WO2023278996A1 - Gel polymer electrolyte composition and applications thereof - Google Patents

Abstract

The disclosure relates to a gel polymer electrolyte (GPE) for use with an electrochemical cell, e.g., a lithium ion battery. The GPE comprises a polymer matrix containing a sulfonated block copolymer and water in salt electrolyte (WiSE). The GPE is characterized as being stable in an electrochemical cell environment, with enhanced ionic conductivity and ionic barrier properties. the WiSE is a metal salt having a salt concentration above saturation point. The polymer matrix is characterized as having an ion exchange capacity (IEC) of at least 0.5 meg/g.

Description

Gel Polymer Electrolyte Composition and Applications Thereof

RELATED APPLICATIONS

[001] This application claims the benefit of priority to U.S. Provisional Patent Application No. 63/215,779 titled “GEL POLYMER ELECTROLYTE COMPOSITION AND APPLICATIONS THEREOF” and filed on June 28, 2021, the entire contents of which is incorporated by reference herein.

FIELD

[002] The disclosure relates to electrolytes for use in electrochemical cells, e.g., a lithium ion battery (LIB), comprising a sulfonated block copolymer and a water-in-salt electrolyte (“WiSE”).

BACKGROUND

[003] Metal-ion and metal-air batteries have been designed to meet increased energy supply requirements for various applications, including, but not limited to, cell phones, computers, tablets, power tools, transportation, energy storage and others. Li-ion batteries containing a liquid electrolyte solution are commonly used for smartphones and power tools. Some may undergo swelling caused by a temperature change or leakage upon exposure to an external force. The electrochemical stability window of water-based electrolytes is usually narrow due to water splitting at >1.23 V, thereby limiting their energy and power density.

[004] Solid-state batteries based on solid electrolytes with high energy and power density were introduced as an option for next-generation batteries. Replacement of liquid electrolytes with solid-state electrolytes affords an opportunity to improve upon the performance and stability (hence, safety) of Li-ion batteries. However, poor interfacial contact or low ionic conductivity at near ambient temperature in the absence of liquid components severely handicaps the electrochemical performance of solid-state batteries.

[005] There still exists a need for Li-ion batteries with improved interfacial contact and enhanced ion-transport properties, e.g., improved energy densities. This disclosure relates to a quasi-solid-state electrolyte, with improved properties compared to liquid electrolytes and solid-state electrolytes.

SUMMARY

[006] In one aspect, the disclosure relates to a gel polymer electrolyte (GPE) composition. The GPE composition comprises, consists essentially of, or consists of, a water-in-salt electrolyte (WiSE) having a metal salt concentration above a saturation point, l and a polymer matrix. The polymer matrix comprises a sulfonated block copolymer having an ion exchange capacity (IEC) of 0.5 - 4.0 meg/g. The sulfonated block copolymer has a general configuration of: A-B-A, (A-B)_n(A), (A-B-A)_n, (A-B-A)_nX, (A-B)_nX, A-D-B, A-B- D, A-D-B-D-A, A-B-D-B-A, (A-D-B)_nA, (A-B-D)_nA (A-D-B)_nX, (A-B-D)_nX, or mixtures thereof, where each letter identifies a contiguous sequence (“block”) composed of a single polymeric species, as well as mixtures thereof. Here, n is an integer from 0 to 30, X is a coupling agent residue, and each block provides a different level of chemical resistance to sulfonation or other chemical functionalization that specifically introduces acidic groups. In embodiments with plurality of A, B and D blocks, the A block, the B block, and the D block can be the same or different. The A block is selected from polymerized (i) para-substituted styrene monomers, (ii) ethylene, (iii) alpha olefins of 3 to 18 carbon atoms; (iv) 1,3- cyclodiene monomers, (v) monomers of conjugated dienes having a vinyl content less than 35 mol percent prior to hydrogenation, (vi) acrylic esters, (vii) methacrylic esters, and (viii) mixtures thereof. The B and D blocks are selected from polymerized vinyl aromatic monomers, a hydrogenated polymer or copolymer of a conjugated diene selected from isoprene, 1,3-butadiene and mixtures thereof. Depending on the choice and arrangement of the blocks, either the B or D block is selectively sulfonated to contain from 10 - 100 mol % sulfonic acid or sulfonate salt functional groups based on the number of monomer units. A Li-ion battery that contains the GPE containing one or more of these acid- functionalized block copolymers can exhibit improved electrochemical stability, coulombic efficiency, cyclic stability, and capacity fading.

[007] In a second aspect, the metal salt is a lithium salt selected from the group consisting of lithium hexafluorophosphate (LiPFe), lithium perchlorate (LiCICL), lithium tetrafluoroborate (LiBF4), lithium hexafluoroarsenate (LiAsFO, lithium tetrach 1 o roal urn i n ate (LiAlCL), lithium trifluoromethanesulfonate (L1CF3SO3), lithium methide (LiC(S02CF3)3, lithiumtrifluoro methanesulfonate (LiTFS), and lithium bis(trifluoromethane sulfonyl) imide (LiN(CF3S02)2)·

[008] In yet another aspect, the film or membrane prepared from the sulfonated block copolymer can exhibit a variety of self-organized nanoscale structures such as an ion- contiguous matrix (typically indicative of an ordered spherical or cylindrical morphology), a layered (lamellar) morphology, or a poorly ordered morphology providing ion-contiguous channels.

DESCRIPTION [009] The following terms will have the following meanings:

[010] “At least one of [a group such as A, B, and C]” or “any of [a group such as A, B, and C]” means a single member from the group, more than one member from the group, or a combination of members from the group. For example, at least one of A, B, and C includes, for example, A only, B only, or C only, as well as A and B, A and C, B and C; or A, B, and C, or any other all combinations of A, B, and C.

[Oil] A list of embodiments presented as “A, B, or C” is to be interpreted as including the embodiments, A only, B only, C only, “A or B,” “A or C,” “B or C,” or “A, B, or C.”

[012] “Block” as used herein refers to a section of a polymer molecule that comprises a plurality of identical constitutional units (repeat or monomeric units) and possesses at least one constitutional or configurative feature that does not appear in the immediately adjacent sections (blocks). For example, block polymer having three blocks encompasses linear and star-shaped polymers having the general construction (A)_m(B)_n(C)_o, in which A, B and C represent different chemical species, and m, n, and o represent the number of repeating units in the individual blocks. (A)_m and (C)₀ are identified in this case as end / terminal blocks, and may have the same or a different monomer composition and/or molar mass (indicated as the number of monomer units m and o). (B),, is termed the middle block and differs in monomer composition from the end blocks (A)_m and (C)₀. Each of the blocks (A)_m, (B)_n, and (C)₀ may in turn consist of one or more homopolymers, random or block polymers, with random copolymers being preferred. The middle block may in turn consist of a plurality of blocks, producing block polymers having more than 3 blocks, such as pentablock copolymers. Star-shaped block copolymers are a special form of branched block copolymers where three or more chains of the general formula [(A)_m(B)_n]_p extend radially from a center (C), with (A)_m and (B)_n being as defined above, and p representing the number of chains, and the individual chains each able to be identical or different. These too may be used as block polymers in the present disclosure.

[013] “Conjugated diene” refers to an organic compound containing conjugated carbon-carbon double bonds and a total of 4 to 12 carbon atoms, such as 4 to 8 carbon atoms, which can be any of 1,3-butadiene and substituted butadienes, including, but not limited, to 1,3 cyclohexadiene, isoprene, 2, 3 -dimethyl- 1 ,3-butadiene, 1 -phenyl- 1,3- butadiene, 1,3-pentadiene, 3-butyl- 1,3-octadiene, chioroprene, and piperylene, or any combination thereof. In embodiments, the conjugated diene block comprises a mixture of butadiene and isoprene monomers. In embodiments, 1,3-butadiene alone is used. [014] “Butadiene” refers to 1,3 -butadiene.

[015] “Monovinyl arene,” or “monoalkenyl arene,” or “vinyl aromatic” refers to an organic compound containing a single carbon-carbon double bond, at least one aromatic moiety, and a total of 8 to 18 carbon atoms, such as 8 to 12 carbon atoms. Examples include any of styrene, o-methyl styrene, p-methyl styrene, p-tert- butyl styrene, 2,4-dimethyl styrene, «-methyl styrene, vinylnaphthalene, vinyltoluene, vinylxylene, or mixtures hereof. In embodiments, the monoalkenyl arene block comprises a substantially pure monoalkenyl arene monomer. In some embodiment, styrene is the major component with minor proportions (less than 10 wt. %) of structurally related vinyl aromatic monomers such as o- methylstyrene, p-m ethyl styrene, p-tert- butyl styrene, 2,4- dimethyl styrene, a- methylstyrene, vinylnaphtalene, vinyltoluene, vinylxylene or combinations thereof. In embodiments, styrene alone is used.

[016] “Vinyl content” refers to the content of a conjugated diene that is polymerized via 1,2-addition in the case of butadiene, or via 3,4-addition in case of isoprene, resulting in a monosubstituted olefin, or vinyl group, adjacent to the polymer backbone. Vinyl content can be measured by nuclear magnetic resonance spectrometry (NMR).

[017] “Coupling efficiency,” expressed as % CE, is calculated from the values of the wt. % of coupled polymer and the wt. % of uncoupled polymer. The wt. % values of coupled polymer and uncoupled polymer are determined from the output of a differential refractometer detector. The intensity of the signal at a specific elution volume is proportional to the amount of material of the molecular weight corresponding to a polystyrene standard detected at that elution volume. The area under the curve spanning the molecular weight range corresponding to coupled polymer is representative of the wt. % coupled polymer, and likewise for the uncoupled polymer. % CE is given by 100 times (wt. % of coupled polymer / wt. % of coupled polymer + wt. % of uncoupled polymer). Coupling efficiency can also be measured by calculating data from gel permeation chromatography (GPC), dividing the integrated areas below the GPC curve of all coupled polymers (including two-arm, three- arm, four arm, etc. copolymers) by the same of the integrated areas below the GPC curve of both coupled and uncoupled polymers.

[018] “Coupling Agent” or “X” refers to the coupling agents commonly used in the SBC art. Examples include, but are not limited to, silane coupling agents, polyvinyl compounds, polyvinyl arene, di- or multivinylarene compounds; di- or multiepoxides; di- or multiisocyanates; di- or multialkoxysilanes; di- or multiimines; di-or multialdehydes; di- or multiketones; alkoxytin compounds; di- or multihalides, such as silicon halides and halosilanes; mono-, di-, or multianhydrides; di- or multiesters.

[019] “Polystyrene content,” or PSC, of a block copolymer refers to the % weight of vinyl aromatic, e.g., polystyrene in the block copolymer, calculated by dividing the sum of molecular weight of all vinyl aromatic blocks by the total molecular weight of the block copolymer. The PSC can be determined using any suitable methodology such as proton NMR.

[020] “Molecular weight” or MW refers to the styrene equivalent molecular weight in kg/mol of a polymer block or a block copolymer. MW can be measured with GPC using polystyrene calibration standards, such as is done according to ASTM 5296-19. The GPC detector can be an ultraviolet or refractive index detector or a combination thereof. The chromatograph is calibrated using commercially available polystyrene molecular weight standards. The MW of polymers measured using GPC so calibrated are styrene equivalent molecular weights or apparent molecular weights. The MW expressed herein is measured at the peak of the GPC trace-and is commonly referred to as the styrene equivalent “peak molecular weight,” designated as M_p.

[021] “Predominant” when used in conjunction with a specified monomer means that the monomer can be used in substantially pure form or can be intentionally mixed with certain specific minor amounts of co-monomer (< 20 wt %) which may be structurally similar to or structurally different from the major monomer constituent of a block segment.

[022] “Electrochemical cell,” refers to a “rechargeable battery,” or “battery,” or a “battery cell,” and includes a positive electrode, a negative electrode, and an electrolyte between and in direct contact therewith which conducts ions (e.g., Na⁺, Mg⁺², Li⁺, and K⁺) but electrically insulates the positive and negative electrodes. In embodiments, a rechargeable battery may include multiple positive electrodes and/or multiple negative electrodes in one container.

[023] “Coin Cell,” coin cell battery or coin battery refers to a small single-cell battery shaped as a squat cylinder, typically 5 to 25 mm (0.197 to 0.984 in) in diameter and 1 to 6 mm (0.039 to 0.236 in) high — resembling a button. Stainless steel usually forms the bottom body and positive terminal of the cell. An insulated top cap is the negative terminal.

[024] “Positive electrode,” refers to the electrode in a secondary battery towards which positive ions, e.g., Li⁺, conduct, flow or move during discharge of the battery.

[025] “Negative electrode” or “anode,” referring to the electrode in a secondary battery from where positive ions, e.g., Li⁺, flow or move during discharge of the battery. [026] “Composite electrolyte” refers to a component of a battery having at least two components: a solid state electrolyte and a binder that bonds to or adheres to the electrolyte, or remains uniformly mixed with the electrolyte.

[027] “Composite electrolyte” comprises the block polymer membrane and the WiSE electrolyte, which may be used interchangeably with “separator.”

[028] “Solid-state electrolyte” refers to a solid material suitable for electrically isolating the negative and positive electrodes, while also providing a conductive pathway for ions such as lithium, sodium, etc.

[029] “Quasi-solid-state electrolyte” or QSSE, also referred to as a GPE, refers to a wide class of composite compounds consisting of a liquid electrolyte and a solid matrix - with the liquid electrolyte immobilized inside the solid matrix, comprised of a macromolecular or supramolecular nano-aggregated or networked system. In embodiments, the QSEE has a high ionic conductivity, e.g., > 1 mS/cm. Quasi-solid-state electrolytes possess long-term stability like solid electrolytes, as well as high ionic conductivity and excellent interfacial contact like liquid electrolytes.

[030] “Anolyte” is the electrolyte on the anode side of an electrochemical cell.

The anolyte can be mixed with, layered upon, or laminated to an anode material.

[031] “Nanobatteries” refers to fabricated batteries employing technology at the nanoscale, e.g., constituent species that measure less than 100 nanometers, or 10^"7 meters.

[032] “A cycle" refers to a single charge and discharge of a battery.

[033] “Gel” as used in context of Gel Polymer Electrolyte refers to a polymer network swollen in a solvent that contains mobile ions (e.g., Li+, Na+, Mg2+, etc.).

[034] “Li-ion battery” or “Li-ion batteries” as used herein refers to rechargeable battery or batteries in general, e.g., Na-ion batteries, Mg-ion batteries, etc., and not just limited to lithium-ion batteries.

[035] The disclosure relates to a GPE for use in electrochemical cells, e.g., lithium- ion batteries and beyond. The GEP comprises a water-in-salt electrolyte (“WiSE”) and a polymer matrix containing a sulfonated block copolymer (SBC), but other block copolymers with different acidic functionalization are also considered. The SBC has properties including high elasticity (lower hysteresis) characteristics to accommodate large volume expansion / contraction in batteries, along with good adhesion properties.

[036] Sulfonated Block Copolymer (SBC): In embodiments, the SBC is a selectively sulfonated negative-charged anionic block copolymer, wherein the “selectively sulfonated” definition includes sulfonic acid, as well as neutralized sulfonate derivatives, e.g., sulfonate salt functional groups. The sulfonated block copolymer in embodiments is as disclosed in Patent Publication Nos. US9861941, US8263713, US8445631, US8012539, US8377514, US8377515, US7737224, US8383735, US7919565, US8003733, US8058353, US7981970, US8329827, US8084546, and US8383735, the relevant portions are incorporated herein by reference.

[037] In embodiments, the sulfonated block polymer has a general configuration of: A-B-A, (A-B)_n(A), (A-B-A)_n, (A-B-A)_nX, (A-B)_nX, A-D-B, A-B-D, A-D-B-D-A, A-B- D-B-A, (A-D-B)_nA, (A-B-D)_nA (A-D-B)_nX, (A-B-D)_nX, or mixtures thereof. Here, n is an integer from 0 to 30 or 2 to 20 in embodiments; and X is a coupling agent residue. At least one block is susceptible to sulfonation or other functionalization that introduces an acid group for improved hydrophilicity. For configurations with multiple A, B or D blocks, the plurality of A blocks, B blocks, or D blocks can be the same or different.

[038] In embodiments, the A blocks are one or more segments selected from polymerized (i) para-substituted styrene monomers, (ii) ethylene, (iii) alpha olefins of 3 to 18 carbon atoms; (iv) 1,3 -cyclodiene monomers, (v) monomers of conjugated dienes having a vinyl content less than 35 mol percent prior to hydrogenation, (vi) acrylic esters, (vii) methacrylic esters, and (viii) mixtures thereof. If the A segments are polymers of 1,3- cyclodiene or conjugated dienes, the segments will be hydrogenated subsequent to polymerization of the block copolymer and before sulfonation of the block copolymer. The A blocks may also contain up to 15 mol % of the vinyl aromatic monomers such as those present in the B blocks.

[039] In embodiments, the A block is selected from para-substituted styrene monomers selected from para-methylstyrene, para-ethylstyrene, para-n-propylstyrene, para- iso-propylstyrene, para-n-butylstyrene, para-.vcc-hutylstyrene, para-Ao-butylstyrene, para-r- butylstyrene, isomers of para-decylstyrene, isomers of para-dodecylstyrene and mixtures of the above monomers. Examples of para-substituted styrene monomers include para -t- butylstyrene and para-methylstyrene, with para-i-butylstyrene being most preferred. Monomers may be mixtures of monomers, depending on the particular source. In embodiments, the overall purity of the para-substituted styrene monomers be at least 90%- wt., or > 95%-wt, or > 98%-wt. of the para-substituted styrene monomer.

[040] In embodiments, the block B comprises segments of one or more polymerized vinyl aromatic monomers selected from unsubstituted styrene monomer, ortho- substituted styrene monomers, meta-substituted styrene monomers, et-methylstyrene monomer, 1,1-diphenylethylene monomer, 1,2-diphenylethylene monomer, and mixtures thereof. In addition to the monomers and polymers noted, the B blocks may also comprise a hydrogenated copolymer of such monomer (s) with a conjugated diene selected from 1,3- butadiene, isoprene and mixtures thereof, having a vinyl content of between 20 and 80 mol percent. These copolymers with hydrogenated dienes may be random copolymers, tapered (or gradient) copolymers, block copolymers or controlled distribution copolymers.

[041] The D block comprises a hydrogenated polymer or copolymer of a conjugated diene selected from isoprene, 1,3-butadiene and mixtures thereof. In other examples, the D block is an acrylate or silicone polymer with a number- average molecular weight of at least 1000. In still another example, the D block is a polymer of isobutylene having a number average molecular weight of at least 1000.

[042] In embodiments, the block B is selectively sulfonated, containing from about 10 to about 100 mol % sulfonic acid or sulfonate salt functional groups based on the number of monomer units. In embodiments, the degree of sulfonation in the B block ranges from 10 to 95 mol%, or 15 - 80 mol%, or 20 - 70 mol%, or 25 - 60 mol%, or > 20 mol%, or > 50 mol%.

[043] The coupling agent X is selected from coupling agents known in the art, including polyalkenyl coupling agents, dihaloalkanes, silicon halides, siloxanes, multifunctional epoxides, silica compounds, esters of monohydric alcohols with carboxylic acids, (e.g., methylbenzoate and dimethyl adipate) and epoxidized oils.

[044] Membranes or films comprising, consisting essentially of, or consisting of the SBC are characterized as selectively permeable with ion exchange capacity (IEC) properties, and excellent moisture vapor transport rates (MVTR) characteristics. The membrane / film also undergoes considerable swelling when it absorbs water, e.g., at least 100% at ambient temperature, or > 150%, or > 400%, or > 500%, or > 700%, or < 800%, or < 1000%, or < 1200%, or 100 - 3000%, or 200 - 2500% at elevated temperatures.

[045] In embodiments, the SBC has an IEC of > 0.5 meq/g, or > 0.75 meq/g, or > 1 meq/g, or > 1.25 meq/g, or > 2.2 meq/g, or > 2.5 meq/g, or > 4.0 meq/g, or < 4.0 meq/g, or 1.5 - 3.5 meq/g. In embodiments, the lower ion exchange capacity membrane (1.0 meq/g) is considered more stable than the higher ion exchange capacity membranes (1.5 and 2.0 meq/g).

[046] In embodiments, the membrane/film composed of the SBC is characterized to have sufficient thickness for fabricating nanostructured materials to use in GPE compositions, e.g., at least 0.1 pm, or 0.25 pm, or 0.75 pm, or > 1 pm, or > 5 pm, or > 10 pm, or < 500 pm, or < 200 pm, or < 900 pm, or <1000 pm.

[047] In embodiments, a film / membrane comprising the SBC in the dry state has a tensile at break of at least 200 psi, or > 1,000 psi, or >1,500 psi, or at least 4000 psi (average); and an elongation at break of at least 40%, or > 100%, or > 200%, or > 250%.

The film / membrane comprising the SBC has a water vapor transport value > 1,000 g /m² , or > 1100 g /m², or > 1200 g /m², or > 1400 g /m² , or > 1500 g /m² , or < 1700 g /m², or < 3000 g /m², or < 2500 g /m² per day, using a gravimetric inverted cup method based on ASTM E 96/E 96M-05 at 25° C. and 50% relative humidity. The film has a wet tensile strength of > 100 psi, or > 500 psi, or > 1000 psi, or > 1500 psi, according to ASTM D412, and a swellability of greater than 100% by weight.

[048] In embodiments, the amount of SBC polymer is in the range of 0.1 to 20 wt.%, or 0.5 - 15 wt.%, or 1 - 20 wt.%, or > 2 wt. %, or > 3 wt. %, or < 15 wt. %, based on the total weight of the GEP.

[049] Optionally Modified SBC. In embodiments, the SBC having a configuration selected from the group consisting of A-B-A, (A-B)_n(A), (A-B-A)_n, (A-B-A)_nX, (A-B)_nX, and combinations thereof, is optionally doped or grafted with a chemical dopant to increase the conductivity property, e.g., increasing the local concentration of ions present in the conducting domain of the polymer. In embodiments, the chemical dopant comprises an ionic liquid, e.g., heterocyclic diazole-based ionic liquid, ionic liquid comprising imidazole- type cations, alkyl-substituted imidazolium, pyridinium, pyrrolidinum cation, or combinations thereof. The amount of polymerized ionic liquid block(s) in embodiments ranges from 2 to 80 mol%, or 5 to 70 mol %, or 7 to 65 mol %, or > 10 mol %, or > 12 mol%, or 15 - 55 mol%, or 20 - 45 mol% of the total SBC.

[050] Alternatively or additionally in embodiments, the SBC is modified with non- conductive fillers in an amount of up to 15 wt.%. In embodiments, the non-conductive fdler comprises inorganic or polymeric particles or fibers varying in thickness, or mixtures thereof. The particles have a mass median diameter (D50) of -100 microns or less, and are selected from the group consisting of flakes, platelets, leaf-like particles, rods, tubes, fibers, needles, and dendritic particles.

[051] Water- in-Salt Electrolyte (“WiSE”): WiSE refers to a highly concentrated electrolyte in which the salt concentration is above the saturation point. In embodiments, WiSE and its many variations can form an ad hoc solid-electrolyte-interphase (SEI) on the anode during the initial charging, offering an electrochemical stability window, high voltages and high energy densities.

[052] The WiSE component is a metal salt, e.g., Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, Sc, Al, Mn, Ce, Cr, or any combination thereof, etc., depending on the application. In embodiments, the WiSE is a sulfone-based salt with a Li cation.

[053] The WiSE component can be a hybrid WiSE having at least two different metal salts, either by type or concentration, for a wide electrochemical potential window, leading to high energy density. In this case, the WiSE comprises a first salt and a second salt with the volume concentration ratio of the first salt to the second salt ranges from 10:90 to 90:10. Each of the first and second salts has a cation and an anion, respectively. The cation of the first salt may be Li⁺, Na⁺, or K⁺, whereas the anion of the first salt may be chloride (CE), sulfate (SCU ^2_, phosphate (PCU ^3_) or nitrate (NO3 ^”). Each of the first salt and the second salt may have the same or different cation(s).

[054] In embodiments, the WiSE is a sodium metal salt, selected from a sodium transition metal based oxide of formula (I): Na_xM_yO_w (I) where M is a transition metal ion or a combination of multivalent ions comprising at least one transition metal ion; 0 < x < 1; 0 < y < 1; w >2; or a sodium metal salt of formula Na_xM_y(X0₄)vF_z (II), wherein M is a transition metal ion or a combination of multivalent ions comprising at least one transition metal; X is S or P; 0 < x < 3; 0 < y < 2; 1 < v < 3; 0 < z < 3. In embodiments, WiSE is a salt selected from NaSbF₆, NaAsF₆, NaBF4, NaCKE, NaPF₆ and a mixture thereof, dissolved in an organic solvent or in an ionic liquid.

[055] In embodiments, the WiSE is a lithium salt, as Li ions are well hydrated in primary solvation sheath with adequate free water. For example, with the use of lithium bis(trifluoromethane sulfonyl)imide (LiTFSI), when LiTFSI concentrations reaches 21 m, there are only 2.6 H2O molecules per lithium ion, in which the electrostatic field cannot be neutralized anymore and the cation solvation sheath structure changes. In embodiments, the WiSE is a lithium salt, selected from the group consisting of lithium hexafluorophosphate (LiPFe), lithium perchlorate (LiCICE), lithium tetrafluoroborate (LiBF4), lithium hexafluoroarsenate (LiAsFrd, lithium tetrachloroaluminate (LiAlCU), lithium trifluoromethanesulfonate (LiCFaSOa), lithium methide (LiCXSChCFa) 3, lithium bis(trifluoromethane sulfonyl) imide, (LiNCCFaSCh) 2).bis(trifluoromethanesulfonyl)imide (LiTFSI), and lithium bis(pentafluoroethanesulfonyl)imide (LiBETI). In embodiments, the WiSE is selected from LiN(S0₂CF3)2 (LiTFSI), LiN(S0₂CHa)2, LiN(S0₂C4H₉)2, LiN(S02C₂F₅)2 (LiBETI), LiN(S02C₄F₉)2, LiN(S02F3)(S0₂C4F₉), FiN(S02C₂F₅)(S0₂C4F₉), FiN(S02C₂F₄S02), FiN(S0₂F)₂ (FiFSI), or FiN(S0₂F)(S0₂CF3) (LiFTI).

[056] In embodiments, the WiSE is a zinc salt, e.g., a zinc halide, having a formula [Zhc₂] > 10 m where X is Cl, F, Br, I, or any combination thereof. In embodiments, the WiSE is a mix of a high concentrations Fi-based salt, e.g., FiTFSI (>5 mol/F, or > 10 mol/F, or 5-24 mol/F) with soluble zinc salt for a stable mixed ionic electrolyte. The soluble zinc salt is one or more of zinc sulfate, zinc nitrate, zinc acetate and zinc chloride, and the concentration of the zinc salt is 0.05-3 mol/F.

[057] In embodiments, the WiSE is selected from the group of AgS0₃CF₃, NaSCN, NaS0₃CF₃, KTFSI, NaTFSI, Ba(TFSI)₂, Pb(TFSI)₂, and Ca(TFSI)₂.

[058] In embodiments, the WiSE is used in a sufficient amount for the film / membrane containing the SBC to swell, providing a flexible GEP with wide working voltage. In embodiments, the WiSE has a water to metal ion molar ratio of < 5.5, or < 10, or a metal ion to water molar ratio of > 0.1, or 0.1 to 0.2, or > 0.25, or > 0.27, or > 0.3, or > 0.36, or < 0.5.

[059] Methods for Making the Gel Polymer Electrolyte: The GPE can be made by first dissolving the SBC in at least one solvent, followed by the addition of the WiSE. In embodiments, after the SBC is dissolved in a solvent, the solvent is removed generating a membrane / film. The membrane / film is then soaked with the WiSE, forming the GPE.

[060] Suitable solvents for use with the SBC include but are not limited to aliphatic hydrocarbons like cyclohexane, in aromatic hydrocarbons like toluene, or tetrahydrofuran (THF) or alcohols like methanol, ethanol, propanol, benzyl alcohol, isopropyl alcohol and the like, in various carbonyl solvents like methylethylketone, acetone, etc., or in a nitrogen containing solvents like N-methyl pyrolidone, N,N-dimethyl acetamide, pyridine, etc. In embodiments, mixtures of solvents can be used as long as homogeneous solutions or stable suspensions in the presence of the sulfonated polymer can be made.

[061] The SBC in solvent can be cast forming a film or membrane, or the SBC in solvent dispersion / solution can be spray-coated onto a substrate, to be subsequently soaked in a WiSE. The size and thickness of the film obtained in the casting method is optimized based on the capability, shape, size, and the battery. In embodiments, the SBC film has a thickness ranging from 10 to 300 pm, or 1-1000 pm, or > 50 pm, or 200 - 500 pm, or < 1000 pm. In some examples, the films are extruded in layers or deposited or laminated onto other composite electrolytes to build up several layers of a composite electrolyte, or a collector it substrate. In embodiment, the SBC is deposited onto a substrate, e.g., a mold of fluorinated ethylene propylene coated aluminum sheets.

[062] The solvent can be removed from the SBC film / membrane, or the spray- coated substrate by any of air-drying, evaporation, thermal heating, microwave exposure, or infrared wavelengths. In embodiments, the morphology of the as-cast SBC film / membrane can be controllably altered by solvent-vapor annealing in the vapor of a suitable solvent (e.g., THF) for a sufficient amount of time, e.g., > 12 hrs., or > 18 hrs., or > 24 hrs., or < 48 hrs. at ambient temperature (or below or above, as desired). The morphology of the as-cast SBC film / membrane can also be altered upon immersion in a polar liquid such as water for a sufficient amount of time, e.g., > 12 hrs., or > 18 hrs, or > 24 hrs., or < 48 hrs. at ambient temperature (or below or above, as desired).

[063] The film / membrane, or the substrate coated with the SBC, is next soaked in a WiSE for a sufficient amount of time, e.g., > 2 hrs. > 4 hrs., > 12 hrs., 16-24 hrs., or < 48 hrs. The soaking can include immersion in a bath of WiSE, or spray-coating, spin coating, applying via a Langmuir-Blodgett (LB) process onto the film / membrane / substrate for a coating with WiSE.

[064] Applications of the Gel Polymer Electrolyte: The gel electrolyte containing SBC is suitable for use in batteries, e.g., Li-ion, Na-ion, or Mg-ion batteries, Li-sulfur batteries, whether Si-based or C-based, etc. The gel electrolyte behaving as a quasi-solid- state electrolyte can be used to physically separate the positive and negative electrodes, avoiding the likelihood of a short circuit.

[065] In embodiments, the GPE is used in dual electrolyte systems in combination with other electrolytes, e.g., one part is liquid and the other part is the GPE, or a dual system with one part solid, and the other part is the GPE, or it can be split for use as a catholyte and an anolyte.

[066] Properties: Due to the structure of the SBC, when soaked with WiSE, the sulfonated midblock is selectively swollen, providing nanoscale channels, through which ions can diffuse, while maintaining structural integrity due to the thermoplastic elastomeric network, which is not possible with traditional polymer electrolytes. The morphology of the SBC, expressed in terms of the contiguity of the channels through which the ions flow, allows ion transport to occur with little resistance. In embodiments, a cylindrical morphology with a hydrophilic matrix or a lamellar morphology is generated from polar casting solvents such as THF. Nonpolar casting solvents or co-solvents yield discrete micelles embedded in a hydrophobic matrix. In embodiments, hydrothermal treatment causes the micelles along the diffusion direction to connect as water enters the membrane, eventually establishing hydrophilic pathways in a contiguous network, thereby improving ion transport.

[067] In embodiments, a battery employing the GPE has a Coulombic Efficiency (CE %) of > 95%, or > 98%, or > 99% over 1000 cycles for expanded voltage windows, e.g., > 2.0 V, > 2.5 V, or > 3V, or < 5V.

[068] In embodiments, a battery employing the GPE has a retention capacity of > 80%, or > 85%, or > 90%, or > 95%, or > 97%, or < 99.5%, after 1000 charge/discharge cycles at 1 A/g at room temperature with respect to the first cycle. The retention capacity of the Li-ion battery refers to a full charge or discharge capacity of a battery obtained after the battery is used for a certain period of time or left unused for a long period of time.

[069] In embodiments, a battery employing the GPE has specific charge capacity ranging from 50- 1000 mAh/g, or > 65 mAh/g, or > 75 mAh/g, or > 85 mAh/g, or > 100 mAh/g, or >120 mAh/g, or > 200 mAh/g, or 400 - 800 mAh/g.

[070] In embodiments, a battery employing the GPE in the presence of bulk M0S3 has a galvanostatic charge-discharge profiles that exhibit specific capacity from 50 - 200 mAh/g, or 150 - 158 mAh/g, or 153 - 157 mAh/g at a current density of 0.1 A/g, and good stability over 1000 cycle, cycling stability with a 30 - 100% capacity retention, or > 35%, or > 40%, or > 50%, or > 60 %, or < 95%, or < 100 % after 1000 cycles at 1 A/g.

[071] Examples: The following examples are intended to be non- limiting.

[072] In the examples, the SBC is a pentablock polymer membrane material from Kraton Corporation. These ionomers were prepared by midblock-selective sulfonation of a parent pentablock polymer with corresponding block weights of 15-10-28-10-15 kDa to different levels 26 and 52 mol% of the midblock. The SBC is designated as SBC-x, where x represents the degree of sulfonation (DOS, expressed in mol%) of the sulfonated-styrene midblock.

[073] Example 1: A number of films were prepared, by first dissolving the SBCs in either pure tetrahydrofuran (SBC- x -THF) or an 85/15 v/v toluene/isopropyl alcohol mixture (SBC- x -TIPA) to produce 2 wt% solutions. Solvent dielectric constants ( k ) were used to assess polarity differences among the casting solvents employed: KTHF = 7.43 and K_TIPA = 4.91. Films resulting from solution casting, followed by solvent evaporation, measured -110 pm thick and were further processing. If membranes are cast from 85/15 w/w toluene/isopropyl alcohol (TIPA), the original irregular morphology cannot be well- defined after water immersion, while for tetrahydrofuran (THF)-cast membranes, the morphology remains, for the most part, lamellar even after immersion in water.

[074] Some of the films were cast in Teflon molds, covered to limit the rate of solvent evaporation and left to dry for 48 hrs. Some of the resultant films were solvent- vapor annealed in THF for 24 hrs. and subsequently dried under vacuum for 2 hours at ambient temperature. After drying, the membrane was immersed in LiTFSl/FFO solutions varying in electrolyte concentration for 24 hrs.

[075] Example 2: The anodes were fabricated by uniformly mixing and compressing LiMniCL, carbon black and poly(tetrafluoroethylene) (PTFE) at a mass ratio of 8:1:1, and the cathodes combined M0S3, carbon black and PTFE at a mass ratio of 7:2:1.

[076] Example 3: The anode was prepared by dispersing 0.2 g of ammonium tetrathiomolybdate (NH4)2MoS4 in 200 ml of water. 1 mol/L HC1 was added drop-by-drop during stirring until the pH of the solution dropped below 3. The solution was then stirred for another 2 hrs. A Redox Reaction occured: MoS4^2~ + 2 H⁺ ® M0S3 + H2S

[077] A gas phase rich in ¾S was maintained to control the loss of sulfur. The obtained product was collected by centrifugation and then washed with deionized water. After freeze-drying, it was annealed under argon at 200 °C for 2 hrs.

[078] Example 4- Fabricating Coin Cell: A number of battery cells (coil cell type) are fabricated. The electrolyte was added to the separator by soaking the SBC membranes in 21 M LiTFSI/fFO for 24 hrs. The WiSE composed of 21 m LiTFSI dissolved in water (21 mol LiTFSI in 1 kg water) was used as the working electrolyte, added to the SBC membrane separator, which was soaked in WiSE solution for 24 hrs. The electrodes were fabricated by uniformly mixing and compressing LiMn20₄, carbon black and PTFE (weight ratio of 8 : 1 : 1) for cathodes and M0S3, carbon black and PTFE (weight ratio of 7:2:1) for anodes respectively. The mass ratio of cathode/anode materials was set to 2:1 and the mass loading of M0S3 was about 2 mg/cm².

[079] Example 5- Testing Coin Cells: Quasi-solid-state electrolyte of example-4 was subjected to electrochemical tests/measurements. In the tests, voltage and current data was recorded over time over a number of charge and discharge cycles. From these data, cell capacity, resistance, columbic efficiency, and other performance data were derived. The test data for electrochemical cells containing glass-fiber separator and SBC for comparison are included in Table 1 below. Cyclic voltammetry (CV) was conducted at scan rate of 1 mV/sec (Redox peak). [080] Table 1: Electrochemical analysis -WiSE-based LiMmCL/MoSs electrolyte /separator

[081] Example 6- Cyclic voltammetry (CV) Measurements: CV data measured at a scan rate of 1 mV/s display one broad but distinct redox peak couple of lithiation / delithiation after two initial cycles. In the initial cycles, the cathodic scan (i.e., battery charging) profile has a distinct peak at 1.8 V that disappears after the fifth cycle, implying an irreversible phase transformation of M0S3 during its lithiation during the initial cycles. The cathodic scan profile remains stable after 5 cycles, indicating the stabilization and reversibility of electrode materials after the initial transformation. In comparison, cells with glass-fiber separators indicate a similar irreversible peak but with a broader area inside the curve, confirming that cells constructed with sulfonated SBC possess a more capacitive-like behavior.

[082] Example 7- Chronopotentiometry Measurements: The measurements are conducted for the assembled coin cells with a VMP3 potentiometer. The cells were cycled between 0.7 and 2 V at a constant rate of 0.1 A/g for 10 cycles and thereafter cycled at 1 A/g for 1000 cycles to assess cycling stability

[083] Example 8 - Coulombic Efficiency: The Coulombic efficiency of SBC and glass-fiber were compared as a separator of the cell. The initial Coulombic efficiency of the cell was 90% for SBC (Nexar™) and 49% for glass-fiber. After 10 cycles, the Coulombic efficiency increases to 96% for SBC (Nexar™) and 82% glass-fiber cells. Efficiency stabilization rate is faster for cells containing SBC (Nexar™) than for glass-fiber separators. The completion of phase transformation and the formation of a stable and protective SEI is faster when SBC (Nexar™) is used as the separator, most likely due to improved Li-ion diffusion through the quasi-solid-state medium.

[084] Example 9: Specific Capacities of M0S3 are 156 mAh/g at 0.1 A/g and 82 mAh/g at 1 A/g for the first cycle for cells constructed with SBC. In comparison, cells constructed with glass-fiber separators reveal an initial specific capacity of 116 mAh/g at 0.1 A/g. C

[085] Example 10- Capacity Retention: The cells containing SBC achieve cycling stability with a 75% capacity retention after 1000 cycles at 1 A/g, corresponding to a capacity decay rate of 0.025% per cycle. In contrast, the cells containing a glass-fiber separator cycled at rates 10 times lower (0.1 A/g) indicate a 59% capacity retention in 1000 cycles, corresponding to a capacity decay of 0.041% per cycle

[086] Example 11 - Morphology: The morphology of the sulfonated block polymer was performed by small-angle X-ray scattering (SAXS). The morphology of the membranes (after immersion in water) is dependent on the casting solvent. If the membranes are cast from 85/15 w/w toluene/isopropyl alcohol (TIP A), the original spherical morphology is replaced by an irregular morphology after water immersion, while for tetrahydrofuran (THF)-cast membranes, the morphology remains, for the most part, lamellar even after immersion in water. After solvent-vapor annealing in THF, both morphologies evolve toward a single equilibrium (lamellar) morphology.

[087] The SAXS intensity profiles for SBC specimens are indicative of the lamellar morphology conducive to ion diffusion, providing a contiguous pathway for ion diffusion. In all electrolyte concentrations except the TIP A0 series, a lamellar morphology developed.

[088] The morphologies of the specimens are presented in Table 2, represented as (casting solvent) (solvent-vapor annealing time, in h) / (electrolyte concentration, in m). For example, TIPA24/21 refers to SBC casted from 85/15 w/w TIPA, subsequently subjected to solvent-vapor annealing in THF for 24 h and finally immersed in an aqueous 21 m FiTFSI solution for 24 h (the immersion time is held constant).

[089] Table 2 - SAXS profiles after immersion in different electrolyte for 24 h.

[090] As used herein, the term “comprising” means including elements or steps that are identified following that term, but any such elements or steps are not exhaustive, and an embodiment can include other elements or steps. As used herein, the term “comprising” means including elements or steps that are identified following that term, but any such elements or steps are not exhaustive, and an embodiment can include other elements or steps. Although the terms “comprising” and “including” have been used herein to describe various aspects, the terms “consisting essentially of’ and “consisting of’ can be used in place of “comprising” and “including” to provide for more specific aspects of the disclosure and are also disclosed.

Claims

1. A gel polymer electrolyte (GPE) composition comprising, a water-in-salt electrolyte (WiSE), wherein the WiSE is a metal salt having a salt concentration above saturation point; a polymer matrix comprising a sulfonated block copolymer having an ion exchange capacity (IEC) of at least 0.5 meg/g; wherein the sulfonated block copolymer has a general configuration of: A-B-A, (A-B)n(A), (A-B-A)n, (A-B-A)_nX, (A-B)nX, A-D-B, A-B-D, A- D-B-D-A, A-B-D-B-A, (A-D-B)_nA, (A-B-D)_nA (A-D-B)_nX, (A-B-D)_nX or mixtures thereof, wherein: n is an integer from 0 to 30,

X is a coupling agent residue, each A and D block is a polymer block resistant to sulfonation, each B block is susceptible to sulfonation, the A block is selected from polymerized (i) para-substituted styrene monomers, (ii) ethylene, (iii) alpha olefins of 3 to 18 carbon atoms; (iv) 1,3-cyclodiene monomers, (v) monomers of conjugated dienes having a vinyl content less than 35 mol percent prior to hydrogenation, (vi) acrylic esters, (vii) methacrylic esters, and (viii) mixtures thereof; the B block is a vinyl aromatic monomer, the D block is a hydrogenated polymer or copolymer of a conjugated diene selected from isoprene, 1,3-butadiene and mixtures thereof; wherein the block B is selectively sulfonated to contain from 10 - 100 mol % sulfonic acid or sulfonate salt functional groups based on the number of monomer units, wherein an electrochemical cell containing the gel polymer electrolyte (GPE) has a retention capacity of at least 70% after 1000 charge/discharge cycles at room temperature with respect to the first cycle.

2. The GPE composition of claim 1, wherein the sulfonated block copolymer has a general configuration of A-D-B-D-A, A-B-D-B-A, (A-D-B)nX, (A-B-D)nX, or mixtures thereof.

3. The GPE composition of claim 1, wherein the sulfonated block copolymer has a configuration A-D-B-D-A, wherein the A block is poly(para-tert-butylstyrene), the D block is hydrogenated polyisoprene, and prior to sulfonation, the B block is polystyrene.

4. The GPE composition of claim 1, wherein the sulfonated block copolymer has a general configuration of: A-B-A, (A-B)_n(A), (A-B-A)_n, (A-B-A)_nX, (A-B)_nX, or mixtures thereof, and wherein the sulfonated block copolymer is doped with an ionic liquid.

5. The GPE composition of claim 1, wherein the sulfonated block copolymer is doped with a non-conductive filler in an amount of up to 15 wt.% based on the total weight of the GPE composition.

6. The GPE composition of claim 1, wherein the sulfonated polymer has an ionic exchange capacity (IEC) of > 0.5 meq/g.

7. The GPE composition of claim 1, wherein the WiSE is a metal salt of an element chosen from the group consisting of Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, Sc, Al, Mn, Ce, Cr, and combinations thereof.

8. The GPE composition of any of claims 1-7, wherein the WiSE is a lithium salt, and wherein the lithium salt is chosen from the group consisting of lithium hexafluorophosphate (LiPFe), lithium perchlorate (LiC10₄), lithium tetrafluoroborate (LiBF4), lithium hexafluoroarsenate (LiAsFe), lithium tetrachloroaluminate (LiAlCL), lithium trifluoromethanesulfonate (LiCEACb), lithium methide (LiC(S0₂CF₃)₃, and lithium bis(trifluoromethane sulfonyl) imide (LiN(CF3S02)2), and mixtures thereof.

9. A method for preparing a gel polymer electrolyte, the method comprises: providing a water-in-salt electrolyte (WiSE), wherein the WiSE is a metal salt having a salt concentration above its saturation point; providing a polymer matrix comprising a sulfonated block copolymer having an ion exchange capacity (IEC) of at least 0.5 meg/g; and soaking of the polymer matrix in the WiSE; wherein the polymer matrix comprises a sulfonated block copolymer having an ion exchange capacity (IEC) of at least 0.5 meg/g; wherein the sulfonated block copolymer has a general configuration of: A-B-A, (A-B)n(A), (A-B-A)n, (A-B-A)_nX, (A-B)nX, A-D-B, A-B-D, A- D-B-D-A, A-B-D-B-A, (A-D-B)_nA, (A-B-D)_nA (A-D-B)_nX, (A-B-D)_nX or mixtures thereof, wherein: n is an integer from 0 to 30,

X is a coupling agent residue, each A and D block is a polymer block resistant to sulfonation, each B block is susceptible to sulfonation, the A block is selected from polymerized (i) para-substituted styrene monomers, (ii) ethylene, (iii) alpha olefins of 3 to 18 carbon atoms; (iv) 1,3-cyclodiene monomers, (v) monomers of conjugated dienes having a vinyl content less than 35 mol percent prior to hydrogenation, (vi) acrylic esters, (vii) methacrylic esters, and (viii) mixtures thereof; the B block is a vinyl aromatic monomer, the D block is a hydrogenated polymer or copolymer of a conjugated diene selected from isoprene, 1,3-butadiene and mixtures thereof; wherein the block B is selectively sulfonated to contain from 10 - 100 mol % sulfonic acid or sulfonate salt functional groups based on the number of monomer units.

10. The method of claim 9, wherein the polymer matrix is a film or a membrane having a thickness of 1-1000 pm.

11. The method of claim 9, wherein the polymer matrix has a lamellar or cylindrical morphology.

12. An electrochemical cell comprising the gel polymer electrolyte (GPE) of any of claims 1-7, wherein the electrochemical cell has a Coulombic Efficiency (CE %) of > 95%.

13. An electrochemical cell comprising the gel polymer electrolyte (GPE) of any of claims 1-7, wherein the electrochemical cell has a specific charge capacity of 50- 1000 mAh/g.

14. An electrochemical cell comprising the gel polymer electrolyte (GPE) of any of claims 1-7, wherein the electrochemical cell has a cycling stability with a 30 - 100% capacity retention after 1000 cycles at 1 A/g.

15. An electrochemical cell comprising the gel polymer electrolyte (GPE) of any of claims 1-7, wherein the polymer matrix is a film or a membrane having a thickness of 1- 1000 pm, and wherein the polymer matrix has a lamellar or cylindrical morphology.