgCoMnZnCu)O, (CaCoNiZnCu)O, or a combination thereof.

10. The high entropy oxide of any one of claims 1-9, wherein the high entropy oxide comprises (MgMnNiZnCu)O.

11. The high entropy oxide of any one of claims 1-10, wherein the high entropy oxide comprises (MgFeTiZnCu)O, (MgFeMnZnCu)O, (MgTiFeZnCu)O, (MgTiMnZnCu)O, (MgMnFeZnCu)O, (MgMnTiZnCu)O, (CaFeNiZnCu)O, (CaTiNiZnCu)O, (CaMnNiZnCu)O, (CaCoFeZnCu)O, (CaCoTiZnCu)O, (CaCoMnZnCu)O, or a combination thereof.

12. The high entropy oxide of any one of claims 1-11, wherein the high entropy oxide comprises (CaFeTiZnCu)O, (CaFeMnZnCu)O, (CaTiFeZnCu)O, (CaTiMnZnCu)O, (CaMnFeZnCu)O, (CaMnTiZnCu)O, or a combination thereof.

13. The high entropy oxide of any one of claims 1-12, wherein the metal cations are present in a substantially equimolar amount in the high entropy oxide.

14. The high entropy oxide of any one of claims 1-13, wherein the high entropy oxide is crystalline.

15. The high entropy oxide of any one of claims 1-14, wherein the high entropy oxide is single-phase rock salt crystalline material.

16. The high entropy oxide of any one of claims 14-15, wherein the metal ions occupy random cation sites in the crystal lattice unit cell.

17. The high entropy oxide of any one of claims 1-16, wherein the high entropy oxide is stabilized by configurational entropy.

18. The high entropy oxide of any one of claims 1-17, wherein the high entropy oxide is capable of lithium storage.

19. A method of making the high entropy oxide of any one of claims 1-18.

20. The method of claim 19, wherein the method comprises nebulized spray pyrolysis, flame spray pyrolysis, reverse co-precipitation, solid state synthesis, or a combination thereof.

21. The method of claim 19 or claim 20, wherein the method comprises reverse coprecipitation.

22. The method of claim 21, wherein the method comprises: dissolving nitrates of the corresponding metals in substantially equimolar amount in water to make a solution; adjusting the pH of the solution to 10 to form a product; and separating, drying, optionally grinding, and calcining the product.

23. The method of claim 22, further comprising agitating the solution.

24. The method of claim 19 or claim 20, wherein the method comprises solid state synthesis.

25. The method of claim 24, wherein the method comprises:contacting substantially equimolar amounts of binary oxides of the metals to form a mixture; and heating the mixture.

26. The method of claim 25, further comprising agitating and / or grinding the mixture before, after and / or while heating the mixture.

27. The method of claim 25 or claim 26, wherein the mixture is heated at a temperature sufficient to overcome the positive enthalpy of mixing in order to obtain a single-phase rock salt structure.

28. The method of any one of claims 25-27, further comprising quenching the mixture after heating.

29. An oxyfluoride derived from the high entropy oxide of any one of claims 1-18.

30. A method of making the oxyfluoride of claim 29, the method comprising fluorinating the high entropy oxide.

31. An electrode comprising the high entropy oxide of any one of claims 1-18 or the oxyfluoride of claim 29.

32. An anode comprising from the high entropy oxide of any one of claims 1-18.

33. A cathode comprising the oxyfluoride of claim 29.

34. The electrode of claim 31, the anode of claim 32, or the cathode of claim 33, wherein the electrode, anode, or cathode is high capacity, stable, fast charging, or a combination thereof.

35. A device, such as a battery, comprising the electrode of claim 31, the anode of claim 32, the cathode of claim 33, or a combination thereof.

36. A battery comprising the electrode of claim 31, the anode of claim 32, the cathode of claim 33, or a combination thereof.

37. The battery of claim 36, wherein the battery is a lithium ion battery.

38. The battery of claim 36 or claim 37, wherein the battery is rechargeable.

39. The battery of any one of claims 36-38, wherein the battery exhibits a capacity retention of 80% or more (e.g., 90% or more) for 10 cycles or more (e.g., 25 cycles or more, 50 cycles or more, or 100 cycles or more).

40. A system comprising one or more of the batteries of any one of claims 36-39.

41. The system of claim 40, wherein the system is an energy storage system.

42. An article comprising one or more of the batteries of any one of claims 36-39.

43. The article of claim 42, wherein the article is a vehicle, such as a hybrid electric vehicle or an all-electric vehicle.

44. The article of claim 42, wherein the article comprises an electronic device, such as a portable electronic device, a laptop, a watch, or a cell phone.

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