Polymeric separator modified by polyacid modifying agent and solid-state batteries comprising same

Abstract

Disclosed is a polymer separator comprising a polymeric layer with two surfaces and a ceramic coating on at least one of the surfaces, wherein the ceramic coating is modified by a polyacid modifying agent. In some embodiments, the polymer separator improves the performance of a battery such as cycle life. In one embodiment, the polyacid modifying agent is a polyacid or a salt thereof. In some embodiments, the polyacid is a polymer including at least one acid group selected from the group consisting of carboxylic acid (-COOH), sulfonic acid (-SO3H), and phosphoric acid (-PO3H2).

Description

POLYMERIC SEPARATOR MODIFIED BY POLYACID MODIFYING AGENT ANDSOLID-STATE BATTERIES COMPRISING SAMECROSS-REFERENCE

[0001] The present application claims the benefit of US Serial No. 63 / 609,066, filed December 12, 2023, the entire content of which is incorporated herein by reference into this application.FIELD

[0002] This disclosure relates to a polymeric separator modified by a polyacid modifying agent and electrochemical device comprising the same.BACKGROUND

[0003] Conventional polymer separators are made of a polyolefin such as polyethylene and polypropylene and may be used in electrochemical devices such as lithium metal and / or lithium metal alloy batteries. To increase the thermal properties, a ceramic coating is usually added to the polyolefin separator. Such ceramic coating, however, exhibits a property and / or performance different from polyolefin, such as binding affinity and wetting behavior with electrolyte molecules during preparation and operation of electrochemical devices such as batteries. Lithium metal is promising as an anode material due to its high capacity, the formation and growth of lithium dendrite may penetrate separator and thus lead to short-circuit in the battery, causing shortened cycle life and / or potential safety issues. There remains a need for polymer separators with improved wetting properties, safety, and / or electrochemical performance.SUMMARY

[0004] Disclosed is a polymer separator comprising a polymeric layer with two surfaces and a ceramic coating on at least one of the surfaces, wherein the ceramic coating is modified by a polyacid modifying agent. In one embodiment, the polyacid modifying agent improves the wetting properties, safety, and / or electrochemical performance.BRIEF DESCRIPTION OF THE FIGURES

[0005] Non-limiting embodiments of the present disclosure will be described by way of example with reference to the accompanying figures, which are schematic and are not intended to be drawn to scale. In the figures, each identical or nearly identical component illustrated is typically represented by a single numeral. For purposes of clarity, not every component is labeled in every figure, nor is every component of each embodiment of the disclosure shown where illustration is not necessary to allow those of ordinary skill in the art to understand the disclosure.

[0006] Fig. 1 illustrates a polymer separator according to one embodiment of the present disclosure.

[0007] Fig. 2 illustrates a polymer separator according to another embodiment of the present disclosure.

[0008] Fig. 3 illustrates a battery comprising cathode, electrolyte, anode and separator according to one embodiment of the present disclosure.

[0009] Fig. 4 illustrates a battery comprising cathode, electrolyte, anode and separator according to another embodiment of the present disclosure.

[0010] Fig. 5 shows specific capacities and cycling numbers of a battery comprising a separator unmodified or modified according to some embodiments of the present disclosure.

[0011] Fig. 6 shows capacity retention rates and cycling numbers of a battery comprising a separator unmodified or modified according to some embodiments of the present disclosure.

[0012] Fig. 7 shows coulombic efficiencies and cycling numbers of a battery comprising a separator unmodified or modified according to some embodiments of the present disclosure.

[0013] Fig. 8 shows specific capacities and cycling numbers of a battery comprising a separator modified by different polyacid salts according to some embodiments of the present disclosure.

[0014] Fig. 9 shows capacity retention rates and cycling numbers of a battery comprising a separator modified by different polyacid salts according to some embodiments of the present disclosure.

[0015] Fig. 10 shows coulombic efficiencies and cycling numbers of a battery comprising a separator modified by different polyacid salts according to some embodiments of the present disclosure.DETAILED DESCRIPTION

[0016] It is to be noted that the transitional term “comprising”, which is synonymous with “including”, “containing” or “characterized by”, is inclusive or open-ended and does not exclude additional, un-recited elements or method steps.

[0017] Disclosed is a polymer separator that may improve the wettability of the separator to electrolyte, and when incorporated into electrochemical devices, such as a lithium metal battery, improve the safety and battery performance. In some embodiments, the polymer separator may have a polymeric layer and a ceramic coating covering at least a portion of at least one side of the polymeric layer, wherein the ceramic coating is modified by a polyacid modifying agent. In some embodiments, the polymer separator modified by the polyacid modifying agent may improve the wettability of the separator to an electrolyte, improve safety and battery performance, and / or extend the life of the battery.

[0018] As shown in Fig. 1, according to some embodiments of the present disclosure, a polymer separator (10) includes a polymeric layer (11) and a ceramic coating (12) on one surface of the polymeric layer (11). In some embodiments, as shown in Fig. 2, a polymer separator (10) comprises a polymeric layer (11) with a first ceramic coating (12) on one surface of the polymeric layer (11) and a second ceramic coating (13) on another, opposing surface of the polymeric layer (11).

[0019] In some embodiments, the polymeric layer (11) exhibits a porous structure. In some embodiments, the polymeric layer includes a polymer typically used for battery separators, such as a polyolefin. In some embodiments, the polyolefin is one or more selected from the group consisting of polyethylene (PE), polypropylene (PP), polyethylene copolymer, polypropylene copolymer, and mixtures thereof.

[0020] In some embodiments, the polymeric layer (11) may include a second polymer to increase the mechanical and physical properties such as strength, ion permeability, wetting properties, processing properties and / or electrical properties. In some embodiments, the second polymer is selected from the group consisting of polyacrylonitriles, polyamides, polyimides, poly vinyl alcohol (PVA), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polysulfone, polyvinyl fluoride, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polymethyl pentene, polyphenylene sulfide, poly acetyl, polyurethane, aromatic polyamide, semiaromatic polyamide, polypropylene terephthalate, polymethyl methacrylate, polystyrene, mixtures thereof.

[0021] In some embodiments, the polymeric layer (1 1) further includes an inorganic particle, which may be the same as or different from the ceramic particle. In some embodiments, the polymeric layer contains the inorganic particles with a weight percentage in a range from 5 wt% to 60 wt%, from 5 wt% to 50 wt%, from 5 wt% to 40 wt%, from 5 wt% to 35 wt%, from 5 wt% to 30 wt%, from 5 wt% to 25 wt%, from 5 wt% to 20wt%, from 5 wt% to 15 wt%, from 5 wt% to 10 wt%, from 7.5 wt% to 60 wt%, from 7.5 wt% to 50 wt%, from 7.5 wt% to 40 wt%, from 7.5 wt% to 35 wt%, from 7.5 wt% to 30 wt%, from 7.5 wt% to 25 wt%, from 7.5 wt% to 20 wt%, from 7.5 wt% to 15wt%, from 7.5 wt% to 10 wt%, from 10 wt% to 60 wt%, from 10 wt% to 50 wt%, from 10 wt% to 40 wt%, from 10 wt% to 35 wt%, from 10 wt% to 30wt%, from 10 wt% to 25 wt%, from 10 wt% to 20 wt%, from 10 wt% to 15wt%, or all and any ranges and subranges therebetween.In some embodiments, the inorganic particles are uniformly distributed in the polymeric layer such that the particles are present throughout the thickness thereof.

[0022] In some embodiments, the polymeric layer (11) has a thickness in a range from 5 pm to 30 pm, from 5 pm to 25 pm, from 5 pm to 20 pm, from 5 pm to 15 pm, from 5 pm to 10 pm, from 7.5 pm to 30 pm, from 7.5 pm to 25 pm, from 7.5 pm to 20 pm, from 7.5 pm to 15 pm, from 7.5 pm to 10 pm, from 10 pm to 30 pm, from 10 pm to 25 pm, from 10 pm to 20 pm, from 10 pm to 15 pm, or all and any ranges and subranges therebetween.

[0023] In some embodiments, the polymeric layer (11) has a porous structure with an average pore size of 0.1 pm or less, 0.075 pm or less, 0.05 pm or less, 0.025 pm or less, 0.02 pm or less, 0.015 pm or less, or 0.01 pm or less.

[0024] In some embodiments, the ceramic coating is applied to at least a portion of one surface of the polymeric layer.

[0025] In some embodiments, the ceramic coating (12, 13) is located between the separator and electrode. In some embodiments, the ceramic coating (12, 13) includes a ceramic particle. In some embodiments, the ceramic coating (12,13) includes a ceramic particle selected from the group consisting of AI2O3, SiCh, B2O3, NbO, NbCh, Nb2Os, TiCh, BaO, PbO, ZrCh, BaTiCh, SrTiCh, CeO2, MgO, CaO, SiC, Fe3O4, Si3N4, Caio(PO4)6(OH)2, Caio(P04)6(OH)2-2xF2x (0<x<l), and mixtures thereof. In some embodiments, the ceramic particles have an average particle size in a range from 1 nm to 1000 nm, from 1 nm to 750 nm, from 1 nm to 500 nm, from 1 nm to 250 nm, from 1 nm to 100 nm, from 1 nm to 75 nm, from 1 nm to 50 nm, from 1 nm to 25 nm, from 5 nm to 1000 nm, from 5 nm to 750 nm, from 5 nm to 500 nm, from 5 nm to 250 nm, from 5 nm to 100 nm, from 5 nm to 75 nm, from 5 nm to 50 nm, from 5 nm to 25 nm, from 10 nm to 1000 nm, from 10 nm to 750 nm, from 10 nm to 500 nm, from 10 nm to 250 nm, from 10 nm to 100 nm, from 10 nm to 75 nm, from 10 nm to 50 nm, from 10 nm to 25 nm, from 20 nm to 1000 nm, from 20 nmto 750 nm, from 20 nm to 500 nm, from 20 nm to 250 nm, from 20 nm to 100 nm, from 20 nm to75 nm, from 20 nm to 50 nm, from 50 nm to 1000 nm, from 50 nm to 750 nm, from 50 nm to 500 nm, from 50 nm to 250 nm, from 50 nm to 100 nm, from 50 nm to 75 nm, or all and any ranges and subranges therebetween.

[0026] In some embodiments, the ceramic coating (12,13) includes a binder such as polyvinylidene fluoride (PVDF) or its copolymer such as poly(vinylidene fluoride-co- hexafluoropropylene), aramid, and polyethylene oxide (PEO). In some embodiments, the binder is selected from the group consisting of polyimide resin, melamine resin, phenol resin, polymethyl methacrylate (PMMA) resin, polystyrene resin, polydivinylbenzene (PDVB) resin polyvinylidene fluoride (PVdF), polyvinylidene fluoride-hexafluoropropylene, polyvinylpyrrolidone, polyacrylonitrile, polyvinyl acetate, cellulose acetate, and mixtures thereof. In some embodiments, the ceramic coating (12, 13) does not include the polyacid modifying agent as a binder.

[0027] In some embodiments, the ceramic coating (12, 13) has a thickness in a range from 100 nm to 20 pm, from 100 nm to 15 pm, from 100 nm to 10 pm, from 100 nm to 7.5 pm, from 100 nm to 5 pm, from 100 nm to 2.5 pm, from 100 nm to 1 pm, from 100 nm to 750 nm, from 100 nm to 500 nm, from 100 nm to 250 nm, from 150 nm to 20 pm, from 150 nm to 15 pm, from 150 nm to 10 pm, from 150 nm to 7.5 pm, from 150 nm to 5 pm, from 150 nm to 2.5 pm, from 150 nm to 1 pm, from 150 nm to 750 nm, from 150 nm to 500 nm, from 150 nm to 250 nm, from 200 nm to 20 pm, from 200 nm to 15 pm, from 200 nm to 10 pm, from 200 nm to 7.5 pm, from 200 nm to 5 pm, from 200 nm to 2.5 pm, from 200 nm to 1 pm, from 200 nm to 750 nm, from 200 nm to 500 nm, from 200 nm to 250 nm, from 500 nm to 20 pm, from 500 nm to 15 pm, from 500 nm to 10 pm, from 500 nm to 7.5 pm, from 500 nm to 5 pm, from 500 nm to 2.5 pm, from 500 nm to 1 pm, from 500 nm to 750 nm, from 1 pm to 20 pm, from 1 pm to 15 pm, from 1 pm to 10 pm, from 1pm to 7.5 pm, from 1 |im to 5 pm, from 1 pm to 2.5 pm, from 1 pm to 1.5 |rm, or all and any ranges and subranges therebetween.

[0028] In some embodiments, the ceramic coating (12, 13) is modified with a polyacid modifying agent. In some embodiments, the polyacid modifying agent is a polyacid or a salt thereof.

[0029] In some embodiments, the polyacid is a polymer including at least one acid group selected from the group consisting of carboxylic acid (-COOH), sulfonic acid (-SO3H), phosphoric acid (- PO3H2) and combinations thereof.

[0030] In some embodiments, the polyacid has a formula selected from the group consisting of:whereinRi, R2, and R3 are independently selected from the group consisting of hydrogen, C1-20 alkyl, C2-20 alkenyl, C2-20 alkynyl, Ce-14 aryl, halogen such as F, Cl, Br and I, pseudo halogen such as -CN, hydroxy (-OH), alkoxy (-OR5) such as -OMe, acyloxy(-C(=O)ORe) such as -C(=O)OMe, C1-20 substituted alkyl, Ce-14 substituted aryl and combinations thereof, wherein Rs and Re are independently C1-20 alkyl either unsubstituted or substituted,R4 is a divalent group including C1-20 alkylene such as -CH2- and -CH2CH2-, -O-, -C(=O)-, - CO(=O)-, arylene such as / >rzra-phenylene, me / a-phenylene, and or / zo-phenylene, heteroarylene, and combinations thereof, and n is in a range from 10 to 1,000,000.

[0031] In some embodiments, “alkyl” refers to a radical of a straight-chain or branched saturated hydrocarbon group having from 1 to 20 carbon atoms (“C1-20 alkyl”). In some embodiments, an alkyl group has 1 carbon atom (“Ci alkyl”). In some embodiments, an alkyl group has 2 to 6 carbon atoms (“C2-6 alkyl”). Examples of C1-20 alkyl groups include methyl (Ci), ethyl (C2), n-propyl (C3), isopropyl (C3), n-butyl (C4), tert-butyl (C4), sec-butyl (C4), isobutyl (C4), n-pentyl (Cs), 3-pentanyl (C5), amyl (C5), neopentyl (Cs), 3-methyl-2-butanyl (Cs), tertiary amyl (Cs), n-hexyl (Ce), n-heptyl (C7), n-octyl (Cs) and the like. Unless otherwise specified, each instance of an alkyl group is independently optionally substituted, i.e., unsubstituted (an “unsubstituted alkyl”) or substituted (a “substituted alkyl”) with one or more substituents; e.g., for instance from 1 to 5 substituents. In certain embodiments, the alkyl group is unsubstituted C1-10 alkyl (e.g., -CH3). In certain embodiments, the alkyl group is substituted C1-10 alkyl. Common alkyl abbreviations include Me (-CH3), Et (-CH2CH3), i-Pr (-CH(CH3)2), n-Pr (-CH2CH2CH3), n-Bu (-CH2CH2CH2CH3), or i-Bu (-CH2CH(CH3)2).

[0032] In some embodiments, C1-20 substituted alkyl is a C1-20 alkyl with at least one substitute such as halogen, hydroxy, and amino. In some embodiments, C1-20 substituted alkyl includes - CH2F, -CH2CI, -CI EBr, -CH2I, -C2H4F, -C2H4CI, -C2H4Br, -C2H4I, -C3H5F, -C3H5CI, -C3HsBr, - C3H5I, -CH2OH, -C2H4OH, -C3H5OH, -CH2NH2, -C2H4NH2, and -C3H5NH2.

[0033] “Alkoxy” refers to the group -OR? wherein Rs is substituted or unsubstituted alkyl, substituted or unsubstitued alkenyl, substituted or unsubstitued alkynyl, substituted or unsubstitued carbocyclyl, substituted or unsubstituted heterocyclyl, substituted or unsubstituted aryl, orsubstituted or unsubstitued heteroaryl. Particular alkoxy groups are methoxy (-OCH3), ethoxy (-OC2H5), / / -propoxy (-OC2H4CH3), isopropoxy (-OCH(CH3)2), / / -butoxyf-OCiHeCHs), te / T- butoxy(-OC(CH3)3), ec-butoxy (-OCHfCHiKCTHs)), / / -pentoxy (-O(CH2)4CH3), / / -hexoxy (- O(CH2)5CH3), and 1,2-dimethylbutoxy.

[0034] “Acyloxy” refers to a radical -OC(=O)Re, wherein Re is hydrogen, substituted or unsubstitued alkyl, substituted or unsubstitued alkenyl, substituted or unsubstitued alkynyl, substituted or unsubstitued carbocyclyl, substituted or unsubstituted heterocyclyl, substituted or unsubstituted aryl, or substituted or unsubstitued heteroaryl, as defined herein. Representative examples include formyl (-C(=O)H), acetyl (-C(=O)CH3), cyclohexylcarbonyl, cyclohexylmethylcarbonyl, benzoyl (-C(=O)-C6H5) and benzylcarbonyl(-C(=O)CH2C6Hs.

[0035] “Aryl” refers to a radical of a monocyclic or polycyclic (e.g., bicyclic or tricyclic) 4n+2 aromatic ring system (e.g., having 6, 10, or 14 71 electrons shared in a cyclic array) having 6-14 ring carbon atoms and zero heteroatoms provided in the aromatic ring system (“Ce-14 aryl”). In some embodiments, an aryl group has six ring carbon atoms (“Ce aryl”; e.g., phenyl). In some embodiments, an aryl group has ten ring carbon atoms (“C10 aryl”; e.g., naphthyl such as 1 - naphthyl and 2-naphthyl). In some embodiments, an aryl group has fourteen ring carbon atoms (“C14 aryl”; e.g., anthracyl). “Aryl” also includes ring systems wherein the aryl ring, as defined above, is fused with one or more carbocyclyl or heterocyclyl groups wherein the radical or point of attachment is on the aryl ring, and in such instances, the number of carbon atoms continues to designate the number of carbon atoms in the aryl ring system. Typical aryl groups include groups derived from aceanthrylene, acenaphthylene, acephenanthrylene, anthracene, azulene, benzene, chrysene, coronene, fluoranthene, fluorene, hexacene, hexaphene, hexalene, as-indacene, s- indacene, indane, indene, naphthalene, octacene, octaphene, octalene, ovalene, penta-2,4-diene, pentacene, pentalene, pentaphene, perylene, phenalene, phenanthrene, picene, pleiadene, pyrene,pyranthrene, rubicene, triphenylene, and trinaphthalene. Particular aryl groups include phenyl, naphthyl, indenyl, and tetrahydronaphthyl. Unless otherwise specified, each instance of an aryl group is independently optionally substituted, i.e., unsubstituted (an “unsubstituted aryl”) or substituted (a “substituted aryl”) with one or more substituents. In certain embodiments, the aryl group is unsubstituted Ce w aryl. In certain embodiments, the aryl group is substituted Ce w aryl. “Fused aryl” refers to an aryl having two of its ring carbon in common with a second aryl or heteroaryl ring or with a carbocyclyl or heterocyclyl ring.

[0036] In certain embodiments, an aryl group substituted with one or more of groups selected from halo, Ci-6 alkyl, Ci-e haloalkyl, cyano, hydroxy, Ci-6 alkoxy, and amino.

[0037] “Heteroaryl” refers to a radical of a 5- to 14-membered monocyclic or polycyclic 4n+2 aromatic ring system (e.g., having 6, 10, or 14 7t electrons shared in a cyclic array) having ring carbon atoms and 1-8 ring heteroatoms provided in the aromatic ring system, wherein each heteroatom is independently selected from nitrogen, oxygen and sulfur (“5- to 14-membered heteroaryl”). In heteroaryl groups that contain one or more nitrogen atoms, the point of attachment can be a carbon or nitrogen atom, as valency permits. Heteroaryl bicyclic ring systems can include one or more heteroatoms in one or both rings. “Heteroaryl” also includes ring systems wherein the heteroaryl ring, as defined above, is fused with one or more carbocyclyl or heterocyclyl groups wherein the point of attachment is on the heteroaryl ring, and in such instances, the number of ring members continues to designate the number of ring members in the heteroaryl ring system. “Heteroaryl” also includes ring systems wherein the heteroaryl ring, as defined above, is fused with one or more aryl groups wherein the point of attachment is either on the aryl or heteroaryl ring, and in such instances, the number of ring members designates the number of ring members in the fused (aryl / heteroaryl) ring system. Bicyclic heteroaryl groups wherein one ring does not contain a heteroatom (e.g., indolyl, quinolinyl, carbazolyl, and the like) the point of attachmentcan be on either ring, i.e., either the ring bearing a heteroatom (e.g, 2-indolyl) or the ring that does not contain a heteroatom (e.g, 5-indolyl).

[0038] “Alkenyl” refers to a radical of a straight-chain or branched hydrocarbon group having from 2 to 20 carbon atoms and one or more carbon-carbon double bonds. “Alkynyl” refers to a radical of a straight-chain or branched hydrocarbon group having from 2 to 20 carbon atoms and one or more carbon-carbon triple bonds.

[0039] “Carbocyclyl” refers to a radical of a non-aromatic cyclic hydrocarbon group having from 3 to 10 ring carbon atoms (“C3-10 carbocyclyl”) and zero heteroatoms in the nonaromatic ring system.

[0040] “Heterocyclyl” refers to a radical of a 3- to 10-membered non-aromatic ring system having ring carbon atoms and 1 to 4 ring heteroatoms, wherein each heteroatom is independently selected from nitrogen, oxygen, sulfur, boron, phosphorus, and silicon (“3- to 10-membered heterocyclyl”).

[0041] In some embodiments, R.4 also comprises a single valent group such as C1-6 alkyl, C2-10 alkenyl, C2-10 alkynyl, Ce-14 aryl, halogen such as F, Cl, Br and I, pseudo halogen such as -CN, hydroxy (-OH), alkoxy, acyloxy, C1-6 substituted alkyl, Ce-14 substituted aryl and combinations thereof as valency permits.

[0042] In some embodiments, the salt in the polyacid modifying agent is one selected from the group consisting of ammonium (NH4+), group 1 of the periodic table such as lithium (Li+), sodium (Na+), potassium (K+), rubidium (Rb+) and cesium (Cs+), group 2 of the periodic table, such as magnesium (Mg2+) and calcium (Ca2+), zinc (Zn2+), and mixtures thereof.

[0043] In some embodiments, the polyacid is selected from the group consisting of polyacrylic acid (PAA), polymethacrylic acid (PMAA), poly(vinylsulfonic acid), poly(styrenesulfonic acid), poly(vinylphosphonic acid), poly(vinylbenzylphosphonic acid), poly(2-methacryoyloxyethyl phosphate) and mixtures thereof.

[0044] In some embodiments, the polyacid has a viscosity average polymer weight in a range from 1000 Dalton to 10,000,000 Dalton. In some embodiments, the polyacid modifying agent has a viscosity average polymer weight in a range from 1000 Dalton to 10,000,000 Dalton. In some embodiments, the polyacid or the polyacid modifying agent has a number average polymer weight in a range from 1000 Dalton to 10,000,000 Dalton. In some embodiments, the polyacid or the polyacid modifying agent has a weight average polymer weight in a range from 1000 Dalton to 10,000,000 Dalton.

[0045] In some embodiments, the polyacid modifying agent has an amount in a range from 0.01 mg to 0.20 mg per square centimeters of surface area of the polymer separator. In some embodiments, the polyacid modifying agent has an amount equal to or less than 10.0 wt%, 9.5 wt%, 9.0 wt%, 8.5 wt%, 8.0 wt%, 7.5 wt%, 7.0 wt%, 6.5 wt%, 6.0 wt%, 5.5 wt%, 5.0 wt%, 4.5 wt% or 4.0 wt% in the polymer separator.

[0046] In some embodiments, at least a portion of the polyacid modifying agent is adsorbed to a surface of the ceramic particle in the ceramic coating. In some embodiments, the ceramic coating does not include any free polyacid modifying agent, which is usually added as a binder to keep the ceramic particle stay on the polymeric layer surface. In some embodiments, at least a portion of the polyacid modifying agent is adsorbed onto the porous surface of the polymeric layer. In some embodiments, the polyacid modifying agent is adsorbed to a surface of the ceramic particle in the ceramic coating and / or the surface of the porous structure of the polymeric layer.

[0047] In some embodiments, the ceramic coating further includes a binder such as polymeric binder, polymerizable monomer or oligomer.

[0048] In some embodiments, the elementary composition of the surface of the polymer separator exhibits a C / Al elementary ratio (alternatively molar ratio) of at least 15.0%, at least 17.5%, at least 20.0wt%, at least 22.5%, or at least 25.0% lower than the one with no treatment.

[0049] In some embodiments, the present disclosure provides an electrochemical device such as solid-state batteries comprising the polymer separator as described herein. In some embodiments, the electrochemical device exhibits improved cycling performance and / or safety.

[0050] In some embodiments, the electrochemical device is a lithium ion battery and / or lithium metal battery. In some embodiments, the electrochemical device is a solid state battery. In some embodiments, the electrochemical device comprises a cell or a stack of cells. In some embodiments, the electrochemical device includes a cell comprising cathode (5), electrolyte (3), the polymer separator (10) including a polymeric layer (11) and a ceramic coating (12) covering at least a portion of one surface (or side), and anode (4) as shown in Fig. 3. In some embodiments, the ceramic coating (12) on the separator (10) faces the anode (4). In some embodiments, the anode (4) comprises an anode current collector. In some embodiments, the anode (4) comprises an anode current collector and a lithium metal anode on the anode current collector.

[0051] In some embodiments, the electrochemical device comprises a cathode (5), electrolyte (3), the polymer separator (10) including a polymeric layer (11), a first ceramic coating (12) covering at least a portion of one side of the polymeric layer (10) and a second ceramic coating (13) covering at least a portion of the other side of the polymeric layer (10), and anode (4) as shown in Fig. 4.

[0052] In some embodiments, the cycle life of a battery is the number of cycles that the battery can go until the capacity drops below 70% of initial capacity. In some embodiments, the cycle life can be measured by a cycling life test based on a conventional battery setting. In some embodiments, a cycling life test can be conducted at a charge rate in a range from 0.01 C to 5.0 C, at a discharge rate in a range from 0.01 C to 5.0 C, and any combinations thereof. In some embodiments, the cycle life of a battery comprising a polymer separator modified by the polyacid modifying agent is increased by at least 10%, at least 12.5%, atleast 15.0%, at least 17.5%, at least 20.0%, at least 22.5%, at least 25.0%, at least 27.5% or at least 30% in comparison with an identicalpolymeric separator except the ceramic coating is not modified by the polyacid modifying agent. Without wishing to be bound by any theory, the increased cycle life may be attributed to the modified surface property of the ceramic coating and the polymeric layer. In some embodiments, the modified surface increases the wettability towards electrolyte molecules and / or facilitates ion transportation.

[0053] In some embodiments, the electrolyte of the electrochemical device such as batteries is a polymer solid electrolyte or a semi-solid electrolyte. In some embodiments, the electrolyte includes a polymer with a concentration in a range from 0.02 wt% to 20 wt%.

[0054] In some embodiments, the polymer in the electrolyte is in situ polymerized after a polymerizable monomer and initiator is mixed with other electrolyte components such as lithium salt and solvent.

[0055] In some embodiments, the polymerizable monomer contains one or more polymerizable groups. In some embodiments, the monomer contains one or more polymerizable groups. In some embodiments, non-limiting specific polymerizable groups include vinyl (-CH=CH2), substituted vinyl (-CR7=CRSR9) and a combination thereof, wherein R7, Rs and R9 are independently hydrogen, halogen, -CN, -NO2, C1-6 alkyl, Ci-ehaloalkyl, C1-6 hydroxyalkyl, C 1-6 aminoalkyl, C2-6 alkenyl, C2- 6 alkynyl, Ce-uaryl or any combination thereof.

[0056] In some embodiments, the polymerizable monomer is selected from the group consisting of methyl acrylate, ethyl methacrylate, butyl methacrylate, methyl acrylate, butyl acrylate, ethylene glycol methyl ether acrylate, ethylene glycol methyl ether methacrylate, acrylonitrile, vinyl acetate, vinyl chloride, vinyl fluoride, and the like, but is not limited thereto. A more substantial example may include a mixture of any one or more selected form trimethylolpropane ethoxylate triacrylate, and other monomers having two or more polymerizable groups and the monomer having one polymerizable group. Non-limiting specific monomers include 2, 2, 3, 3-tetrafluorobutane- 1,4-diacrylate, 2,2,3,3,4,4,5,5-octafluorohexane-l,6-diyl diacrylate, 2,2,3,3,4,4,5,5-octafluorohexane-l,6-diyl bis(2-methylacrylate), polyethylene glycol) diacrylate (Mn=500 - 5000), triethylene glycol dimethacrylate (TEGDMA), diurethane dimethacrylate, and any combination thereof. In some embodiments, the monomer is selected from the group consisting of tetraallyl silane (TAS), 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane, triethoxyvinylsilane, allyltriethoxysilane, pentaerythritol tetraacrylate (PETA), pentaerythritol tetramethacrylate (PETMA), tris[2-(acryloyloxy)ethyl] isocyanurate (TAEI), di(trimethylolpropane) tetraacrylate (Di-TMPTA), trimethylolpropane propoxylate triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate and dipentaerythritol hexaacrylate.

[0057] In some embodiments, the polymerizable oligomer has at least one polymerizable bond and a number-average molecular weight in a range from 200 to 100,000 Dalton, from 200 to 50,000 Dalton, from 200 to 20,000 Dalton, from 200 to 10,000 Dalton, from 200 to 5,000 Dalton, from 200 to 2,000 Dalton, from 200 to 1,000 Dalton, from 500 to 100,000 Dalton, from 500 to 50,000 Dalton, from 500 to 20,000 Dalton, from 500 to 10,000 Dalton, from 500 to 5,000 Dalton, from 500 to 2,000 Dalton, from 500 to 1,000 Dalton, from 1,000 to 100,000 Dalton, from 1,000 to 50,000 Dalton, from 1,000 to 20,000 Dalton, from 1,000 to 10,000 Dalton, from 1,000 to 5,000 Dalton, from 1,000 to 2,000 Dalton, or all and any ranges and subranges therebetween.

[0058] In some embodiments, the polymerization is a thermal polymerization. In some embodiments, the polymerization is conducted by exposing to a light source such as UV light with or without a photoinitiator.

[0059] In one aspect, the present disclosure provides a method of preparing the polymer separator as disclosed herein. In some embodiments, the method may comprise:1) mixing a polyacid modifying agent with a solvent into a mixture; and2) placing a polymer separator comprising a polymeric layer and a ceramic coating into the mixture thus obtaining a polymer separator modified by the polyacid modifying agent

[0060] In some embodiments, the solvent for the mixture is selected from the group consisting of water, ethanol, 1-propanol, isopropanol, tetrahydrofuran, dimethylformamide (DMF), 1,3-dioxane, 1,4-dioxane, dimethylacetamide, acetone, 1,4-butanediol and mixtures thereof.

[0061] In some embodiments, the mixture is adjusted to a pH value. In some embodiments, the mixture has a pH value in a range from 3.0 to 11.0, from 3.0 to 10.5, from 3.0 to 10.0, from 3.0 to9.5, from 3.0 to 9.0, from 3.0 to 8.5, from 3.0 to 8.0, from 3.0 to 7.5, from 3.0 to 7.0, from 3.0 to6.5, from 3.0 to 6.0, from 3.0 to 5.5, from 3.0 to 5.0, from 4.0 to 11.0, from 4.0 to 10.5, from 4.0 to 10.0, from 4.0 to 9.5, from 4.0 to 9.0, from 4.0 to 8.5, from 4.0 to 8.0, from 4.0 to 7.5, from 4.0 to 7.0, from 4.0 to 6.5, from 4.0 to 6.0, from 4.0 to 5.5, from 4.0 to 5.0, from 5.0 to 11.0, from 5.0 to 10.5, from 5.0 to 10.0, from 5.0 to 9.5, from 5.0 to 9.0, from 5.0 to 8.5, from 5.0 to 8.0, from 5.0 to 7.5, from 5.0 to 7.0, from 5.0 to 6.5, from 5.0 to 6.0, from 5.0 to 5.5, from 6.0 to 11.0, from 6.0 to 10.5, from 6.0 to 10.0, from 6.0 to 9.5, from 6.0 to 9.0, from 6.0 to 8.5, from 6.0 to 8.0, from 6.0 to 7.5, from 6.0 to 7.0, from 6.0 to 6.5, from 7.0 to 11 .0, from 7.0 to 10.5, from 7.0 to 10.0, from 7.0 to 9.5, from 7.0 to 9.0, from 7.0 to 8.5, from 7.0 to 8.0, from 7.0 to 7.5, from 8.0 to 11.0, from 8.0 to 10.5, from 8.0 to 10.0, from 8.0 to 9.5, from 8.0 to 9.0, from 8.0 to 8.5, or all and any ranges and subranges therebetween.

[0062] In some embodiments, after the polymer separator is placed into the mixture for a period of time, a rinsing is conducted to remove excess modifying agent from the polymer separator. In some embodiments, a drying step is further conducted to remove solvent. In some embodiments, the polyacid modifying agent has a concentration in the mixture in a range from 0.01 wt% to 1.00 wt%, from 0.01 wt% to 0.90 wt%, from 0.01 wt% to 0.80 wt%, from 0.01 wt% to 0.70 wt%, from0.01 wt% to 0.60 wt%, from 0.01 wt% to 0.50 wt%, from 0.01 wt% to 0.40 wt%, from 0.01 wt%to 0.30 wt%, from 0.01 wt% to 0.20 wt%, from 0.01 wt% to 0.10wt%, from 0.02 wt% to 1.00 wt%, from 0.02 wt% to 0.90 wt%, from 0.02 wt% to 0.80 wt%, from 0.02 wt% to 0.70 wt%, from 0.02 wt% to 0.60 wt%, from 0.02 wt% to 0.50 wt%, from 0.02 wt% to 0.40 wt%, from 0.02 wt% to 0.30 wt%, from 0.02 wt% to 0.10 wt%, from 0.05 wt% to 1.00 wt%, from 0.05 wt% to 0.90 wt%, from 0.05 wt% to 0.80 wt%, from 0.05 wt% to 0.70 wt%, from 0.05 wt% to 0.60 wt%, from 0.05 wt% to 0.50 wt%, from 0.05 wt% to 0.40 wt%, from 0.05 wt% to 0.30 wt%, from 0.05 wt% to 0.20 wt%, from 0.05 wt% to 0.10 wt%, from 0.07 wt% to 1.00 wt%, from 0.07 wt% to 0.90 wt%, from 0.07 wt% to 0.80 wt%, from 0.07 wt% to 0.70 wt%, from 0.07 wt% to 0.60 wt%, from 0.07 wt% to 0.50 wt%, from 0.07 wt% to 0.40 wt%, from 0.07 wt% to 0.30 wt%, from 0.07 wt% to 0.20 wt%, from 0.07 wt% to 0.10 wt%, from 0.10 wt% to 1.00 wt%, from 0.10 wt% to 0.90 wt%, from 0.10 wt% to 0.80 wt%, from 0.10 wt% to 0.70 wt%, from 0.10 wt% to 0.60 wt%, from 0.10 wt% to 0.50 wt%, from 0.10 wt% to 0.40 wt%, from 0.10 wt% to 0.30 wt%, from 0.10 wt% to 0.20 wt%, or all and any ranges and subranges therebetween.

[0063] In some embodiments, the rinsing is conducted with a second solvent such as DI water to remove polyacid modifying agents that are weakly and / or physically bonded to the surface. In some embodiments, after rinsing, there are no free polyacid modifying agents. In some embodiments, all polyacid modifying agents are strongly attached to the ceramic particle surface.

[0064] The disclosure will be better understood by reference to the Experimental Details which follow, but those skilled in the art will readily appreciate that the specific experiments detailed are only illustrative, and are not meant to limit the disclosure as described herein, as numerous variations and modifications of these exemplary embodiments are possible without undue experimentation. All such variations and modifications are within the scope of the teachings of this disclosure. It will be appreciated that the foregoing description and following examples, nomatter how detailed they may appear in text, the disclosure may be practiced in many ways, and the disclosure should be construed in accordance with the appended claims and equivalents thereof.ExamplesExample 1Modification of polymer separator

[0065] A treatment solution was representatively prepared by mixing 1 g polyacrylic acid (PAA) having a viscosity average molecular weight (Mv) of around 3,000,000 Dalton with 200 mL DI water at room temperature followed by stirring until full dissolution of PAA. The pH value of the treatment solution was around 4.0 - 5.0.

[0066] A polymer separator comprising a polyethylene (PE) polymeric layer with a thickness around 12 qm and two ceramic coatings on both surfaces of the polymeric layer (each ceramic coating with a thickness around 4 qm) was used in this example. The polymer separator was submerged into the treatment solution for 12-24 hours, leading to a soaked polymer separator.

[0067] The soaked polymer separator was rinsed by water until no polymer could be visibly observed on the separator. A PAA-modified polymer separator sample 1 was obtained after drying.

[0068] The elementary composition of the surface of the separator was measured by an energy dispersive spectroscopy (EDS) under TEM.

[0069] A coin cell assembly was prepared by using NMC811 as the cathode, a lithium strip with a thickness of 20 um as anode, an electrolyte comprising 3.5M lithium bis(fluorosulfonyl)imide (LiFSI) in sulfolane with 1.5 wt% FS-3100, and the modified polymer separator sample 1 as the separator.

[0070] The coin cell was cycled at room temperature from 2.80V to 4.25V at 0.1C charge / discharge for cycle 1, which is also known as formation step. The cell was then cycled at 0.33C charge and 0.33C discharge for cycles 2 and 3, 0.33 C charge and 1 C discharge for cycles4 and 5, and 0.33 C charge and 1.5 C discharge for cycles 6 and 7 for the rate testing. After the rate testing, the cell was further cycled at 0.5C charge / discharge for measuring the cycle life of the cell, wherein the cycle life of a battery is the number of cycles that the battery can go until the capacity drops below 70% of initial capacity according to some embodiments of the present disclosure. During the cycle life measurements, a 0.1C charge and 0.1C discharge cycle was performed every 10 cycles to measure the specific capacity of the cell.Example 2

[0071] A modified polymer separator sample 2 was prepared by following the method in example 1 except that the polyacid modifying agent is sodium salt of PAA with a weight average molecular weight (Mw) of around 15,000 Dalton (NaPAA), wherein the weight percentage of NaPAA in the treatment solution was around 0.5wt% and the pH was 7.0-8.0.

[0072] A coin cell was assembled using the polymer separator sample 2 and tested by following the method in example 1.Example 3

[0073] A modified polymer separator sample 3 was prepared by following the method in example 1 except that the polyacid modifying agent is lithium salt of PAA (LiPAA), wherein LiPAA was synthesized by mixing PAA having a viscosity average molecular weight (Mv) of around 3,000,000 Dalton with a predetermined amount of LiOH. The weight percentage of LiPAA in the treatment solution was 0.5wt% and the pH was around 7.0 - 8.0.

[0074] A coin cell was assembled using the polymer separator sample 3 and tested by following the procedure in example 1.Examples 4 and 5

[0075] A polymer separator sample 4 was prepared by following the method in example 1 except that a PAA with a viscosity average molecular weight of 1.25 million Dalton was used. A polymerseparator sample 5 was similarly prepared by using a PAA with a viscosity average molecular weight of 250 k Dalton.Comparative example

[0076] A polymer separator comprising a polymeric layer with a thickness around 12 pm and two ceramic coatings on both surfaces of the polymeric layer (each ceramic coating with a thickness around 4 pm) without any further treatment was used as a comparative example.

[0077] A coin cell was assembled and tested by following the method in example 1.

[0078] Figs. 5 to 7 show the rate measurement and cycling performance of batteries comprising a polymer separator without any treatment (comparative example), modified by PAA (sample 1), and modified by NaPAA (sample 2). Table 1 shows the cycle life of the batteries (cells). The average cycle life of the battery with sample 1 polymer separator, i.e., modified by PAA, is increased from 120 cycles for the comparative sample 1 to 146 cycles for sample 1 with an improvement of 22%. As for the battery with sample 2 polymer separator modified by NaPAA, the average cycle life is increased to 138 cycles with an improvement of 15% in comparison with that of the comparative sample 1 . The average cycle life of a battery with a polymer separator modified by LiPAA increased to 146 cycles with an improvement of 22% in comparison with that of the comparative sample 1.Table 1 Cycle life of batteries comprising different separators

[0079] The influence of the cation of the polyacid modifying agent on the electrochemical performance was also investigated. As shown in Figs. 8-10, the battery comprising the polymerseparator modified by LiPAA exhibits a better electrochemical performance in comparison to the one modified by NaPAA. Without wishing to be bounded by any theory, the lithium ion in the polyacid modifying agent is immobilized to the ceramic particle surface, which facilitates the wetting of electrolyte molecules such as lithium salt and / or the ion transportation during charge and discharge of the battery.Table 2 Ratios of C / Al on surface of polymer separators

[0080] The polyacid modifying agent changes the elementary composition on the surface of the ceramic coating. As shown in Table 2, the samples treated with PAA exhibit a lower elementary ratio of C / Al in comparison to the one without treatment. Samples 1, 4, and 5 exhibit C / Al ratios which are 22.2%, 28.2% and 25.7% lower than the one without any treatment. The molecular weight of the modifying agent appears to have no significant impact on the C / Al ratio.

[0081] The weight percentage of the polyacid modifying agent in polymer separator was measured by comparing the mass difference before and after treatment. As shown in Table 3, the polyacid modifying agent in the polymer separator varies from 5.64% to 8.91wt%.Table 3 Weight percentage of poly acid modifying agent in polymer separators* the weight percentage of modifying agent in polymer separator is calculated by Am / ml, wherein Am is the mass difference of the polymer separator before and after the treatment, m 1 is the mass of the polymer separator after treatment.Aspects

[0082] In a first aspect, the present disclosure provides a polymer separator comprising: a) a polymeric layer comprising a first surface and a second surface opposing the first surface; and b) a ceramic coating on at least one surface of the polymeric layer, wherein the ceramic coating comprises a ceramic particle and the ceramic coating is modified by a polyacid modifying agent.

[0083] In a second aspect according to the first aspect, the polyacid modifying agent is a polyacid or a salt thereof.

[0084] In a third aspect according to the second aspect, the polyacid is a polymer including at least one acid group selected from the group consisting of carboxylic acid (-COOH), sulfonic acid (-SO3H), and phosphoric acid (-PO3H2).

[0085] In a fourth aspect according to the second or third aspect, wherein the polyacid comprises a polymer with a formula selected from the group consisting of:whereinRi, R2, and R3 are independently selected from the group consisting of hydrogen, halogen, pseudo halogen, C1-20 alkyl, C2-20 alkenyl, C2-20 alkynyl, Ce-14 aryl, hydroxy (-OH), alkoxy (- ORs), acyloxy(-C(=O)OR6), Ci -20 substituted alkyl, Ce-14 substituted aryl and combinations thereof, wherein Rs and Re are independently C1-20 alkyl either unsubstituted or substituted,R4 is a divalent group, and n is in a range from 10 to 1,000,000.

[0086] In a fifth aspect according to the fourth aspect, wherein R4 is selected from the group consisting of C1-20 alkylene, oxyl (-O-), carbonyl (-C(=O)-), carboxyl (-CO(=O)-), arylene, hydrogen, halogen, pseudo halogen, C 1-20 alkyl, C2-20 alkenyl, C2-20 alkynyl, Ce-w aryl, hydroxy (- OH), alkoxy (-OR5), acyloxy(-C(=O)ORe), C 1-20 substituted alkyl, Ce-14 substituted aryl, heteroarylene, and combinations thereof. In some embodiments, the phenylene is / / ra-phenylene, meta-phenylene, or o / VAo-phenylene.

[0087] In a sixth aspect according to any of the second through fifth aspects, the polyacid comprises at least one selected from the group consisting of polyacrylic acid (PAA), polymethacrylic acid (PMAA), poly(vinylsulfonic acid), poly(styrenesulfonic acid), poly(vinylphosphonic acid), poly(vinylbenzylphosphonic acid) poly(2-methacryoyloxyethyl phosphate), and mixtures thereof.

[0088] In a seventh aspect according to any of the second through fifth aspects, the salt comprises a cation comprising at least one selected from the group consisting of ammonium (NH4+), lithium (Li+), sodium (Na+), potassium (K+), rubidium (Rb+), cesium (Cs+), magnesium (Mg2+), calcium (Ca2+), zinc (Zn2+), and mixtures thereof.

[0089] In an eighth aspect according to any preceding aspect, the polyacid modifying agent has a viscosity average polymer weight in a range from 1,000 Dalton to 10,000,000 Dalton.

[0090] In a nineth aspect according to any preceding aspect, the polyacid modifying agent has an amount in a range from 0.01 mg to 0.20 mg per square centimeters of surface area of the polymer separator.

[0091] In a tenth aspect according to any preceding aspect, the polymeric layer comprises a polyolefin. In some embodiments, the polyolefin comprises at least one selected from the groupconsisting of polyethylene (PE), polypropylene (PP), polyethylene copolymer, polypropylene copolymer, and mixtures thereof.

[0092] In an eleventh aspect according to any preceding aspect, the ceramic particle of the ceramic coating comprises at least one selected from the group consisting of AI2O3, SiO2, MgO, CaO, CeCh, SiC, Fe3O4, Si3Ni, B2O3, NbO, NbCh, Nb2O5, TiO2, BaO, PbO, ZrO2, BaTiO3, SrTiO3, Caio(P04)s(OH)2, Caio(P04)6(OH)2-2xF2x(0<x<l), and mixtures thereof.

[0093] In a twelfth aspect according to any preceding aspect, the polymeric layer has a thickness in a range from 5 pm to 30 pm and the polymeric layer has an average pore size of 0.1 pm or less.

[0094] In a thirteenth aspect according to any preceding aspect, the ceramic particle in the ceramic coating has an average particle size in a range from 1 nm to 1 micrometer. In some embodiments, the ceramic coating has a thickness in a range from 100 nm to 20 pm.

[0095] In a fourteenth aspect according to any preceding aspect, at least one surface of the polymer separator exhibits a C / Al elementary molar ratio of at least 15% lower than an identical polymer separator except it has a ceramic coating that is not modified by a polyacid modifying agent.

[0096] In a fifteenth aspect, the present disclosure provides an electrochemical device comprising the polymer separator according to any preceding aspect.

[0097] In a sixteenth aspect according to the fifteenth aspect, the electrochemical device exhibits a cycle life of at least 10 % higher than an identical polymer separator except it has a ceramic coating that is not modified by a polyacid modifying agent.

[0098] In a seventeenth aspect, the present disclosure provides a method of preparing a polymer separator, comprising: a) mixing a polyacid modifying agent with a solvent into a mixture; and b) placing a polymer separator comprising a polymeric layer and a ceramic coating into the mixture thus obtaining a polymer separator modified by the polyacid modifying agent.

[0099] In an eighteenth aspect according to the seventeenth aspect, the polyacid modifying agent has a weight percentage in a range from 0.01 wt% to 1.0 wt% in the mixture. In some embodiments, the solvent comprises at least one selected from the group consisting of water, ethanol, 1-propanol, isopropanol, tetrahydrofuran, dimethylformamide (DMF), 1,3-dioxane, 1,4-dioxane, di methyl acetamide, acetone, 1,4-butanediol and mixtures thereof.

[0100] In a nineteenth aspect according to the seventeenth or eighteenth aspect, the mixture has a pH value in a range from 3.0 to 11.0.

[0101] In a twentieth aspect according to any of the seventeenth through nineteenth aspects, the method further comprises a step of rinsing after placing the polymer separator into the mixture. In some embodiments, the method further comprises a step of drying to remove the solvent from the polymer separator.

[0102] Various embodiments of the features of this disclosure are described herein. However, it should be understood that such embodiments are provided merely by way of example, and numerous variations, changes, and substitutions can occur to those skilled in the art without departing from the scope of this disclosure. It should also be understood that various alternative to the specific embodiments described herein are also within the scope of this disclosure.

Claims

We claim:

1. A polymer separator comprising: a) a polymeric layer comprising a first surface and a second surface opposing the first surface; and b) a ceramic coating on at least one surface of the polymeric layer, wherein the ceramic coating comprises a ceramic particle and the ceramic coating is modified by a polyacid modifying agent.

2. The polymer separator of claim 1, wherein the poly acid modifying agent is a polyacid or a salt thereof.

3. The polymer separator of claim 2, wherein the polyacid is a polymer including at least one acid group selected from the group consisting of carboxylic acid (-COOH), sulfonic acid (-SO3H), and phosphoric acid (-PO3H2).

4. The polymer separator of claim 2, wherein the polyacid comprises a polymer with a formula selected from the group consisting of:whereinRi, R2, and R3 are independently selected from the group consisting of hydrogen, halogen, pseudo halogen, C1-20 alkyl, C2-20 alkenyl, C2-20 alkynyl, Ce-14 aryl, hydroxy (-OH), alkoxy (- ORs), acyloxy(-C(=O)ORs), Ci -20 substituted alkyl, Ce-14 substituted aryl and combinations thereof, wherein R5 and Re are independently C1-20 alkyl either unsubstituted or substituted, R4 is a divalent group, and n is in a range from 10 to 1,000,000, and wherein R4 is selected from the group consisting of C 1-20 alkylene, oxyl (-O-), carbonyl (-C(=O)-), carboxyl (-CO(=O)-), arylene, hydrogen, halogen, pseudo halogen, C1-20 alkyl, C2-20 alkenyl, C2-20 alkynyl, Ce-w aryl, hydroxy (-OH), alkoxy (-OR5), acyloxy(-C(=O)ORe), Ci -20 substituted alkyl, Ce-14 substituted aryl, heteroarylene, and combinations thereof.

5. The polymer separator of claim 2, wherein the polyacid comprises at least one selected from the group consisting of polyacrylic acid (PAA), polymethacrylic acid (PMAA), poly(vinylsulfonic acid), poly(styrenesulfonic acid), poly(vinylphosphonic acid), poly(vinylbenzylphosphonic acid) poly (2-methacryoyl oxy ethyl phosphate), and mixtures thereof.

6. The polymer separator of claim 2, wherein the salt comprises a cation comprising at least one selected from the group consisting of ammonium (NH4+), lithium (Li+), sodium (Na+), potassium (K+), rubidium (Rb+), cesium (Cs+), magnesium (Mg2+), calcium (Ca2+), zinc (Zn2+), and mixtures thereof.

7. The polymer separator of claim 1, wherein the polyacid modifying agent has an amount in a range from 0.01 mg to 0.20 mg per square centimeters of surface area of the polymer separator.

8. The polymer separator of claim 1, wherein the polymeric layer comprises a polyolefin and has a thickness in a range from 5 pm to 30 pm and an average pore size of 0.1 pm or less.

9. The polymer separator of claim 1, wherein the ceramic particle of the ceramic coating comprises at least one selected from the group consisting of AI2O3, SiO2, MgO, CaO, CeO2, SiC, Fe3O4, Si3N4, B2O3, NbO, NbO2, Nb2O5, TiO2, BaO, PbO, ZrO2, BaTiO3, SrTiO3, Caio(PO4)e(OH)2, Caio(P04)6(OH)2.2xF2x (0<x<l), and mixtures thereof and the ceramic particle has an average particle size in a range from 1 nm to 1 micrometer.

10. The polymer separator of claim 1 , wherein at least one surface of the polymer separator exhibits a C / Al molar ratio of at least 15% lower than an identical polymer separator except it has a ceramic coating that is not modified by a polyacid modifying agent.

11. An electrochemical device comprising the polymer separator of claim 1.

12. The electrochemical device of claim 11, wherein the electrochemical device exhibits a cycle life of at least 10 % higher than an identical polymer separator except it has a ceramic coating that is not modified by a polyacid modifying agent.

13. A method of preparing a polymer separator, comprising: a) mixing a polyacid modifying agent with a solvent into a mixture; and b) placing a polymer separator comprising a polymeric layer and a ceramic coating into the mixture thus obtaining a polymer separator modified by the polyacid modifying agent.

14. The method of claim 13, wherein the polyacid modifying agent has a weight percentage in a range from 0.01 wt% to 1.0 wt% in the mixture.

15. The method of claim 13, wherein the mixture has a pH value in a range from 3.0 to 11.0.

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