Reticulated solid electrolyte separator

Abstract

The present invention discloses a method of making a reticulated solid electrolyte / separator (RSES) that is suitable as both an electrolyte and a separator in a solid state battery.SOLUTION: Reticulated composites are fabricated by cast-and-dry of slurries composed of high MW resins (with solution viscosity above cm2 at 5% in NMP at RT) dissolved in solvents including, but not limited to, LLZO, LSP, LIPON or their derivatives, in which nanoparticles of solid electrolytes exhibiting high yield stresses (50 dynes / 1m2 or more) and high specific surface areas (i.e., above 10m2 / g, preferably above 100cp / g) are dispersed. The reticulated solid electrolyte / separator exhibits excellent cyclability and high ionic conductivity, resists lithium dendrite penetration, and maintains high dimensional stability (less than 10% shrinkage) at high temperatures (up to 140 °C.). Further, the present disclosure relates to an electrochemical cell comprising such a reticulated film composite that functions as both an electrolyte and a separator.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention discloses a method for producing a reticulated (porous, open-cell matrix structure) film composite suitable as a separator in an electrochemical cell. [Background technology]

[0002] Lithium-ion batteries have come a long way and can meet many transportation needs. However, safety improvements are needed due to the reactive and flammable liquid organic electrolytes in lithium-ion battery cells. Therefore, there is growing interest in replacing liquid electrolytes with more robust, non-flammable solid-state lithium-ion conducting materials. Furthermore, solid electrolyte materials not only enable more robust cell operation but also facilitate the integration of lithium metal anodes, which offer the highest volumetric energy density. Combining both solid electrolytes and lithium metal anodes can meet the dramatic cost reduction, desirable density, and cycle life requirements of EV applications.

[0003] There are several unresolved challenges associated with the use of solid-state lithium-ion conductors with lithium metal anodes. The main issues are non-uniform interfacial lithium deposition, which can lead to the formation of lithium dendrites; low ionic conductivity, especially at the interfaces between the solid electrolyte and the cathode and anode; low redox stability, especially at the cathode or anode interfaces; and insufficient mechanical strength and flexibility, especially to accommodate the expansion / contraction of the lithium metal anode. These challenges have so far hindered the large-scale adoption of all-solid-state batteries in the transportation and energy storage sectors.

[0004] Solid-state batteries are a battery technology that uses solid electrodes and solid electrolytes instead of the liquid or polymer electrolytes found in lithium-ion or lithium-polymer batteries. During charge and discharge cycles, lithium dendrites gradually grow from the lithium metal surface through the electrolyte, eventually contacting the positive electrode. This causes an internal short circuit in the battery, rendering it unusable after a relatively short calendar life. Lithium dendrite formation can also reduce the battery's coulombic efficiency. Furthermore, cycling of lithium electrodes can result in "mossy" lithium deposits that can detach from the negative electrode, thereby reducing the battery's capacity. Most attempts to prevent lithium dendrite growth have been unsuccessful or commercially impractical.

[0005] A typical approach to preparing electrolyte / separator composites is based on mixing a polymer binder with a ceramic and tape-casting the slurry to create a flexible film with ceramic particles dispersed in a polymer matrix. However, the non-contiguous network of ceramic particles allows lithium ions to diffuse throughout the polymer matrix, limiting overall ionic conductivity.

[0006] There are also known separators based on nonwoven fabrics, such as inorganic nonwoven fabrics made from glass or ceramic materials, or organic nonwoven fabrics such as cellulose polyacrylonitrile, polyamide, polyethylene terephthalate, etc., and / or engineering resins (U.S. Pat. Nos. 8,936,878 and 9,412,986).

[0007] Electrospun nanofibers have been tried to increase the permeation in composite materials (U.S. Pat. No. 9,180,412). The use of electrospun nanofibers is another way to increase the length of the ceramic network within the polymer matrix. However, nanofibers are usually oriented along the membrane plane and cannot provide a continuous ceramic permeation network along the conduction direction of battery applications, i.e., perpendicular to the membrane plane. Nanofibers also tend to be randomly distributed within the polymer matrix, resulting in clumping and resistive interconnections that are detrimental to achieving high ionic conductivity.

[0008] Separators for lithium-ion batteries are often made from melt-processable plastics, solution-cast or extruded to form a film, which is then stretched to create 30–60% porosity within the film. Common separators today are generally based on polypropylene (melting point approximately 160–165°C), polyethylene (melting point approximately 110–135°C), or blends thereof. These purely porous polymer separators, when used in batteries with lithium metal anodes, are known to be susceptible to lithium dendrite infiltration, potentially causing short circuits within the cell. Therefore, they are not considered intrinsically safe.

[0009] Among fluoropolymers, PVDF has been found to be useful as a binder in non-aqueous electrolytic devices and as a separator coating due to its excellent electrochemical resistance and excellent adhesion. The separator forms a barrier between the anode and cathode of the battery, preventing electronic short circuits while providing high ionic transport.

[0010] Garnet-type LLZO exists in two stable crystalline forms, the cubic phase being highly stable and exhibiting very low ionic conductivity (~10 -6 S cm -1), the cubic phase has been found to have disordered Li sites, resulting in much higher bulk ionic conductivity (~10 -4 S cm -1 Therefore, much research has focused on the preparation of the cubic phase by applying either heat treatment or the incorporation of other metals, such as Al, Ga, or Ta, into the LLZO structure. For example, Al-doped LLZO exhibits high ionic conductivity (5.1 × 10 -4 S cm -1 ) and also improved the surface and interface properties (Solid State Ionics, 2000, vol. 131, pp. 143-157).

[0011] Lu and colleagues (Chemical Engineering Journal, Vol. 367 (2019), PP. 230-238) attempted to prepare a hybrid matrix of PVDF and LLZTO (garnet-type Li6.5La3Zr1.5Ta0.5O12) as an ion-conducting medium. They cast a mixture of LLZTO and PVDF-HFP to obtain a solid matrix. Summary of the Invention [Problem to be solved by the invention]

[0012] There is an urgent need for porous media that can prevent lithium dendrite crossover within lithium metal anodes and / or during ultrafast charging of lithium-ion batteries. A viable solution is to have a highly uniform, microporous interface between the cathode and anode, which can facilitate uniform lithium ion transport to reduce or avoid dendrite formation while resisting oxidation. Furthermore, the material must exhibit sufficient mechanical strength to resist dendrite penetration if dendrites do form. [Means for solving the problem]

[0013] "Copolymer" is used to mean a polymer having two or more different monomer units. "Polymer" is used to include homopolymers and copolymers. Resin and polymer are used interchangeably. Polymers can be homogeneous, heterogeneous, or have a gradient distribution of comonomer units. All cited references are incorporated herein by reference. As used herein, unless otherwise specified, percent means weight percent. Unless otherwise specified, molecular weight is the weight average molecular weight measured by GPC using polymethyl methacrylate standards. Crystallinity and melting temperature are measured by DSC at a heating rate of 10°C / min as described in ASTM D3418. Melt viscosity is measured according to ASTM D3835 at 230°C and is expressed as a function of 100 s. -1 The dilute solution viscosity and reduced viscosity of polymers are measured at room temperature as described in ASTM D2857.

[0014] By reticulated film or coating is meant a film or coating that has a porous, open-cell matrix structure. "Open" means that the pores are not enclosed. Fluid can move between the pores. The percentage of voids or porosity can be measured by compressing the open-cell matrix, measuring the density, or by filling the voids with a liquid and measuring the change in density. Preferably, the voids (porosity) are measured by density, which means that the density of the film is compared to the density of the solid resin.

[0015] Nano-sized fillers or nano-sized particles means that the size of the fillers or particles is less than 1 μm, preferably less than 500 nm, preferably less than 200 nm. Nano-sized particles can be less than 100 nm. Particle size is the volume average particle size measured by light scattering (such as with a Nicom or Microtech instrument).

[0016] High specific surface area particles are particles with a surface area of ​​1m 2 / g, preferably 5m 2 / g, more preferably 10m 2 / g. Preferably, it is greater than 1 m 2 / g~1000m 2 / g, more preferably 1m 2 / g~700m 2 / g, and even more preferably 10m 2 / g~500m 2 / g. The particle surface area is 5 to 700 m 2 / g. Some high surface area particles have a three-dimensional branched structure, sometimes called a fractal shape, which can result in particles with large aspect ratios. A fractal shape is an aggregation of primary particles with three-dimensional branching.

[0017] High molecular weight means a solution viscosity measured at 5% in NMP at room temperature (25°C) of at least 100 cp, preferably 100 cp to 10,000 cp, more preferably 100 cp to 5000 cp, or a reduced viscosity, Rv of at least 0.2 dl / g and at most 2 dl / g.

[0018] Yield stress is the minimum shear stress required to initiate fluid flow. A high yield stress is at least 50 dynes / cm 2 , preferably 100 dynes / cm 2 Larger, 125 dynes / cm 2 The yield stress is up to 5000 dynes / cm 2 , preferably up to 3000 dynes / cm 2 The slurry must also be castable, which means that the solution viscosity of the slurry is less than 20,000 cP, preferably less than 10,000 cP at room temperature.

[0019] The present invention provides a reticulated film composite having nano-sized pores and a method for producing the reticulated film composite having nano-sized pores. The nano-sized pores have an average pore size of less than 500 nm, preferably 2 nm to 500 nm. The present invention also provides an electrode coating for a battery produced from the reticulated film composite having nano-sized pores.

[0020] Reticulated film composites can be made using different types of resins and a wide variety of nano-sized particles. Reticulated film composites can be made with particles having a fractal shape structure made from aggregates of primary particles.

[0021] The network film composite material is prepared by combining high surface area particles (lithium-based conductive material) with a polymer resin in a solvent at room temperature (25°C), and exhibits high yield stress (50 dynes / cm) even at low solids content (i.e., total solids content less than 30% by weight, preferably less than 20% by weight, more preferably less than 12% or even less than 10%). 2 The slurry is cast and dried at elevated temperatures to form a network film composite with nano-sized pores.

[0022] Unexpectedly, slurries of high surface area particles (i.e., lithium-based conductive materials) and polymer resins (e.g., high MW-PVDF (5% solution viscosity in NMP at room temperature exceeds 100 cp) or high MW-PMMA (reduced viscosity, Rv 0.5 dl / g) made in NMP exhibited high yield stress (50 dynes / cm) even at low solids contents (i.e., total solids contents less than 12%). 2 It was found that this high yield stress slurry could exhibit a yield stress of 50 to 180°C, or 80 to 180°C, preferably 120°C or higher. When this high yield stress slurry was cast and dried at a high temperature (i.e., 50 to 180°C, or 80 to 180°C, preferably 120°C or higher), a reticular membrane composite material with nano-sized pores was formed. DETAILED DESCRIPTION OF THE INVENTION

[0023] In one embodiment of the present invention, high molecular weight PVDF that is semi-crystalline (having a solution viscosity of greater than 100 cp at 5% in NMP at room temperature) was used in the present invention.

[0024] High molecular weight resins such as PMMA (reduced viscosity, Rv, greater than 0.5 dl / g) and high MW PAA (having a solution viscosity of 100 to up to 1000 cp, preferably up to 5000, in water at room temperature and pH 7) are used to produce high yield stress slurries (50 dynes / cm 2 ) can be obtained, ultimately producing a reticulated film composite with properties similar to those of reticulated films made from PVDF.

[0025] Reticulated film composites can be made using different types of resins and a wide variety of nano-sized particles.

[0026] Solid lithium-based electrolyte filler-type nanoparticles useful in the present invention, for example, lithium-containing conductive fillers, include, but are not limited to: Li7La3Zr2O 12 (LLZO), Li3PS4(LSP), Li6PS5X (X=Cl, Br, or I) (lithium argyrodite), lithium phosphate nitride (Lipon), Li 2+2x Zn 1-x GeO4 (X=0.55) (LISICON type), Li 0.34 La 0.51 TiO3 (perovskite-based), or a mixture thereof. LLZO-based nanoparticles, LSP-based nanoparticles, LIPON-based nanoparticles, or a mixture thereof can also be used in the present invention. LLZO doped with other metals, such as Al, Ga, or Ta, can also be used in the present invention.

[0027] To improve ionic conductivity, optionally, ion-conducting lithium salts, including but not limited to LiCl, LiPF6, LiTDI, LiFSI, and LiTFSI, can be added to the mixture at 0.01 to 10 wt %, preferably 0.1 to 3 wt %, based on the total membrane weight. LiTDI is lithium 4,5-dicyano-2-(trifluoromethyl)imidazole. LiFSI is lithium bis(fluorosulfonyl)imide. LiTFSI is lithium bis(trifluoromethanesulfonyl)imide.

[0028] Optionally, reinforcing fillers can be added to the mixture to improve mechanical strength or modify other characteristics of the RSES (Reticulated Solid Electrolyte Separator). The type of filler can also vary widely. For example, insulating fillers include, but are not limited to, alumina, silica, BaTiO3, CaO, ZnO, bohemite, TiO2, SiC, ZrO2, boron silicate, BaSO4, nanoclay, or mixtures thereof. Also useful organic fillers are aramid fillers and fibers, polyetheretherketone and polyetherketoneketone fibers, PTFE fibers, and chopped fibers, including, but not limited to, nanofibers, carbon nanotubes, and mixtures thereof.

[0029] The resin should have a high solution viscosity (i.e., greater than 100 cp measured at 5% in NMP at room temperature). Preferably, the solution viscosity is 100 to 10,000 cp, more preferably 100 to 5000 cp, at 5% solids in NMP at room temperature. For water-soluble polymers, the solution viscosity, measured in 2% water at room temperature (25°C) and pH 7, is 100 cp to 10,000 cp, preferably 100 cp to 5,000 cp. The pH varies from 2 to 12 depending on the type of polymer and its application. Polymers useful in the present invention include, but are not limited to, the following homopolymers and copolymers: polyvinylidene fluoride (PVDF), polyethylene tetrafluoride ethylene (PETFE), polyvinyl fluoride (PVF), poly(alkyl)acrylates, poly(alkyl)methacrylates, polystyrene, polyvinyl alcohol (PVOH), polyesters, polyamides, polyacrylonitrile, polyacrylamide, carboxymethyl cellulose CMC, polyacrylic acid (PAA), polymethacrylic acid (PMAA). Other useful polymers include polyether ketone ketone, polyether ether ketone, and polyesters.

[0030] Polyvinylidene Fluoride In a preferred embodiment, the polymer is a polyvinylidene fluoride homopolymer or copolymer. As used herein, the term "vinylidene fluoride polymer" (PVDF) includes within its meaning homopolymers, copolymers, and terpolymers, typically of high molecular weight. Copolymers of PVDF are particularly preferred because they are softer (have lower Tm, melting point, and reduced crystalline structure). Such copolymers include vinylidene fluoride copolymerized with at least one comonomer. The most preferred copolymers and terpolymers of the present invention are those in which vinylidene fluoride units constitute at least 50 mol%, at least 70 mol%, preferably at least 75 mol%, more preferably at least 80 mol%, and even more preferably at least 85 mol, of the total weight of all monomer units in the polymer.

[0031] Copolymers, terpolymers and higher polymers of vinylidene fluoride can be made by reacting vinylidene fluoride with one or more monomers from the group consisting of: vinyl fluoride; trifluoroethene; tetrafluoroethene; one or more partially or fully fluorinated α-olefins such as 3,3,3-trifluoro-1-propene, 1,2,3,3,3-pentafluoropropene, 3,3,3,4,4-pentafluoro-1-butene, and hexafluoropropene; and the partially fluorinated olefin hexafluoroisobutylene.

[0023] In some preferred embodiments, the comonomer is selected from the group consisting of tetrafluoroethylene, trifluoroethylene, chlorotrifluoroethylene, hexafluoropropene, vinyl fluoride, pentafluoropropene, tetrafluoropropene, perfluoromethyl vinyl ether, perfluoroethyl vinyl ether, perfluoro-n-propyl vinyl ether, and perfluoro-2-propoxypropyl vinyl ether; fluorinated dioxoles such as perfluoro(1,3-dioxole) and perfluoro(2,2-dimethyl-1,3-dioxole); allyl, partially fluorinated allyl, or fluorinated allyl monomers (such as 2-hydroxyethyl allyl ether or 3-allyloxypropanediol); and ethene or propene. In some preferred embodiments, the comonomer is selected from the group consisting of tetrafluoroethylene, trifluoroethylene, chlorotrifluoroethylene, hexafluoropropene, vinyl fluoride, pentafluoropropene, tetrafluoropropene, perfluoromethyl vinyl ether, and perfluoropropyl vinyl ether.

[0032] Particularly preferred are copolymers composed of at least about 75 and up to 90 mole percent vinylidene fluoride and, correspondingly, 10-25 mole percent hexafluoropropene. Terpolymers of vinylidene fluoride, hexafluoropropene, and tetrafluoroethylene also represent a class of vinylidene fluoride copolymers embodied herein.

[0033] In one embodiment, the vinylidene fluoride polymer has up to 50 wt. %, preferably up to 20 wt. %, more preferably up to 15 wt. % hexafluoropropene (HFP) units and 50 wt. %, preferably 80 wt. %, more preferably 85 wt. % or more VDF units. It is desirable to distribute the HFP units as uniformly as possible to provide a PVDF-HFP copolymer with good dimensional stability in end-use environments such as batteries.

[0034] Copolymers of PVDF for use in the separator coating composition preferably have a high molecular weight as measured by melt viscosity. High molecular weight means a melt viscosity of 100 s at 232°C according to ASTM method D-3835. -1 By "PVDF" is meant a PVDF having a melt viscosity of greater than 10 kPoise, preferably greater than 20 kPoise, as measured at 1000 kJ / cm².

[0035] Fluoropolymers such as polyvinylidene-based polymers may be produced by any process known in the art, with processes such as emulsion and suspension polymerization being preferred and described in US 6,187,885 and EP 0120524.

[0036] Synthetic Polyamide Polyamides are polymers (long, multi-unit molecules) in which the repeating units of the molecular chain are linked together by amide groups. The general chemical formula for amide groups is CO-NH. They can be formed by the interaction of an amine (NH2) group with a carboxyl (CO2H) group, or by the polymerization of amino acids or amino acid derivatives (molecules containing both amino and carboxyl groups).

[0037] The synthesis of polyamides is well described in the art, for example in WO15 / 071604, WO14179034, EP0550308, EP0550315, US9637595.

[0038] The polyamide may be the condensation or ring-opening product of: one or more amino acids, such as aminocaproic acid, 7-aminoheptanoic acid, 11-aminoundecanoic acid and 12-aminododecanoic acid, or one or more lactams, such as caprolactam, oenantholactam, lauryllactam; and - one or more salts or mixtures of diamines such as hexamethylenediamine, dodecamethylenediamine, metaxylylenediamine, bis(p-aminocyclohexyl)methane, and trimethylhexamethylenediamine with diacids such as isophthalic acid, terephthalic acid, adipic acid, azelaic acid, suberic acid, sebacic acid, dodecanedicarboxylic acid, and the like.

[0039] Examples of polyamides may include PA6, PA7, PA8, PA9, PA10, PA11, and PA12, as well as copolyamides such as PA6,6.

[0040] Copolyamides result from the condensation of at least two alpha,omega-aminocarboxylic acids or two lactams, or one lactam and one alpha,omega-aminocarboxylic acid. Copolyamides result from the condensation of at least one alpha,omega-aminocarboxylic acid (or one lactam), at least one diamine and at least one dicarboxylic acid.

[0041] Examples of lactams include those having 3 to 12 carbon atoms on the main ring, which may be substituted, such as β,β-dimethylpropiolactam, α,α-dimethylpropiolactam, amylolactam, caprolactam, caprylactam, and laurolactam.

[0042] Examples of alpha, omega-aminocarboxylic acids include aminoundecanoic acid and aminododecanoic acid. Examples of dicarboxylic acids include adipic acid, sebacic acid, isophthalic acid, butanedioic acid, 1,4 cyclohexanedicarboxylic acid, terephthalic acid, sodium or lithium salts of sulfoisophthalic acid, dimerized fatty acids (these dimerized fatty acids have a dimer content of at least 98% and are preferably hydrogenated), and dodecanedioic acid, and HOOC(CH2)10-COOH.

[0043] The diamine can be an aliphatic diamine having 6 to 12 carbon atoms. It can be aryl and / or saturated cyclic type. Examples include hexamethylenediamine, piperazine, tetramethylenediamine, octamethylenediamine, decamethylenediamine, dodecamethylenediamine, 1,5-diaminohexane, 2,2,4-trimethyl-1,6-diaminohexane, diamine polyols, isophoronediamine (IPD), methylpentamethylenediamine (MPDM), bis(aminocyclohexyl)methane (BACM), and bis(3-methyl-4-aminocyclohexyl)methane (BMACM).

[0044] Examples of copolyamides include: copolymer of caprolactam and lauryllactam (PA6 / 12), copolymer of caprolactam, adipic acid, and hexamethylenediamine (PA6 / 6-6), copolymer of caprolactam, lauryllactam, adipic acid, and hexamethylenediamine (PA6 / 12 / 6-6), copolymer of caprolactam, lauryllactam, 11-aminoundecanoic acid, azelaic acid, and hexamethylenediamine (PA6 / 6-9 / 11 / 12), copolymer of caprolactam, lauryllactam, 11-aminoundecanoic acid, adipic acid, and hexamethylenediamine (PA6 / 6-6 / 11 / 12), and copolymer of lauryllactam, azelanic acid, and hexamethylenediamine (PA6-9 / 12).

[0045] Polyamides also include polyamide block copolymers such as polyether-b-polyamides and polyester-b-polyamides.

[0046] Another polyamide is Arkema's ORGASOL® ultrafine polyamide 6, 12, and 6 / 12 powders, which are microporous and have open cells due to their manufacturing process. The particle size range of these powders is very narrow and can be 5-60 μm depending on the grade. Lower average particle sizes of 5-20 μm are preferred.

[0047] acrylic As used herein, acrylic polymers are meant to include polymers, copolymers, and terpolymers formed from methacrylate and acrylate monomers, as well as mixtures thereof. Methacrylate and acrylate monomers may comprise 51-100% of the monomer mixture, with 0-49% of other ethylenically unsaturated monomers present, including, but not limited to, styrene, alpha-methylstyrene, and acrylonitrile. Suitable acrylate and methacrylate monomers and comonomers include, but are not limited to, methyl acrylate, ethyl acrylate and methacrylate, butyl acrylate and butyl methacrylate, isooctyl methacrylate and acrylate, lauryl acrylate and methacrylate, stearyl acrylate and stearyl methacrylate, isobornyl acrylate and methacrylate, methoxyethyl acrylate and methacrylate, 2-ethoxyethyl acrylate and methacrylate, and dimethylaminoethyl acrylate and methacrylate monomers. (Meth)acrylic acids, such as methacrylic acid and acrylic acid, can be comonomers. Acrylic polymers include multilayer acrylic polymers, such as core-shell structures, that are typically prepared by emulsion polymerization.

[0048] styrene As used herein, styrenic polymers are meant to include polymers, copolymers, and terpolymers formed from styrene and alpha-methylstyrene monomers, as well as mixtures thereof. Styrene and alpha-methylstyrene monomers may comprise 50-100% of the monomer mixture, with 0-50% of other ethylenically unsaturated monomers present, including, but not limited to, acrylates, methacrylates, and acrylonitrile. Styrenic polymers include, but are not limited to, polystyrene, acrylonitrile-styrene-acrylate (ASA) copolymers, styrene-acrylonitrile (SAN) copolymers, styrene-butadiene copolymers such as styrene-butadiene rubber (SBR), methyl methacrylate-butadiene-styrene (MBS), and styrene-(meth)acrylate copolymers such as styrene-methyl methacrylate copolymer (S / MMA).

[0049] As used herein, polyolefin is meant to include polyethylene, polypropylene, and copolymers of ethylene and propylene. Ethylene and propylene monomers may comprise 51-100% of the monomer mixture, with 0-49% of other ethylenically unsaturated monomers present, including, but not limited to, acrylates, methacrylates, acrylonitrile, and anhydrides. Examples of polyolefins include ethylene ethyl acetate copolymer (EVA), ethylene (meth)acrylate copolymers, ethylene anhydride copolymers and grafted polymers, propylene (meth)acrylate copolymers, propylene anhydride copolymers and grafted polymers.

[0050] Solvents useful in the present invention for making the slurry include, but are not limited to, water, N-methyl-2-pyrrolidone (NMP), toluene, tetrahydrofuran (THF), acetone, and hydrocarbons. In a preferred embodiment, the solvent is NMP, water, or acetone. The solvent must be able to dissolve the polymer used to provide a visibly clear solution. For example, PVDF is soluble in NMP. PVDF is insoluble in water, so water is not used with PVDF. Polyvinyl alcohol (PVOH), polyacrylamide, carboxymethyl cellulose (CMC), polyacrylic acid (PAA), and their copolymers are generally water-soluble.

[0051] Other additives The coating compositions of the present invention may further contain effective amounts of other additives, including, but not limited to, fillers, leveling agents, defoamers, pH buffers, and other minor ingredients commonly used in formulations, while still meeting the requirements of the desired separator.

[0052] The slurry coating composition of the present invention may further optionally comprise a wetting agent, thickener, or rheology modifier.

[0053] One or more wetting agents can be present in the coating composition slurry in an amount of 0 to 5 parts, or 0.1 to 5 parts, preferably 0 to 3 parts, or 0.1 to 3 parts, per 100 parts of solvent. Surfactants can function as wetting agents, but wetting agents can also include non-surfactants. In some embodiments, the wetting agent can be an organic solvent. The presence of an optional wetting agent can help ensure uniform dispersion of powdered materials in the slurry. Useful wetting agents include, but are not limited to, ionic and nonionic surfactants such as the TRITON series (Dow) and PLURONIC series (BASF), BYK-346 (BYK Additives), and organic liquids compatible with the solvent (including, but not limited to, NMP, DMSO, and acetone).

[0054] Thickeners and / or rheology modifiers may be present in the coating composition in an amount of 0 to 10 parts, preferably 0 to 5 parts, of one or more thickeners or rheology modifiers per 100 parts of water (all parts by weight). The addition of thickeners or rheology modifiers to the dispersions described above prevents or slows settling of the powdered materials while providing a suitable slurry viscosity for the casting process. In addition to organic rheology modifiers, inorganic rheology modifiers may also be used, either alone or in combination.

[0055] The ratio of resin to total solids and nanoparticle filler is chosen to achieve a high yield stress, i.e., 50 dynes / cm 2 Higher, preferably 75 dynes / cm 2 Greater than, and even more preferably, 100 dynes / cm 2 Greater than or 200 dynes / cm 2 The yield stress should be selected to produce a slurry with a yield stress of up to 5000 dynes / cm. 2 , preferably up to 3000 dynes / cm 2 is.

[0056] The solids content of the slurry can be 2% to 30% by weight solids, preferably 2 to 20% by weight, even more preferably 2 to 12% by weight, or 2 to 10% by weight (based on the sum of the weight of the polymer and the weight of the nanoparticles).

[0057] The nanoparticles have a high specific surface area, good dispersibility in a solvent, and preferably have a fractal structure.

[0058] Several factors can affect the porosity or density of a reticulated film composite; for example, reducing the solids in the slurry (i.e., from 10% to 6%) will create a few percent higher porosity, a higher drying temperature (i.e., 180°C instead of 100°C) will increase porosity by a few percent, higher MW resins will result in higher porosity, and fillers with higher surface areas will result in higher porosity. All of these tunable properties can be applied to produce reticulated film composites with properties desired for specific applications.

[0059] Purpose One application of PVDF reticulated film composites with nanoparticles (examples include lithium-based conductive materials) and porosities of 20-80%, preferably 25-80%, is as a separator / electrolyte in solid-state batteries to enhance safety and improve battery performance. The reticulated film composite not only shrinks at high temperatures, but also expands in hot spots within the battery to further isolate runaway electrodes from each other.

[0060] Another advantage of the reticulated film composite is that it can be co-cast with the electrode, i.e., two slurry layers (active electrode and separator layer) can be simultaneously cast onto the current collector using a wet-on-wet technique using a double slot die-casting machine. The integrated electrode and separator structure is then formed during the drying and calendaring steps.

[0061] Reticulated film composites (solid-state ion contact materials) of lithium-based conductive materials, such as cubic nano-LLZO or other nanosized lithium-based conductive materials, can be used as electrolytes / separators in solid-state lithium batteries to enhance battery performance and safety. The use of reticulated composite films minimizes the diffusion length or path that electrons or ions must travel and maximizes interfacial area. The resins can be polyvinylidene fluoride, which resists oxidation on the cathode side, and specialized acrylic or PEO (polyethylene oxide) resins, which resist reduction on the anode side. Furthermore, reticulated film composites can accommodate volume changes that occur during charge and discharge and resist the potential for dendrite intrusion.

[0062] The temperature response can be tailored by varying the resin composition. For example, a reticulated film composite made from a resin with a higher HFP content (i.e., 20% HFP) will swell / expand at a lower temperature compared to one with a lower HFP content (i.e., 8% HFP), which may require a higher temperature to achieve the same swelling / expansion. The preferred weight percentage of HFP in the PVDF copolymer is 1-25% by weight, although higher weight percentages of HFP can be used. Another advantage of reticulated film composites is that they can be cast simultaneously with electrodes; that is, two slurry layers (active electrode and separator layer) can be simultaneously cast onto a current collector using a wet-on-wet technique using a double-slot die-casting machine. The integrated electrode and separator structure is then formed during the drying and calendering steps. For multilayer composite structures, such as electrode separators for electrochemical devices or filter media, wet-on-wet casting is possible. Using the wet-on-wet technique, the two layers intertwine, eliminating abrupt interfaces and improving adhesion. The network film or coating can be cast directly onto the substrate simultaneously with the substrate in one step in a wet-on-wet process.

[0063] Use of the coating to form a separator In a preferred embodiment, the compositions of the present invention can withstand the harsh environment within a battery or any other electrochemical device and can be easily processed into a coating. When coated onto an electrode, the coating functions as an electrolyte / separator without the need for a separate separator base. The separator coating comprises particles of an electrochemically conductive lithium-based conductive material. Preferably, the lithium-based conductive nanoparticles comprise the greatest volume percent of the separator / electrolyte coating composition.

[0064] The conductive nanoparticles in the coating composition allow interstitial volume to form between them, thereby forming micropores and helping to maintain the physical shape of the spacer. Furthermore, the particles have the characteristic of not changing their physical properties even at high temperatures of 200°C or higher, so coated separators using these particles have excellent heat resistance. The inorganic particles can be in the form of particles or fibers. Mixtures of these are also contemplated.

[0065] Low density materials are preferred over high density materials as they can reduce the weight of the resulting battery.

[0066] In one embodiment, the particles or fibers may be surface treated chemically (such as by etching or functionalization), mechanically, or by irradiation (such as by plasma treatment).

[0067] The lithium-based particles are nano-sized, and if the pores are too large, they are more likely to develop internal short circuits during repeated charge / discharge cycles.

[0068] The lithium-based conductive particles are present in the coating composition at 20-95 wt. %, preferably 20-90 wt. %, based on the total weight of polymer solids and inorganic particles. If the inorganic content is less than 20 wt. %, the binder polymer is present in such a large amount that it reduces the interstitial volume formed between the inorganic particles, thus reducing pore size and porosity, resulting in poor battery quality.

[0069] The reticulated film composite can also be used as a catalyst support to provide a high surface area medium for catalytically driven reactions and improve catalytic efficiency. Catalysts can be incorporated into the reticulated film or deposited on it.

[0070] Casting Method The coating can be cast onto a solid substrate and then lifted off the substrate and placed onto the electrode, or it can be cast directly onto the electrode.

[0071] The coating composition can be applied to at least one surface of the electrode by means known in the art, such as by brush, roller, inkjet, dip, knife, gravure, wire, squeegee, foam applicator, curtain coating, vacuum coating, slot die, or spray. The coating is then dried on the electrode at room temperature or elevated temperature. The final dried coating thickness is preferably 1 to 200 μm, preferably 1 to 100 μm, and more preferably 2 to 50 μm.

[0072] The coated electrodes can be used to form electrochemical devices such as batteries, capacitors, electric double layer capacitors, membrane electrode assemblies (MEAs), or fuel cells by means known in the art. Non-aqueous batteries can be formed by placing a negative electrode and a positive electrode on either side of the coating. For example, if a cathode is coated, an anode can be placed next to the coating to form an anode-separator-coated cathode assembly.

[0073] Aspects of the present invention Aspect 1: A network coating or film comprising a) a resin and b) nanoparticles, The coating or film has an interconnected porous structure, the porous structure being 10% to 80% by volume of interconnected pores, the resin has a solution viscosity of about 100 cp to 10,000 cp, preferably 100 cp to 5000 cp (5 wt% for NMP, 2% water for aqueous polymers, room temperature), the nanoparticles are lithium-based and electrically conductive, and the surface area is 1 to 1000 m 2 / g of net coating or film. Aspect 2: The reticulated coating or film of aspect 1, wherein the average pore size is less than 500 nm, preferably less than 100 nm, and more preferably less than 50 nm. Aspect 3: The reticulated coating or film of aspect 1 or 2, wherein the resin is selected from the group consisting of polyvinylidene fluoride (PVDF), PVDF copolymers, polyethylene tetrafluoride ethylene (PETFE), polyvinyl fluoride (PVF), polyacrylate, polymethacrylate, polystyrene, polyvinyl alcohol (PVOH), polyester, polyamide, polyacrylonitrile, polyacrylamide, carboxymethyl cellulose CMC, polyacrylic acid (PAA), polymethacrylic acid (PMAA), and copolymers thereof, and combinations thereof. Aspect 4: The reticulated coating or film of any one of Aspects 1 to 3, wherein the resin comprises a homopolymer or copolymer of polyvinylidene fluoride. Aspect 5: The reticulated coating or film of any one of aspects 1 to 3, wherein the resin comprises polyacrylic acid. Aspect 6: The reticulated coating or film of any one of Aspects 1 to 3, wherein the resin comprises carboxymethyl cellulose. Aspect 7: The reticulated coating or film of any one of aspects 1 to 3, wherein the resin comprises polyacrylic acid and / or polymethacrylic acid. Aspect 8: The reticulated coating or film of any one of Aspects 1 to 7, wherein the nanoparticles are selected from the group consisting of: Li7La3Zr2O 12 (LLZO), Li3PS4(LSP), Li6PS5X (X=Cl, Br, or I) (lithium argyrodite), lithium phosphate nitride (Lipon), Li 2+2x Zn 1-x GeO4 (X=0.55) (LISICON type), Li 0.34 La 0.51 TiO3 (perovskite type), doped LLZO, or a mixture thereof. Aspect 9: The reticulated coating or film of any one of aspects 1 to 7, wherein the nanoparticles comprise LLZO. Aspect 10: The reticulated coating or film of any one of aspects 1 to 7, wherein the nanoparticles comprise LSP or LIPON. Aspect 11: The reticulated coating or film according to any one of aspects 1 to 10, wherein the weight percentage ratio of polymer to said nanoparticles is 80:20 to 10:90, preferably 70:30 to 20:80. Aspect 12: The surface area of ​​the nanoparticles is 1 to 700 m 2 / g, more preferably 1 to 600m 2 12. The network coating or film according to any one of aspects 1 to 11, wherein the network coating or film has a viscosity of 1000 MPa or less. Aspect 13: The reticulated coating or film according to any one of aspects 1 to 12, wherein the coating has a thickness of 1 to 300 μm, preferably 1 to 100 μm, and more preferably 2 to 50 μm. Aspect 14: The reticulated coating or film of any one of aspects 1 to 13, wherein the nanoparticles have a size of less than 500 nm, preferably less than 200 nm. Aspect 15: The reticulated coating or film of any one of aspects 1 to 13, wherein the nanoparticles are less than 100 nm in size. Aspect 16: A method of making a reticulated coating or film, said method comprising the steps of: a) providing a resin dissolved in a solvent, wherein the polymer has a molecular weight such that the solution viscosity is about 100 cp to 10,000 cp, preferably 100 cp to 5000 cp (5 wt % water for NMP or 2 wt % water for aqueous polymers, room temperature); b) providing nanoparticles, wherein the nanoparticles have a surface area of ​​1 to 1000 m 2 / g); c) combining the resin solution with the nanoparticles to form a slurry, wherein the ratio of weight percent of the polymer to weight percent of the nanoparticles is 80:20 to 5:95; d) casting the slurry to form a coating or film; e) drying the formed coating or film. Including, the coating or film after drying has a porous structure, the porous structure being 10% by volume to 80% by volume of interconnected pores; The slurry has a viscosity of 50 dynes / cm 2 ~5000 dynes / cm 2 , preferably 75 to 3000 dynes / cm 2 and the solid content of the slurry is 2 to 30% by weight, preferably 2 to 20% by weight. Aspect 17: The method of aspect 16, wherein the average pore size is less than 1000 nm. Aspect 18: The method of aspect 16, wherein the average pore size is less than 500 nm, more preferably less than 100 nm. Aspect 19: The method of any one of aspects 16 to 18, wherein the resin is selected from the group consisting of: polyvinylidene fluoride (PVDF), PVDF copolymer, polyethylene tetrafluoride ethylene (PETFE), polyvinyl fluoride (PVF), polyacrylate, polymethacrylate, polystyrene, polyvinyl alcohol (PVOH), polyester, polyamide, polyacrylonitrile, polyacrylamide, carboxymethyl cellulose CMC, polyacrylic acid (PAA), polymethacrylic acid (PMAA), and copolymers thereof, and combinations thereof. Aspect 20: The method of any one of Aspects 16 to 18, wherein the resin comprises a polyvinylidene fluoride homopolymer or copolymer. Aspect 21: The method of any one of Aspects 16 to 18, wherein the resin comprises polymethacrylate. Aspect 22: The method of any one of Aspects 16 to 18, wherein the resin comprises carboxymethyl cellulose. Aspect 23: The method according to any one of aspects 16 to 18, wherein the resin comprises polyacrylic acid and / or polymethacrylic acid. Aspect 24. The method of any one of Aspects 16 to 23, wherein the nanoparticles are selected from the group consisting of: Li7La3Zr2O 12 (LLZO), Li3PS4(LSP), Li6PS5X (X=Cl, Br, or I) (lithium argyrodite), lithium phosphate nitride (Lipon), Li 2+2x Zn 1-xGeO4 (X=0.55) (LISICON type), Li 0.34 La 0.51 TiO3 (perovskite type), doped LLZO, or a mixture thereof. Aspect 25: The method of any one of aspects 16 to 23, wherein the nanoparticles comprise LLZO. Aspect 26: The method of any one of Aspects 16 to 23, wherein the nanoparticles comprise LSP. Aspect 27: The method according to any one of aspects 16 to 26, wherein the solvent is selected from the group consisting of water, N-methyl-2-pyrrolidone (NMP), toluene, tetrahydrofuran (THF), acetone, and a hydrocarbon. Aspect 28: The method according to any one of aspects 16 to 26, wherein the solvent is selected from the group consisting of NMP, water, acetone, and combinations thereof, and preferably NMP. Aspect 29: The method according to any one of Aspects 16 to 26, wherein the solvent comprises water. Aspect 30: The method of any one of aspects 16 to 26, wherein the solvent comprises NMP. Aspect 31: The method of any one of Aspects 16 to 30, wherein the solids content of the formed slurry, including both the solvent and the nanoparticles, is 2 to 30%, preferably 2 to 15% by weight. Aspect 32: The method of any one of Aspects 16 to 30, wherein the solids content of the formed slurry, including both the solvent and the nanoparticles, is 2 to 12 wt %. Aspect 33: The method according to any one of Aspects 16 to 32, wherein the ratio of the weight percentage of the polymer to the weight percentage of the nanoparticles is 80:20 to 5:95, preferably 80:20 to 10:90. Aspect 34: The method of any one of Aspects 16 to 32, wherein the ratio of weight percentage of the polymer to weight percentage of the nanoparticles is 70:30 to 20:80. Side 35: The surface area of ​​the nanoparticles is 1 to 700 m 2 / g, more preferably 1 to 600m 2 The method according to any one of aspects 16 to 34, wherein the total weight of the polymer is 1 / g. Aspect 36: The method of any one of aspects 16 to 34, wherein the coating has a thickness of 1 to 300 μm, preferably 1 to 100 μm, and more preferably 2 to 50 μm. Aspect 37. The method of any one of Aspects 16 to 36, wherein the nanoparticles have a size of less than 500 nm, preferably less than 200 nm. Aspect 38: The method of any one of Aspects 16 to 36, wherein the nanoparticles have a size of less than 100 nm. Aspect 39: The method of any one of aspects 16 to 38, wherein the network film or coating is cast directly and simultaneously with the substrate in a single step of a wet-on-wet process. Aspect 40: A reticulated coating or film produced by the method of any one of aspects 16 to 39. Aspect 41: A battery comprising the coating or film of any one of aspects 1-15. Aspect 42: An article comprising the reticulated coating or film of any one of aspects 1 to 15, wherein the article is selected from the group consisting of an electrochemical device and a particulate filter.

[0074] Melt viscosity is 100s at 232°C according to ASTM method D-3835 -1 It is measured at

[0075] The particle size of the nanoparticles can be measured using a Malvern Masturizer 2000 particle size analyzer. Data is presented as weight average particle size (diameter).

[0076] Powder / latex average discrete particle size can be measured using a NICOMP™ 380 submicron particle sizer that uses laser light scattering. Data is presented as weight average particle size (diameter).

[0077] The density of the composite was calculated by dividing the weight of the composite by the volume of a particular sample. The composite was first cast onto aluminum foil, and then stamp-cut from the cast composite to obtain a surface area of ​​1.33 cm. 2 The samples were prepared. The thickness of the samples was measured with a micrometer with an accuracy of 0.1 μm. The weight of the composite was measured using an analytical balance, and the weight of the aluminum foil was subtracted. The density of the solid material was based on published literature values: PVDF polymer = 1.78 g / cm. 3 , PMMA = 1.13 g / cm 3 , CMC=1.6g / cm 3 is.

[0078] The BET specific surface area, pore volume, and pore size distribution of materials can be determined using a QUANTACHROMENOVA-E gas sorption apparatus. Nitrogen adsorption and desorption isotherms are generated at 77 K. Multipoint Brunauer-Emmett-Teller (BET) nitrogen adsorption methods are used to determine the specific surface area. Nonlocal Density Functional Theory (NLDFT, N2, 77 K, slit pore model) is used to determine the pore volume and pore size distribution.

[0079] Solution viscosity: ASTM 2857

[0080] Yield stress inverse calculation: Brookfield Viscometer DV-III Ultra, spindle CP52 calculation based on the Herschel-Bulkley model equation:

number

[0081] τ is the shear stress. To get viscosity, we need to divide by the shear rate. The calculation is:

number

[0082] In the formula, k is expressed in centipoise, so divide by 100 to get D / cm 2 Then we need to add τ° to it. Working backwards to calculate τ°, the equation becomes:

number

[0083] Example 1: Three different reticulated film composites of PVDF (Kynar) and LLZO with approximately 8% solids using NMP as the solvent. The PVDF to LLZO ratios are 50:50, 30:70, and 70:30. Porosity is determined by comparing the measured density to the solid density. The difference in density is due to porosity. [1 - (measured density / solid density)] x 100 = % porosity. A network-like film was formed. Porosity could be achieved using the method of the present invention. The porosity can be varied by adjusting the weight ratio of resin to nanoparticles.

[0084] Example 2: Reticulated film composites made from LLZO with PVDF (Kynar HSV-900), PMMA with RV=1.1, and LLZO with approximately 8% and 15% solids using NMP as the solvent. The PVDF to LLZO ratios are 50:50, 30:70, and 70:30, and the PMMA to LLZO ratios are 50:50, 30:70, and 70:30. Porosity is determined by comparing the measured density to the solid density. The difference in density is due to porosity. [1 - (measured density / solid density)] x 100 = % porosity. Reticulated films were formed using a variety of polymers, demonstrating the porosity that can be achieved using the method of the present invention. By adjusting the weight ratio of resin to nanoparticles, the porosity can be varied.

Claims

1. A network coating or film comprising: a) a resin and b) nanoparticles, The coating or film has an interconnected porous structure, the porous structure being 10% to 80% interconnected pores by volume, the resin has a solution viscosity of about 100 cp to 10,000 cp, preferably 100 cp to 5000 cp (5 wt % for NMP, 2% water for water-soluble polymers, room temperature), the nanoparticles are lithium-based and electrically conductive, and have a surface area of ​​1 to 1000 m 2 / g of a net coating or film.

2. 2. A reticulated coating or film according to claim 1, wherein the average pore size is less than 500 nm, preferably less than 100 nm, more preferably less than 50 nm.

3. 3. The reticulated coating or film of claim 1 or 2, wherein the resin is selected from the group consisting of: polyvinylidene fluoride (PVDF), PVDF copolymers, polyethylene tetrafluoride ethylene (PETFE), polyvinyl fluoride (PVF), polyacrylate, polymethacrylate, polystyrene, polyvinyl alcohol (PVOH), polyester, polyamide, polyacrylonitrile, polyacrylamide, carboxymethyl cellulose CMC, polyacrylic acid (PAA), polymethacrylic acid (PMAA), and copolymers thereof, and combinations thereof.

4. 3. The reticulated coating or film of claim 1 or 2, wherein the resin comprises a homopolymer or copolymer of polyvinylidene fluoride.

5. 3. The reticulated coating or film of claim 1 or 2, wherein the resin comprises polymethacrylate and / or carboxymethyl cellulose.

6. 3. The reticulated coating or film of claim 1 or 2, wherein the resin comprises polyacrylic acid.

7. 3. The network coating or film of claim 1 or 2, wherein the nanoparticles are selected from the group consisting of: Li 7 La 3 Zr 2 O 12 (LLZO), Li 3 P.S. 4 (LSP), Li 6 P.S. 5 X (X = Cl, Br, or I) (lithium argyrodite), lithium phosphate nitride (Lipon), Li 2+2x Zn 1-x GeO 4 (X=0.55) (LISICON system), Li 0.34 La 0.51 TiO 3 (perovskite-based), doped LLZO, or mixtures thereof.

8. 3. The reticulated coating or film of claim 1 or 2, wherein the nanoparticles comprise LLZO.

9. 3. The reticulated coating or film of claim 1 or 2, wherein the nanoparticles comprise LSP or LIPON.

10. 3. A reticulated coating or film according to claim 1 or 2, wherein the weight percentage ratio of polymer to said nanoparticles is between 80:20 and 10:90, preferably between 70:30 and 20:

80.

11. The surface area of ​​the nanoparticles is 1 to 700 m 2 / g, more preferably 1 to 600 m 2 11. The network coating or film of claim 10, wherein the tensile strength is 1 / g.

12. A net-like coating or film according to claim 1 or 2, wherein the coating has a thickness of from 1 to 300 μm, preferably from 1 to 100 μm, more preferably from 2 to 50 μm.

13. 3. A reticulated coating or film according to claim 1 or 2, wherein the nanoparticles have a size of less than 500 nm, preferably less than 200 nm.

14. 1. A method of making a reticulated coating or film, said method comprising the steps of: a) providing a resin dissolved in a solvent, wherein the polymer has a molecular weight such that the solution viscosity is about 100 cp to 10,000 cp, preferably 100 cp to 5000 cp (5 wt % in NMP or 2 wt % water for aqueous polymers, at room temperature); b) providing nanoparticles, wherein the nanoparticles have a surface area of ​​1 to 1000 m 2 / g); c) combining the resin solution with the nanoparticles to form a slurry, wherein the ratio of weight percent of the polymer to weight percent of the nanoparticles is between 80:20 and 5:95; d) casting the slurry to form a coating or film; e) drying the formed coating or film. Including, the coating or film after drying has a porous structure, the porous structure being 10% to 80% by volume of interconnected pores; The slurry has a viscosity of 50 dynes / cm 2 ~5000 dynes / cm 2 , preferably 75 to 3000 dynes / cm 2 and the solids content of the slurry is 2 to 30 wt% solids, preferably 2 to 20 wt% solids.

15. 15. The method of claim 14, wherein the resin is selected from the group consisting of: polyvinylidene fluoride (PVDF), PVDF copolymers, polyethylene tetrafluoride ethylene (PETFE), polyvinyl fluoride (PVF), polyacrylate, polymethacrylate, polystyrene, polyvinyl alcohol (PVOH), polyester, polyamide, polyacrylonitrile, polyacrylamide, carboxymethyl cellulose CMC, polyacrylic acid (PAA), polymethacrylic acid (PMAA), and copolymers thereof, and combinations thereof.

16. The method of claim 14 , wherein the resin comprises a homopolymer or copolymer of polyvinylidene fluoride.

17. 16. The method of claim 14 or 15, wherein the average pore size is less than 1000 nm, more preferably less than 500 nm.

18. 16. The method of claim 14 or 15, wherein the nanoparticles are selected from the group consisting of: Li 7 La 3 Zr 2 O 12 (LLZO), Li 3 P.S. 4 (LSP), Li 6 P.S. 5 X (X = Cl, Br, or I) (lithium argyrodite), lithium phosphate nitride (Lipon), Li 2+2x Zn 1-x GeO 4 (X=0.55) (LISICON system), Li 0.34 La 0.51 TiO 3 (perovskite-based), doped LLZO, or mixtures thereof.

19. 16. The method of claim 14 or 15, wherein the solids content of the formed slurry, including both the solvent and the nanoparticles, is 2-15 wt %.

20. 16. The method of claim 14 or 15, wherein the network film or coating is cast directly and simultaneously with the substrate in one step in a wet-on-wet process.

21. A battery comprising the reticulated coating or film of any one of claims 1 to 13.

22. An article comprising the reticulated coating or film on any one of sides 1-13, wherein the article is an electrochemical device.

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