Polymer-particle gradient electrolytes, methods of making same, and uses thereof

Abstract

Polymer-particle gradient electrolytes, methods of making polymer-particle gradient electrolytes, and uses thereof. In various examples, a polymer-particle gradient electrolyte comprises a gradient or gradients of metal oxide particles, which may be between a surface of a cathode and an anode of a device, disposed in a polymeric material. In various examples, a polymer-particle gradient electrolyte is made by allowing a gradient of metal oxide particles to form in or forming a gradient in a precursor mixture and polymerizing monomers in the precursor mixture, which may be carried out in situ in a precursor device. In various examples, a device, such as, for example, an electrochemical device, e.g., a battery, which may be a solid-state battery, comprises one or more polymer-particle gradient electrolyte(s).

Description

POLYMER-P ARTICLE GRADIENT ELECTROLYTES, METHODS OF MAKING SAME, AND USES THEREOFCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 618,742, filed January 8, 2024; the contents of the above-identified application are hereby fully incorporated herein by reference in their entirety.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

[0002] This invention was made with government support under grant no. DESCOO 16082 awarded by the Department of Energy and grant no. HP-1919013 awarded by the National Science Foundation. The government has certain rights in the invention.BACKGROUND

[0003] The growing interest in lithium metal as a replacement anode material for the commonly employed lithium-infused graphite materials used in state-of-the art lithium-ion batteries is reflected in the increasing number of studies and literature reviews. It is understood that an important driver of this interest is the nearly 10-fold increase in theoretical specific capacity of the anode achieved by replacing the graphite host with lithium metal. The combination of the high chemical activity and low reduction potential of Li-metal introduces multiple technical barriers that have been thoroughly discussed in several recent reviews.

[0004] Solid-state electrolytes (SSEs) are generally thought to provide a straightforward strategy towards lithium metal batteries that are safer and less prone to run-away thermal events associated with non-planar, mossy Li deposition during battery recharge. However, these benefits are typically accompanied by sacrificed room -temperature ionic conductivity and poor electrode-electrolyte contact. Significant efforts have been concentrated on overcoming these challenges using solid electrolyte that emerge from wettable precursors, and through regulation of ionic pathways throughout SSE’s crystal structure design.Employing Li-metal anode also requires a solid-electrolyte interphase (SEI) capable of maintaining chemical and mechanical integrity at the high reduction potentials at which Li plates during battery charging, and which protect the freshly deposited Li from continuous loss due to parasitic chemical reactions with electrolyte components.

[0005] Inorganic-organic hybrid electrolytes are of particular interest due to their ability to separate the mechanical, ion-transport, and interfacial functions of an electrolyte using discrete ingredients with properties optimized for these functions. A consequence is that suchelectrolytes are unique in their ability to provide combinations of high, liquid-like ionic conductivity and solid-like mechanical strength — comparable to SSEs. Typically, hybrid electrolytes are created by suspending electrochemically inert particles (typically metal oxides) in an ion-conducting liquid or plasticized polymer host. Among the advantages of such materials are their ease of fabrication, straightforward compatibility with normal battery manufacturing methods, and versatility in the chemistry of the suspended particles and suspending electrolyte that can be used. Oxide particles suspended in a liquid electrolyte adsorb ionic species, creating a space-charge layer on their surface, which has been thought to facilitate ion-pair dissociation and transport in the electrolyte. AI2O3 particles in solid Lil, for instance, have been reported to adsorb Li+on their surface, resulting in an increased vacancy concentration in lithium sublattice that increases the overall conductivity. Si O2 introduced to PbF2 has likewise been argued to adsorb F’, creating fluoride vacancies. The overwhelming majority of studies of suspension electrolytes focus on systems containing electrochemically inert, nanosized particles in the dilute concentration regime. These advantages are countered by the generally high interfacial impedances that occur if the particles segregate to the electrode and by the potential for irreversible loss of Li ions that either bind too strongly or which chemically react with the oxide particles.SUMMARY OF THE DISCLOSURE

[0006] The present disclosure provides, inter alia, methods of making polymer-particle gradient electrolytes. The present disclosure also provides polymer-particle gradient electrolytes and uses thereof.

[0007] In an aspect, the present disclosure provides methods of making polymer-particle gradient electrolytes. In various examples, a polymer-particle gradient electrolyte is producedn situ. In various examples, a method produces a polymer-particle gradient electrolyte of the present disclosure. In various examples, a method of forming a polymer-particle gradient electrolyte comprises: allowing (e.g., holding or the like) a precursor mixture (which may be a suspension) comprising: one or more monomer(s), one or more Lewis Acid(s) (e.g., Lewis Acid initiator(s) or the like), a plurality of metal oxide particles, optionally, one or more crosslinker(s) and / or one or more additive salt(s), where the precursor mixture is disposed between a first substrate (such as, for example, a cathode material, a cathode, or the like) and a second substrate (such as, for example, an anode material, an anode, or the like); and allowing (e.g., holding or the like) the precursor mixture to form a gradient (e.g., as described herein) of the metal oxide particles from a first surface of the first substrate disposedsubstantially opposite or opposite to the second substrate to a first surface of the second substrate disposed substantially opposite or opposite to the first substrate, where at least a portion of the monomer(s) polymerize forming the polymer-particle gradient electrolyte. In various examples, the monomer(s) undergo(es) or are polymerizable by ring-opening polymerization or the like. In various examples, at least a portion, substantially all, or all of the monomer(s) is / are ring-strained cyclic ethers or the like. In various examples, the metal oxide particle(s) is / are chosen from lithium oxide particles, sodium oxide particles, zinc oxide particles, aluminum oxide particles, structural analogs thereof, and the like, and any combination thereof. In various examples, the metal oxide particles comprise a size of about 100 nm to about 10 micron(s), which may be a longest linear dimension and / or an average size, including all 0.1 nm values and ranges therebetween. In various examples, substantially all or all of the metal oxide particles have a density or size that results in formation of the gradient (e.g., resulting from standing (e.g., gravity or the like) or application of a force). In various examples, the metal oxide particles inhibit (e.g., partially inhibit or the like) polymerization of at least a portion of the monomer(s) (e.g., near the metal oxide particles on a particle size scale).

[0008] In an aspect, the present disclosure provides precursor devices. In various examples, a precursor device is configured to carry out one or more method(s) of making a particle gradient electrolyte of the present disclosure. In various examples, a precursor device comprises one or more precursor mixture(s), each precursor mixture comprising components suitable for producing a polymer-particle gradient electrolyte of the present disclosure. In various examples, each precursor mixture is disposed between a cathode material, a cathode, or the like and an anode material, an anode, or an anode current collector, or the like of a precursor device. In various examples, the precursor device further comprises a separator disposed in a precursor mixture or in one or more or all of the precursor mixture(s). In various examples, the precursor device is configured to (after formation and polymerization of at least a portion of the monomer(s)) function as an electrochemical device (such as, for example, a battery, a supercapacitor, a fuel cell, an electrolyzer, an electrolytic cell, or the like.

[0009] In an aspect, the present disclosure provides polymer-particle gradient electrolytes. In various examples, a polymer-particle gradient electrolyte comprises a gradient of metal oxide particles. In various examples, a polymer-particle gradient electrolyte is made by a method of the present disclosure. In various examples, a polymer-particle gradient electrolyte comprises: one or more polymeric material(s) (such as, for example, polymer(s) orthe like, or any combination thereof); and a plurality of metal oxide particles, where the plurality of metal oxide particles is disposed in the polymeric material(s) and forms a gradient. In various examples, a polymer-particle gradient electrolytes or electrolytes is / are a component or components of a device described herein. In various examples, the metal oxide particles form a gradient along an axis from a first surface (which may be an exterior surface) of the polymer-particle gradient electrolyte to a second surface of the polymer-particle gradient electrolyte (which may be an exterior surface) disposed substantially opposite or opposite to the first surface of the polymer-particle gradient electrolyte, or the like. In various examples, the metal oxide particles form a gradient concentration from a first concentration to a second concentration along an axis (e.g. depth, height, thickness, or length) in the polymer-particle gradient electrolyte, where the first concentration is larger than the second concentration (such as, for example, the first concentration is about 1.2 to about 10 times the second concentration, including all 0.1 values and ranges therebetween). In various examples, the polymer-particle gradient electrolyte has a first concentration in about 10 vol. % to about 95 vol. % at a first portion of the electrolyte and a second concentration in about 1 vol.% to about 40 vol.% at a second portion of the electrolyte along an axis. In various examples, the metal oxide particle gradient (e.g., number or particles per unit of volume or the like), which may be a decreasing gradient, comprises a linear or a non-linear gradient from the first substrate to the second substrate and / or the polymer gradient (e.g., number or polymer chains per unit of volume or the like), which may be an increasing gradient, comprises a linear or a non-linear gradient from the first substrate to the second substrate and / or the metal oxide gradient comprises a linear (which may be a decreasing gradient or the like). In various examples, the metal oxide particle gradient(s) and / or the polymer gradient(s) is / are independently a continuous gradient, a linear gradient, a non-linear gradient, or the like, or any combination thereof, which may be generally increasing or generally decreasing or decreasing. In various examples, a gradient(s) is / are independently along an axis of the polymer-particle gradient electrolyte (such as, for example, an axis from a first surface of the first substrate disposed substantially opposite or opposite to a second substrate to a first surface of the second substrate, which may be substantially perpendicular or perpendicular to the first surface of the first surface of the substrate (or first substrate) and / or the first surface of the second substrate (or the second substrate)). In various examples, a gradient comprises a metal oxide particle-rich phase proximate to the first substrate and / or a polymer-rich phase proximate to the second substrate.

[0010] In an aspect, the present disclosure provides devices. In various examples, a device comprises one or more polymer-particle gradient electrolyte(s) of the present disclosure, which may be made by a method of the present disclosure and / or in a precursor device of the present disclosure. A device may be an electrochemical device. Non-limiting examples of electrochemical devices include batteries, supercapacitors, fuel cells, electrolyzers, electrolytic cells, and the like. In various examples, an electrochemical device is an ion-conducting electrochemical device (such as, for example, a lithium-ion conducting electrochemical device or the like). In various examples, a device is an anode-free device. In various examples, device is an anode-free battery (such as, for example, a lithium-ion battery or the like). In various examples, at least a portion of the polymer-particle gradient electrolyte(s) functions as a separator or the like.BRIEF DESCRIPTION OF THE FIGURES

[0011] For a fuller understanding of the nature and objects of the disclosure, reference should be made to the following detailed description taken in conjunction with the accompanying figures.

[0012] FIG. 1 shows (a) a schematic illustration of method used to synthesize Li2O / poly(l,3-dioxolane) (poly(DOL)) hybrid electrolytes with attractive gradient properties produced by gravity settling of Li2O. (b) A cell design using a pair of Celgard 3501 separators is used to sequester the particle-rich phase to the region near the Li anode, (c) Results from Fourier transform infrared spectroscopy (FTIR) analysis of the anode and cathode facing sections of the separators, (d) SEM analysis of the structure of the cathode and anode-facing separator surfaces, compared with that of the pristine Celgard material. It is apparent that polymerization of 1,3-dioxolane (DOL) yields a material that covers the pores on the cathode-facing separator (e), however the separator on the anode side is seen to still retain the porous structure (f). All scale bars indicate 2pm (pm = micron(s) or micrometer(s)), and larger scale images are shown in FIG. 5.

[0013] FIG. 2 shows (a) normalized ionic conductivity value following Maxwell model for Li2O / DOL suspension electrolytes at various volume fractions. Data points seen are averaged from the conductivity values obtained at different temperatures, as shown in FIG. 8. (b) As polymerization of a Li2O / DOL hybrid electrolyte (1stlayer: 10N7 (Pure (1) - Lewis Acid neutralized); 2ndlayer: (Pure (2) disposed on 1stlayer - Lewis Acid initiated) poly(DOL) +2 M LiTFSI + 1 mM Al(OTf)3), proceeds with time, the ionic conductivity measured at 30°C first rises and stabilizes at values higher than observed either for theprecursor Li20 / D0L suspension or pure poly(DOL) electrolyte with the same salt concentration, (c) Temperature-dependent ionic conductivity values for in .s / ' / zz-formed Li2O / poly(DOL) hybrid electrolyte, for a Li20 / D0L suspension electrolyte, and for in situ- formed poly(DOL) electrolyte, (d) Temperature-dependent changes in ionic conductivity of an in situ-formed Li2O / poly(DOL) hybrid electrolyte as a function of time following the onset of polymerization.

[0014] FIG. 3 shows galvanostatic charge and discharge of Li||NCM811 in hybrid Li2O / DOL electrolytes containing (a) 10 vol.% and (b) 50 vol.% Li2O and 2 M LiTFSI. (c) The discharge capacity (circles) and Coulombic efficiency (CE) (triangles) of the cells in (a) and (b) over 120 cycles (arrows indicate increasing cycle number). Cells were run with Li||NCM811 configuration at C / 10 for the first five cycles, followed by 1C for the rest of the cycle, (d) CE obtained in Li||Cu half-cells configuration for different Li2O volumetric concentrations. The resulting CE value at each concentration is presented in (e).

[0015] FIG. 4 shows (a) galvanostatic cycling performance and electrochemical properties of Anode-free Cu||NCM811 cells based on Li2O / poly(DOL) electrolytes for 10 vol.% Li2O. The poly(DOL) was polymerized inside the battery cell using 1 mM Al(OTf)3 and the cells were cycled at a rate of 0.5 mA / cm2(C / 2). For the results in (a) a salt blend consisting of 2 M LiTFSI + 0.5 M LiNCL (here termed N5) was used. The respective discharge capacities (circles) and CE (triangles) values are shown in (b). Included in (b) are discharge capacity values of DOL + 2 M LiTFSI electrolyte without and with the addition of 10 vol.% Li2O, cycled at C / 10 for 5 cycles and a comparable C / 2 rate for the rest of the cycles. Solid electrolyte interphase (SEI) buildup during the formation step at C / 10 is detailed in FIG. 16. CE values are used to predict capacity fading shown in the dashed line of (c), while solid data points show actual capacity fading. The difference between CE of this electrolyte and a control DOL + 2 M LiTFSI electrolyte is shown in (d). The corresponding Li||NCM811 cell performance for the same electrolyte as in (a) is shown in FIG. 15. (e) Cyclic voltammetry (CV) measured in cells in which Li2O particles in a carbon cloth (CC) current collector are paired with Cu-foil in a DOL + 2 M LiTFSI electrolyte, (f) X-ray photoelectron spectroscopy (XPS) of Li2O@CC electrode post-CV and held at oxidation potential for 5 hours indicating existence of oxygen, carbon, and lithium. Two peaks attributed to lithium oxide (Li2O) and lithium peroxide (Li2O2) are seen in the (g) O scan and (h) Li scan.

[0016] FIG. 5 shows (a) hybrid electrolyte formed outside of electrochemical cell indicates solid-like behavior with (b) stratified layers of suspension and polymeric layer.SEM images of polymerized separator at (c) 4 pm and (d) 20 pm scale. Suspension-laden separator is shown in (f) 4 pm and (g) 40 pm scale, (e) Postmortem image of Lithium metal for Li || NCM811 cell configuration with added Li2O and (h) Copper substrate for Cu || NCM81 1 cell configuration with Li2O included after more than 50 cycles.

[0017] FIG. 6 shows (a) particle size distribution measured at minute 1 to 15 with 1- minute interval and (b) the average size at each minute.

[0018] FIG. 7 shows (a) differential scanning calorimetry (DSC) curve of poly(DOL) layer near and away from Li2O particle settlement at 10 vol.% particle concentration and its corresponding (b) thermogravimetric analysis (TGA) curve along with result for 30 vol.% Li2O.

[0019] FIG. 8 shows temperature-dependent ionic conductivity of QSSE with various Li2O contents in (a) DOL electrolyte with 2 M LiTFSI and (b) ethylene carbonate (EC) with 2 M LiTFSI and 0.5 M LiNCL. Ionic conductivity at 30°C and activation energy value Eaof (b) DOL electrolyte and (d) EC electrolyte.

[0020] FIG. 9 shows (a) Maxwell dependence of normalized conductivity on Li2O volume fractions at temperatures of 10 - 60°C and (b) the collapsed universal plot with data points showing temperature-averaged normalized conductivity values (stars, which represent the average values from (a)).

[0021] FIG. 10 shows (a) strain-dependent loss and storage moduli G" and G' and (b) stress-strain curves of Li2O suspensions of 10, 30, and 50 vol.%.

[0022] FIG. 11 shows morphology of Li-metal deposited on Cu-foil for 10 mAh with electrolyte of (a, b) DOL with 2 M LiTFSI, (c,d) QSSE with 10 vol.% Li2O, (e,f) 30 vol.% Li2O, and (g,h) 50 vol.% Li2O. Scale bars of (a, c, e, g) show 100 pm and (b, d, f, h) 10 pm.

[0023] FIG. 12 shows electrochemical impedance spectroscopy (EIS) Nyquist plot of QSSE at volume fractions of 0 - 50 vol.%.

[0024] FIG. 13 shows discharge capacity (circles) and CE (triangles) of control cases in anode-free Cu||NCM811 configuration of (a) DOL + 2M LiTFSI. (b) Unpolymerized DOL + Li2O (open symbols) and polymerized poly(DOL) without Li2O (closed symbols) can only cycle at C / 10 and are close to failure during SEI formation step.

[0025] FIG. 14 shows corresponding galvanostatic stripping and plating for electrolyte utilized in FIG. 4a but including Li-metal anode in a Li||NCM811 configuration instead of anode-free, (a) SEI formation step at C / 10 with the first and fifth cycle shown for the hybrid electrolyte, (b) Post-SEI formation step, battery was cycled at C / 2 for 100 cycles (arrowsindicate increasing cycle number, with the corresponding discharge capacity (circles) and CE (triangles) at all cycle shown in (c).

[0026] FIG. 15 shows (a) cyclic voltammogram (arrows indicate increasing scan rate) of control liquid electrolyte in carbon cloth and Cu-foil configuration, without any Li2O particle addition like seen in FIG. 4e. (b) Correlation of peak current to the square root of scan rate, extracted from FIG. 4e, is seen to have a linear relationship, (c) At the highest scan rate of 5.0 mV / s, reduction and oxidation peak areas are seen to have the same value.

[0027] FIG. 16 shows (a) X-ray diffraction (XRD) analysis of pristine Li2O, pristine Li2C>2, and Li2O on the Cu substrate after the third discharge of a Cu||Li2O cell, (b) Raman spectra of Li2O after cycling for more than 100 cycles, compared to spectra for pristine Li2O and Li2O2. The presence of Li2O2 is identified by red stars above the peaks.

[0028] FIG. 17 shows electrochemical performance for anode-free 10N5 in Cu||NCM811 configuration at different current rates of C / 2, 1C (= 1 mA / cm2), 2C, and C / 2.

[0029] FIG. 18 shows galvanostatic stripping (bottom) and plating (top) (arrows indicate increasing cycle number) of hybrid electrolyte containing poly(DOL) and (a) 10N7, (c) 50N5, (e) 50N7, and (b, d, f) their corresponding discharge capacity (triangles) and CE (circles).

[0030] FIG. 19 shows predicted capacity fade in 50N7 hybrid electrolyte, calculated from the experimental CE at different cycle numbers. This value is compared to the actual experimental value of capacity at each cycle.

[0031] FIG. 20 shows effects of LiNCL concentration on interfacial and bulk properties of hybrid electrolytes, (a) Nyquist plot obtained from EIS, (b) transference number measured through the Bruce- Vincent method (solid circles) compared to pure poly(DOL) (star) and pure QSSE (triangle), and (c) ionic conductivity at 30°C.

[0032] FIG. 21 shows effects of particle volume fraction on ionic conductivity.

[0033] FIG. 22 shows effects of particle volume fraction on CE.

[0034] FIG. 23 shows effects of initiator concentration on ionic conductivity.DETAILED DESCRIPTION OF THE DISCLOSURE

[0035] Although subject matter of the present disclosure is described in terms of certain embodiments and examples, other embodiments and examples, including embodiments and examples that do not provide all of the benefits and features set forth herein, are also within the scope of this disclosure. For example, various structural, logical, and process step changes may be made without departing from the scope of the disclosure.

[0036] As used herein, unless otherwise indicated, “about”, “substantially”, or “the like”, when used in connection with a measurable variable (such as, for example, a parameter, an amount, a temporal duration, or the like) or a list of alternatives, is meant to encompass variations of and from the specified value including, but not limited to, those within experimental error (which can be determined by, e.g., a given data set, an art accepted standard, etc. and / or with, e.g., a given confidence interval (e.g. 90%, 95%, or more confidence interval from the mean), such as, for example, variations of + / - 10% or less, + / -5% or less, + / -1% or less, and + / -0.1% or less of and from the specified value), insofar such variations in a variable and / or variations in the alternatives are appropriate to perform in the instant disclosure. As used herein, the term “about” may mean that the amount or value in question is the exact value or a value that provides equivalent results or effects as recited in the claims or taught herein. That is, it is understood that amounts, sizes, compositions, parameters, and other quantities and characteristics are not and need not be exact, but may be approximate and / or larger or smaller, as desired, reflecting tolerances, conversion factors, rounding off, measurement error, or the like, or other factors known to those of skill in the art such that equivalent results or effects are obtained. In general, an amount, size, composition, parameter, or other quantity or characteristic, or alternative is “about” or “the like,” whether or not expressly stated to be such. It is understood that where “about,” is used before a quantitative value, the parameter also includes the specific quantitative value itself, unless specifically stated otherwise.

[0037] Ranges of values are disclosed herein. The ranges set out a lower limit value and an upper limit value. Unless otherwise stated, the ranges include the lower limit value, the upper limit value, and all values between the lower limit value and the upper limit value, including, but not limited to, all values to the magnitude of the smallest value (either the lower limit value or the upper limit value) of a range. It is to be understood that such a range format is used for convenience and brevity, and thus, should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. To illustrate, a numerical range of “0.1% to 5%” should be interpreted to include not only the explicitly recited values of 0.1% to 5%, but also, unless otherwise stated, include individual values (e.g., 1%, 2%, 3%, and 4%) and the sub-ranges (e.g., 0.5% to 1.1%; 0.5% to 2.4%; 0.5% to 3.2%, and 0.5% to 4.4%, and other possible sub-ranges) within the indicated range. It is also understood (as presented above) that there are a number of values disclosed herein, and that each value isalso herein disclosed as “about” that particular value in addition to the value itself. For example, if the value “10” is disclosed, then “about 10” is also disclosed. Ranges can be expressed herein as from “about” one particular value, and / or to “about” another particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about, it will be understood that the particular value forms a further disclosure. For example, if the value “about 10” is disclosed, then “10” is also disclosed.

[0038] As used herein, unless otherwise stated, the term “group” refers to a chemical entity that is monovalent (i.e., has one terminus that can be (is) covalently bonded to other chemical species), divalent, or polyvalent (i.e., has two or more termini that can be (are) covalently bonded to other chemical species). The term “group” also includes radicals (e.g., monovalent radicals and multivalent radicals, such as, for example, divalent radicals, trivalent radicals, and the like). Illustrative examples of groups include:the like.

[0039] As used herein, unless otherwise stated, the term “structural analog” refers to any precursor mixture component (such as, for example, metal oxide particle, monomer, Lewis Acid, crosslinker, additive salt, or the like) or device component (such as, for example, electrolyte or the like), or any portion thereof (such as, for example, one or more group(s) thereof or the like), or the like if one atom or group of atoms, functional group or functional groups, or substructure or substructures is / are replaced with another atom or group of atoms, functional group or functional groups, substructure or substructures, or the like. In various examples, the term “structural analog” refers to any precursor mixture component (such as, for example, metal oxide particle, monomer, Lewis Acid, crosslinker, additive salt, or the like) or device component (such as, for example, electrolyte or the like), or any portion thereof (such as, for example, one or more group(s) thereof or the like), or the like that is derived from an original precursor mixture component (such as, for example, metal oxide particle, monomer, Lewis Acid, crosslinker, additive salt, or the like) or device component (such as, for example, electrolyte or the like), or any portion thereof (such as, for example, one or more group(s) thereof or the like), or the like by a chemical reaction, where the precursor mixture component (such as, for example, metal oxide particle, monomer, Lewis Acid, crosslinker, additive salt, or the like) or device component (such as, for example, electrolyte or the like), or any portion thereof (such as, for example, one or more group(s) thereof or the like), or the like is modified or partially substituted such that at least onestructural feature of the precursor mixture component (such as, for example, metal oxide particle, monomer, Lewis Acid, crosslinker, additive salt, or the like) or device component (such as, for example, electrolyte or the like), or any portion thereof (such as, for example, one or more group(s) thereof or the like), or the like is retained.

[0040] The present disclosure provides, inter alia, methods of making polymer-particle gradient electrolytes. The present disclosure also provides polymer-particle gradient electrolytes and uses thereof.

[0041] In an aspect, the present disclosure provides methods of making polymer-particle gradient electrolytes. In various examples, a polymer-particle gradient electrolyte is produced in situ (e.g., in a device, such as, for example, a battery, which may be a secondary battery or the like, or the like). In various examples, a method produces a polymer-particle gradient electrolyte of the present disclosure. Non-limiting examples of methods are described herein.

[0042] In various examples, a method of forming a polymer-particle gradient electrolyte (which may be referred to as a hybrid electrolyte) comprises: allowing (e.g., holding or the like) (e.g., as a result of gravity) a precursor mixture (which may be a suspension) comprising: one or more monomer(s), one or more Lewis Acid(s) (e.g., Lewis Acid initiator(s) or the like), a plurality of metal oxide particles, and, optionally, one or more crosslinker(s) and / or one or more additive salt(s), where the precursor mixture is disposed between a first substrate (such as, for example, a cathode material, a cathode, or the like) and a second substrate (such as, for example, an anode material, an anode, or the like), to form a gradient or gradients in the precursor mixture, where at least a portion of the monomer(s) polymerize forming the polymer-particle gradient electrolyte. In various examples, a method of forming a polymer-particle gradient electrolyte (which may be referred to as a hybrid electrolyte) comprises: forming a gradient or gradients in a precursor mixture (which may be a suspension) comprising: one or more monomer(s), one or more Lewis Acid(s) (e.g., Lewis Acid initiator(s) or the like), a plurality of metal oxide particles, and, optionally, one or more crosslinker(s) and / or one or more additive salt(s), where the precursor mixture is disposed between a first substrate (such as, for example, a cathode material, a cathode, or the like) and a second substrate (such as, for example, an anode material, an anode, or the like), such as, for example, applying a force to the precursor mixture such that the gradient or gradients are formed), where at least a portion of the monomer(s) polymerize forming the polymer-particle gradient electrolyte.

[0043] In various examples, a method of forming a polymer-particle gradient electrolyte (which may be referred to as a hybrid electrolyte) comprises: providing a precursor mixture(which may be a suspension) comprising: one or more monomer(s), one or more Lewis Acid(s) (e.g., Lewis Acid initiator(s) or the like), a plurality of metal oxide particles, and, optionally, one or more crosslinker(s) and / or one or more additive salt(s), where the precursor mixture is disposed between a first substrate (such as, for example, a cathode material, a cathode, or the like) and a second substrate (such as, for example, an anode material, an anode, or the like); and allowing (e.g., holding or the like) the precursor mixture to form (e.g., as a result of gravity) (or optionally, applying a force to the mixture such that) a gradient of the metal oxide particles from a first surface of the first substrate disposed substantially opposite or opposite to the second substrate to a first surface of the second substrate (e.g., disposed substantially opposite or opposite to the first substrate), where at least a portion of the monomer(s) polymerize forming the polymer-particle gradient electrolyte.

[0044] Various precursor mixtures can be used. A precursor mixture may be referred to as a reaction mixture. In various examples, a precursor mixture (which may be a suspension) consists essentially of: one or more monomer(s), one or more Lewis Acid(s) (e.g., Lewis Acid initiator(s) or the like), and a plurality of metal oxide particles, and any additional components that do not materially affect the basic and novel properties of the precursor mixture (such as, for example, properties of the precursor mixture that do not materially affect the ability of the precursor mixture to form a polymer-particle gradient electrolyte of the present disclosure, the function of the formed polymer-particle gradient electrolyte (e.g., in a device or the like), or the like, or any combination thereof. In various examples, a precursor mixture (which may be a suspension) consists of: one or more monomer(s), one or more Lewis Acid(s) (e.g., Lewis Acid initiator(s) or the like), and a plurality of metal oxide particles. In various examples, a precursor mixture (which may be a suspension) does not comprise a solvent, a liquid electrolyte, or the like. In various examples, a precursor mixture (which may be a suspension) does not comprise a solvent, a liquid electrolyte, or the like.

[0045] A method may comprise continuous agitation of a precursor mixture prior to allowing a gradient or gradients to form in a precursor mixture or forming a gradient or gradients in a precursor mixture. Without intending to be bound by any particular theory, it is considered the continuous agitation prevents undesirable polymerization of the monomer or monomers.

[0046] A precursor mixture can comprise various monomers. Combinations of monomers may be used. In various examples, monomer(s) undergo(es) or are polymerizable by ringopening polymerization or the like. In various examples, at least a portion, substantially all, or all of the monomer(s) is / are ring-strained cyclic ethers or the like. Non-limiting examplesof monomers include cyclic ether monomer(s) (such as, for example, monomers comprising an ether oxygen covalently bound to two independent alkyl groups or two or more ether oxygens and two or more alkyl groups disposed between adjacent ether oxygen groups, where the alkyl groups and ether oxygens form a ring). Non-limiting examples of cyclic ether monomer(s) include 1,3-dioxolane (DOL), 1,3-dioxepane, 1,3,7-trioxocane (TOC), and 1,3- benzodi oxole, 1,2-epoxybutane, glycidyl octafluoropentyl ether, 4-fluoro- 1,3 -di oxolane, and 2-fluoro-l,3-dioxolane, structural analogs thereof, and the like, and any combination thereof.

[0047] A precursor mixture can comprise various Lewis Acids. Combinations of Lewis Acids may be used. In various examples, a Lewis Acid is a polymerization initiator or capable of initiating a polymerization (e.g., a polymerization described herein). Non-limiting examples of Lewis Acids include aluminum salts (such as, for example, Al(OTf)3 (OTf = triflate / CFsSOs ) and the like), chloride salts (such as, for example, InCh, ZnCh, and the like), structural analogs thereof, and the like, and any combination thereof. Non-limiting examples of Lewis Acids include tritiate salts, oxalate salts, bicarbonate salts, chloride salts, structural analogs thereof, and the like, and any combination thereof (e.g., where the metal cation(s) of the Lewis Acid(s) is / are polymerization catalyst).

[0048] A precursor mixture can comprise various amounts of a Lewis Acid or Lewis Acids. In various examples, Lewis Acid(s) is / are present (independently or in the aggregate) at about 0.2 mM to about 5.0 mM based on the total volume of the precursor mixture, including all 0.05 mM values and ranges therebetween (e.g., about 0.5 mM to about 1.0 mM).

[0049] A precursor mixture may comprise one or more crosslinker(s) (which may be referred to as crosslinking agent(s)). Non-limiting examples of crosslinkers include trimethylolpropane triglycidyl ether (TMPTGE) structural analogs thereof, and the like, and any combination thereof. In various examples, at least at portion, substantially all, or all of at least one of the resulting polymer(s) is / are crosslinked polyDOL, where the resulting polymer is crosslinked using trimethylolpropane triglycidyl ether (TMPTGE).

[0050] A precursor mixture can comprise various metal oxide particles. Combinations of metal oxide particles may be used. In various examples, the metal oxide particles are substantially the same or the same (e.g., structurally and / or compositionally substantially the same or the same). In various examples, at least two or more metal oxide particles are substantially different or different (e.g., structurally and / or compositionally substantially different or different). Non-limiting examples of metal oxide particles include lithium oxide particles, sodium oxide particles, zinc oxide particles, aluminum oxide particles, structural analogs thereof, and the like, and any combination thereof. In various examples, a metaloxide particle comprises (or has) the following formula: MXO, where x is an integer, such as, for example, 1 or 2, and / or M is a metal, such as, for example, lithium, sodium, zinc, or the like, or MxOywhere x is an integer, such as, for example, 2, or 3 and y is an integer, such as, for example, is 2 or 3, and / or M is a metal, such as, for example, aluminum or the like.

[0051] In various examples, the metal oxide particles do not comprise silicon oxide particles (such as, for example, silicon oxide nanoparticles or the like). In various examples, the metal oxide particles are not Lewis Bases or the like. In various examples, all or substantially all the metal oxide particles are not metal oxide nanoparticles.

[0052] Metal oxide particles can have various sizes. In various examples, metal oxide particles comprise a size (such as, for example, a linear dimension (e.g., a diameter or the like) or the like) of about 100 nm (nm = nanometer(s)) (or greater than 100 nm) to about 10 micron(s), which may be a longest linear dimension and / or an average size, including all 0.1 nm values and ranges therebetween. In various examples, substantially all (e.g., about 90% or more, about 95% or more, about 98% or more, about 99% or more, about 99.5% or more, about 99.9% or more, or about 99.99% or more) or all of the metal oxide particles comprise a size (such as, for example, a linear dimension (e.g., a diameter or the like) or the like) of about 100 nm (or greater than 100 nm) to about 10 micron(s) (micrometer(s)), which may be a longest linear dimension and / or an average size, including all 0.1 nm values and ranges therebetween.

[0053] In various examples, substantially all or all of the metal oxide particles have a density or size that results in formation of the gradient (e.g., resulting from standing (e.g., gravity or the like) or application of a force). In various examples, the metal oxide particles inhibit (e.g., partially inhibit or the like) polymerization of at least a portion of the monomer(s) (e.g., near the metal oxide particles on a particle size scale).

[0054] Various amounts of metal oxide particles can be used. In various examples, metal oxide particles is / are present at about 10 volume percent (vol. %) to about 40 vol. %, including all 0.1 vol. % values and ranges therebetween (e.g., about 10 vol. % to about 20 vol. %), which may be based on the total volume of the precursor mixture.

[0055] A precursor mixture may comprise one or more additive salt(s). Combinations of additive salt(s) may be used. In various examples, an additive salt is not a monomer as described herein or a Lewis Acid as described herein. Non-limiting examples of additive salts include lithium salts (which may be fluorine-containing lithium salts or the like and / or used in (or suitable for use in) a lithium-ion conducting device, such as, for example, a lithium-ion conducting battery or the like), sodium salts (which may be fluorine-containingsodium salts or the like and / or used in (or suitable for use in) a sodium-ion conducting device, such as, for example, a sodium-ion conducting battery or the like), or the like, or any combination thereof. Non-limiting examples of lithium-containing salts include lithium hexafluorophosphate (LiPFe), lithium bis(oxalato)borate (LiBOB), lithium difluoro(oxalato)borate (LiODFB), lithium trifluoromethanesulfonate (LiOTf), lithium perchlorate (LiCIC ), structural analogs thereof, and the like, and any combination thereof. Non-limiting examples of sodium salts include sodium difluoro(oxalato)borate (NaDFOB), sodium bis(oxalato)borate (NaBOB), sodium hexafluorophosphate (NaPFe), structural analogs thereof, and the like, and any combination thereof. In various examples, an additive salt or salts is / are present in a precursor mixture (e.g., independently or in the aggregate) at about 0.1 M (moles / L) to about 2 M (based on the volume of the precursor mixture), including all 0.01 M values and ranges therebetween.

[0056] A method comprises forming a gradient or gradients of metal oxide particles (e.g., in a precursor mixture). In various examples, a gradient or gradients of metal oxide particles is / are from a first surface of a first substrate disposed substantially opposite or opposite to a second substrate to a first surface to a second substrate disposed substantially opposite or opposite to the first substrate. In various examples, the substrates are in a precursor device or the like. In various examples, a method comprises allowing a precursor mixture to form a gradient or gradients of metal oxide particles (e.g., in a precursor mixture). In various examples, a gradient or gradients are formed by a gravitational force or gravitational settling, or the like. In various examples, precursor mixture is held for a time (such as, for example, about 10 minutes or more, about 15 minutes or more, about 20 minutes or more, about 30 minutes or more) sufficient to form a gradient or gradients. One having ordinary skill in the art will appreciate that the time necessary to form a gradient or gradients depends on factors, such as, for example, metal oxide particle size, metal oxide particle density, metal oxide particle loading, volume of the precursor mixture, and the like, environmental conditions (e.g., temperature or the like), and any combination thereof. It is within the purview of one having ordinary skill in the art to determine or select a suitable time to form a gradient or gradients. In various examples, a method comprises applying a force to a precursor mixture to form a gradient or gradients. In various examples, a gradient or gradients are formed (e.g., by holding the precursor mixture, which may be for a selected or pre-determined time) as a result of gravity, by a gravitational force, or the like. In various examples, an applied force is centrifugal force or the like. In various examples, a gradient or gradients form in a gravity preferred direction or a non-gravity preferred direction.

[0057] In various examples, a metal oxide particle gradient (e.g., number or particles per unit of volume or the like), which may be decreasing gradient, comprises a linear gradient (which may be a decreasing linear gradient or the like) or a non-linear gradient (which may be a decreasing non-linear gradient or the like) from a first substrate (e.g., an anode or the like) to a second substrate and / or a polymer gradient (e.g., number or polymer chains per unit of volume or the like), which may be an increasing gradient, comprises a linear gradient (which may be a increasing linear gradient or the like) or a non-linear gradient (which may be a increasing non-linear gradient or the like) from a first substrate (e.g., an anode or the like) to the second substrate. In various examples, the metal oxide particle gradient(s) and / or the polymer gradient(s) is / are independently a continuous gradient, a linear gradient, a non-linear gradient, or the like, or any combination thereof, which may be generally increasing or generally decreasing or decreasing. In various examples, a gradient or gradients is / are independently along an axis of the polymer-particle gradient electrolyte (such as, for example, an axis from a first surface of the first substrate disposed substantially opposite or opposite to the second substrate to a first surface of a second substrate (e.g., disposed substantially opposite or opposite to the first substrate), which may be substantially perpendicular or perpendicular to the first surface of the first substrate and / or the first surface of the second substrate. In various examples, a gradient comprises a metal-oxide particle-rich phase proximate to a first substrate (e.g., an anode or the like) and a polymer-rich phase proximate to the second substrate (e.g., a cathode). In various examples, the metal oxide particles have a gradient concentration from a first concentration to a second concentration along an axis (e.g. depth, height, thickness, or length) in the polymer-particle gradient electrolyte, where the first concentration is larger than the second concentration, or where the first concentration is at least about 1.2, about 1.3, about 1.4, about 1.5, about 2, about 3, about 4, 5 times of the second concentration, or where the first concentration is about 1.2 to about 10 times of the second concentration, including all O.Olvalues and ranges therebetween (e.g., about 1.2, about 1.3, about 1.4, about 1.5, about 2, about 3, or about 4, 5 times of the second concentration). In various examples, the polymer-particle gradient electrolyte has a first concentration in about 10 vol. % to about 95 vol. %, including all 0.1 vol.% values and ranges therebetween, at a first portion of the electrolyte and a second concentration in about 1 vol.% to about 40 vol.%, including all 0.1 vol.% values and ranges therebetween, at a second portion of the electrolyte along an axis.

[0058] In various examples, a monomer or monomers polymerize(s) to form a polymeric material (e.g., a polymer or polymers, or the like). In various examples, a monomer ormonomer polymerize(s) to form a polymer or polymers (such as, for example, polyether(s) or the like). In various examples, the polymer(s) is / are independently homopolymer(s), copolymer(s), or the like, or any combination thereof. In various examples, at least a portion, substantially all, or all of the polymer(s) formed by polymerization of the monomer(s) (such as, for example ring-opening polymerization or the like), independently is / are at least partially amorphous (comprise(s) amorphous domains), are substantially amorphous, or are completely amorphous. In various examples, at least a portion of, substantially all, or all of the polymer(s) is / are independently crosslinked. In various examples, the polymer(s) independently comprise a molecular weight (Mwand / or Mn) (such as, for example, an average molecular weight (average Mwand / or average Mn) of about 2 kg (kg = kilograms(s)) / mol to about 20 kg / mol (e.g., about 8 kg / mol to about 15 kg / mol), including all 0.1 kg / mol values and ranges therebetween. In various examples, the majority of, substantially all, or all of the polymeric material is proximate to the cathode or cathodes of a device.

[0059] After polymerization, there may be unpolymerized monomer(s). In various examples, after polymerization, the monomer(s) is / are present at about 10% (e.g., wt.% or the like) to about 80% (e.g., wt.% or the like) relative to the polymer(s) (e.g., the total weight of the polymer(s)), including all 0.1% (e.g., wt.% or the like) values and ranges therebetween (e.g., about 14% (e.g., wt.% or the like) to about 19% (e.g., wt.% or the like)).

[0060] In an aspect, the present disclosure provides precursor devices. In various examples, a precursor device is configured to carry out one or more method(s) of making a particle gradient electrolyte of the present disclosure. In various examples, a precursor device comprises one or more precursor mixture(s), each precursor mixture comprising components suitable for producing a polymer-particle gradient electrolyte of the present disclosure. Nonlimiting examples of precursor devices are described herein.

[0061] In various examples, a precursor device comprises one or more precursor mixture(s) (which may be a suspension or suspensions) as described herein, which may be the same or two or more of which may be different. In various examples, a precursor mixture comprises: one or more monomer(s), one or more Lewis Acid(s) (e.g., Lewis Acid initiator(s) or the like), a plurality of metal oxide particles, and, optionally, one or more crosslinker(s) and / or one or more additive salt(s). In various examples, a precursor mixture is disposed between a cathode material, a cathode, or the like and an anode material, an anode, or an anode current collector, or the like. In various examples, the metal oxide particles of a precursor mixture are the same or substantially the same (e.g., the same or substantially thesame structurally and / or the same or substantially the same compositionally). In various examples, at least a portion (e.g., at least two or more) of the metal oxide particles of a precursor mixture are different or substantially different (e.g., different or substantially different structurally and / or different or substantially different compositionally). In various examples, the monomer(s), the Lewis Acid(s), the metal oxide particles, and if present, the crosslinker(s), the additive salt(s), the cathode material, the cathode, the anode material, the anode, the anode current collector, are independently as described herein.

[0062] A precursor device may comprise a separator. In various examples, a precursor device comprises a separator disposed in a precursor mixture or in each of the precursor mixtures. Non-limiting examples of separators include separators comprising polypropylene (such as, for example, Celgard® 3400, 3401, 3500, or 3501, or the like) or the like. In various examples, the separator is a surfactant-coated separator.

[0063] In various examples, a polymer-particle gradient electrolyte further comprises a separator disposed in the polymer-particle gradient electrolyte. In various examples, a precursor device further comprises a separator disposed in the precursor mixture after the placement of anode and before the cathode, or after the placement of cathode and before the anode. In various examples, the separator is placed between the anode and the cathode and is immersed in the precursor mixture (which may be a suspension).

[0064] In various examples, a precursor device is configured to (after formation and polymerization of at least a portion of the monomer(s)) function as a device, such as, for example, an electrochemical device or the like. Non-limiting examples of precursor devices include precursor devices configured to (after formation and polymerization of at least a portion of the monomer(s)) function as a battery (such as, for example, a primary battery or cell or cells, a secondary battery or cell or cells, or the like, which may be a rechargeable and / or an ion-conducting battery (e.g., a lithium-ion or a sodium-ion conducting, or the like, battery) and / or a solid-state battery or the like), a supercapacitor, a fuel cell, an electrolyzer, an electrolytic cell, or the like.

[0065] In an aspect, the present disclosure provides polymer-particle gradient electrolytes. In various examples, a polymer-particle gradient electrolyte comprises a gradient of metal oxide particles. In various examples, a polymer-particle gradient electrolyte is made by a method of the present disclosure. Non-limiting examples of polymer-particle gradient electrolytes are described herein.

[0066] In various examples, a polymer-particle gradient electrolyte comprises: one or more polymeric material(s) (such as, for example, one or more polymer(s) or the like, or anycombination thereof); and a plurality of metal oxide particles, where the plurality of metal oxide particles is disposed in the polymeric material(s) and form a gradient as described herein (e.g., a gradient along an axis from a first surface (which may be an exterior surface) of the polymer-particle gradient electrolyte to a second surface of the polymer-particle gradient electrolyte (which may be an exterior surface) disposed substantially opposite or opposite to the first surface of the polymer-particle gradient electrolyte, or the like). The polymeric material(s) is / are formed by polymerization of monomers (such as, for example, monomers described herein). In various examples, at least a portion, substantially all, or all of the polymeric material (s) is / are independently crosslinked. In various examples, the majority of, substantially all, or all of the polymeric material is proximate to the cathode or cathodes of a device.

[0067] In various examples, a metal oxide particle gradient comprises (i) a linear gradient, a non-linear gradient, or the like along an axis of the polymer-particle gradient electrolyte substantially perpendicular or perpendicular to a first surface of the polymer- particle gradient electrolyte and / or a second surface of the polymer-particle gradient electrolyte, where the second surface is disposed substantially opposite or opposite the first surface and / or (ii) a polymer gradient along an axis (which may be the same as the metal oxide particle gradient axis) of the polymer-particle gradient electrolyte substantially perpendicular or perpendicular to a first surface of the polymer-particle gradient electrolyte and / or a second surface of the polymer-particle gradient electrolyte, where the second surface is disposed substantially opposite or opposite the first surface. In various examples, a metal oxide particle gradient comprises or also comprises a metal -oxide particle-rich phase proximate to a first surface of the substrate and / or a polymer-rich phase proximate to a second surface of the substrate, wherein the second surface is disposed substantially opposite or opposite to the first surface.

[0068] In various examples, a polymer-particle gradient electrolytes or electrolytes is / are a component or components of a device described herein (such as, for, example, a battery (such as, for example, a primary battery or cells or cells, a secondary battery or cell or cells, or the like, which may be a rechargeable and / or an ion-conducting battery (e.g., a lithium-ion or a sodium-ion conducting, or the like, battery) and / or a solid-state battery or the like), a supercapacitor, a fuel cell, an electrolyzer, an electrolytic cell, or the like. Non-limiting examples of primary batteries and secondar batteries include Li-ion batteries, Li metal batteries, and the like. In various examples, the device is anode free (e.g., the device does not comprise an anode, an anode material, or the like).

[0069] In various examples, the polymeric material(s) and the metal oxide particle(s), are independently as described herein. In various examples, the metal oxide particles is / are is / are present at about 10 vol. % to about 40 vol. %, including all 0.1 vol. / % values and ranges therebetween (e.g., about 10 vol. % to about 20 vol. %), which may be based on the total volume of the polymer-particle gradient electrolyte.

[0070] In various examples, the metal oxide particles have a gradient concentration from a first concentration to a second concentration along an axis (e.g. depth, height, thickness, or length) in the polymer-particle gradient electrolyte, where the first concentration is larger than the second concentration, or where the first concentration is at least 1.2, 1.3, 1.4, 1.5, 2, 3, 4, 5 times of the second concentration, or where the first concentration is 1.2 to 10 times of the second concentration, including all 0.1 values and ranges therebetween. In various examples, the polymer-particle gradient electrolyte has a first concentration in about 10 vol. % to about 95 vol. % at a first portion of the electrolyte and a second concentration in about 1 vol.% to about 40 vol.% at a second portion of the electrolyte along an axis.

[0071] In various examples, the metal oxide particles in the polymer-particle gradient electrolyte undergo or participate in a reversible redox reaction. Without intending to be bound by any particular theory, it is considered that the metal oxide particles in the polymer- particle gradient electrolyte results in a device comprising one or more of the polymer- particle gradient electrolyte(s) exhibiting one or more desirable properties (such as, for example, increased CE (which may approach 100%), increased cycle (such as, for example, battery cycle or the like) life, which may be relative to the same device that does not comprise the polymer-particle gradient electrolyte(s).

[0072] In various examples, a polymer-particle gradient electrolyte further comprises a separator disposed in a polymer-particle gradient electrolyte. In various examples, the separator is disposed between the anode and the cathode and in contact with the polymer- particle gradient electrolyte.

[0073] A polymer-particle gradient electrolyte may comprise one or more additive salt(s). Combinations of additive salts may be used. In various examples, an additive salt is not a monomer as described herein or a Lewis Acid as described herein. Non-limiting examples of additive salts include lithium salts (which may be fluorine-containing lithium salts or the like and / or used in (or suitable for use in) a lithium-ion conducting device, such as, for example, a lithium-ion conducting battery or the like), sodium salts (which may be fluorine-containing sodium salts or the like and / or used in (or suitable for use in) a sodium-ion conducting device, such as, for example, a sodium-ion conducting battery or the like), or the like, or anycombination thereof. Non-limiting examples of lithium-containing salts include lithium hexafluorophosphate (LiPFe), lithium bis(oxalato)borate (LiBOB), lithium difluoro(oxalato)borate (LiODFB), lithium trifluoromethanesulfonate (LiOTf), lithium perchlorate (LiCIC ), structural analogs thereof, and the like, and any combination thereof. Non-limiting examples of sodium salts include sodium difluoro(oxalato)borate (NaDFOB), sodium bis(oxalato)borate (NaBOB), sodium hexafluorophosphate (NaPFe), structural analogs thereof, and the like, and any combination thereof.

[0074] In various examples, a polymer-particle gradient electrolyte is formed in situ. In various examples, a polymer-particle gradient electrolyte is formed in situ in a device or the like, such as, for example, a precursor device of the present disclosure).

[0075] In an aspect, the present disclosure provides devices. In various examples, a device comprises one or more polymer-particle gradient electrolyte(s) of the present disclosure. In various examples, a device comprises one or more polymer-particle gradient electrolyte(s) made by a method of the present disclosure and / or in a precursor device of the present disclosure. Non-limiting examples of devices are described herein.

[0076] A device may be an electrochemical device. Non-limiting examples of electrochemical devices include batteries, supercapacitors, fuel cells, electrolyzers, electrolytic cells, and the like. In various examples, an electrochemical device is an ionconducting electrochemical device (such as, for example, a lithium-ion conducting electrochemical device or the like).

[0077] In various examples, a device is an anode-free device. In various examples, device is an anode-free battery (such as, for example, a lithium-ion battery or the like) or the like. In various examples, at least a portion of the polymer-particle gradient electrolyte(s) functions as a separator or the like.

[0078] In various examples, a device is an anode-free electrochemical device (e.g. an anode-free battery or the like) or the like. In various examples, an anode-free electrochemical device (e.g. an anode-free battery or the like) comprises one or more polymer-particle gradient electrolyte(s), a cathode; a first current connector, optionally a second current connector (e.g., placed close, such as, for example, proximate) to the cathode and away, such as, for example, distant) from the electrolyte). An anode-free electrochemical device (e.g. an anode-free battery or the like) may further comprise a separator (e.g., where the one or more polymer-particle gradient electrolyte(s) and separator(s) is / are placed between the cathode and the first current connector. In various examples, each of the one or more polymer-particle gradient electrolyte(s) comprise(s) one or more types of metal oxide particles having (orforming) a gradient concentration from a first concentration to a second concentration along an axis (e.g. depth, height, thickness, or length), where the first concentration is larger than the second concentration, or where the first concentration is at least 1.2, 1.3, 1.4, 1.5, 2, 3, 4, 5 times of the second concentration, or where the first concentration is 1.2 tolO times of the second concentration, including all 0.1 values and ranges therebetween. In various examples, the polymer-particle gradient electrolyte(s) has a first concentration in about 10 vol. % to about 95 vol. % at a first portion of the electrolyte and a second concentration in about 1 vol.% to about 40 vol.% at a second portion of the electrolyte along an axis.

[0079] In various examples, a metal anode of a device (such as, for example, a device after substantial operation) does not comprise a solid electrolyte interphase (SEI) layer on at least a portion or all of the relevant portion(s) of the anode and / or a cathode-electrolyte interphase (CEI) layer disposed on at least a portion or all of the relevant portion(s) of the cathode.

[0080] A device can be various batteries. Non-limiting examples of batteries include secondary / rechargeable batteries, primary batteries, and the like. In various examples, a battery is an ion conducting battery or the like. In various examples, a battery is an ionconducing battery (such as, for example, a metal-ion conducting battery or the like) or the like. In various examples, an ion conducting battery is a lithium-ion conducting battery, a potassium-ion conducting battery, a sodium-ion conducting battery, a calcium-ion conducting battery, a magnesium-ion conducting battery, a zinc-ion conducting battery, an aluminum-ion conducting battery, or an iron-ion conducting battery, or the like. A battery may be a metal battery, such as, for example, a lithium-metal battery, or the like. A device may be a solid- state battery or a liquid electrolyte battery. In various examples, a device is a lithium-ion conducting battery (such as, for example, a lithium-ion conducting solid-state battery or the like) and / or the polymer-particle gradient electrolyte(s) is / are a lithium-ion conductor(s). In various examples, a device is a sodium-ion conducting battery (such as, for example, a sodium-ion conducting solid-state battery or the like) and / or the polymer-particle gradient electrolyte(s) is / are a sodium ion conductor(s).

[0081] A battery comprises one or more polymer-particle gradient electrolyte(s) of the present disclosure and / or one or more polymer-particle gradient electrolyte(s) made by a method of the present disclosure and / or in a precursor device of the present disclosure. In various examples, a battery further comprises: a cathode; optionally, an anode; optionally, an anode current collector; optionally, a cathode current collector; and optionally, a separator. Invarious examples, each polymer-particle gradient electrolyte(s), and, if present, a separator, is / are disposed between a cathode and an anode.

[0082] A device, which may be a battery or the like, may comprise one or more cathode(s), which may comprise one or more cathode material(s). Examples of suitable cathode materials are known in the art. In various examples, a cathode / cathode material comprises (or is) a conducting carbon material or the like. Any of the cathodes / cathode materials may comprise a conducting carbon aid.

[0083] In various examples, the cathode material(s) is / are one or more lithium- containing cathode material(s), one or more sodium-containing cathode materials, or the like. Non-limiting examples of lithium-containing cathode materials include lithium nickel manganese cobalt oxides, LiCoCL, LiNii / sCoinMni CL, LiNio.5Coo.2Mno.3O2, lithium manganese oxides (LMOs), lithium iron phosphates (LFPs), LiMnPO4, LiCoPO4, and Li2MMn30s, where M is chosen from Fe, Co, and the like, and combinations thereof, and the like, and combinations thereof. Non-limiting examples of sodium-containing cathode materials include sodium-containing transition metal oxide materials, polyanionic materials, Prussian-blue compounds, and the like.

[0084] In various examples, a cathode is a high-voltage cathode. Non-limiting examples of high-voltage cathodes include cathodes comprising one or more NMC ternary cathode material(s) independently comprising nickel, manganese, and cobalt (e.g., LiNio.8Mno.1Coo.1O2 (NMC811), LiNio.6Mno.2Coo.2O2 (NMC622), or the like), and the like.

[0085] A device, which may be a battery or the like, may comprise a conversion-type cathode. Non-limiting examples of conversion-type cathode materials include air, oxygen, iodine, sulfur, sulfur composite materials, polysulfides, metal sulfides, such as, for example, M0S2, FeS2, TiS2, and the like, and any combination thereof.

[0086] A device, which may be a battery or the like, may comprise one or more anodes(s), which may comprise one or more anode material(s). Examples of suitable anode materials are known in the art. In various examples, an anode / anode material comprises (or is) a conducting carbon material or the like. Any of the anodes / anode materials may comprise a conducting carbon aid.

[0087] In various examples, an anode comprises (or is) a material chosen from lithium metal, lithium-ion conducting anode materials (e.g., where the lithium ion-conducting anode material is a lithium containing material chosen from lithium carbide, LieC, lithium titanates (LTOs), and the like, and combinations thereof), and combinations thereof. In various examples, an anode comprises (or is) a material chosen from sodium metal, sodium-ionconducting anode materials (e.g., where the sodium-containing anode material is chosen from Na2CsH4O4 and Nao.66Lio.22Tio.78O2, and combinations thereof), and the like, and combinations thereof. In various examples, an anode comprises a material chosen from silicon-containing materials, tin and its alloys, tin / carbon, and phosphorus, and the like.

[0088] A device, which may be a battery, may further comprise one or more other electrolyte(s) (which is / are not a not a polymer-particle gradient electrolyte of the present disclosure), such as, for examples, a solid electrolyte or electrolytes, liquid electrolyte or electrolytes, or any combination thereof. It may be desirable that the electrolyte by nonflammable (e.g., a non-flammable aqueous electrolyte). Examples of suitable electrolytes are known in the art. Non-limiting examples of electrolytes include electrolytes comprising carbonates, ethers, structural analogs thereof, or the like, or any combination thereof.

[0089] A device may further comprise one or more current collector(s). In various examples, a current collector is disposed on at least a portion of the anode(s) and / or the cathode(s). In various examples, an anode is a current collector (e.g., the anode does not comprise an anode material). In various examples, a current collector is a conducting metal or metal alloy.

[0090] A polymer-particle electrolyte or electrolytes, a cathode, an anode, an anode, if present, a separator(s), if present, other electrolyte(s), if present, and the current collector(s), if present, can form a cell of a battery. A battery may comprise a plurality of the cells and each adjacent pair of the cells is separated by a bipolar plate. The number of cells in the battery may be determined by the performance requirements (e.g., voltage output and the like) of the battery and is limited only by fabrication constraints. For example, the battery comprises 1 to 500 cells, including all integer number of cells and ranges therebetween.

[0091] In various examples, a device, which may be a battery or the like, exhibits one or more or all of the following: improved voltage stability (e.g., greater than about 4 V); substantially flat or flat metal (e.g., Li, Na, or the like) deposition on an anode side for greater than about 100 cycles; improved cycle life (e.g., greater than about 100 cycles); high coulombic efficiency (e.g., greater than about 98%); low interfacial resistance (e.g., less than about 1000 (1 cm2); high room-temperature (e.g., about 18 °C to about 25 °C, including all 0.1 °C values and ranges therebetween) ionic conductivity (e.g., greater than about 1 mS / cm); improved elastic modulus (e.g., greater than about 100 Pa); or high degradation temperature (e.g., greater than about 100°C).

[0092] The following Statements provide examples of methods of making polymer- particle gradient electrolytes, polymer-particle gradient electrolytes and uses thereof of the present disclosure:Statement 1. A method of forming a polymer-particle gradient electrolyte (which may be referred to as a hybrid electrolyte) comprising: providing a precursor mixture (which may be a suspension) comprising: one or more monomer(s), one or more Lewis Acid(s) (e.g., Lewis Acid initiator(s) or the like), a plurality of metal oxide particles, and optionally, one or more crosslinker(s), where the precursor mixture is disposed between a first substrate (such as, for example, a cathode material, a cathode, or the like) and a second substrate (such as, for example, an anode material, an anode, or the like); and allowing (e.g., holding or the like) the mixture to form (e.g., as a result of gravity) (or optionally, applying a force to the mixture such that) a gradient of the metal oxide particles from a first surface of the first substrate disposed substantially opposite or opposite to the second substrate to a first surface of the second substrate (e.g., disposed substantially opposite or opposite to the first substrate), where at least a portion of the monomer(s) polymerize forming the polymer-particle gradient electrolyte.Statement 2. A method according to Statement 1, where the monomer(s) is / are cyclic ether monomer(s) (such as, for example, monomers comprising an ether oxygen covalently bound to two independent alkyl groups or two or more ether oxygens and two or more alkyl groups disposed between adjacent ether oxygen groups, where the alkyl groups and ether oxygens form a ring).Statement 3. A method according to Statement 2, where the cyclic ether monomer(s) is / are chosen from 1,3-dioxolane (DOL), 1,3-dioxepane, 1,3, 7-tri oxocane (TOC), and 1,3- benzodi oxole, 1,2-epoxybutane, glycidyl octafluoropentyl ether, 4-fluoro- 1,3 -di oxolane, and 2-fluoro-l,3-dioxolane, structural analogs thereof, and the like, and any combination thereof. Statement 4. A method according to any one of the preceding Statements, where, after polymerization, the monomer(s) is / are present at about 10% (e.g., wt.% or the like) to about 80% (e.g., wt.% or the like) relative to the polymer(s) (e.g., relative to the total weight of the polymer(s) or the like), including all 0.1 percent values and ranges therebetween (e.g., about 14% (e.g., wt.% or the like) to about 19% (e.g., wt.% or the like)).Statement 5. A method according to any one of the preceding Statements, where in Lewis Acid(s) is / are chosen from aluminum salts (such as, for example, Al(OTf)3 and the like), chloride salts (such as, for example, InCh, ZnCh, and the like), structural analogs thereof, and the like, and any combination thereof.Statement 6. A method according to any one of the preceding Statements, where the Lewis Acid(s) is / are is / are present at about 0.2 mM to about 5.0 mM based on the total volume of the precursor mixture, including all 0.05 mM values and ranges therebetween (e.g., about 0.5 mM to about 1.0 mM).Statement 7. A method according to any one of the preceding Statements, where in metal oxide particles is / are chosen from lithium oxide particles, sodium oxide particles, zinc oxide particles, aluminum oxide particles, structural analogs thereof, and the like, and any combination thereof.Statement 8. A method according to any one of the preceding Statements, where the metal oxide particles comprise a size (such as, for example, a linear dimension (e.g., a diameter or the like) or the like) of about 100 nm (or greater than 100 nm) to about 10 micron(s), which may be a longest linear dimension and / or an average size, including all 0.1 nm values and ranges therebetween.Statement 9. A method according to any one of the preceding Statements, where the metal oxide particles is / are is / are present at about 10 volume percent (vol. %) to about 40 vol. %, including all 0.1 vol. % values and ranges therebetween (e.g., about 10 vol. % to about 20 vol. %), which may be based on the total volume of the precursor mixture.Statement 10. A precursor device (such as, for example, a device configured to carry out a method of forming a polymer-particle gradient electrolyte of the present disclosure (such as, for example, a method of forming a polymer-particle gradient electrolyte of any one of Statements 1 to 9)) comprising: a precursor mixture (which may be a suspension) comprising: one or more monomer(s), one or more Lewis Acid(s) (e.g., Lewis Acid initiator(s) or the like), a plurality of metal oxide particles, and optionally, one or more crosslinker(s) and / or one or more additive salt(s), where the precursor mixture is disposed between a cathode material, a cathode, or the like and an anode material, an anode, an anode current collector, or the like.Statement I L A precursor device according to Statement 10, where the precursor device is configured to (after formation and polymerization of at least a portion of the monomer(s)) function as an electrochemical device or the like.Statement 12. A precursor device according to Statement 10 or 11, where the electrochemical device is a battery, a supercapacitor, a fuel cell, an electrolyzer, or an electrolytic cell, or the like.Statement 13. A precursor device according to Statement 12, where the battery is a primary battery, a secondary battery, or the like.Statement 14. A precursor device according to Statement 12 or 13, where the battery is a solid-state battery or the like.Statement 15. A polymer-particle gradient electrolyte comprising: one or more polymeric material(s) (such as, for example, polymer(s) or the like, or any combination thereof); and plurality of metal oxide particles, where the plurality of metal oxide particles is disposed in the polymeric material(s) and form a gradient as described herein (e.g., a gradient along an axis from a first surface (which may be an exterior surface) of the polymer-particle gradient electrolyte to a second surface (which may be an exterior surface) disposed substantially opposite or opposite to the first surface of the polymer-particle gradient electrolyte, or the like).Statement 16. A device comprising one or more polymer-particle gradient electrolyte(s) of the present disclosure (such as, for example, one or more polymer-particle gradient(s) according to any one of Statement 15, one or more polymer-particle gradient(s) formed by a method of any one of Statements 1 to 9).Statement 17. A device according to Statement 16, where the device is an electrochemical device or the like.Statement 18. A device according to Statement 17, where the electrochemical device is a battery, a supercapacitor, a fuel cell, an electrolyzer, or an electrolytic cell, or the like. Statement 19. A device according to Statement 18, where the battery is a primary battery, a secondary battery, or the like.Statement 20. A device according to Statement 17 or 18, where the battery is a solid-state battery or the like.Statement 21. A device according to any one of Statements 18 to 20, where battery is an ionconducing battery (such as, for example, a metal-ion conducting battery or the like) or the like.Statement 22. A device according to Statement 21, where the ion conducting battery is a lithium-ion conducting battery, a potassium-ion conducting battery, a sodium-ion conducting battery, a calcium-ion conducting battery, a magnesium-ion conducting battery, a zinc-ion conducting battery, an aluminum-ion conducting battery, or an iron-ion conducting battery, or the like.Statement 23. A device according to any one of Statements 18 to 22, where the battery further comprises: a cathode; optionally, an anode; optionally, an anode current collector; optionally, a cathode current collector; and optionally, a separator, where the polymer-particle gradient electrolyte(s), and, if present, the separator, is / are disposed between the cathode and anode.Statement 24. A device according to any one of Statements 18 to 23, where the device is a lithium-ion conducting battery (such as, for example, a lithium-ion conducting solid-state battery or the like) and / or the polymer-particle gradient electrolyte(s) is / are a lithium-ion conductor or lithium ion conductors.Statement 25. A device according to Statement 23 or 24, where the cathode comprises (or is) a material chosen from lithium-containing cathode materials (e.g., where the lithium- containing cathode material is chosen from lithium nickel manganese cobalt oxides (such as, for example, LiNii Coi / sMni / sCh, nickel-rich layered lithium nickel manganese cobalt oxides (e.g., LiNio.8Mno.1Coo.1O2 (NMC811), LiNio.eMno.2Coo.2O2 (NMC622), and the like), and the like, which may be polycrystalline), LiCoO2, LiNio.5Coo.2Mno.3O2, lithium manganese oxides (LMOs), lithium iron phosphates (LFPs), LiMnP04, LiCoPO4, and Li2MMn30s, where M is chosen from Fe, Co, and the like, and combinations thereof, and the like, and combinations thereof).Statement 26. A device according to any one of Statements 23 to 25, where the anode comprises (or is) a material chosen from lithium metal, lithium-ion conducting anode materials (e.g., where the lithium ion-conducting anode material is a lithium containing material chosen from lithium carbide, LieC, lithium titanates (LTOs), and the like, and combinations thereof), and combinations thereof.Statement 27. A device according to any one of Statements 18 to 23, where the device is a sodium-ion conducting solid-state battery and / or the polymer-particle gradient electrolyte(s) is / are a sodium ion conductor(s).Statement 28. A device according to Statement 23 or 27, where cathode comprises (or is) a material chosen from sodium-containing cathode materials (e.g., where the sodium- containing cathode material is chosen from Na2V20s, P2-Na2 / 3Fei / 2Mni / 2O2, Na3V2(PO4)3, NaMni / 3Coi / 3Nii / 3PO4, Na2 / 3Fei / 2Mni / 2O2@graphene composites, and the like, and combinations thereof), conversion type cathode materials (e.g. sulfur, oxygen, iodine, metal sulfides (such as, for example, M0S2, FeS2, and TiS2, and the like), and the like.Statement 29. A device according to any one of Statements 23, 27, or 28, where the anode comprises (or is) a material chosen from sodium metal, sodium-ion conducting anode materials (e.g., where the sodium-containing anode material is chosen from Na2CsH4O4 and Nao.66Lio.22Tio.78O2, and combinations thereof), and the like, and combinations thereof. Statement 30. A device according to any one of Statements 23 to 29, where the cathode and / or anode further comprises (or is) a conducting carbon material or the like.Statement 31. A device according to any one of Statements 23, 24, 25, 27, or 28, where the cathode comprises a conversion type material chosen from sulfur, sulfur composite materials, and polysulfide materials, air (oxygen), iodine, metal sulfides (such as, for example, M0S2, FeS?, TiS2, and the like, and any combination thereof).Statement 32. A device according to any one of Statements 23, 24, 26, 27, or 29, where the anode comprises a material chosen from silicon-containing materials, tin and alloys thereof, tin / carbon, and phosphorus, and the like, and any combination thereof.Statement 33. A device according to any one of Statements 23 to 32, where the device further comprises one or more other electrolyte(s) (which is not a polymer-particle gradient electrolyte of the present disclosure).Statement 34. A device according to Statement 33, where the other electrolyte(s) is / are chosen from liquid electrolytes, solid electrolytes, and the like, and any combination thereof. Non-limiting examples of electrolytes include electrolytes comprised of carbonates and ethers, structural analogs thereof, and the like, and any combination thereof.Statement 35. A device according to any one of Statements 23 to 34, where the device further comprises an anode current collector or collectors (e.g., independently disposed on at least a portion of the anode or anode material) and / or a cathode current collector or collectors (e.g., independently disposed on at least a portion of the cathode or cathode material).Statement 36. A device according to Statement 35, where the anode current collector(s) and / or cathode current collectors(s) is / are independently a conducting metal, a metal alloy, or the like.Statement 37. A device according to any one of Statements 23 to 36, where the polymer- particle gradient electrolyte(s), the cathode, the anode, if present, the separator(s), if present, the other electrolyte(s), if present, the current collector(s), if present, form a cell, and the battery comprises a plurality of the cells and each adjacent pair of the cells is separated by a bipolar plate.Statement 38. A device according to any one of Statements 16 to 37, where the device exhibits one or more or all of the following: desirable voltage stability (e.g., greater than about 4 V (V = volt(s))); desirable (e.g., flat or the like) metal (Li or Na) deposition on anode side for greater than about 100 cycles; desirable Improved cycle life (e.g., greater than about 100 cycles); desirable Coulombic efficiency (e.g., greater than about 98%); desirable interfacial resistance (e.g., less than about 1000 (1 cm2); desirable room-temperature roomtemperature (e.g., about 18 °C to about 25 °C, including all 0.1 °C values and ranges therebetween) ionic conductivity (e.g., greater than about 1 mS / cm); desirable elasticmodulus (e.g., greater than about 100 Pa); or desirable degradation temperature (e.g., greater than about 100°C); or the like.Statement 39. An anode-free electrochemical device (e.g. an anode-free battery or the like) or a device according to any one of the Statements 16 to 38, comprising one or more polymer- particle gradient electrolyte(s), a cathode; a first current connector, optionally a second current connector (e.g. placed close to the cathode and away from the electrolyte), and optionally a separator; where the one or more polymer-particle gradient electrolyte(s) and optionally the separator is / are placed between the cathode and the first current connector, where the one or more polymer-particle gradient electrolyte(s) comprise one or more types of metal oxide particles having a gradient concentration from a first concentration to a second concentration along an axis (e.g. depth, height, thickness, or length), where the first concentration is larger than the second concentration, or where the first concentration is at least about 1.2, about 1.3, about 1.4, about 1.5, about 2, about 3, about 4, about 5 times of the second concentration, or where the first concentration is about 1.2 to about 10 times of the second concentration, including all 0.1 values and ranges therebetween.

[0093] The steps of the methods described in the various embodiments and examples disclosed herein are sufficient carry out a method of the present disclosure. Thus, in various examples, a method consists essentially of a combination of the steps of the methods disclosed herein. In various other examples, a method consists of such steps.

[0094] The following Examples are presented to illustrate the present disclosure. The examples are not intended to be limiting in any matter.EXAMPLE 1

[0095] This example provides, inter alia, a description of methods of making polymer- particle gradient electrolytes and polymer-gradient electrolytes of the present disclosure, and uses thereof.

[0096] Solid-state electrolytes (SSEs) are of increasing scientific and practical interest for their ability to improve operability and safety of secondary lithium metal batteries (LMBs). They are presently understood to be less challenged by poor room-temperature ionic conductivity in the bulk than by complex interfacial chemistry and poor ion transport through the interfaces that SSEs form with the LMB anode and cathode. A class of suspension electrolytes comprised of micrometer-sized lithium oxide (Li2O) particles dispersed in polymerizable 1,3-dioxolane (DOL) liquid hosts was investigated. Ring-opening polymerization of the DOL host by Lewis-Acid salts inside a battery cell produces polymer-inorganic hybrid electrolytes with unusual gradient properties on both the particle and battery cell length scales. Such electrolytes sustain stable charge-discharge behavior in Li||NCM811 and anode-free Cu||NCM811 electrochemical cells, with Coulombic efficiency (CE) above 99%. In the un-polymerized state, the electrolytes manifest Maxwell conductivity behavior up to 40 vol.% Li2O, indicating that the particles behave like perfect insulators and do not influence ion transport. In contrast, in situ Lewis-Acid initiated polymerization of the DOL yields solid-state electrolytes with surprisingly high ionic conductivity (<J > 4 mS / cm at a temperature as low as -30°C) and beneficial gradient properties. On the particle length scale, Li2O retards ring-opening polymerization of DOL near particles, facilitating efficient iontransport in a fluid-like region near the particle surface. On battery cell length-scales, gravity- assisted settling creates gradients in Li2O particle concentration in the hybrid electrolytes, which are in turn shown to yield gradients in physical and electrochemical properties of the in situ-formed poly(DOL) SPE. Furthermore, by means of electrochemical and spectroscopic analyses, it was found that Li2O particles in the electrolyte participate in a reversible redox reaction that increases the effective CE in anode-free cells to values approaching 100%, enhancing battery cycle life.

[0097] Hybrid solid polymer electrolytes (HSPEs) were created in which electrochemically active particles, such as Li2O, are used to regulate both the physicochemical properties of the in situ-formed solid-state, poly(DOL) electrolytes in bulk and in the solid-electrolyte interphase. It was shown that such electrolytes enable extended cycling of anode free Cu||NCM811 with low interfacial resistances and effective values of the Columbic efficiencies computed by fitting the cycling data to a power-law decay function markedly larger than observed in either the unpolymerized or polymerized electrolyte in the absence of the Li2O particles. The electrolytes also manifest interesting gradient physical and transport properties (z.e., they are solid-like polymers far from the anode surface and are liquid-like near the anode).

[0098] Results and Discussion. A simple force balance comparing the gravitational, buoyancy, and thermal force, k77r, on particles of radius, r, and density, ps, dispersed in a liquid of density Pf, indicates that particles with radii above a critical value, r > rc=1 ( 3 kT 14- - - - will settle in a suspension to create a two-phase material in which a ^7ig^Ps~Pf)j substantially particle-free liquid phase coexists with a porous, granular material with solvent in its pores. Here k is Boltzmann constant (1.38 X 10-23m2kg / s2K), g the gravitationalacceleration (9.8 m / s2), and T is temperature (303 K). Taking the density of Li2O as ps« 2 g / mL at T= 303K, it was found that that rc= 0.62 pm for the Li2O / DOL ( y = 1.32g / mL) suspensions and rc= 0.57 pm for the Li2O / EC ( y = 1.06g / mL) suspensions. Thus, a Li2O / DOL or Li2O / EC suspension electrolyte composed of 100-mesh Li2O microspheres will exist as a two-phase system — a supernatant liquid containing Li2O particles with sizes less than around 600nm and a precipitated porous bed formed by gravitational settling of larger particles.

[0099] FIGS. 5 and 7 show that Lewis-Acid initiated polymerization of Li2O / DOL suspensions produces a two-phase material in which an Li2O-lean poly(DOL) layer coexists with a Li2O-rich liquid DOL layer. Interestingly, it was found that if the suspensions are continuously agitated to prevent settling of Li2O particles, the ring-opening polymerization of DOL is completely arrested. A straightforward explanation of these observations is possible. Lithium oxide (Li2O) particles are Lewis bases with pH of 10 in Li2O / DOL suspensions. It is noted further that Li2O particles are known to adsorb anionic species on their surfaces. It was concluded that the Li2O particles neutralize the Lewis Acid Al(OTf)3 initiator needed for ring-opening polymerization of DOL. In the absence of mixing, the particle concentration is highest in the gravity preferred direction, which means that DOL polymerization would occur at a progressively lower rate as the concentration of particles rises. In the synthesis cell configuration illustrated in FIG 5a, this would result in an essentially liquid DOL electrolyte near the base of the cell. The liquid DOL electrolyte is in equilibrium with a hybrid Li2O / poly(DOL) electrolyte with a reduced concentration of Li2O particles that are too small to settle on the timescale of the polymerization reaction, which is consistent with what is observed.

[0100] Analysis of the particle size distribution using an Anton Paar Particle Size Analyzer (PSA) indicates that immediately after mixing the average suspended particle size is 18 ± 0.6 pm (FIG. 6). The particles are evidently large-enough to spontaneously settle. Indeed, after a period of approximately 15 mins following mixing, gravity-driven settling is observed and a moderately narrower particle size distribution is seen in the supernatant, with particle size plateauing at 25 ± 0.5 pm by the 15thminute. This is also accompanied by a new peak in the distribution associated with much smaller particles with sizes between 1.5 - 2.0 pm. SEM analysis of the settled particle phase reveal that some of the Li2O particles have sizes as large as 80 pm (FIG. 5g). FIG. 7 illustrates the gradient property produced by particle settling. The resultant hybrid electrolyte is composed primarily of poly(DOL) with meltingpoints at Tm= 31°C and 49°C as well as recrystallization temperature of Tc= — 15°C. On the other hand, Poly(DOL) formed near the settled particles lacks an obvious melting point and its glass transition temperature is shifted to a lower value. These observations imply that whereas a lower molecular weight, amorphous polymer is formed by ring-opening polymerization of DOL in the particle-rich sediment, a semicrystalline poly(DOL) material is formed when the polymerization occurs in the Li2O-particle lean supernatant.Thermogravimetric analysis in fact suggests that a more liquid-like organic-rich phase results from polymerization of DOL in the particle-rich phase.

[0101] To understand how such a two-phase electrolyte might influence reversibility of a Li||NCM811 battery cell or, more challengingly, a Cu||NCM811 anode-free battery cell, coin cells were created with the configurations illustrated in FIG. 1c. The cells were designed with two separators (Celgard 3501, which is manufactured to have micron-sized pores) as illustrated, and the Li / Cu anode oriented in the gravity assisted direction. In assembling the cells, Li2O / DOL suspension was dropped on the anode side and both separators applied in sequence. A DOL electrolyte containing 1 mM Al(OTf)3 was thereafter applied to the cathode side and the cathode installed to complete the cell assembly.

[0102] In situ ring-opening polymerization of Li2O / DOL electrolytes in such cells would produce materials with distinct characteristics in the separator near the particle-laden anode versus near the particle-lean cathode (FIG. 1c). Analysis by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) largely confirm these expectations. FTIR analysis of the separator near the cathode reveals a strong poly(DOL) peak at -1000 cm’1, with no evidence of Li2O particles (FIG. lb). The opposite is seen for the separator near the anode, which is rich in Li2O particles. SEM images reveal striking morphological differences between the two separators. As polymer precursor wets the separator and polymerization happens, the cathode facing separator is seen to lose its porous microstructure as poly(DOL) forms within the pores (FIG. le). In contrast the anode-facing separator retains its porous structure (FIG. If). Thus, it was confirmed that the poly(DOL) electrolyte is formed primarily at the battery cathode.

[0103] At the highly reducing potentials at which Li+is plated at a battery anode, all electrolyte components would be expected to degrade in time. The formation of a well- formed SEI containing inorganic and organic components at the anode is a well-practiced strategy for passivating the electrode to prevent continuous electrolyte degradation. Li2O is an SEI component that have been reported in some systems, hence suspension electrolyte made up of Li2O suspension is a pathway to create an ideal SEI that protects the anode and,as was demonstrated, possesses ionic conduction mechanism closely related to liquid electrolytes. At the other end of the battery, highly oxidized cathode surface at high potentials tend to arouse interfacial irreversible reaction between cathode and electrolyte, forming the so-called cathode-electrolyte interphase (CEI) that could lead to capacity loss. It is then important to suppress side reactions of liquid DOL, which has low oxidative stability, to facilitate use in LMBs based on high-voltage cathodes. This can be done by polymerizing DOL into poly(DOL) near the cathode. The stratification of these two layers, all formed in situ, is an overall pathway in creating more reliable SSEs that fit the anode / cathode duality of batteries.

[0104] Oxide particles are conventionally thought to help ion dissociation by adsorbing ionic species, and hence create a space-charge layer that serves as an ionic conduction pathway, here no such effects were seen. The strong Lewis basicity of the Li2O particles might then be expected to exert a large influence on ion transport by facilitating ion pair dissociation. To elucidate the role played by Li2O on the ion-transport properties, a simple, theoretical framework attributed to Maxwell was employed to describe ionic conductivity data obtained in Li2O / DOL suspensions electrolytes. The Maxwell analysis has previously been applied to quantitatively explain ion transport in suspension electrolytes under electrochemical driving forces. The conductivity (J of a suspension of particles with conductivity, <Jp, is related to that of the suspending medium, <J0, and particle concentration, , through (Equation 1). The coefficient a is a function of the suspending medium, <J0, and particle, ap, conductivity (Equation 2). For perfectly insulating particles, op« <J0, a = 1 / 2 and cr / cio isafunction of (p only (Equation 3).(Equation 1)(Equation 2)<7 > 2 (1 — )(Equation 3) <TQ 2 + <p

[0105] The temperature-dependent ionic conductivity of Li2O / DOL electrolytes was measured as a function of (p (see FIG 7a) and compare the experimental results with theoretical predictions based on Equation 3 in FIG. 2a. It is seen that up to a particle concertation of approximately 40 vol.%, ion transport in Li2O / DOL electrolytes are in nearly perfect agreement with the Maxwell model, revealing that the Li2O particles behave as perfect insulators. It was wondered whether these observations are a consequence of the lowdielectric constant (SDOL = 19) of DOL and performed similar experiments using suspension electrolytes in which the same Li2O particles were dispersed in a solvent, ethylene carbonate (EC), with a substantially higher dielectric constant (SEC = 89.8). FIG. 9 again clearly show agreement with Equation 3 for particle concentrations up to 40 vol.%. Additionally, it is noted that notwithstanding the decrease in ionic conductivity with increasing Li2O particle volume fraction, no significant changes in the activation energy Eafor ion transport are observed (see FIG. 8), especially for suspensions with particle volume fractions 10vol. %. This result confirms that the ion conduction mechanism is essentially unaffected by the Li2O particles and implies that the ions move primarily via a network formed by the liquid DOL electrolyte.

[0106] Like many particulate additives, Li2O addition offers a degree of mechanical reinforcement. FIG. 10 shows results from strain-dependent measurement of Li2O suspensions in DOL containing 1 M LiTFSI, where strain was varied from 0.025 - 10% at a constant angular frequency. Storage G' and loss G" moduli reflect the solid-like and viscous- like contributions within the material, and both increase with increasing Li2O particle concentration. G' shows value as high as 100 Pa for 10 vol.%, comparable to those of low molecular weight polymers or oligomers used as polymer electrolytes. Increasing Li2O concentration to 30 vol.% causes G' to have a value of 1000 Pa. As suspension reaches 50 vol.%, G' of 4 x 105Pa is observed. This very high modulus is comparable to values typically observed in crystalline polymers or soft materials close to their glass / jamming transition.

[0107] The increase in mechanical strength is also accompanied by changes in the stressstrain curve. Materials that manifest a yield point typically first display a linear stress-strain response before yielding alters the slope of the stress-strain curve. Many suspensions are known to have yield stress, and the denser the suspensions, the more likely yielding occurs as it takes a certain degree of deformation for particles to move and get out of their “cages”. Suspension with 10 vol.% Li2O does not exhibit any yield stress, but increasing particle concentration causes yielding behavior in the suspension. The yield stress value Ty, taken from the point where deviation from linearity in the stress-strain curve happens, increases with increasing particle concentration and eventually reaching Ty« 100 Pa at 50 vol.% Li2O content. The more tortuous pathway due to particle aggregation likely causes deviation from Maxwell prediction and explains the declining conductivity value with increasing volume fraction (FIG. 2a).

[0108] Hybrid electrolytes created by polymerizing DOL containing Li2O particles utilizing the method shown in FIG. la, manifest higher ionic conductivity values than both precursor materials (FIG. 2b and c). The hybrid electrolyte for example exhibits an ionic conductivity value of <5 = 4.3 mS / cm at 30°C while pure poly(DOL) and pure suspension have <J = 2.4 and 3.2 mS / cm, respectively. Remarkably, the enhanced conductivity values ( <J > 1 mS / cm) remain even at temperatures as low as -30°C. It is interesting that such high low- temperature ionic conductivity values are unattainable for the semicrystalline poly(DOL) electrolyte. Furthermore, the hybrid electrolytes manifest the lowest activation energy Eaof 4.2 ± 0.2 kJ / mol compared to pure poly(DOL) (Ea= 6.9 ± 0.2 kJ / mol) and pure suspension (Ea= 4.6 ± 0.3 kJ / mol). Eavalues are calculated through Arrhenius equation (5 = Ae~Ea^RTwith A being a pre-exponential factor, R universal gas constant, and T temperature.

[0109] The hybrid electrolyte conductivity is seen to evolve with polymerization time, with conductivity value first increasing and ultimately plateauing after around five hours of polymerization. Temperature-dependent conductivity at the 1st, 5th, 10th, 24th, and 96thhour is shown in FIG. 2d. A key finding is that the discontinuous transition in conductivity seen in the 1sthour, gaping below and above 30°C, indicated by two shaded regimes in the figure largely eases as polymerization progresses with time, as seen in the continuous trend at 96thhour. A shift from a Vogel-Fulcher-Tamman (VFT)-like behavior of amorphous poly(DOL) hybrid electrolyte to an Arrhenius one as crystallization of poly(DOL) takes place was previously reported. As crystallization and associated chain reconfiguration in semicrystalline polymers typically produce large changes in the conduction mechanism near the melting point or glass transition temperature Tg. Discontinuous changes in ionic conductivity have been reported extensively to accompany these thermal transitions in a range of polymers. Stratification of polydisperse microsphere suspension has been extensively examined; larger particles settle, and smaller ones get suspended in liquids. This is also what was observed through TGA (see FIG. 7b), with a concentration gradient increasing towards the plane of highest gravitational force. The stratification process is a time-dependent process, with the system shifting from a non-equilibrium state to an equilibrium, stratified one.

[0110] To evaluate the electrochemical features of the hybrid electrolytes Li2O / DOL suspension electrolytes containing 10 vol.% (FIG. 3a) and 50 vol.% Li2O (FIG. 3b) and 2 M LiTFSI in Li||NCM811 full and Li||Cu half cells were studied. A fixed current density of 1 mA / cm2was used for these experiments. The results reveal that at either of the Li2O concentrations studied, the cells cycle stably, reaching a discharge capacity of 1.45 mAh / cm2by 100 cycles (FIG. 3c). Prior to cycling cells were subjected to a solid electrolyte interphase (SEI) buildup process at a low current density of C / 10 for the first five cycles. The results are also interesting because DOL is not commonly used as a stand-alone electrolyte solvent in LMBs due to their poor oxidative stability (< 4 V) and chemical instability with the most used lithium salts, like LiPFe.[OHl] Results in FIG. 3d and 3e reveal that notwithstanding the uniform stable cycling observed, the Coulombic efficiency (CE) and morphology of plated Lithium metal varies with Li2O volume fraction (FIG. 11). SEM analysis of the Cu electrode harvested from the Li||Cu half cells after depositing 10 mAh / cm2Li on the copper reveal that the relationship between electrodeposit morphology and Li2O concentration is non-monotonic. Specifically, the roughest Li deposits are observed for the pure DOL electrolyte, followed by electrolytes containing 50 vol.%, 30 vol.%, and 10 vol.% Li2O. The trend is not the same for the CE measured in Li||Cu cells. These measurements show that the CE rises from 98.0% for cells containing the pure DOL electrolyte to 98.8% for cells containing suspension electrolytes with 10 vol.% Li2O (FIG. 3d). CE further increases to 99.2% for electrolytes containing 20 vol.% Li2O and changes negligibly thereafter with increasing Li2O concentration. Nyquist plots (FIG. 12) indicate that both the coarser lithium deposits and plateauing CE values coincide with an increase in interfacial resistance at higher Li2O particle concentrations.

[0112] Anode-free lithium cells provide a particularly challenging testbed for evaluating the attributes of any hybrid or solid-state electrolyte. Because Li metal is not present during cell assembly, an anode-free LMB is also viewed as attractive from a practical point of view because it removes safety issues involved in handling lithium metal in a manufacturing setting and enhances the battery’s energy density as the electrode weight is reduced. Reliable anode-free LMBs are presently hindered by the low Coulombic efficiency (CE) due to interfacial reactivity, transport associated with the nonuniform deposition of Lithium as well as its parasitic chemical and electrochemical reactions with electrolyte components. FIG. 4a reports the galvanostatic cycling of Cu||NCM811 cells containing hybrid electrolytes created by ring-opening polymerization of a 10%Li2O / DOL suspension containing 1 mM Al(OTf)3 + 2 M LiTFSI + 0.5 M LiNCL. This electrolyte is identified as 10N5 in what follows exhibits a nearly constant CE value of 97% and a first-cycle discharge capacity of approximately 1.4 mAh / cm2at a cycling rate of C / 2. As illustrated FIG. 4b the discharge capacity of the cells decreases gradually with cycling, but the rate of decrease is significantly lower than observed in previous studies of anode-free LMBs, and markedly lower than for anode-free cells based on the control electrolytes (z.e., DOL and Li2O / DOL suspension electrolytes) (see also, FIG.13), underscoring the benefits of polymerization of the DOL. As illustrated in FIG. 4c, the results shown in FIG. 4b are remarkable for another reason. Specifically, for an anode-free battery cell that runs with a nearly constant CE, the discharge capacity at the nthcycle is related to the value at the 1stcycle (n = 1), as a simple power-law of CE:CapacitynCEn(Equation 4)Capacityn= 1

[0113] The dashed line in FIG. 4c was obtained using Eq. 4, with the value estimated from the experimentally measured discharge and charge capacity per cycle (CE ~ 0.97) inserted in the expression. A plot of log (Capacityn) against n linearizes Eq. 4, with theslope equal to log CE. Comparing this line to the actual discharge capacity measured for the anode-free cells, a large discrepancy is observed. Namely, the anode-free cells containing the hybrid electrolyte show more efficient utilization of the Li stored in the cathode. The experimentally determined capacities were fitted to the linearized version of Eq. 4 and extracted the CE value required to obtain the best fit. It is apparent that the effective CE ~ 0.994 of the cells is much closer to unity. The apparent increment in CE at each cycle was estimated by taking the nthroot difference of the discharge capacity measured in the anode- free cells cycled in the control electrolyte from those measured in thel0N5 hybrid electrolyte. This analysis reveals a relatively stable increment of around 15% at each cycle (FIG. 4d).

[0114] It was hypothesized that in addition to the role in reinforcing mechanical properties of the hybrid electrolytes, in retarding polymerization of DOL, and in producing gradient properties in the hybrid electrolytes, the Li2O particles contribute some amount of Li to compensate for losses each cycle. As partial confirmation of the hypothesis, FIG. 14 reports results from galvanostatic cycling of a Li||NCM811 cell that utilizes the 10N5 electrolyte under the same conditions used for the measurements (FIG. 4a). The presence of excess Li in the cells clearly improves their cycling. As a more direct test of the hypothesis, XRD and Raman spectroscopic analysis of Cu anodes harvested from the cycled cells was performed. The results shown FIG. 16 support formation of Li2O2 in the electrodes, but the signals are relatively weak. To assess the role of the Li2O in this process and to evaluate the reversibility of the formed Li2O2 under our cell running conditions, extensive cyclic voltammetry measurements using Li2O||Cu cells was performed (see FIG. 4e). The Li2O electrodes used for these studies were created by sandwiching Li2O particles between carbon cloth (CC) as a current collector and using liquid DOL + 2 M LiTFSI as the electrolyte. Three peaks are evident in the cyclic voltammograms, with peak (3) attributed todecomposition of the liquid electrolyte. CV results for control CC||Cu cells employing the same electrolyte show an irreversible reduction peak at ~ -3.0 V, and no observable peaks (1) and (2) (FIG. 15a). These peaks are then attributed to the oxidation (1) and reduction (2) of Li2O. The voltammograms also indicate that the peaks currents increase approximately as the square root of scan rate (FIG. 15a) indicating that the reactions are transport limited. The findings are consistent with previous reports which show that Li2O undergoes an oxidation reaction during discharging to form Li2O2, a prominent reaction in lithium-air battery systems.

[0115] Additional support comes from XPS analysis of the Li2O electrodes used for the CV experiments. Results shown in FIG. 4f- h were obtained by holding the Li2O electrodes at an oxidizing potential of approximately 1.5 V (vs Li+ / Li) for 5 hours. The high-resolution O Is spectra were deconvoluted into two primary peaks centered at 531 ± 0.4 eV and 529 ± 0.3 eV, which indicate oxide (Li2O) and peroxide (I^Ch) bonding modalities respectively. An average of three measurements (Table 1) revealed a 2:3 ratio of peroxide to oxide on the surface (up-to lOnm scanning depth). These observations were further corroborated by high- resolution Li Is scans - deconvoluted into two peaks centered at 53.3 ± 0.2 eV for Li2O, and 54.4 ± 0.4eV for Li2C>2 - which also indicate a 2:3 distribution.E = E° + — ln-^- (Equation 5)\Ep— Ep / 2| = 2.2 (Equation 6)

[0116] Table 1. Three locations of Li2O@Cu were probed through XPS, with the resulting Li2O and Li2O2 percentage listed for both high resolution O- and Li-scan. Survey scan shown in FIG. 4g presents different atomic percentage of elements of O, C, and Li.

[0117] The Li2OLi2C>2 + 2Li++ 2e' reaction is also seen to be reversible in the DOL electrolyte. The Nernst equation (Equation 5) can also be utilized to see the reversibility ofthe redox reaction. It relates the potential of an electrochemical cell E to the standard potential of a species E°, as well as the relative activities of oxidized / reduced analyte at equilibrium. R is universal gas constant, F is Faraday’s constant, n is the number of electrons, and T is temperature. Estimating E° as half-peak potential Ep / 2and taking E as the potential at the peak current Ep, it is straightforward to conclude that reversible redox reactions should have a value of 57 mV at T = 25°C (Equation 6). The results in FIG. 15c reveal that for peaks (1) and (2), these values are 39 mV and 43 mV, respectively. The charge provided by the redox reaction, quantified by the area under the i - V curve, is shown to be approximately equal (FIG. 15c) indicative of a reversible reaction.

[0118] To evaluate the longer-term, electrochemical fitness of the anode free cells, cells cycled at a fixed rate of C / 2 for 100 cycles were subjected to varying rates: 1C and 2C before returning it to the original current rate to C / 2. The results shown in FIG. 17 show that the cells remain stable and that more than 92% of the capacity measured at the 100thcycle is recovered at the 140thcycle, when the C / 2 rate is restored. The combined effects of Li2O particle concentration and LiNCL concentration on galvanostatic cycling of the anode-free Cu||NCM811 cells were investigated. The results shown in FIG. 18 show that a higher concentration of Li2O or LiNCL increases the CE, but lowers the discharge capacity, which is accompanied by a higher overpotential. Consistent with the results shown in FIG. 4 for hybrid electrolytes with 10% Li2O, results shown in FIG. 19 show that a best fit line to the linearized form of Eq. 4 again shows effective CE is increased when Li2O particles are present in the electrolyte.

[0119] The role of LiNCL as an electrolyte additive in LMBs and LIBs has been extensively studied and the main finding of these studies support its role in building a stable SEI. The effect of LiNCL concentration on the hybrid electrolytes was studied and higher interfacial resistance indicated by amplified circumference and an additional semicircle in the Nyquist plot were observed (FIG. 20). This second semicircle grows with increasing LiNCL content. Increasing LiNCL concentration from 0.5M (N5) to 0.7M (N7) does not seem to affect transference number and conductivity significantly.

[0120] Suspension electrolytes made up of micron-sized Li2O particles in DOL undergo Al(OTf)3 Lewis Acid-initiated ring-opening polymerization inside a battery cell to create hybrid solid-state electrolytes (SPEs) with room temperature ionic conductivities exceeding 1 mS / cm at Al(OTf)3 and beneficial gradient properties. The gradient properties are thought to arise from neutralization of the Lewis-Acid initiator by the basic Li2O particles. Gravitationalsettling of the Li2O particles is shown to drive macrophase separation, which in-tum results in gradients in polymerization inside the cell. Likewise, retardation of ring-opening near the surface of Li2O particles creates a region of limited or no polymerization near the Li2O particle surfaces, yielding solid-state materials with room temperature ionic conductivity exceeding 4 mS / cm. This behavior contrasts markedly with observations in Li20 / D0L suspension electrolytes, which manifest simple Maxwellian conductivity in which particles act as simple insulating inclusions in the liquid DOL host. Used as electrolytes in conventional Li||NCM81, as well as anode-free Cu||NCM811 cells, the hybrid electrolytes enable extended long-term cycling. Curiously, it was found that the cycling achieved in the anode-free cells is substantially better than expected from the nominal Coulombic Efficiencies (CE) deduced from their charge / discharge characteristic. The cycling profiles were fit to a power law and estimate the effective CE in the cells to be 99% or higher, indicating that cycling benefits from a source of Li other than the NCM811 cathode. By means of cyclic voltammetry and spectroscopic analysis, it was shown that reversible redox reaction of the Li2O particles localized near the anode contribute a small amount of Li each cycle that compensates to an extent for the normal parasitic losses, extending the cycle life of the anode free cells to levels heretofore unseen in the literature.

[0121] Materials and Methods. Electrolyte and battery preparation. To fundamentally understand the source of the enhanced Coloumbic Efficiency extended cycling of anode-free Lithium Battery Cells, thermal, transport, and electrochemical properties of Li2O / poly(DOL) and Li2O / DOL electrolytes, as well as their analogous Li2O-free electrolyte controls, were investigated. Acknowledging the importance of cathode electrolyte interphase (CEI) for high- voltage batteries and anodic solid electrolyte interphase (SEI) for batteries with better cycling stability, hybrid solid-state electrolytes formed by ring-opening polymerization of Li2O / DOL suspension electrolyte using a Lewis Acid initiator is of particular interest. To fabricate such electrolytes in Li||NCM811 and so-called anode free, Cu||NCM811, cells Li2O / DOL suspensions (see FIG. la) were first created. The Li2O particles (100 mesh, ravg< 150pm) was purchased from BeanTown Chemical and used as obtained. Electrolytes suitable for electrochemical studies were created by adding a combination of two salts (LiTFSI and LiNCL) known from previous studies to work in tandem to enable formation of good interphases on Li; the studies described in this EXAMPLE used electrolytes comprised either of 2 M LiTFSI + 0.5 M LiNO3(N5) or 2 M LiTFSI + 0.7 M LiNO3(N7). Different volume fractions of added Li2O were utilized, and the hybrid electrolytes with x vol.% are denoted as either xN5 or xN7 (10 vol.% in N7 electrolyte is denoted as 10N7). A similar strategy wasused to create Li20 / Ethylene Carbonate (EC) electrolytes for comparison studies. DOL, EC, and LiTFSI were purchased from Sigma-Aldrich and LiNCL was purchased from Chem- Impex Int’l. Suspension electrolytes with Li2O particles in either N5 or N7 were first dropped onto Cu-foil and a Celgard 3501 separator was placed on top of the suspension. Another Celgard 3501 separator was used and DOL with 2 M LiTFSI was added. To create solid-state Li2O / poly(DOL) hybrid electrolytes, 1 mM of the Lewis Acid initiator, Al(OTf)3, was introduced to the top layer of DOL electrolyte. Poly(DOL) utilized throughout this study was polymerized by 2 M LiTFSI and 1 mM Al(OTf)3. By varying the concentration of Li2O from 10 to 50 vol.%, hybrid poly(DOL) electrolytes with a range of physical and electrochemical properties were facilely created. The hybrid electrolyte on Cu-foil was paired with Nickel cobalt manganese oxide (NCM811) cathode obtained from NEI Corporation, and coin 2302- type cells were assembled. All cells were rested for 10 hours before any electrochemical testing as polymerization concludes over time, outlined by previous kinetics studies.

[0122] Material characterizations. FTIR spectra were characterized using a Thermo Scientific spectrometer in the attenuated total reflection (ATR) mode. The porous morphology of Celgard separators was imaged by field emission Zeiss Gemini 500 scanning electron microscope (SEM). DC conductivity measurement was carried out using Novocontrol broadband dielectric / impedance spectrometer in the same coin 2032 cells without electrodes and Teflon ring instead of separators. Oscillatory shear measurements were performed using strain-controlled ARES-LS rheometer (Rheometric Scientific) with a cone and plate geometry (10 mm, 4° cone angle and 25mm, 1° cone angle). Thermogravimetric analysis (TGA) was conducted using TA Instruments Q500 under nitrogen atmosphere at 10°C / min ramping rate. TA Instruments Differential Scanning Calorimetry (DSC) Auto 2500 was utilized to evaluate thermal transitions under nitrogen flow at 10°C / min ramping rate. XRD tests were conducted on a Bruker D8 Discover powder diffractometer using Cu Ka radiation of approximate wavelength = 1 .54 . X-ray photoelectron spectroscopy (XPS) was performed using Thermo Scientific Nexsa G2 X-Ray Photoelectron Spectrometer, with operating pressure of approximately 10'10Torr, monochromatic Al Ka x-rays at 1486.6 eV, with 400 pm diameter analysis spot. A flood gun was used for charge neutralization of non-conductive samples; all samples were charge corrected using adventitious carbon binding energy (284.8 eV). Raman spectra were collected using a WITec-Alpha 300R confocal Raman microscope. A 532 nm green laser was used, a grating of 1200 1 / mm (± 1 cm1), 15 accumulations, and 30 s integration time. Particle size analysis was done by Anton Paar particle size analyzer (PSA 1190) utilizing laser diffraction in liquiddispersion of Li20 / D0L with concentration of ~ 5 vol.%. Stirring and sonication were done within the first minute of measurement and stopped to measure particle size over time every minute for 15 minutes.

[0123] Electrochemical testing. Galvanostatic stripping / plating tests were performed using Neware CT-3008 battery tester at room temperature. Electrochemical impedance spectroscopy (EIS) measurements were performed by Solartron Frequency Response Analyzer (Model 1252) with frequencies ranging from 50kHz to lOmHz and at an amplitude of 10 mV. Cyclic voltammetry (CV) was performed on BioLogic SP-200 potentiostat.EXAMPLE 2

[0124] This example provides, inter alia, a description of methods of making polymer- particle gradient electrolytes and polymer-gradient electrolytes of the present disclosure, and uses thereof.

[0125] The data described in this Example was obtained using polymer-particle gradient electrolytes of present disclosure, which were made as described in EXAMPLE 1.

[0126] Effects of particle volume fraction. Viable particle concentration can be from (p = 10 - 40 vol.%, as conduction mechanism starts to deviate from the ideal Maxwell prediction past 40 vol.% (FIG. 21). However, it should be noted that the Coulombic efficiency (CE) of electrochemical cells saturates after only 20 vol.% of particle content (FIG. 22).

[0127] Effects of initiator concentration. Initiator Al(OTf)3 concentration can determine the molecular weight of the resulting poly(l,3-dioxolane) polymer. The addition of 10 times higher Al(OTf)3 concentration actually results in 10 times lower ionic conductivity value, as seen in FIG. 23, comparing 1 mM and 10 mM Al(OTf)3. Taking into account physicochemical properties at different molecular weights and ionic conductivity, about 0.5 to about 1.0 mM is in certain cases considered a desirable initiator content.

[0128] Although the present disclosure has been described with respect to one or more particular embodiments and / or examples, it will be understood that other embodiments and / or examples of the present disclosure may be made without departing from the scope of the present disclosure.

Claims

CLAIMS:

1. A method of forming a polymer-particle gradient electrolyte comprising: providing a precursor mixture comprising: one or more monomer(s), one or more Lewis Acid(s), a plurality of metal oxide particles, and optionally, one or more crosslinker(s), and optionally, one or more additive salt(s), wherein the precursor mixture is disposed between a first substrate and a second substrate; and allowing the mixture to form a gradient of the metal oxide particles from a first surface of the first substrate disposed substantially opposite to the second substrate to a first surface of the second substrate disposed substantially opposite to the first substrate, wherein at least a portion of the monomer(s) polymerize forming the polymer-particle gradient electrolyte.

2. The method according to claim 1, wherein the monomer(s) is / are cyclic ether monomer(s).

3. The method of claim 2, wherein the cyclic ether monomer(s) is / are chosen from 1,3- dioxolane (DOL), 1,3-dioxepane, 1,3, 7 -tri oxocane (TOC), and 1,3 -benzodi oxole, 1,2- epoxybutane, glycidyl octafluoropentyl ether, 4 -fluoro- 1,3 -di oxolane, and 2-fluoro-l,3- dioxolane, structural analogs thereof, and any combination thereof.

4. The method of claim 1, wherein, after polymerization, the monomer(s) is / are present at about 10 wt.% to about 80 wt.% relative to the total weight of the polymer(s).

5. The method of claim 1, wherein in Lewis Acid(s) is / are chosen from aluminum salts, chloride salts, structural analogs thereof, and any combination thereof.

6. The method of claim 1, wherein the Lewis Acid(s) is / are is / are present at about 0.2 mM to about 5.0 mM based on the total volume of the precursor mixture.

7. The method of claim 1, wherein in metal oxide particles is / are chosen from lithium oxide particles, sodium oxide particles, zinc oxide particles, aluminum oxide particles, structural analogs thereof, and any combination thereof.

8. The method of claim 1, wherein the metal oxide particles comprise a size of about 100 nm to about 10 micron(s).

9. The method of claim 1, wherein the metal oxide particles is / are is / are present at about 10 volume percent (vol. %) to about 40 vol. % based on the total volume of the precursor mixture.

10. A precursor device comprising: a precursor mixture comprising: one or more monomer(s), one or more Lewis Acid(s),= a plurality of metal oxide particles, optionally, one or more crosslinker(s), and optionally, one or more additive salt(s), wherein the precursor mixture is disposed between a cathode material, a cathode, and an anode material, an anode, or an anode current collector.

11. The precursor device of claim 10, wherein the precursor device is configured to (after formation and polymerization of at least a portion of the monomer(s)) function as an electrochemical device.

12. The precursor device of claim 10, wherein the electrochemical device is a battery, a supercapacitor, a fuel cell, an electrolyzer, or an electrolytic cell.

13. The precursor device of claim 12, wherein the battery is a primary battery or a secondary battery.

14. The precursor device of claim 12, wherein the battery is a solid-state battery.

15. A polymer-particle gradient electrolyte comprising:one or more polymeric material(s); and a plurality of metal oxide particles, wherein the plurality of metal oxide particles is disposed in the polymeric material(s) and form a gradient.

16. The polymer-particle gradient electrolyte of claim 15, wherein the gradient comprises a linear gradient or a non-linear gradient along an axis of the polymer-particle gradient electrolyte perpendicular to a first surface of the polymer-particle gradient electrolyte.

17. The polymer-particle gradient electrolyte of claim 15, further comprising a polymer gradient along an axis of the polymer-particle gradient electrolyte perpendicular to a first surface of the polymer-particle gradient electrolyte.

18. The polymer-particle gradient electrolyte of claim 15, further comprising a metal-oxide particle-rich phase proximate to a first surface of the polymer-particle gradient electrolyte and / or a polymer-rich phase proximate to a second surface of the polymer-particle gradient electrolyte, wherein the second surface is disposed substantially opposite to the first surface.

19. A device comprising one or more polymer-particle gradient electrolyte(s) of claim 15.

20. The device of claim 19, wherein the device is an electrochemical device.

21. The device of claim 19, wherein the electrochemical device is a battery, a supercapacitor, a fuel cell, an electrolyzer, or an electrolytic cell.

22. The device of claim 21, wherein the battery is a primary battery or secondary battery.

23. The device of claim 21, wherein the battery is a solid-state battery.

24. The device of claim 21, wherein the battery is an ion-conducing battery.

25. The device of claim 24, wherein the ion conducting battery is a lithium-ion conducting battery, a potassium-ion conducting battery, a sodium-ion conducting battery, a calcium-ionconducting battery, a magnesium-ion conducting battery, a zinc-ion conducting battery, an aluminum-ion conducting battery, or an iron-ion conducting battery.

26. The device of claim 21, wherein the battery further comprises: a cathode; optionally, an anode; optionally, an anode current collector; optionally, a cathode current collector; and optionally, a separator, wherein the polymer-particle gradient electrolyte(s), and, if present, the separator, is / are disposed between the cathode and anode.

27. The device of claim 21, wherein the device is a lithium-ion conducting battery and / or the polymer-particle gradient electrolyte(s) is / are a lithium-ion conductor or lithium-ion conductors.

28. The device of claim 26, wherein the cathode comprises a material chosen from lithium nickel manganese cobalt oxides, LiCoCh, LiNio.5Coo.2Mno.3O2, lithium manganese oxides (LMOs), lithium iron phosphates (LFPs), LiMnP04, LiCoPO4, and Li2MMn30s, wherein M is chosen from Fe, Co, and combinations thereof, and combinations thereof and / or the anode comprises a material chosen from lithium metal, lithium carbide, LieC, lithium titanates (LTOs), and combinations thereof.

27. The device of claim 21, wherein the device is a sodium-ion conducting solid-state battery and / or the polymer-particle gradient electrolyte(s) is / are a sodium ion conductor(s).

29. The device of claim 26, wherein cathode comprises a material chosen from Na2V20s, P2- Na2 / 3Fei / 2Mni / 2O2, Na3V2(PO4)3, NaMni / sComNii / sPCU, Na2 / 3Fei / 2Mni / 2O2@graphene composites, conversion-type cathode materials and / or the anode comprises a material chosen from sodium metal, Na2CsH4O4, Nao.66Lio.22Tio.78O2, and combinations thereof.

30. The device of claim 26, wherein the cathode and / or anode further comprises a conducting carbon material.

31. The device of claim 26, wherein the cathode comprises a conversion type material chosen from sulfur, sulfur composite materials, polysulfide materials, air, iodine, and metal sulfides.

32. The device of claim 26, wherein the anode comprises a material chosen from silicon- containing materials, tin and alloys thereof, tin / carbon, and phosphorus.

33. The device of claim 19, wherein the device further comprises one or more other electrolyte(s).

34. The device of claim 33, wherein the other electrolyte(s) is / are chosen from liquid electrolytes, solid electrolytes, and any combination thereof.

35. The device of claim 35, wherein the anode current collector and / or cathode current collector is / are a conducting metal or a metal alloy.

36. The device of claim 26, wherein the polymer-particle gradient electrolyte(s), the cathode, the anode, if present, the separator(s), if present, the other electrolyte(s), if present, the current collector(s), if present, form a cell, and the battery comprises a plurality of the cells and each adjacent pair of the cells is separated by a bipolar plate.

37. The device of claim 19, wherein the device exhibits one or more or all of the following:1) voltage stability of greater than about 4 Volts;2) flat metal (Li or Na) deposition on anode side for greater than about 100 cycles;3) cycle life of greater than about 100 cycles;4) Coulombic efficiency of greater than about 98%;5) interfacial resistance of less than about 1000 (1 cm2;6) room-temperature ionic conductivity of greater than about 1 mS / cm;7) elastic modulus of greater than about 100 Pascals (Pa); or8) degradation temperature of greater than about 100°C.

38. An anode-free electrochemical device comprising one or more polymer-particle gradient electrolyte(s) of claim 15, a cathode; a first current connector, optionally a second current connector, and optionally a separator; wherein the one or more polymer-particle gradientelectrolyte(s) and optionally the separator is / are placed between the cathode and the first current connector, wherein the one or more polymer-particle gradient electrolyte(s) comprise one or more types of metal oxide particles having a gradient concentration from a first concentration to a second concentration along an axis, wherein the first concentration is larger than the second concentration.

39. The anode-free electrochemical device of claim 38, wherein the first concentration is about 1.2 to about 10 times of the second concentration.

40. The anode-free electrochemical device of claim 38, wherein the polymer-particle gradient electrolyte has a first concentration in about 10 vol. % to about 95 vol. % at a first portion of the electrolyte and a second concentration in about 1 vol.% to about 40 vol.% at a second portion of the electrolyte along an axis.

Images