Coated microporous membranes, and battery separators, batteries, vehicles, and devices containing the same

Abstract

Disclosed herein are battery separators comprising microporous membranes and coatings. The coatings can comprise, consist of, or consist essentially of polymeric components, inorganic components, or combinations thereof. The battery separators described herein are, among other things, thinner, stronger, and more electrolyte wettable than some conventional battery separators. The battery separators can be used in secondary or rechargeable batteries, including lithium-ion batteries. The batteries can be used in vehicles or devices, such as cell phones, tablets, laptops, and electronic vehicles.

Description

[Technical Field]

[0001] Priority This application claims priority to U.S. Provisional Patent Application No. 62 / 788,200, filed January 4, 2019, which is incorporated herein by reference in its entirety.

[0002] The present disclosure or invention relates to coated microporous membranes or films, and more particularly to coated microporous membranes or films used as battery separators, textiles, filters, and the like.

[0003] In at least one aspect, a battery separator is disclosed that includes a microporous membrane having a coating on one or both sides thereof. The coating can comprise, consist of, or consist essentially of an inorganic component and at least one of the following: a wet adhesive polymer and a dry adhesive polymer. In some preferred embodiments, the coating is on only one side of the microporous membrane, and in some other preferred embodiments, the coating is on both sides of the microporous membrane.

[0004] In at least some embodiments, the coating can comprise, consist of, or consist essentially of an inorganic component and a wet adhesive polymer. In some embodiments, the coating comprising, consisting of, or consisting essentially of an inorganic component and a wet adhesive polymer is "inorganic-rich," or comprises, consists of, or consists essentially of 50% to 80% inorganic components. In some embodiments, the coating comprising, consisting of, or consisting essentially of an inorganic component and a wet adhesive polymer is "polymer-rich," or comprises, consists of, or consists essentially of 10% to less than 50% inorganic components.

[0005] In at least selected embodiments where the coating comprises, consists of, or consists essentially of an inorganic component and a wet adhesion polymer, the electrolyte wettability of the coating is a contact angle <35°, or in some embodiments, a contact angle <30°. Polymer-rich coatings may exhibit contact angles <35°, while inorganic-rich coatings may exhibit contact angles <30°.

[0006] In at least certain embodiments, when the coating comprises, consists of, or consists essentially of an inorganic component and a wet adhesion polymer, the wet adhesion polymer is a fluoropolymer such as PVDF or PVDF-HFP.

[0007] In at least selected embodiments, the coating comprises, consists of, or consists essentially of an inorganic component and a wet adhesive polymer. In some preferred embodiments, the inorganic component and the wet adhesive polymer have similar particle sizes, or the inorganic component has a larger average particle size compared to the wet adhesive polymer when the coating is dry. When the coating is wet with an electrolyte, in some embodiments, the wet adhesive polymer swells or grows, causing the average particle size of the wet adhesive polymer to become larger than the average particle size of the inorganic component.

[0008] In at least certain embodiments, the coating comprises, consists of, or consists essentially of an inorganic component and a dry adhesive polymer. In some embodiments, the dry adhesive polymer has a glass transition temperature of less than 100° C., less than 90° C., less than 80° C., or less than 70° C. In some preferred embodiments, the dry adhesive polymer has a glass transition temperature of 30° C. to 80° C., 40° C. to 70° C., 40° C. to 65° C., 45° C. to 60° C., 45° C. to 55° C., or 45° C. to 50° C.

[0009] In at least selected embodiments, the coating comprises an inorganic component, a dry adhesive polymer, and a wet adhesive polymer, in some embodiments the coating is inorganic-rich, while in other embodiments the coating is polymer-rich. [Background technology]

[0010] As technological demands for lighter, longer-lasting, and thinner batteries increase, so do the demands on the thickness, safety, performance, quality, and manufacturing of battery separators. Various techniques have been developed to improve the performance characteristics of membranes or porous substrates used as separators in lithium batteries. One area of ​​focus is the application of various coatings to the surface of battery separators to improve one or more performance characteristics of the separator. Such coatings can be applied using a variety of techniques, including dip coating, knife coating, gravure coating, curtain coating, and spray coating. Summary of the Invention [Problem to be solved by the invention]

[0011] Coating developments are also focused on improving battery safety, particularly preventing thermal runaway in lithium-ion batteries. For example, abusive conditions such as overcharging, deep discharging, and internal short circuits can lead to battery temperatures far exceeding safe operating temperatures. Because lithium-ion battery electrolytes are often non-aqueous, these liquids can combust at high temperatures, potentially causing violent self-destruction of the battery if left unchecked. Battery shutdown, i.e., the cessation of ion flow across the separator between the anode and cathode, is a safety mechanism used to prevent thermal runaway. Improved separators for certain lithium-ion batteries should provide the ability to shut down ion flow at temperatures at least slightly below the temperature at which thermal runaway occurs, while maintaining mechanical properties. Faster shutdown at lower temperatures and for longer periods, giving the user or device additional time to power down the system, is highly desirable.

[0012] Another safety and efficiency issue for lithium-ion batteries is short circuits (hard or soft) that occur when electrodes come into contact with each other. Hard shorts can occur when electrodes come into direct contact with each other, or when large or multiple lithium dendrites grow from the anode and contact the cathode. A hard short results in a rapid increase in temperature, which, if left unchecked, can quickly turn into a thermal runaway event. Soft shorts can occur when small or limited lithium dendrites grow from the anode and contact the cathode. Soft shorts can reduce the cycling efficiency of the battery. While conventional ceramic-coated separators often demonstrate effectiveness in preventing hard and soft shorts, they can have limitations. Therefore, there is a continuing need to improve the safety and performance of separators and separator coatings. [Means for solving the problem]

[0013] In at least selected embodiments, objects, or aspects, the present invention or disclosure may address the above-mentioned needs, desires, or problems, and / or may provide or disclose new or improved coated microporous membranes, porous substrates, base membranes, or thin films, and / or may provide or disclose new or improved coated microporous membranes, porous substrates, base membranes, or thin films, and / or may provide or disclose new or improved coatings, thin coatings, ultra-thin coatings, or nanocoatings, more particularly for use as battery separators, textiles, filters, and the like.

[0014] Disclosed herein are various new or improved coated microporous membranes that can be used as battery separators in secondary batteries, such as, for example, lithium-ion batteries. The coated microporous membranes disclosed herein solve many of the aforementioned problems encountered when fabricating and operating secondary batteries in which the battery separator comprises, consists of, or consists essentially of a coated microporous membrane.

[0015] In at least one aspect, a battery separator is disclosed that includes a microporous membrane having a coating on one or both sides thereof. The coating can comprise, consist of, or consist essentially of an inorganic component and at least one of the following: a wet adhesive polymer and a dry adhesive polymer. In some preferred embodiments, the coating is on only one side of the microporous membrane, and in some other preferred embodiments, the coating is on both sides of the microporous membrane.

[0016] In at least some embodiments, the coating can comprise, consist of, or consist essentially of an inorganic component and a wet adhesive polymer. In some embodiments, the coating comprising, consisting of, or consisting essentially of an inorganic component and a wet adhesive polymer is "inorganic-rich," or comprises, consists of, or consists essentially of 50%-80% inorganic component. In some embodiments, the coating comprising, consisting of, or consisting essentially of an inorganic component and a wet adhesive polymer is "polymer-rich," or comprises, consists of, or consists essentially of less than 10-50% inorganic component.

[0017] In at least selected embodiments where the coating comprises, consists of, or consists essentially of an inorganic component and a wet adhesion polymer, the electrolyte wettability of the coating is a contact angle <35°, or in some embodiments, a contact angle <30°. Polymer-rich coatings may exhibit contact angles <35°, while inorganic-rich coatings may exhibit contact angles <30°.

[0018] In at least certain embodiments, when the coating comprises, consists of, or consists essentially of an inorganic component and a wet adhesion polymer, the wet adhesion polymer is a fluoropolymer such as PVDF or PvdF.

[0019] In at least selected embodiments, the coating comprises, consists of, or consists essentially of an inorganic component and a wet adhesive polymer. In some preferred embodiments, the inorganic component and the wet adhesive polymer have similar particle sizes, or the inorganic component has a larger average particle size compared to the wet adhesive polymer when the coating is dry. When the coating is wet with electrolyte, in some embodiments, the wet adhesive polymer swells or grows, causing the average particle size of the wet adhesive polymer to become larger than the average particle size of the inorganic component.

[0020] In at least certain embodiments, the coating comprises, consists of, or consists essentially of an inorganic component and a dry adhesive polymer. In some embodiments, the dry adhesive polymer has a glass transition temperature of less than 100° C., less than 90° C., less than 80° C., or less than 70° C. In some preferred embodiments, the dry adhesive polymer has a glass transition temperature of 30° C. to 80° C., 40° C. to 70° C., 40° C. to 65° C., 45° C. to 60° C., 45° C. to 55° C., or 45° C. to 50° C.

[0021] In at least selected embodiments, the coating comprises an inorganic component, a dry adhesive polymer, and a wet adhesive polymer, in some embodiments the coating is inorganic-rich, while in other embodiments the coating is polymer-rich.

[0022] In at least some embodiments, the coating comprises, consists of, or consists essentially of an inorganic component and at least one of a dry adhesive polymer and a wet adhesive polymer, and the coating has a thickness of less than 5 microns, less than 3 microns, or 1 micron or less. In some preferred embodiments, the coating has a thickness of less than 5 microns, less than 3 microns, or 1 micron or less, and the inorganic component, dry adhesive polymer, and / or wet adhesive polymer has an average particle size of 200-600 nm, 200-500 nm, 300-500 nm, 200-400 nm, or 200-300 nm.

[0023] In at least selected embodiments, the coating of a battery separator comprises, consists of, or consists essentially of an inorganic component and at least one of a dry adhesive polymer and a wet adhesive polymer, and the coating exhibits at least one of a wet adhesion greater than 30 N / m, a dry adhesion greater than 16 N / m, and an electrolyte absorption of greater than or equal to 2 g / sample after 60 minutes.

[0024] In at least one embodiment, a battery separator is disclosed having a coating on one or both sides of a microporous membrane, the coating comprising, consisting of, or consisting essentially of a polymer that at least one of reduces the surface coefficient of friction of the microporous membrane and reduces the shutdown onset temperature of the microporous membrane.

[0025] In at least selected embodiments, a battery separator is disclosed or provided, comprising a coating on one or both surfaces of a microporous membrane, the coating comprising a polymer that at least one of reduces the coefficient of surface friction of the microporous membrane and reduces the shutdown onset temperature of the microporous membrane. For example, the coated microporous membrane exhibits a lower coefficient of surface friction and / or a lower shutdown onset temperature compared to an uncoated microporous membrane (i.e., a microporous membrane without a coating on one or both surfaces). In some embodiments, the coating comprises, consists of, or consists essentially of the aforementioned polymer and inorganic component. In some embodiments, the aforementioned polymer that at least one of reduces the coefficient of surface friction of the microporous membrane and reduces the shutdown onset temperature of the microporous membrane has a melting temperature within the range of 100°C to 130°C, 110°C to 130°C, 120°C to 130°C, or 120°C to 125°C. In some embodiments, the polymer is polyethylene, including polyethylene, having a melting point within the aforementioned range. In some embodiments, the polymer is included in the coating as polymer beads.

[0026] In at least certain embodiments, the battery separator comprising a coating of a polymer that reduces the shutdown onset temperature of the microporous membrane exhibits a shutdown onset temperature of ≦160° C., ≦150° C., ≦140° C., ≦130° C., ≦120° C., ≦110° C., ≦100° C., ≦90° C., or ≦80° C. In some embodiments, the battery separator comprising a coating of a polymer that reduces the surface coefficient of friction exhibits a pin removal force of less than 350 N, less than 300 N, less than 250 N, less than 200 N, less than 150 N, or less than 100 N.

[0027] In at least another aspect, a battery separator is disclosed having a coating on one or both sides of a microporous membrane, the coating comprising, consisting of, or consisting essentially of a crosslinked or crosslinkable polymer. In some embodiments, the crosslinked or crosslinkable polymer is or comprises a trifunctional or multifunctional acrylate. In some embodiments, the crosslinked or crosslinkable polymer is a thermosetting polymer. In some embodiments, the crosslinked or crosslinkable polymer comprises a diepoxide, triepoxide, or multiepoxide monomer. In some embodiments, the coating comprises, consists of, or consists essentially of a crosslinked or crosslinkable polymer and an inorganic component. In some preferred embodiments, the coating is free of inorganic components and comprises only a crosslinked or crosslinkable polymer.

[0028] In at least some embodiments, the battery separator with a coating comprising, consisting of, or consisting essentially of a crosslinked polymer exhibits reduced cracking susceptibility when subjected to a puncture split test compared to the microporous membrane by itself (uncoated). In some embodiments, the battery separator with a coating comprising, consisting of, or consisting essentially of a crosslinked polymer exhibits a reduced standard deviation in TD elongation compared to the microporous membrane by itself (uncoated). In some embodiments, the battery separator with a coating comprising, consisting of, or consisting essentially of a crosslinked polymer exhibits a reduced MD shrinkage (%) measured at 130°C for 1 hour compared to the microporous membrane by itself (uncoated). In some embodiments, the battery separator with a coating comprising, consisting of, or consisting essentially of a crosslinked polymer exhibits an extended shutdown compared to the microporous membrane by itself (uncoated). In some embodiments, the battery separator with a coating comprising, consisting of, or consisting essentially of a crosslinked polymer exhibits an increased TD tensile compared to the microporous membrane by itself (uncoated). In some embodiments, the battery separator with a coating comprising, consisting of, or consisting essentially of a crosslinked polymer exhibits increased loading compared to the microporous membrane by itself (uncoated). In some embodiments, the battery separator with a coating comprising, consisting of, or consisting essentially of a crosslinked polymer exhibits reduced electrolyte loss (e.g., 1% reduction, 2% reduction, 3% reduction, 4% reduction) or slows electrolyte evaporation (improving electrolyte retention) compared to the microporous membrane by itself (uncoated). In some embodiments, the battery separator with a coating comprising, consisting of, or consisting essentially of a crosslinked polymer has an incremental thickness of 300 nm or less than the microporous membrane by itself (uncoated).In some embodiments, the thickness is in increments of 200 nm or less, in increments of 100 nm or less, or in increments of 50 nm or less.

[0029] In at least another aspect, a separator is disclosed that includes a porous substrate having a first surface and an oppositely facing second surface, and a coating disposed on the first surface, the second surface, or both the first and second surfaces, the coating including a first layer having a first density and a second layer having a second density, the first density and the second density being different from one another. In some embodiments, the density of the first layer is at most 1.3 g / cm. 3 , or 0.1 g / cm 3 ~1.3g / cm 3 In some embodiments, the second layer has a density of at least 1.3 g / cm 3 and in some embodiments the second layer has a density of 1.3 g / cm 3 ~3g / cm 3 In some embodiments, the first layer is disposed closest to the surface of the porous substrate, and in some embodiments, the second layer is disposed closest to the surface of the porous substrate. When the first layer is disposed closest to the surface of the porous substrate, the second layer can be disposed on top of the first layer. When the second layer is disposed closest to the surface of the porous substrate, the first layer can be disposed on top of the second layer. In embodiments, when the first layer is disposed on top of the second layer, or when the second layer is disposed on top of the first layer of a two-layer coating, the coverage of the layer disposed on top of the other layer is at least 80% coverage of the underlying layer. In some preferred embodiments, the coverage is at least 85%, at least 90%, at least 95%, or 100%.

[0030] In some preferred embodiments, at least 1.3 g / cm 3 The second layer, having a density of up to 1.3 g / cm, is positioned closest to the surface of the porous substrate. 3A first layer having a density of 0.1 to 0.9 microns is disposed on the first layer. The first layer may form a continuous layer covering at least 80% of the surface of the second layer. In some embodiments, the second layer comprises, consists of, or consists essentially of an inorganic component; in some embodiments, the second layer may comprise, consist of, or consist essentially of an inorganic component and an organic component. In some embodiments, the second layer comprises at least 50% of the inorganic component. In some embodiments, the first layer comprises, consists of, or consists essentially of an organic component; in some embodiments, the first layer may comprise, consist of, or consist essentially of an organic component and an inorganic component. In some embodiments, the first layer may comprise at least 50% of the organic component. In some embodiments, the first layer is 0.1 to 0.9 microns thick, preferably 0.1 to 0.7 microns thick, and most preferably 0.1 to 0.5 microns thick.

[0031] In at least certain embodiments, the organic component comprises, consists of, or consists essentially of methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, sec-butyl methacrylate, pentyl methacrylate, 2-ethylbutyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, isooctyl methacrylate, isononyl methacrylate, lauryl methacrylate, tetradecyl methacrylate, polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF:HFP), polytetrafluoroethylene (PTFE), polyethylene oxide. (PEO), poly(vinyl alcohol) (PVA), polyacrylonitrile (PAN), polyacrylamide, polyvinyl acetate, polyvinylpyrrolidone, polytetraethylene glycol diacrylate, polypropylene (PP) including isotactic PP, high density PP, ultra-high molecular weight PP, and low density PP, polyethylene (PE) including high density PE, ultra-high molecular weight PE, and low density PE, polyvinyl acetate, polyvinyl chloride, bisphenol A polycarbonate (BPA-PC), cycloolefin copolymer (COC), polysulfone (PSF), polyetherimide (PEI), polyurethane, acrylonitrile butadiene styrene (ABS), polyimide, polyamide, copolymer of any of the foregoing, or any combination thereof.

[0032] In at least selected embodiments, the inorganic component comprises, consists of, or consists essentially of a ceramic, a metal oxide, a metal hydroxide, a metal carbonate, a silicate, kaolin, talc, a mineral, a glass, or any combination thereof. In some embodiments, the inorganic component comprises, consists of, or consists essentially of aluminum oxide (Al2O3), boehmite (Al(O)(OH)), titanium oxide (TiO2), silicon oxide (SiO2), zinc oxide (ZnO2), zirconium dioxide (ZrO2), barium sulfate (BaSO4), barium titanium oxide (BaTiO3), aluminum nitride, silicon nitride, calcium fluoride, barium fluoride, zeolite, apatite, kaolin, mullite, spinel, olivine, mica, tin dioxide (SnO2), indium tin oxide, an oxide of a transition metal, or any combination thereof.

[0033] In at least some embodiments, the porous or microporous substrate or membrane (or base membrane or thin film) used in any of the embodiments described herein is most preferably a single-layer, two-layer, three-layer, or multi-layer dry-process membrane. In some embodiments, the porous substrate or microporous membrane comprises a polyolefin. The polyolefin may comprise, consist of, or consist essentially of polypropylene, polypropylene blends, polypropylene copolymers, polyethylene, polyethylene blends, polyethylene copolymers, or any combination thereof. In some embodiments, the porous substrate or microporous membrane may be a two-layer, three-layer, or multi-layer dry-process membrane, with each layer comprising the same or a different polyolefin composition as the other layers of the porous substrate or microporous membrane.

[0034] Dry-process microporous membranes or porous substrates are most preferred, although other polymer membrane types may also be used, such as Celgard® dry-stretched process polyolefin membrane products from Celgard, Inc., Charlotte, North Carolina, USA, wet-process, particle-stretched, BNBOPP, and the like.

[0035] In some embodiments, the microporous membrane or porous substrate has an average pore size of 0.01 nm to 1 μm.

[0036] In at least certain embodiments, additives are added to the porous substrate or microporous membrane, and the additives can comprise, consist of, or consist essentially of functionalized polymers, ionomers, cellulose nanofibers, inorganic particles, lubricants, nucleating agents, cavitation enhancers, fluoropolymers, crosslinking agents, X-ray detectable materials, polymer treatments, high temperature melt index (HTMI) polymers, electrolyte additives, energy dissipative immiscible additives, or any combination thereof.

[0037] In one embodiment, a method of making a separator having coatings of different densities is described, the method comprising coating a first surface, an opposing second surface, or both the first and second surfaces of a porous substrate with a first layer and a second layer, the first layer having a first density and the second layer having a second density different from the first density.

[0038] In another aspect, a battery separator is disclosed. The battery separator can comprise, consist of, or consist essentially of: a porous substrate having a first surface and an opposite-facing second surface; and a coating disposed on the first surface, the second surface, or both the first and second surfaces of the porous substrate, the coating comprising an inorganic component and an adhesive polymer. In some embodiments, the adhesive polymer can be selected from a "dry adhesive" polymer having a glass transition temperature below 100°C, preferably below 70°C, a "wet adhesive" polymer that swells and gels in a non-aqueous electrolyte, or a combination thereof. In some embodiments, the adhesive polymer is a "wet adhesive" polymer that comprises, consists of, or consists essentially of a fluoropolymer.

[0039] In some embodiments, the adhesive polymer has a first size when dry and a second size when wet with electrolyte, the first size being smaller than the second size. In some embodiments, the adhesive polymer swells from the first size to the second size upon absorbing electrolyte. In some embodiments, the battery separator described herein has inorganic components that extend or protrude further outward from the first and / or second surface when dry, and when the battery separator is wet with electrolyte, the adhesive polymer swells from the first size to the second size, thereby extending further outward from the first and / or second surface of the substrate than the inorganic components. In some embodiments, the swollen adhesive polymer covers the inorganic components, and the inorganic components are not exposed at the surface of the battery separator. In some embodiments, the inorganic components are substantially covered by the swollen adhesive polymer. In some embodiments, both the inorganic component and the adhesive polymer are exposed on the first and / or second surface of the substrate when the separator is dry, and only the adhesive polymer is exposed when the separator is wet.

[0040] The inorganic component can include, consist of, or consist essentially of ceramic, metal oxide, metal hydroxide, metal carbonate, silicate, kaolin, talc, mineral, glass, or any combination thereof. In some cases, the inorganic component can include, consist of, or consist essentially of aluminum oxide (Al2O3), boehmite (Al(O)(OH)), titanium oxide (TiO2), silicon oxide (SiO2), zinc oxide (ZnO2), zirconium dioxide (ZrO2), barium sulfate (BaSO4), barium titanium oxide (BaTiO3), aluminum nitride, silicon nitride, calcium fluoride, barium fluoride, zeolite, apatite, kaolin, mullite, spinel, olivine, mica, tin dioxide (SnO2), indium tin oxide, oxides of transition metals, or any combination thereof.

[0041] In some embodiments, the adhesive polymer is selected from the group consisting of methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, sec-butyl methacrylate, pentyl methacrylate, 2-ethylbutyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, isooctyl methacrylate, isononyl methacrylate, lauryl methacrylate, tetradecyl methacrylate, polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF:HFP), polytetrafluoroethylene (PTFE), polyethylene oxide (PEO), poly(vinyl alcohol) (PVA), poly The polymer may comprise, consist of, or consist essentially of acrylonitrile (PAN), polyacrylamide, polyvinyl acetate, polyvinylpyrrolidone, polytetraethylene glycol diacrylate, polypropylene (PP) including isotactic PP, high density PP, ultra-high molecular weight PP, and low density PP, polyethylene (PE) including high density PE, ultra-high molecular weight PE, and low density PE, polyvinyl acetate, polyvinyl chloride, bisphenol A polycarbonate (BPA-PC), cycloolefin copolymer (COC), polysulfone (PSF), polyetherimide (PEI), polyurethane, acrylonitrile butadiene styrene (ABS), polyimide, polyamide, copolymer of any of the foregoing, or any combination thereof.

[0042] In some embodiments, the coating has a thickness of 0.1 to 0.9 microns, in some embodiments, the coating has a thickness of 0.1 to 0.7 microns, in some embodiments, the coating has a thickness of 0.1 to 0.5 microns.

[0043] In another aspect, disclosed herein is a battery separator that can comprise, consist of, or consist essentially of: a porous substrate having a first surface and an opposite-facing second surface, and a coating disposed on the first surface, the second surface, or both the first and second surfaces of the porous substrate, the coating comprising an electrolyte-absorbing material.

[0044] In some embodiments, the coating further comprises a first heat-activated polymer disposed on the electrolyte-absorbing material, encapsulated between the first heat-activated polymer and the porous substrate.

[0045] In some other embodiments, the electrolyte-absorbing material is substantially encapsulated within a plurality of polymer microcapsules, the microcapsules comprising a first heat-activated polymer, and in some embodiments, the coating further comprises a second heat-activated polymer overlying the layer of microencapsulated electrolyte-absorbing material.

[0046] In some embodiments, the first heat-activated polymer has a melting point of 80° C. to 200° C., 80° C. to 150° C., 80° C. to 140° C., 80° C. to 130° C., 80° C. to 120° C., 80° C. to 110° C., 80° C. to 100° C., or 80° C. to 90° C. In some embodiments, the electrolyte-absorbing material is not coated upon melting of the first heat-activated polymer and can absorb electrolyte.

[0047] In some embodiments, when a second heat-activated polymer is used, the first heat-activated polymer has a melting point between 80° C. and 200° C. and the second heat-activated polymer has a lower melting point. In these embodiments, the electrolyte-absorbing material is exposed upon melting of the first and second heat-activated polymers.

[0048] In some embodiments, the electrolyte-absorbing material comprises, consists of, or consists essentially of aluminum oxide (Al2O3), boehmite (Al(O)(OH)), titanium oxide (TiO2), silicon oxide (SiO2), zinc oxide (ZnO2), zirconium dioxide (ZrO2), barium sulfate (BaSO4), barium titanium oxide (BaTiO3), aluminum nitride, silicon nitride, calcium fluoride, barium fluoride, zeolite, apatite, kaolin, mullite, spinel, olivine, mica, tin dioxide (SnO2), indium tin oxide, transition metal oxide, ceramic, metal oxide, metal hydroxide, metal carbonate, silicate, kaolin, talc, mineral, glass, or any combination thereof. In some embodiments, the electrolyte-absorbing material has a high porosity of 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, or 90% or more.

[0049] In some embodiments, the first heat-activatable polymer is selected from the group consisting of methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, sec-butyl methacrylate, pentyl methacrylate, 2-ethylbutyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, isooctyl methacrylate, isononyl methacrylate, lauryl methacrylate, tetradecyl methacrylate, polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF:HFP), polytetrafluoroethylene (PTFE), polyethylene oxide (PEO), poly(vinyl alcohol) (PVA), The polymer may comprise, consist of, or consist essentially of polyacrylonitrile (PAN), polyacrylamide, polyvinyl acetate, polyvinylpyrrolidone, polytetraethylene glycol diacrylate, polypropylene (PP) including isotactic PP, high density PP, ultra-high molecular weight PP, and low density PP, polyethylene (PE) including high density PE, ultra-high molecular weight PE, and low density PE, polyvinyl acetate, polyvinyl chloride, bisphenol A polycarbonate (BPA-PC), cycloolefin copolymer (COC), polysulfone (PSF), polyetherimide (PEI), polyurethane, acrylonitrile butadiene styrene (ABS), polyimide, polyamide, copolymer of any of the foregoing, or any combination thereof.

[0050] In some embodiments, the second heat-activatable polymer is selected from the group consisting of methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, sec-butyl methacrylate, pentyl methacrylate, 2-ethylbutyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, isooctyl methacrylate, isononyl methacrylate, lauryl methacrylate, tetradecyl methacrylate, polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF:HFP), polytetrafluoroethylene (PTFE), polyethylene oxide (PEO), poly(vinyl alcohol) (PVA), The polymer may comprise, consist of, or consist essentially of polyacrylonitrile (PAN), polyacrylamide, polyvinyl acetate, polyvinylpyrrolidone, polytetraethylene glycol diacrylate, polypropylene (PP) including isotactic PP, high density PP, ultra-high molecular weight PP, and low density PP, polyethylene (PE) including high density PE, ultra-high molecular weight PE, and low density PE, polyvinyl acetate, polyvinyl chloride, bisphenol A polycarbonate (BPA-PC), cycloolefin copolymer (COC), polysulfone (PSF), polyetherimide (PEI), polyurethane, acrylonitrile butadiene styrene (ABS), polyimide, polyamide, copolymer of any of the foregoing, or any combination thereof.

[0051] In some embodiments, the porous substrate comprises a monolayer, bilayer, trilayer, or multilayer dry-stretched process membrane. The porous substrate may comprise a polyolefin. The polyolefin may comprise, consist of, or consist essentially of polypropylene, polypropylene blends, polypropylene copolymers, polyethylene, polyethylene blends, polyethylene copolymers, or any combination thereof. In some embodiments, the porous substrate comprises a bilayer, trilayer, or multilayer dry-process membrane, each layer comprising, consisting of, or consisting essentially of the same or different polyolefin composition as the other layers of the porous substrate.

[0052] In another aspect, a method for self-protecting a battery against a thermal event is disclosed. The method may include, consist of, or consist essentially of: melting a first heat-activated polymer in a battery separator in a battery environment to uncover an electrolyte-absorbing material, the battery separator being the battery separator described above. In some embodiments, the uncovered electrolyte-absorbing material is exposed to electrolyte present in the battery environment. In some embodiments, the exposed electrolyte-absorbing material absorbs the electrolyte.

[0053] In some embodiments of the methods disclosed herein, the first heat-activated polymer and the electrolyte-absorbing material are disposed between a second heat-activated polymer and the porous substrate, and in some embodiments, the second heat-activated polymer has the same or a different composition as the first heat-activated polymer.

[0054] In some embodiments, the second heat-activated polymer can have a melting point lower than that of the first heat-activated polymer. The second heat-activated polymer can be melted first to expose the underlying first heat-activated polymer capable of encapsulating the electrolyte-absorbing material. In some embodiments, the first heat-activated polymer can be melted after the second heat-activated polymer is melted to expose the electrolyte-absorbing material.

[0055] In another aspect, a method is disclosed herein, the method comprising, consisting of, or consisting essentially of: melting the second heat-activatable polymer to form an electrolyte solution absorbing barrier on the surface of the porous substrate, in some embodiments, the second heat-activatable polymer encapsulates at least a portion of the uncoated electrolyte solution of the uncoated electrolyte solution-absorbing material upon melting.

[0056] In another aspect, a secondary battery is disclosed that includes any of the battery separators described herein. The secondary battery can be a lithium ion battery. The secondary battery can be a cylindrical, prismatic, stacked, or pouch battery.

[0057] In another aspect, a vehicle or device is disclosed that includes the secondary battery described herein, wherein the vehicle or device can be at least one selected from a mobile phone, a laptop, a tablet, an electronic vehicle, and a hybrid vehicle. [Brief explanation of the drawings]

[0058] [Figure 1] FIG. 1 is a cross-sectional view of a porous substrate with a coating on one side. [Figure 2] FIG. 2 is a cross-sectional view of a porous substrate having a first layer on both sides. [Figure 3] FIG. 3 is a cross-sectional view of a porous substrate having a second layer on each side. [Figure 4] FIG. 4 is a cross-sectional view of a porous substrate with a coating on both sides. [Figure 5] FIG. 5 is a cross-sectional view of a porous substrate with a coating on both sides. [Figure 6] FIG. 6 is a cross-sectional view of a porous substrate having a coating on one side and a first layer on the other side. [Figure 7] FIG. 7 is a cross-sectional view of a porous substrate having a coating on one side and a second layer on the other side. [Figure 8] FIG. 8 is a cross-sectional view of a porous substrate having a coating on one side and a first layer on the other side. [Figure 9] FIG. 9 is a cross-sectional view of a porous substrate having a coating on one side and a second layer on the other side. [Figure 10] FIG. 10 is a cross-sectional view of a porous substrate having a first coating on one side and a second coating on the other side. [Figure 11A]FIG. 11A is a cross-sectional view of a porous substrate having a coating on one side, the coating in a dry state. [Figure 11B] FIG. 11B is a cross-sectional view of a porous substrate having the coating of FIG. 11A on one side, the coating in a wet state. [Figure 12] FIG. 12 is a cross-sectional view of a porous substrate having a first thermally active polymer layer disposed between a second thermally active polymer layer and the porous substrate. [Figure 13] FIG. 13 is a cross-sectional view of a porous substrate having a coating on one side thereof, the coating being an electrolyte-absorbing material substantially encapsulated within a plurality of polymer microcapsules. [Figure 14] FIG. 14 is a cross-sectional view of the porous substrate depicted in FIG. 13 further including a second heat-activatable polymer coating the microencapsulated electrolyte-absorbing material. [Figure 15] FIG. 15 is a schematic diagram of a coated separator according to some embodiments described herein. [Figure 16] FIG. 16 shows cross-sectional and surface SEM images of a separator with a coating according to some embodiments described herein. [Figure 17] FIG. 17 shows images of electrolyte wettability of separators coated according to some embodiments described herein compared to uncoated microporous membranes or base membranes. [Figure 18] FIG. 18 shows electrolyte wettability images of separators coated according to some embodiments described herein compared to uncoated microporous membranes or base membranes, CCS, and PCS. [Figure 19] FIG. 19 is a chart showing the average dry adhesion and wet adhesion of separators coated according to some embodiments described herein. [Figure 20]FIG. 20 shows an image of the transferred electrode material after peeling when testing the adhesion of a separator coated according to some embodiments described herein. [Figure 21] FIG. 21 is a graph of electrolyte absorption for separators coated with some embodiments and comparative products described herein. [Figure 22] FIG. 22 shows the shutdown behavior of a coated microporous membrane according to some embodiments described herein compared to an uncoated microporous membrane. [Figure 23] FIG. 23 is a graph showing the pin removal force of several coated microporous membranes described herein compared to an uncoated microporous membrane. [Figure 24] FIG. 24 is a graph showing the benefits of cross-linked coating. [Figure 25] FIG. 25 shows the shutdown behavior of a coated microporous membrane according to some embodiments described herein compared to an uncoated microporous membrane. [Figure 26] FIG. 26 shows images of the results of a puncture test of a coated microporous membrane according to some embodiments described herein compared to an uncoated microporous membrane. [Figure 27] FIG. 27 shows the results of compressive elongation of microporous membranes with several coatings according to some embodiments described herein. [Figure 28] FIG. 28 shows the TMA (machine direction, MD), TMA (transverse direction, TD), and electrolyte loss results for several coated microporous membrane embodiments described herein compared to a comparative uncoated microporous membrane. DETAILED DESCRIPTION OF THE INVENTION

[0059] In at least one aspect, a battery separator is disclosed that includes a microporous membrane having a coating on one or both sides thereof. The coating can comprise, consist of, or consist essentially of an inorganic component and at least one of the following: a wet adhesive polymer and a dry adhesive polymer. In some preferred embodiments, the coating is on only one side of the microporous membrane, and in some other preferred embodiments, the coating is on both sides of the microporous membrane.

[0060] In at least some embodiments, the coating can comprise, consist of, or consist essentially of an inorganic component and a wet adhesive polymer. In some embodiments, the coating comprising, consisting of, or consisting essentially of an inorganic component and a wet adhesive polymer is "inorganic-rich," or comprises, consists of, or consists essentially of 50% to 80% inorganic component. In some embodiments, the coating comprising, consisting of, or consisting essentially of an inorganic component and a wet adhesive polymer is "polymer-rich," or comprises, consists of, or consists essentially of 10% to less than 50% inorganic component.

[0061] In at least selected embodiments where the coating comprises, consists of, or consists essentially of an inorganic component and a wet adhesion polymer, the electrolyte wettability of the coating is a contact angle <35°, or in some embodiments, a contact angle <30°. Polymer-rich coatings may exhibit contact angles <35°, while inorganic-rich coatings may exhibit contact angles <30°.

[0062] In at least certain embodiments, when the coating comprises, consists of, or consists essentially of an inorganic component and a wet adhesion polymer, the wet adhesion polymer is a fluoropolymer such as PVDF.

[0063] In at least selected embodiments, the coating comprises, consists of, or consists essentially of an inorganic component and a wet adhesive polymer. In some preferred embodiments, the inorganic component and the wet adhesive polymer have similar particle sizes, or the inorganic component has a larger average particle size compared to the wet adhesive polymer when the coating is dry. When the coating is wet with electrolyte, in some embodiments, the wet adhesive polymer swells or grows, causing the average particle size of the wet adhesive polymer to become larger than the average particle size of the inorganic component.

[0064] In at least certain embodiments, the coating comprises, consists of, or consists essentially of an inorganic component and a dry adhesive polymer. In some embodiments, the dry adhesive polymer has a glass transition temperature of less than 100° C., less than 90° C., less than 80° C., or less than 70° C. In some preferred embodiments, the dry adhesive polymer has a glass transition temperature of 30° C. to 80° C., 40° C. to 70° C., 40° C. to 65° C., 45° C. to 60° C., 45° C. to 55° C., or 45° C. to 50° C.

[0065] In at least selected embodiments, the coating comprises an inorganic component, a dry adhesive polymer, and a wet adhesive polymer, in some embodiments the coating is inorganic-rich, while in other embodiments the coating is polymer-rich.

[0066] I. Coated separator 1 In one aspect, coated porous or microporous thin films, base membranes, membranes, separators, or substrates (hereinafter "coated separators" or "separators") are described herein and may offer one or more advantages over conventional uncoated substrates. In some embodiments, the separators described herein include a porous substrate having a first surface and an opposite-facing second surface, and a coating disposed on the first surface, the second surface, or both the first and second surfaces of the porous substrate. The coating may include a first layer having a first density and a second layer having a second density, where the second density is different from the first density.

[0067] The substrates described herein may include one or more layers comprising one or more of a polyolefin, a fluorocarbon, a polyamide, a polyester, a polyacetal (or polyoxymethylene), a polysulfide, a polyvinyl alcohol, a polyvinylidene, a copolymer thereof, or a combination thereof. In some embodiments, the substrates described herein comprise a polyolefin, including polypropylene, polyethylene, a blend of polyolefins, one or more copolymers of polyolefins, or any combination thereof.

[0068] Polyolefins may include, but are not limited to, polyethylene, polypropylene, polybutylene, polymethylpentene, copolymers thereof, and blends thereof. In some embodiments, the polyolefin may be an ultra-low molecular weight, low molecular weight, medium molecular weight, high molecular weight, or ultra-high molecular weight polyolefin, such as medium or high molecular weight polyethylene (PE) or polypropylene (PP). For example, the ultra-high molecular weight polyolefin may have a molecular weight of 450,000 or greater, such as 500,000 or greater, 650,000 or greater, 700,000 or greater, 800,000 or greater, 1 million or greater, 2 million or greater, 3 million or greater, 4 million or greater, 5 million or greater, 6 million or greater, or greater. High molecular weight polyolefins can have a molecular weight in the range of 250,000 to 450,000, such as 250,000 to 400,000, 250,000 to 350,000, or 250,000 to 300,000. Medium molecular weight polyolefins can have a molecular weight of 150 to 250,000, such as 100,000, 125,000, 130,000, 140,000, 150,000 to 225,000, 150,000 to 200,000, or 150,000 to 200,000. Low molecular weight polyolefins can have a molecular weight in the range of 100,000 to 150,000, such as 100,000 to 1250,000. The ultra-low molecular weight polyolefin may have a molecular weight of less than 100,000. The above values ​​are weight average molecular weights. In some embodiments, higher molecular weight polyolefins may be used to enhance the strength or other properties of porous substrates or batteries, including those described herein. In some embodiments, low molecular weight polymers, such as medium, low, or ultra-low molecular weight polymers, may be beneficial. For example, without wishing to be bound by theory, it is believed that the crystallization behavior of low molecular weight polyolefins may result in porous substrates with smaller pores, resulting from at least the MD stretching process that forms the pores.

[0069] Fluorocarbons may include polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), fluorinated ethylene propylene (FEP), ethylene chlorotrifluoroethylene (ECTFE), ethylene tetrafluoroethylene (ETFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), perfluoroalkoxy (PFA) resins, copolymers thereof, or combinations thereof. Polyamides may include, but are not limited to, polyamide 6, polyamide 6 / 6, nylon 10 / 10, polyphthalamide (PPA), copolymers thereof, or combinations thereof. Polyesters may include, but are not limited to, polyester terephthalate (PET), polybutylene terephthalate (PBT), poly-1-4-cyclohexylene dimethylene terephthalate (PCT), polyethylene naphthalate (PEN), or liquid crystal polymers (LCP). Polysulfides may include, but are not limited to, polyphenyl sulfide, polyethylene sulfide, copolymers thereof, or combinations thereof. Polyvinyl alcohols may include, but are not limited to, ethylene vinyl alcohol, copolymers thereof, or combinations thereof. Polyvinylidenes may include, but are not limited to, fluorinated polyvinylidenes (such as polyvinylidene chloride and polyvinylidene fluoride), copolymers thereof, and blends thereof.

[0070] The substrate may optionally comprise a semi-crystalline polymer, such as a polymer having a crystallinity in the range of 20% to 80%.

[0071] In some embodiments, the substrates described herein may include a single layer, a two layer, a three layer, or multiple layers. For example, a three layer or multilayer substrate may include two outer layers and one or more inner layers. In some cases, the substrate may include one, two, three, four, five, or more inner layers. As described in more detail below, the layers may be extruded and / or laminated together.

[0072] The substrates described herein can be made by a dry stretch process (such as the Celgard® dry stretch process described herein) in which one or more polymers are extruded to form the substrate. Each of the outer and inner layers can be a monoextrusion, where the layer is extruded by itself without any sublayers (laminations), or each layer can include multiple coextruded sublayers. For example, each layer may include multiple sublayers, such as a coextruded two-sublayer, three-sublayer, or multi-sublayer substrate, which can collectively be considered a single "layer." A coextruded two-layer substrate will have two sublayers; a coextruded three-layer substrate will have three layers; a coextruded multilayer substrate will have two or more, three or more, four or more, five or more, etc. The exact number of sublayers in a coextruded layer is determined by the design of the extruder and not necessarily by the materials coextruded to form the coextruded layer. For example, a coextruded two-sublayer, three-sublayer, or multi-sublayer substrate may be formed using the same material in each of two, three, four, or more sublayers, which are considered separate sublayers even if each sublayer is made of the same material.

[0073] In some embodiments, the tri-layer or multi-layer substrates described herein can include two outer layers (e.g., a first outer layer and a second outer layer) and a single or multiple inner layers. The multiple inner layers can be mono-extruded or co-extruded layers. Laminate barriers can be formed between each inner layer and / or between each outer layer and an inner layer. Laminate barriers can be formed when two surfaces, such as two surfaces of different substrates or layers, are laminated together using heat, pressure, or heat and pressure.

[0074] In some embodiments, the substrates described herein can have the following non-limiting structures: PP, PE, PP / PP, PP / PE, PE / PP, PE / PE, PP / PP / PP, PP / PP / PE, PP / PE / PE.PP / PE / PP, PE / PP / PE, PE / PE / PP, PP / PP / PP / PP, PP / PE / PE / PP, PE / PP / PP / PE, PP / PE / PP / PP, PE / PE / PP / PP, PE / PP / PE / PP, PP / PE / PE / PE / PP, PE / PP / PP / PP / PE, PP / PP / PE / PP / PP, PE / PE / PP / PP / PE / PE, PP / PE / PP / PE / PP, PP / PP / PE / PE / PP / PP, PE / PE / PP / PP / PE / PE, PE / PP / PE / PP / PE / PP, PP / PE / PP / PE / PP / PE, PP / PP / PP / PE / PP / PP / PP, PE / PE / PE / PP / PE / PE / PE, PP / PE / PP / PE / PP / PE / PP, PE / PP / PE / PP / PE / PP / PE, PE / PP / PE / PP / PE / PP / PE / PP, PP / PE / PP / PE / PP / PE / PP / PE, PP / PP / PE / PE / PP / PP / PE / PE, PP / PE / PE / PE / PE / PE / PE / PP, PE / PP / PP / PP / PP / PP / PP / PE, PP / PP / PE / PE / PEPE / PP / PP, PP / PP / PP / PP / PE / PE / PE / PE, PP / PP / PP / PP / PE / PP / PP / PP / PP, PE / PE / PE / PE / PP / PE / PE / PE / PE, PP / PE / PP / PE / PP / PE / PP / PE / PP, PE / PP / PE / PP / PE / PP / PE / PP / PE, PE / PE / PE / PE / PE / PP / PP / PP / PP, PP / PP / PP / PP / PP / PE / PE / PE / PE, PP / PP / PP / PP / PP / PE / PE / PE / PE / PE, PE / PE / PE / PE / PE / PP / PP / PP / PP / PP, PP / PE / PP / PE / PP / PE / PP / PE / PP / PE, PE / PP / PE / PP / PE / PP / PE / PP / PE / PP, PE / PP / PP / PP / PP / PP / PP / PP / PP / PP / PE, PP / PE / PE / PE / PE / PE / PE / PE / PE / PE / PP, PP / PP / PE / PE / PP / PP / PE / PE / PP / PP, PE / PE / PP / PP / PP / PP / PP / PP / PP / PE / PE, PP / PP / PP / PE / PE / PP / PP / PP / PP / PE, or PE / PE / PE / PP / PP / PE / PE / PE / PP / PP.For purposes of reference herein, PE refers to a single layer in a multi-layer substrate that includes PE. Similarly, PP refers to a single layer in a multi-layer substrate that includes PP. Thus, the PP / PE designation represents a two-layer substrate with a polypropylene (PP) layer and a polyethylene (PE) layer.

[0075] Individual layers within a substrate may include multiple sublayers, which may be formed by coextrusion or combining individual sublayers to form individual layers of the multilayer substrate. Using a multilayer substrate with a PP / PE / PP structure, each individual PP or PE layer may include two or more coextruded sublayers. For example, if each PP or PE layer is composed of three sublayers, the individual PP layers may be represented as PP = (PP1, PP2, PP3) and the individual PE layers may be represented as PE = (PE1, PE2, PE3). Thus, the PP / PE / PP structure may be represented as (PP1, PP2, PP3) / (PE1, PE2, PE3) / (PP1, PP2, PP3). The PP1, PP2, and PP3 sublayers may each have the same composition, or each sublayer may have a different polypropylene composition than one or both of the other polypropylene sublayers. Similarly, the PE1, PE2, and PE3 sublayers may each have the same composition, or each sublayer may have a different polyethylene composition than one or both of the other polyethylene sublayers. This principle applies to other multi-layer boards having more or fewer layers than the exemplary three layer board above.

[0076] In some embodiments, the substrates described herein have an overall thickness of 1 micron to 60 microns, 1 micron to 55 microns, 1 micron to 50 microns, 1 micron to 45 microns, 1 micron to 40 microns, 1 micron to 35 microns, 1 micron to 30 microns, 1 micron to 25 microns, 1 micron to 20 microns, 1 micron to 15 microns, 1 micron to 10 microns, 5 microns to 50 microns, 5 microns to 40 microns, 5 microns to 30 microns, 5 microns to 25 microns, 5 microns to 20 microns, 5 microns to 10 microns, 10 microns to 40 microns, 10 microns to 35 microns, 10 microns to 30 microns, or 10 microns to 20 microns.

[0077] In some embodiments, each layer of a bi-layer, tri-layer, or multi-layer substrate may have a thickness equal to, less than, or greater than the thickness of the other layers. For example, in a tri-layer substrate comprising a PP / PE / PP (polypropylene / polyethylene / polypropylene) or PE / PP / PE (polyethylene / polypropylene / polyethylene) structure, the polypropylene layer may have a thickness equal to, less than, or greater than the thickness of the polyethylene layer.

[0078] In some embodiments, the substrates described herein can be three-layer laminated PP / PE / PP (polypropylene / polyethylene / polypropylene) or PE / PP / PE (polyethylene / polypropylene / polyethylene) substrates. In some cases, the structural ratios of the layers of the substrate are 45 / 10 / 45%, 40 / 20 / 40%, 39 / 22 / 39%, 38 / 24 / 38%, 37 / 26 / 37%, 36 / 28 / 36%, 35 / 30 / 35%, 34.5 / 31 / 34.5%, 34 / 32 / 34%, 33.5 / 33 / 33.5%, 33 / 34 / 33%, 32.5 / 35%. / 32.5%, 32 / 36 / 32%, 31.5 / 37 / 31.5%, 31 / 38 / 31%, 30.5 / 39 / 30.5%, 30 / 40 / 30%, 29.5 / 41 / 29.5%, 29 / 42 / 29%, 28.5 / 43 / 28.5%, 28 / 44 / 28%, 27.5 / 45 / 27.5%, or 27 / 46 / 27%.

[0079] The substrates described herein may further include fillers, elastomers, wetting agents, lubricants (oils), flame retardants, nucleating agents, antioxidants, colorants, and / or other additional elements consistent with the objectives of the present disclosure. For example, the substrates may include fillers such as calcium carbonate, zinc oxide, diatomaceous earth, talc, kaolin, synthetic silica, mica, clay, boron nitride, silicon dioxide, titanium dioxide, barium sulfate, aluminum hydroxide, magnesium hydroxide, or combinations thereof. The elastomer may include ethylene-propylene copolymer (EPR), ethylene-propylene-diene copolymer (EPDM), styrene-butadiene copolymer (SBR), styrene-isoprene copolymer (SIR), ethylidene norbornene copolymer (ENB), epoxy, polyurethane, or combinations thereof. The wetting agent may include ethoxylated alcohols, primary polymeric carboxylic acids, glycols (such as polypropylene glycol and polyethylene glycol), functionalized polyolefins, and the like. The lubricant (oil) may include silicone, fluoropolymer, oleamide, stearamide, erucamide, calcium stearate, lithium stearate, or other metal stearates. The flame retardant may include brominated flame retardants, ammonium phosphate, ammonium hydroxide, alumina trihydrate, and phosphate esters. The nucleating agent may include any nucleating agent not inconsistent with the objectives of the present disclosure, such as the beta-nucleating agent for polypropylene disclosed in U.S. Patent No. 6,602,593.

[0080] The substrate described in some embodiments herein may be produced by a dry stretching process. The substrate is understood to be a thin, flexible polymer membrane, film, sheet, foil, or substrate having a plurality of pores therethrough. In some cases, the porous substrate is produced by a dry stretching process (also referred to as the CELGARD® dry stretching process). This refers to a process in which pores are formed by stretching a non-porous, semi-crystalline extruded polymer precursor in the machine direction (MD), the transverse direction (TD), or both the MD and TD. See, for example, Kesting, Robert E., Synthetic Polymeric Membranes, A Structural Perspective, Second Edition, John Wiley & Sons, New York, NY, (1985), pp. 290-297, which is incorporated herein by reference. Such a dry stretching process is different from the wet process and the particle stretching process. In the wet process, commonly known as the phase inversion process, extraction process, or TIPS process, polymeric materials are mixed with processing oils (sometimes referred to as plasticizers), the mixture is extruded, and pores are formed when the processing oil is removed. These wet process substrates can be stretched before or after oil removal, but the primary pore-forming mechanism is the use of the processing oil. See, for example, Kesting, Ibid., pp. 237-286, incorporated herein by reference. In the particle stretching process, particles such as silica or calcium carbonate are used as pore-forming agents. The polymeric materials are mixed with the particles, the mixture is extruded, and pores are formed when the particles are removed. These particle-filled substrates can be stretched before or after particle removal, but the primary pore-forming mechanism is the use of the particles. The porous substrates described herein may optionally be any of the Celgard® polyolefin microporous separator substrates, preferably available from Celgard, Inc., Charlotte, North Carolina, USA.

[0081] The porous substrate can be a macroporous substrate, a mesoporous substrate, a microporous substrate, or a nanoporous substrate. The porosity of the substrate can be any porosity consistent with the objectives of the present disclosure. For example, any porosity that can form an acceptable battery separator is acceptable. In some embodiments, the porosity of the porous substrate is 20% to 90%, 20% to 80%, 40% to 80%, 20% to 70%, 40% to 70%, 40% to 60%, greater than 20%, greater than 30%, or greater than 40%. Porosity is measured using ASTM D-2873 and is defined as the percentage of voids, e.g., pores, measured in the machine direction (MD) and transverse direction (TD) of the substrate, within the area of ​​the porous substrate. In some embodiments, the pores are slit-shaped, circular, rectangular, trapezoidal, or elliptical with a sphericity of 0.25 to 8.0.

[0082] The substrate may have any Gurley value consistent with the purposes of this disclosure, such as a Gurley value acceptable for use as a battery separator. The Gurley value is the Japanese Industrial Standard (JIS) Gurley and can be measured using an air permeability tester such as an OHKEN air permeability tester. JIS Gurley is defined as the time in seconds required for 100 cc of air to pass through 1 square inch of substrate at a constant pressure of 4.9 inches of water (1 inch = 2.54 cm). In some embodiments, the porous films or substrates described herein have a JIS Gurley value (s / 100cc) of 100 or more, 150 or more, 160 or more, 170 or more, 180 or more, 190 or more, 200 or more, 210 or more, 220 or more, 230 or more, 240 or more, 250 or more, 260 or more, 270 or more, 280 or more, 290 or more, 300 or more, 310 or more, 320 or more, 330 or more, 340 or more, 350 or more, 100 to 800, 200 to 700, 200 to 600, 200 to 500, 200 to 400, 200 to 300, or 300 to 600.

[0083] The substrate, when uncoated, can have a puncture strength of 200 gf or greater, 210 gf or greater, 220 gf or greater, 230 gf or greater, 240 gf or greater, 250 gf or greater, 260 gf or greater, 270 gf or greater, 280 gf or greater, 290 gf or greater, 300 gf or greater, 310 gf or greater, 320 gf or greater, 330 gf or greater, 340 gf or greater, 350 gf or greater, or up to 400 gf or greater.

[0084] In some embodiments, the substrates described herein may include one or more additives in at least one layer of the porous substrate. In some embodiments, at least one layer of the porous substrate includes two or more additives, such as two, three, four, five, or more. The additives may be present in one or both of the outermost layers of the porous substrate, one or more inner layers, all inner layers, or all inner layers and both outermost layers. In some embodiments, the additives may be present in one or more outermost layers and one or more innermost layers. In such embodiments, the additives may be released from the outermost layer or layers over time, and the additive supply in the outermost layer or layers may be replenished by migration of additives from the inner layers to the outermost layers. In some embodiments, each layer of the substrate may include a different additive or combination of additives than adjacent layers of the substrate.

[0085] In some embodiments, the additive comprises a functionalized polymer. As will be understood by those skilled in the art, a functionalized polymer is a polymer in which a functional group is attached to the polymer backbone. In some embodiments, the functionalized polymer is a maleic anhydride-functionalized polymer. In some embodiments, such maleic anhydride-modified polymers are maleic anhydride homopolymer polypropylene, copolymer polypropylene, high density polypropylene, low density polypropylene, very high density polypropylene, very low density polypropylene, homopolymer polyethylene, copolymer polyethylene, high density polyethylene, low density polyethylene, very high density polyethylene, or very low density polyethylene.

[0086] In some embodiments, the additive comprises an ionomer. As will be understood by those skilled in the art, an ionomer is a copolymer that contains both ionic and nonionic repeating groups. The ionic repeating groups may comprise less than 25%, less than 20%, or less than 15% of the ionomer. In some embodiments, the ionomer may be a lithium (Li), sodium (Na), or zinc (Zn) based ionomer.

[0087] In some embodiments, the additive comprises cellulose nanofibers.

[0088] In some embodiments, the additive comprises inorganic particles having a narrow size distribution. For example, the difference between D10 and D90 in the distribution is less than 100 nanometers, less than 90 nanometers, less than 80 nanometers, less than 70 nanometers, less than 60 nanometers, less than 50 nanometers, less than 40 nanometers, less than 30 nanometers, less than 20 nanometers, or less than 10 nanometers. In some embodiments, the inorganic particles are selected from at least one of SiO2, TiO2, or a combination thereof.

[0089] In some embodiments, the additive comprises a lubricant. The lubricants or lubricating oils described herein can be any lubricant not inconsistent with the objectives of the present disclosure. As will be understood by those skilled in the art, lubricants (oils) are compounds that act to reduce friction between a variety of different surfaces, including polymer:polymer, polymer:metal, polymer:organic materials, and polymer:inorganic materials. Specific examples of lubricants or lubricating oils described herein are compounds containing siloxane functional groups, including siloxanes and polysiloxanes, and fatty acid salts, including metal stearates.

[0090] The lubricants (oils) described herein may be compounds containing two or more, three or more, four or more, five or more, six or more, seven or more, eight or more, nine or more, or ten or more siloxy groups. Siloxanes, as understood by those skilled in the art, are a class of molecules with a backbone of alternating silicon (Si) and oxygen (O) atoms, each of which may have an attached hydrogen (H) or a saturated or unsaturated organic group such as —CH or —CH. Polysiloxanes are polymerized siloxanes, typically having a high molecular weight. In some embodiments described herein, the polysiloxane may be a high molecular weight, such as an ultra-high molecular weight, polysiloxane. In some embodiments, high and ultra-high molecular weight polysiloxanes may have a weight average molecular weight in the range of 500,000 to 1,000,000.

[0091] The fatty acid salts described herein can be any fatty acid salts consistent with the objectives of the present disclosure. In some cases, the fatty acid salts can be any fatty acid salts that act as lubricants. The fatty acid of the fatty acid salt can be a fatty acid having 12 to 22 carbon atoms. For example, the metal fatty acid can be selected from the group consisting of lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, palmitoleic acid, behenic acid, erucic acid, and arachidic acid. The metal can be any metal consistent with the objectives of the present disclosure. In some cases, the metal is an alkali metal or alkaline earth metal, such as Li, Be, Na, Mg, K, Ca, Rb, Sr, Cs, Ba, Fr, or Ra. In some embodiments, the metal is Li, Be, Na, Mg, K, or Ca.

[0092] The fatty acid salt can be lithium stearate, sodium stearate, lithium oleate, sodium oleate, sodium palmitate, lithium palmitate, potassium stearate, or potassium oleate.

[0093] Lubricants containing fatty acid salts described herein may have melting points of 200° C. or higher, 210° C. or higher, 220° C. or higher, 230° C. or higher, or 240° C. or higher. Fatty acid salts such as lithium stearate (melting point 220° C.) or sodium stearate (melting point 245-255° C.) have such melting points.

[0094] In some embodiments, the additive may include one or more nucleating agents. As will be appreciated by those skilled in the art, a nucleating agent is an inorganic material that aids, increases, or enhances the crystallization of a polymer, including, in some embodiments, a semi-crystalline polymer.

[0095] In some cases, the additives may include cavitation promoters. As will be understood by those skilled in the art, cavitation promoters are materials that form, assist in the formation of, increase the formation of, or enhance the formation of bubbles or voids in the polymer.

[0096] The additive may optionally include a fluoropolymer, such as the fluoropolymers discussed in detail herein.

[0097] In some embodiments, the additive may include a crosslinking agent.

[0098] The additives described herein may, in some embodiments, include an X-ray detectable material. The X-ray detectable material may be any X-ray detectable material consistent with the objectives of the present disclosure, such as those disclosed in U.S. Pat. No. 7,662,510, which is incorporated herein by reference in its entirety. Suitable amounts of X-ray detectable material or elements are also disclosed in U.S. Pat. No. 7,662,510, and in some embodiments, may be used in amounts up to 50 wt %, up to 40 wt %, up to 30 wt %, up to 20 wt %, up to 10 wt %, up to 5 wt %, or up to 1 wt %, based on the total weight of the porous film or substrate. In one embodiment, the additive is barium sulfate.

[0099] In some embodiments, the additive can include a lithium halide. The lithium halide can be lithium chloride, lithium fluoride, lithium bromide, or lithium iodide. The lithium halide can be lithium iodide, which is both ionically conductive and electrically insulating. In some cases, a material that is both ionically conductive and electrically insulating can be used as part of a battery separator.

[0100] In some embodiments, the additive may include a polymer processing agent. As will be understood by those skilled in the art, polymer processing agents or additives are added to improve the processing efficiency and quality of polymer compounds. In some embodiments, the polymer processing agent may be an antioxidant, stabilizer, lubricant, processing aid, nucleating agent, colorant, antistatic agent, plasticizer, or filler.

[0101] In some embodiments, the additive can include a high temperature melt index (HTMI) polymer. The HTMI polymer can be any HTMI polymer not inconsistent with the objectives of the present disclosure. In some cases, the HTMI polymer can be at least one selected from the group consisting of PMP, PMMA, PET, PVDF, aramid, syndiotactic polystyrene, polyimide, polyamide, and combinations thereof.

[0102] The additive may optionally include an electrolyte. The electrolyte described herein may be any electrolyte not inconsistent with the objectives of the present disclosure. The electrolyte may be any additive that battery manufacturers, particularly lithium battery manufacturers, typically add to improve battery performance. The electrolyte must also be compatible with the polymer used in the polymeric porous substrate, such as by being miscible with the polymer, or compatible with the coating slurry. The compatibility of the additive may be supported or improved by coating or partially coating the additive. For example, exemplary electrolytes are disclosed in "A Review of Electrolyte Additives for Lithium-Ion Batteries," J. of Power Sources, vol. 162, issue 2, 2006, pp. 1379-1394, which is incorporated herein by reference in its entirety. In some embodiments, the electrolyte is at least one selected from the group consisting of a solid electrolyte interphase (SEI) improver, a cathode protectant, a flame retardant additive, a LiPF salt stabilizer, an overcharge protectant, an aluminum corrosion inhibitor, a lithium precipitation agent or improver, a solvation promoter, an aluminum corrosion inhibitor, a wetting agent, and a viscosity improver. In some embodiments, the electrolyte can have multiple properties, such as a wetting agent and a viscosity improver.

[0103] Exemplary SEI improvers include VEC (vinyl ethylene carbonate), VC (vinylene carbonate), FEC (fluoroethylene carbonate), and LiBOB (lithium bis(oxalato)borate). Exemplary cathode protectants include N,N'-dicyclohexylcarbodiimide, N,N-diethylaminotrimethylsilane, and LiBOB. Exemplary flame retardant additives include TTFP (tris(2,2,2-trifluoroethyl)phosphate), fluorinated propylene carbonate, and MFE (methyl nonafluorobutyl ether). Exemplary LiPF6 salt stabilizers include LiF, TTFP (tris(2,2,2-trifluoroethyl)phosphite), 1-methyl-2-pyrrolidinone, fluorinated carbamates, and hexamethyl-phosphoramide. Exemplary overcharge protection agents include xylene, cyclohexylbenzene, biphenyl, 2,2-diphenylpropane, and phenyl-tert-butyl carbonate. Exemplary Li deposition improvers include AlI3, SnI2, cetyltrimethylammonium chloride, perfluoropolyether, and tetraalkylammonium chlorides with long alkyl chains. Exemplary ionic salvation promoters include 12-crown-4 and TFPPB (tris(pentafluorophenyl)). Exemplary Al corrosion inhibitors include borates such as LiBOB and LiODFB. Exemplary wetting agents and viscosity reducers include cyclohexane and PO5.

[0104] In some embodiments, the electrolyte additive is air-stable or oxidation-resistant. Battery separators containing the electrolyte additives disclosed herein can have a shelf life of several weeks to several months, for example, from 1 week to 11 months.

[0105] In some embodiments, the additive may comprise an energy-dissipative, immiscible additive, meaning that the additive is not miscible with the polymer used to form the layer of the porous film or substrate that contains the additive.

[0106] As mentioned above, the substrates described herein can be MD-stretched or TD-stretched to render the substrate porous. In some cases, the substrates are produced by sequentially stretching an MD-stretched substrate in the TD, or by sequentially stretching a TD-stretched substrate in the MD. In addition to sequential MD-TD stretching (with or without relaxation), the substrates may be simultaneously subjected to biaxial MD-TD stretching (with or without relaxation). Furthermore, simultaneous or sequential MD-TD stretching of porous substrates may be followed by stretching, relaxation, heat setting, or currying steps to reduce substrate thickness, reduce roughness, reduce porosity, increase TD tensile strength, improve uniformity, and / or reduce TD crack susceptibility.

[0107] In some embodiments, the substrate has a thickness of 0.01 nm to 1 micron, 0.01 micron to 1 micron, 0.02 micron to 1 micron, 0.03 micron to 1 micron, 0.04 micron to 1 micron, 0.05 micron to 1 micron, 0.06 micron to 1 micron, 0.07 micron to 1 micron, 0.08 micron to 1 micron, 0.09 micron to 1 micron, 0.1 micron to 1 micron, 0.2 micron to 1 micron, 0.3 micron to 1 micron, 0.4 micron to 1 micron, 0.5 micron to 1 micron, 0.6 micron to 1 micron, 0.7 micron to 1 micron, 0.8 micron to 1 micron, 0.9 micron to 1 micron, 0.01 micron to 0.9 micron, 0.01 micron to 0.8 micron, 0.01 micron to 0.7 micron, 0.01 micron to 0.6 micron, 0.01 micron to 0.5 micron The porous membrane may comprise pores having an average pore size of 0.01 microns to 0.4 microns, 0.01 microns to 0.3 microns, 0.01 microns to 0.2 microns, 0.01 microns to 0.1 microns, 0.01 microns to 0.09 microns, 0.01 microns to 0.08 microns, 0.01 microns to 0.07 microns, 0.01 microns to 0.06 microns, 0.01 microns to 0.05 microns, 0.01 microns to 0.04 microns, 0.01 microns to 0.03 microns, 1 micron, 0.9 microns, 0.8 microns, 0.7 microns, 0.6 microns, 0.5 microns, 0.4 microns, 0.3 microns, 0.2 microns, 0.1 microns, 0.09 microns, 0.08 microns, 0.07 microns, 0.06 microns, 0.05 microns, 0.04 microns, 0.03 microns, 0.02 microns, or 0.01 microns.

[0108] In one embodiment, a porous substrate may be produced using an exemplary process including: a controlled reduction in thickness of a stretched substrate, e.g., a multi-layer porous substrate, thereby controlling the reduction in the % porosity of such stretched substrate, e.g., a multi-layer porous substrate; and / or a controlled improvement in the strength and properties and / or performance of such stretched substrate, e.g., a multi-layer porous substrate, for example, a controlled improvement in the puncture strength, machine direction and / or transverse tensile strength, uniformity, wettability, coatability, workability, compression, springback, flexurality, air permeability, thickness, pin removal force, mechanical strength, surface roughness, hot tip hole propagation, and / or combinations thereof, of such stretched substrate, e.g., a multi-layer porous substrate; and / or a stretching and subsequent calendering step, for example, a machine direction stretching followed by a transverse direction stretching (with or without a machine direction relaxation step) and subsequent calendering step, as a way to produce a unique structure, pore structure, material, substrate, base substrate, and / or separator.

[0109] In some cases, the TD tensile strength of a multilayer substrate may be further improved by adding a calendering step following TD stretching. The calendering process typically involves heat and pressure, which allows for the thickness of the porous substrate to be reduced. The calendering step can restore the loss of MD and TD tensile strength caused by TD stretching. Furthermore, the increase in MD and TD tensile strength due to calendering can result in a more balanced ratio of MD and TD tensile strength, which is beneficial to the overall mechanical performance of the multilayer substrate.

[0110] The calendering process can use uniform or non-uniform heat, pressure, and / or speed to selectively densify heat-sensitive materials, provide uniform or non-uniform calendering conditions (smooth roll, rough roll, patterned roll, micropatterned roll, nanopatterned roll, speed variations, temperature variations, pressure variations, humidity variations, dual roll processes, multiple roll processes, or combinations thereof), create improved, desirable, or unique structures, properties, and / or performance, and create or control the resulting structures, properties, and / or performance. In one embodiment, a calendering temperature of 50°C to 70°C and a line speed of 40 to 80 ft / min can be used, with a calendering pressure of 50 to 200 psi. In some cases, higher pressures can result in thinner separators, while lower pressures can result in thicker separators.

[0111] In some embodiments, the porous substrate or membrane described herein can include a coating disposed on the first surface, the second surface, or both the first and second surfaces of the porous substrate. As shown in FIG. 1 or FIG. 1 of the drawings, a separator or coated separator or coated membrane 100 comprises a substrate 1 in which a first surface 10 of the substrate 1 faces away from a second surface 11 of the substrate. In some embodiments, the coating can include a first layer and a second layer. In some cases, the first layer of the coating can be disposed on the first surface, the second surface, or both the first and second surfaces of the substrate. When the first layer is disposed on the first and / or second surface of the substrate, a second layer of the coating can be disposed on one or both of the first layer of the coating.

[0112] In some cases, the second layer of the coating may be disposed on the first surface, the second surface, or both the first and second surfaces of the substrate. When the second layer is disposed on the first and / or second surfaces of the substrate, the first layer of the coating may be disposed on one or both of the second layers of the coating.

[0113] In a further embodiment, the first layer of the coating may be disposed on one of the first surface or the second surface of the substrate, and the second layer of the coating may be disposed on the other of the first surface or the second surface of the substrate, in this embodiment, the first layer disposed on one of the substrates may optionally be covered with a second layer, and the second layer disposed on the other of the substrates may optionally be covered with a first coating, so that the first and second surfaces (a) have opposite configurations of coating layers.

[0114] Furthermore, in other embodiments, the first layer may be disposed on both a first and a second surface of the substrate, with only one of the two first layers on the substrate being further coated with a second layer of coating. Similarly, in other examples, the second layer may be disposed on both a first and a second surface of the substrate, with only one of the two second layers on the substrate being further coated with a first layer of coating.

[0115] The first and second layers may each have any thickness consistent with the objectives of the present disclosure. In some cases, the first layer may have a thickness of 100 nm to 20 microns, 500 nm to 15 microns, 500 nm to 10 microns, 500 nm to 5 microns, or 500 nm to 1 micron, and the second layer may have a thickness of 500 nm to 20 microns, 500 nm to 15 microns, 500 nm to 10 microns, 500 nm to 5 microns, or 500 nm to 1 micron. The thicknesses of the first and second layers may be the same or different.

[0116] 1-10 illustrate different combinations in which a first layer and a second layer may be disposed on a substrate described herein. In FIGS. 1-10, a substrate 1 described herein has a first surface 10 and an oppositely facing second surface 11. A coating 20 described herein may be disposed on the first surface 10, the second surface 11, or both the first surface 10 and the second surface 11 of the substrate 1. The coating 20 may include a first layer 20a, a second layer 20b, or, as shown in FIG. 1, both a first layer and a second layer 20a. In FIG. 1, the exemplary coating 20 is disposed on the first surface 10 of the substrate. The second layer 20b is disposed directly on the first surface 10, and the first layer 20a is disposed on the second layer 20b. This general arrangement is merely exemplary; in other embodiments, the first layer 20a may be disposed directly on the first surface 10, and the second layer 20b may be disposed on the first layer 20a. FIG. 2 illustrates an exemplary separator embodiment in which a first layer 20a is disposed on both the first and second surfaces of the substrate 1. Again, the first layer 20a is disposed on both the first and second surfaces of the substrate 1, although in some embodiments, the first layer 20a is disposed on only one of the first and second surfaces. FIG. 3 illustrates an exemplary separator embodiment in which a second layer 20b is disposed on both the first and second surfaces of the substrate 1. In some cases, the second layer 20b is disposed on only one of the first and second surfaces of the substrate. FIG. 4 illustrates an embodiment in which a first layer 20a is disposed on both the first and second surfaces of the substrate 1, and a second layer 20b is disposed on each of the first layers 20a. Thus, in the embodiment of FIG. 4, the first layer 20a is encapsulated or disposed between the substrate 1 and the second layer 20b. FIG. 5 illustrates an embodiment in which a second layer 20b is disposed on both the first and second surfaces of the substrate 1, and the first layer 20a is disposed on each of the second layers 20b. Thus, in the embodiment of Figure 5, the second layer 20b is encapsulated or disposed between the substrate 1 and the first layer 20a.

[0117] In some embodiments, the separators described herein can include a substrate having different combinations of first and second layers on its first and second surfaces. For example, as shown in FIG. 6 , in some embodiments, separator 105 can include a first layer 20a disposed on one surface of the substrate and coated with a second layer 20b, and another first layer 20a disposed on the opposite surface of substrate 1. In FIG. 7 , separator 106 includes a first layer 20a disposed on one surface of the substrate and coated with a second layer 20b, and another second layer 20b disposed on the opposite surface of substrate 1. FIG. 8 illustrates an embodiment in which separator 107 includes a second layer 20b disposed on one surface of the substrate and coated with a first layer 20a, and a first layer 20a disposed on the opposite surface of substrate 1. FIG. 9 illustrates an embodiment in which separator 108 includes a second layer 20b disposed on one surface of the substrate and coated with a first layer 20a, and a first layer 20a disposed on the opposite surface of substrate 1. In the embodiment shown in Figure 10, the separator 109 comprises a first layer 20a disposed on the first surface 10 of the substrate 1 and a second layer 20b disposed on the first layer 20a. Furthermore, in the case of Figure 10, the second layer 20b is disposed on the second surface 11 of the substrate 1, and the first layer 20a is disposed on the second layer 20b.

[0118] In some embodiments, a first layer 20a described herein can have a first density and a second layer 20b described herein can have a second density. In some cases, the first density is different from the second density. In some cases, the first layer has a density of 0.1 g / cm 3 ~1.3g / cm 3 , 0.1g / cm 3 ~1g / cm 3 , 0.1g / cm 3 ~0.8g / cm 3 , 0.1g / cm 3 ~0.5g / cm 3 , 0.5g / cm 3 ~1.3g / cm 3 , 0.8g / cm 3 ~1.3g / cm 3 , 1g / cm 3 ~1.3g / cm 3 , up to ~0.5g / cm 3, up to ~0.8g / cm 3 , or up to 1.3g / cm 3 In some cases, the second layer may have a density of 1.3 g / cm 3 ~3g / cm 3 , 1.8g / cm 3 ~3g / cm 3 , 2g / cm 3 ~3g / cm 3 , 2.5g / cm 3 ~3g / cm 3 , 1.3g / cm 3 ~2.5g / cm 3 , 1.3g / cm 3 ~2g / cm 3 , 1.3g / cm 3 ~1.8g / cm 3 , at least 1.3 g / cm 3 , at least 1.8g / cm 3 , at least 2 g / cm 3 , or at least 2.5 g / cm 3 In a preferred embodiment, the first layer described herein may have a density of up to 1.3 g / cm 3 and the second layer described herein has a density of at least 1.3 g / cm 3 Includes density.

[0119] When the first layer covers the second layer, the first layer covers at least 30%, 40%, 50%, 60%, at least 70%, or at least 80% of the second layer. In one embodiment, the first layer forms a continuous layer on the second layer with at least 90% coverage. When the second layer covers the first layer, the second layer covers at least 60%, at least 70%, or at least 80% of the first layer. In one embodiment, the second layer forms a continuous layer on the first layer with at least 90% coverage.

[0120] In one embodiment, the first layer described herein can comprise at least 50% by weight, at least 60% by weight, at least 70% by weight, at least 80% by weight, at least 90% by weight, 95% or more by weight, 50-100% by weight, 60-100% by weight, 70-100% by weight, 80-100% by weight, 90-100% by weight, 50-90% by weight, 50-80% by weight, 50-70% by weight, 50-60% by weight, or 60-80% by weight of organic components. The organic components are methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, sec-butyl methacrylate, pentyl methacrylate, 2-ethylbutyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, isooctyl methacrylate, isononyl methacrylate, lauryl methacrylate, tetradecyl methacrylate, polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF:HFP), polytetrafluoroethylene (PTFE), polyethylene oxide (PEO), poly(vinyl alcohol) (PVA), poly The polymer may include acrylonitrile (PAN), polyacrylamide, polyvinyl acetate, polyvinylpyrrolidone, polytetraethylene glycol diacrylate, polypropylene (PP) including isotactic PP, high density PP, ultra-high molecular weight PP, and low density PP, polyethylene (PE) including high density PE, ultra-high molecular weight PE, and low density PE, polyvinyl acetate, polyvinyl chloride, bisphenol A polycarbonate (BPA-PC), cycloolefin copolymer (COC), polysulfone (PSF), polyetherimide (PEI), polyurethane, acrylonitrile butadiene styrene (ABS), polyimide, polyamide, copolymers of any of the foregoing, or any combination thereof.

[0121] As described herein, the organic component may, in some cases, be a "sticky" component, either alone or after being combined with a solvent or electrolyte solution. Thus, the first layer described herein may have a "sticky" or "viscous" texture or surface. In some cases, the organic component functions as a binder or adhesive, holding and / or immobilizing other components of the coating on the surface of the separator. The organic component described herein may also be characterized as a gel-forming polymer, which forms a gel upon contact with a liquid, such as an electrolyte solution.

[0122] The first layer described herein may optionally further comprise an inorganic component, the inorganic component being 50% by weight or less, 25% by weight or less, 15% by weight or less, 5% by weight or less, or 0.5% by weight or less, based on the total weight of the first layer. The inorganic component described herein may comprise, consist of, or consist essentially of a ceramic, a metal oxide, a metal hydroxide, a metal carbonate, a silicate, kaolin, talc, a mineral, a glass, or any combination thereof. In some embodiments, the inorganic components described herein can include aluminum oxide (Al2O3), boehmite (Al(O)(OH)), titanium oxide (TiO2), silicon oxide (SiO2), zinc oxide (ZnO2), zirconium dioxide (ZrO2), barium sulfate (BaSO4), barium titanium oxide (BaTiO3), aluminum nitride, silicon nitride, calcium fluoride, barium fluoride, zeolite, apatite, kaolin, mullite, spinel, olivine, mica, tin dioxide (SnO2), indium tin oxide, oxides of transition metals, or any combination thereof.

[0123] The second layer described herein can comprise 50-100 wt%, 50-90 wt%, 50-80 wt%, 50-70 wt%, 50-60 wt%, 60-100 wt%, 70-100 wt%, 80-100 wt%, 90-100 wt%, or at least 50 wt% of the inorganic component described above, based on the total weight of the second layer. In some embodiments, the second layer can further comprise an organic component described herein, where the organic component is 49 wt% or less, 40 wt% or less, 30 wt% or less, 20 wt% or less, 10 wt% or less, 5 wt% or less, or less than 3 wt% based on the total weight of the second layer.

[0124] In some embodiments, the first and second layers of the coatings described herein have a different average porosity than the other layers. In some cases, the first and second layers of the coatings described herein can have similar or the same average porosity. For example, the first layer described herein can have an average porosity of up to 50%, up to 45%, up to 40%, up to 35%, up to 30%, up to 25%, up to 20%, up to 15%, up to 10%, or up to 5%. The second layer described herein can have an average porosity of up to 50%, up to 45%, up to 40%, up to 35%, up to 30%, up to 25%, up to 20%, up to 15%, up to 10%, or up to 5%. In some particular examples, the first and second layers of the coatings have a porosity of up to 10% by volume.

[0125] II. How to Make a Coated Separator In another aspect, a method of making a coated separator as described in Section I includes coating a first surface, an opposing second surface, or both the first and second surfaces of a porous substrate according to Section I with a first layer and a second layer, wherein the first layer has a first density and the second layer has a second density different from the first density. The first and second layers are described in Section I above.

[0126] III. Battery separator with swelling coating In one aspect, a battery separator can include a porous substrate as described in Section I having a first surface and an oppositely facing second surface. A coating disposed on the first surface, the second surface, or both the first and second surfaces of the porous substrate includes an inorganic component and a polymer as described in Section I. In some embodiments, the polymer is an electrolyte-absorbing polymer. For purposes herein, the polymer will be referred to as an "electrolyte-absorbing polymer," although, as explained in more detail below, the polymer is not limited to "electrolyte-absorbing" polymers. Instead, the polymer can include any polymer that absorbs a liquid, such as a solvent, and swells upon absorbing such a liquid, consistent with the objectives of the present disclosure.

[0127] In some cases, the electrolyte-absorbing polymer has a first size when dry and a second size when the electrolyte-absorbing polymer contacts the electrolyte, the first size being smaller than the second size, and the electrolyte-absorbing polymer may swell from the first size to the second size upon absorbing the electrolyte, solvent, or other liquid.

[0128] In some embodiments, when a coating of inorganic components and electrolyte-absorbing polymer is disposed on the surface of a porous substrate in a dry state, the inorganic components of the coating extend further outward, away from the first and / or second surfaces of the substrate, than the electrolyte-absorbing polymer, when the electrolyte-absorbing polymer is a first size. In this dry state, the inorganic components can potentially improve the handleability of the porous substrate by preventing contact with the electrolyte-absorbing polymer during battery separator manufacturing or assembly into a battery or device. Because the electrolyte-absorbing polymer can have "sticky" or adhesive-like properties that can pick up and adhere undesirable contaminants, larger inorganic components can block or impede access to the electrolyte-absorbing polymer. However, when the battery separator is assembled in a battery, it is undesirable to expose the inorganic components to the electrolyte or electrodes. Therefore, when the electrolyte-absorbing polymer comes into contact with the electrolyte or other liquid, the electrolyte-absorbing polymer can absorb the electrolyte or other liquid and swell to a second size in a wet state. In some embodiments, when the electrolyte-absorbing polymer has a second size, the electrolyte-absorbing polymer extends further outward from the first and / or second surface of the porous substrate than the inorganic component, and the second size is formed when the electrolyte-absorbing polymer absorbs an electrolyte or liquid. In a wet state, the electrolyte-absorbing polymer of the second size can form a "tacky" or adhesive-like coating on the separator, which can be advantageous in some cases. For example, the adhesiveness of the coating can aid or improve the attachment of the separator to different components in the battery, such as the electrodes.

[0129] When the electrolyte-absorbing polymer is in a wet state and has a second size, the inorganic component can be encapsulated between the porous substrate and the electrolyte-absorbing polymer. Figures 11A and 11B show a porous substrate 1 having a coating on one side of the substrate 1. The coating includes an electrolyte-absorbing polymer 30 and an inorganic component 35. As shown in Figure 11A, when the electrolyte-absorbing polymer 30 is in a dry state, the electrolyte-absorbing polymer 30 has a first size designated "H1." When the electrolyte-absorbing polymer 30 has a first size H1, the inorganic component 35 extends further outward from the surface of the substrate 1. Thus, the inorganic component 35 has a size equal to or greater than H1. In Figure 11B, the electrolyte-absorbing polymer 30 is in a wet state, having absorbed an electrolyte or liquid. In the wet state, the electrolyte-absorbing polymer 30 is swollen and has a thickness of a second size H2. In this example, the electrolyte-absorbing polymer 30 extends further outward from the surface of the substrate 1, and the inorganic component 35 is coated / encapsulated within and / or between the electrolyte-absorbing polymer 30 and the substrate 1. In other words, the inorganic component has a height, thickness, or diameter that is less than the thickness of the second size H2. Notably, while FIGS. 11A and 11B show a separator 1 coated on a single surface, the battery separator is not limited to this configuration. Rather, in some embodiments, the battery separator may be coated on both a first surface and a second surface. Furthermore, if both surfaces are coated, the inorganic component and / or the electrolyte-absorbing polymer may be the same type or different types for each surface.

[0130] The inorganic components described in this section can include, consist of, or consist essentially of ceramics, metal oxides, metal hydroxides, metal carbonates, silicates, kaolin, talc, minerals, glasses, or any combination thereof. In some embodiments, the inorganic components described in this section can include aluminum oxide (Al2O3), boehmite (Al(O)(OH)), titanium oxide (TiO2), silicon oxide (SiO2), zinc oxide (ZnO2), zirconium dioxide (ZrO2), barium sulfate (BaSO4), barium titanium oxide (BaTiO3), aluminum nitride, silicon nitride, calcium fluoride, barium fluoride, zeolite, apatite, kaolin, mullite, spinel, olivine, mica, tin dioxide (SnO2), indium tin oxide, oxides of transition metals, or any combination thereof.

[0131] The electrolyte-absorbing polymers described in this section are not limited to methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, sec-butyl methacrylate, pentyl methacrylate, 2-ethylbutyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, isooctyl methacrylate, isononyl methacrylate, lauryl methacrylate, tetradecyl methacrylate, polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF:HFP), polytetrafluoroethylene (PTFE), polyethylene oxide (PEO), poly(vinyl alcohol) ( The polymer may include PVA), polyacrylonitrile (PAN), polyacrylamide, polyvinyl acetate, polyvinylpyrrolidone, polytetraethylene glycol diacrylate, polypropylene (PP) including isotactic PP, high density PP, ultra-high molecular weight PP, and low density PP, polyethylene (PE) including high density PE, ultra-high molecular weight PE, and low density PE, polyvinyl acetate, polyvinyl chloride, bisphenol A polycarbonate (BPA-PC), cycloolefin copolymer (COC), polysulfone (PSF), polyetherimide (PEI), polyurethane, acrylonitrile butadiene styrene (ABS), polyimide, polyamide, copolymer of any of the foregoing, or any combination thereof.

[0132] IV. Self-protection battery separator In another embodiment, a battery separator can include a porous substrate described in Section I having a first surface and an opposite-facing second surface. A coating is disposed on the first surface, the second surface, or both the first and second surfaces of the porous substrate, the coating comprising an electrolyte-absorbing material.

[0133] The electrolyte-absorbing material may include any electrolyte-absorbing material not inconsistent with the objectives of the present disclosure. In some embodiments, the electrolyte-absorbing material may include aluminum oxide (Al2O3), boehmite (Al(O)(OH)), titanium oxide (TiO2), silicon oxide (SiO2), zinc oxide (ZnO2), zirconium dioxide (ZrO2), barium sulfate (BaSO4), barium titanium oxide (BaTiO3), aluminum nitride, silicon nitride, calcium fluoride, barium fluoride, zeolite, apatite, kaolin, mullite, spinel, olivine, mica, tin dioxide (SnO2), indium tin oxide, oxides of transition metals, ceramics, metal oxides, metal hydroxides, metal carbonates, silicates, kaolin, talc, minerals, glasses, or any combination thereof.

[0134] The coatings described herein may further include a first heat-activated polymer disposed on the electrolyte-absorbing material. In some embodiments, the electrolyte-absorbing material is sandwiched, coated, and / or encapsulated between the first heat-activated polymer and the porous substrate. Figure 12 illustrates this embodiment in which an electrolyte-absorbing material 40 is sandwiched, coated, and / or encapsulated between a first heat-activated polymer 41 and a substrate 1.

[0135] The first heat-activatable polymer layer can have any thickness consistent with the objectives of the present disclosure. In some cases, the first heat-activatable polymer layer has a thickness of 100 nm to 20 microns, 500 nm to 15 microns, 500 nm to 10 microns, 500 nm to 5 microns, 500 nm to 4 microns, 500 nm to 3 microns, 500 nm to 2 microns, or 500 nm to 1 micron.

[0136] In some embodiments, the electrolyte-absorbing material is substantially encapsulated within a plurality of polymer microcapsules, the microcapsules comprising a first heat-activated polymer. Figure 13 illustrates this embodiment in which the electrolyte-absorbing material 40 is substantially encapsulated within a plurality of polymer microcapsules 41.

[0137] In the event of a battery's thermal runaway, when the temperature of the battery's environment reaches or exceeds the melting point of the first heat-activated polymer, the coated or microencapsulated electrolyte-absorbing material may become exposed and / or uncoated when the first heat-activated polymer melts. As known in the art, the "runaway temperature" may vary based on the conditions and the specific structure of the battery. Exemplary runaway temperatures range from approximately 120 to 220°C and may be determined or estimated by experiment or reaction modeling, as needed. Upon exposure, the electrolyte-absorbing material may come into contact with the electrolyte present in the battery and absorb the electrolyte. Absorption of the electrolyte disrupts the battery structure, disrupting charge transfer between the battery and the electrodes and terminating the thermal runaway event. Therefore, the first heat-activated polymer may be formed from a polymer with a melting point lower than the temperature associated with battery thermal runaway.

[0138] The first heat-activatable polymer is selected from the group consisting of methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, sec-butyl methacrylate, pentyl methacrylate, 2-ethylbutyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, isooctyl methacrylate, isononyl methacrylate, lauryl methacrylate, tetradecyl methacrylate, polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF:HFP), polytetrafluoroethylene (PTFE), polyethylene oxide (PEO), poly(vinyl alcohol) (PVA), , polyacrylonitrile (PAN), polyacrylamide, polyvinyl acetate, polyvinylpyrrolidone, polytetraethylene glycol diacrylate, polypropylene (PP) including isotactic PP, high density PP, ultra-high molecular weight PP, and low density PP, polyethylene (PE) including high density PE, ultra-high molecular weight PE, and low density PE, polyvinyl acetate, polyvinyl chloride, bisphenol A polycarbonate (BPA-PC), cycloolefin copolymer (COC), polysulfone (PSF), polyetherimide (PEI), polyurethane, acrylonitrile butadiene styrene (ABS), polyimide, polyamide, copolymer of any of the foregoing, or any combination thereof.

[0139] In some embodiments, the first heat-activatable polymer described herein has a melting point of 80°C to 200°C, 100°C to 200°C, 120°C to 200°C, 140°C to 200°C, 160°C to 200°C, 180°C to 200°C, 80°C to 180°C, 80°C to 160°C, 80°C to 140°C, 80°C to 120°C, 80°C to 100°C, 100°C to 180°C, 100°C to 160°C, or 100°C to 140°C.

[0140] As used herein, a battery environment can be the environment with the battery itself or it can be a simulated battery environment.

[0141] In another embodiment, the coatings described herein may further include a second heat-activated polymer coating the layer of microencapsulated electrolyte-absorbing material. Figure 14 illustrates this embodiment, where a second heat-activated polymer 42 coats a layer of microencapsulated electrolyte-absorbing material 40 in a first heat-activated polymer 41.

[0142] The second heat-activatable polymer layer can have any thickness consistent with the objectives of the present disclosure. In some cases, the second heat-activatable polymer layer has a thickness of 500 nm to 20 microns, 500 nm to 15 microns, 500 nm to 10 microns, 500 nm to 5 microns, 500 nm to 4 microns, 500 nm to 3 microns, 500 nm to 2 microns, or 500 nm to 1 micron.

[0143] The second heat-activated polymer may have the same or a different composition than the first heat-activated polymer. In some embodiments, the second heat-activated polymer is selected from the group consisting of methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, sec-butyl methacrylate, pentyl methacrylate, 2-ethylbutyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, isooctyl methacrylate, isononyl methacrylate, lauryl methacrylate, tetradecyl methacrylate, polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF:HFP), polytetrafluoroethylene (PTFE), polyethylene oxide (PEO), poly(vinyl alcohol), and the like. Polypropylene (PP) including isotactic PP, high density PP, ultra-high molecular weight PP, and low density PP, polyethylene (PE) including high density PE, ultra-high molecular weight PE, and low density PE, polyvinyl acetate, polyvinyl chloride, bisphenol A polycarbonate (BPA-PC), cycloolefin copolymer (COC), polysulfone (PSF), polyetherimide (PEI), polyurethane, acrylonitrile butadiene styrene (ABS), polyimide, polyamide, copolymer of any of the foregoing, or any combination thereof.

[0144] In some embodiments, the second heat-activatable polymer described herein has a melting point of 150°C to 200°C, 160°C to 200°C, 170°C to 200°C, 180°C to 200°C, 190°C to 200°C, 150°C to 190°C, 150°C to 180°C, 150°C to 170°C, 150°C to 160°C, 160°C to 180°C, at least 150°C, or greater than or equal to 150°C.

[0145] In one embodiment, a first heat-activatable polymer described herein has a melting point between 80°C and 200°C, and a second heat-activatable polymer described herein has a melting point between 150°C and 200°C.

[0146] When the first heat-activated polymer is heated to a temperature above its melting point, it can melt and expose the electrolyte-absorbing material and the second heat-activated polymer. In some cases, the electrolyte-absorbing material is exposed to the electrolyte and subsequently absorbs the electrolyte, disrupting charge transfer between the battery's electrodes. In some cases, the battery separator is exposed to heat sufficient to melt the first and second heat-activated polymers. In these cases, the battery separator can self-heal, with the second heat-activated polymer melting and encapsulating the first layer of electrolyte-absorbing material upon exposure to heat sufficient to melt the first heat-activated polymer. Thus, prior to a thermal event, the coatings described herein include electrolyte-absorbing material, such as particles, sealed or sealed (i.e., not exposed) within the coating. When a thermal event occurs, the electrolyte-absorbing material can be unsealed or unsealed, exposing the material to the electrolyte.

[0147] V. Battery self-protection methods In another aspect, a method for protecting a battery against a thermal event is described herein. In some cases, the method for protecting a battery against a thermal event includes melting a first heat-activated polymer in a battery separator in a battery environment to uncover an electrolyte-absorbing material. The battery separator described in this section may be the battery separator described in Section IV. The uncovered electrolyte-absorbing material is exposed to an electrolyte present in the battery environment. The method further includes absorbing the electrolyte with the electrolyte-absorbing material while the electrolyte-absorbing material is uncovered. As discussed in Section IV, absorption of the electrolyte can disrupt electrical connection between the cathode and anode of the battery, shutting down a thermal runaway event.

[0148] In embodiments in which the battery separator described in Section IV includes a first heat-activated polymer and an electrolyte-absorbing material disposed between a second heat-activated polymer and a porous substrate, the methods described herein include melting the second heat-activated polymer to form a barrier-less electrolyte on the surface of the porous substrate, where the barrier-less electrolyte is formed by the second heat-activated polymer encapsulating at least a portion of the uncovered electrolyte-absorbing material upon melting.

[0149] Various embodiments of the present invention have been described to achieve various objectives of the present invention. It should be recognized that these embodiments are merely illustrative of the principles of the present invention. Numerous modifications and adaptations of the present invention will be readily apparent to those skilled in the art without departing from the spirit and scope of the present invention.

[0150] VI. Composite Materials, Vehicles, or Devices The composites, jelly rolls, pancakes, or systems described herein include any of the separators described above and one or more electrodes, e.g., an anode, a cathode, or an anode and a cathode, where the separator is in direct contact with the electrodes. The particular type of electrode can be any electrode type consistent with the objectives of the present disclosure. For example, the electrode can be one suitable for use in a lithium-ion secondary battery.

[0151] A suitable anode can be any anode, preferably having an energy capacity of 372 mAh / g or greater, preferably ≧700 mAh / g, and most preferably ≧1000 mAh / g. The anode can be constructed from lithium metal foil or lithium alloy foil (e.g., lithium aluminum alloy), or mixtures of lithium metal and / or lithium alloy with materials such as carbon (e.g., coke, graphite), nickel, copper, and the like.

[0152] Suitable cathodes may be any cathode compatible with the anode, and may include intercalation compounds, insertion compounds, or electrochemically active polymers. Suitable intercalation materials include, for example, MoS2, FeS2, MnO2, TiS2, NbSe3, LiCoO2, LiNiO2, LiMn2O4, VO 13 , V2O5, and CuCl2. Suitable polymers include, for example, polyacetylene, polypyrrole, polyaniline, and polythiophene.

[0153] The electrolyte may be a liquid (organic or inorganic), a gel, or a polymer. Typically, the electrolyte is primarily composed of a salt and a medium (e.g., in a liquid electrolyte, the medium is referred to as the solvent, while in a gel electrolyte, the medium may be the polymer matrix). The salt may be a lithium salt. Examples of lithium salts include LiPF6, LiAsF6, LiCF3SO3, LiN(CF3SO3)3, LiBF6, LiClO4, BETTE electrolyte (commercially available from 3M Company, Minneapolis, Minnesota, USA), and combinations thereof. Examples of solvents include ethylene carbonate (EC), propylene carbonate (PC), EC / PC, 2-methyltetrahydrofuran (2-MeTHF) / EC / PC, dimethyl carbonate (EC / DMC), dimethylethane (EC / DME), diethyl carbonate (EC / DEC), ethyl methyl carbonate (EC / EMC), EC / EMC / DMC / DEC, EC / EMC / DMC / DEC / PE, PC / DME, and DME / PC. Examples of polymer matrices include polyvinylidene fluoride (PVDF), PVDF:THF (PVDF:tetrahydrofuran), PVDF:CTFE (PVDF:chlorotrifluoroethylene), PVDF:HFP (PVDF:hexafluoropropylene), polyacrylonitrile (PAN), and polyethylene oxide (PEO).

[0154] Any of the separators and batteries, cells, or composites described above may be incorporated into any vehicle, such as an electronic vehicle or device, that is fully or partially battery powered, such as a cell phone or laptop.

[0155] VII. Coated separator 2 Also disclosed herein are battery separators having a coating on one or both sides of a microporous membrane, the coating on one or both sides comprising, consisting of, or consisting essentially of: an inorganic component and at least one of a wet adhesive polymer and a dry adhesive polymer. In some preferred embodiments, the coating is on one side, and in other preferred embodiments, the coating is on both sides.

[0156] A. Microporous membrane The microporous membrane of the battery separator is not particularly limited, and any microporous membrane may be used. As used herein, the term "microporous" means that the membrane has micropores with a diameter of 0.05 to 1.0 microns. In some embodiments, the microporous membrane has an average pore size or diameter of 0.01 to 1.0 microns, 0.05 to 1.0 microns, 0.01 to 0.9 microns, 0.01 to 0.8 microns, 0.01 to 0.7 microns, 0.01 to 0.6 microns, 0.01 to 0.5 microns, 0.01 to 0.4 microns, 0.01 to 0.4 microns, 0.01 to 0.3 microns, 0.01 to 0.2 microns, or 0.01 to 0.1 microns.

[0157] The shape of the pores in the microporous membrane is not particularly limited and can be slit-shaped, elliptical, circular, or substantially circular. For example, round-shaped pores are disclosed in U.S. Patent Application Publication No. 2011 / 0223486, which is incorporated herein by reference in its entirety.

[0158] In some preferred embodiments, the microporous membrane is formed by a dry stretch process, such as the Celgard® dry stretch process. The dry stretch process may include, consist of, or consist essentially of extrusion, annealing, stretching (uniaxial or biaxial), and optional calendaring and / or pore filling steps. In some embodiments, the microporous membrane may be formed by a method including at least one of a dry stretch process, a wet process (phase inversion), BNOPP, particle stretching, coextrusion, lamination, sintering, printing, extrusion, and electrospinning.

[0159] The structure of the microporous membrane is not so limited, and the structure can be a single layer, a two layer, a three layer, or a multi-layer structure.

[0160] In some embodiments, the microporous membrane is a single layer or monolayer structure. Dry-process monolayer microporous membranes can be formed by extruding a single non-porous monolayer precursor (monoextrusion) and stretching the precursor to form pores. In some preferred embodiments, the monolayer microporous membrane can comprise, consist of, or consist essentially of polypropylene, polyethylene, a combination of polypropylene and polyethylene, a combination of polypropylene and additives, or a combination of polyethylene and additives.

[0161] In some embodiments, the microporous membrane can be a bilayer structure. Dry-process bilayer microporous membranes can be formed by laminating two extruded (monoextruded) monolayers together or by coextruding two layers together. Bilayers can also be formed by a bubble membrane extrusion process in which a bubble collapses on itself to form the bilayer. Each layer of the bilayer structure can comprise, consist of, or consist essentially of polypropylene, polyethylene, a combination of polypropylene and polyethylene, a combination of polypropylene and additives, or a combination of polyethylene and additives. Each layer of the bilayer can have the same or different compositions.

[0162] In some embodiments, the microporous membrane can have a tri-layer structure. Dry-process tri-layer microporous membranes can be formed by laminating three monolayers together. For example, two monoextruded polypropylene-containing monolayers can be laminated with one monoextruded polyethylene-containing monolayer to form a PP / PE / PP tri-layer structure, or two monoextruded polyethylene-containing monolayers can be laminated with one monoextruded polypropylene-containing monolayer to form a PE / PP / PE tri-layer structure. In some embodiments, the trilayer can be coextruded to form a tri-layer structure. For example, the coextruded trilayer can have a PP / PE / PP or PE / PP / PE structure, where PE is the polyethylene-containing coextruded layer and PP is the polypropylene-containing coextruded layer. In some other embodiments, a tri-layer structure can be formed by laminating a monoextruded monolayer with a coextruded bi-layer.

[0163] In some embodiments, the microporous membrane can be a multilayer structure. For example, some exemplary multilayer structures are disclosed in U.S. Patent No. 9,908,317 and WO / 2018 / 089748, both of which are incorporated herein by reference in their entireties.

[0164] In some embodiments, a multilayer microporous membrane or film comprises 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 11 or more, 12 or more, 13 or more, 14 or more, 15 or more, 15 or more, 16 or more, 17 or more, 18 or more, 19 or more, 20 or more, 21 or more, 22 or more, 23 or more, 24 or more, 25 or more, 26 or more, 27 or more, 28 or more, 29 or more, 30 or more, 40 or more, 50 or more, 60 or more, 70 or more, 80 or more, 90 or more, or 100 or more layers. The term "layer" includes a monoextruded layer having a thickness of 2 to 20 microns. As will be understood by those skilled in the art, a monoextruded layer is a layer extruded by itself, not with other layers. Additionally, each layer of a coextruded bilayer, trilayer, or multilayer film is considered a "layer" for purposes of determining whether a given battery separator is a multilayer battery separator. A coextruded bilayer film will have two layers, a coextruded trilayer film will have three layers, and a coextruded multilayer film will have two or more layers, preferably three or more. The exact number of layers in a bilayer, trilayer, or multilayer coextruded film is determined by the design of the extruder and not necessarily by the materials coextruded to form the coextruded film. For example, a coextruded bilayer, trilayer, or multilayer film may be formed using the same material in each of two, three, or four or more layers, but these layers are considered separate layers even if each layer is made of the same material. The exact number is also determined by the design of the extruder. The layers of the coextruded bi-layer, tri-layer, or multi-layer film each have a thickness of 0.01 to 20 microns, preferably 0.1 to 5 microns, and most preferably 0.1 to 3 microns, 0.1 to 2 microns, 0.1 to 1 micron, 0.01 to 0.9 microns, 0.01 to 0.8 microns, 0.01 to 0.7 microns, 0.01 to 0.6 microns, 0.01 to 0.5 microns, 0.01 to 0.4 microns, 0.01 to 0.3 microns, or 0.01 to 0.2 microns. These layers are microlayers.

[0165] In some embodiments, the multilayer microporous films or membranes disclosed herein comprise two or more, or preferably three or more, coextruded layers. A coextruded layer is a layer formed by a coextrusion process. At least two, or preferably at least three, consecutive coextruded layers can be formed by the same or separate coextrusion processes. For example, at least two or at least three consecutive layers can be formed by the same coextrusion process, or two or more layers can be coextruded by one process and two or more layers can be coextruded by another process, or two or more layers formed by one process can be laminated to two or more layers formed by separate processes, thereby combining to form four or more consecutive coextruded layers. In some preferred embodiments, two or more, or preferably three or more, coextruded layers are formed by the same coextrusion process. For example, two or more, or preferably three or more, four or more, five or more, six or more, seven or more, eight or more, nine or more, ten or more, fifteen or more, twenty or more, twenty-five or more, thirty-five or more, forty-five or more, fifty-five or more, fifty-five or more, or sixty or more coextruded layers can be formed by the same coextrusion process. In a more preferred embodiment, the extrusion process is carried out by extruding two or more polymer mixtures, which can be the same or different, without a solvent. A preferred coextrusion process is a dry process, such as the Celgard® dry-draw process.

[0166] In some embodiments, the multilayer microporous films or membranes described herein are made by forming a coextruded bilayer (two coextruded layers), trilayer (three coextruded layers), or multilayer (two or more, preferably three or more coextruded layers) film and then laminating the bilayer, trilayer, or multilayer film to at least one, preferably two, other films. The at least one, but preferably two, other films can be nonwoven films, monoextruded films, or coextruded films. In preferred embodiments, the other films are coextruded films having the same number of coextruded layers as the coextruded bilayer, trilayer, or multilayer film. For example, if a coextruded trilayer film is formed, the other layers are also coextruded trilayers.

[0167] Lamination of a bi-, tri-, or multi-layer coextruded film with at least one other monoextruded monolayer film or bi-, tri-, or multi-layer film may use heat, pressure, or preferably heat and pressure.

[0168] The thickness of the microporous membrane is not particularly limited and can be 1 to 50 microns, preferably 5 to 30 microns, 5 to 25 microns, 5 to 20 microns, 5 to 15 microns, or 5 to 10 microns.

[0169] In some embodiments, the microporous membrane may be combined with another microporous membrane or a nonwoven fabric, which may or may not be microporous. If the nonwoven fabric is microporous, it is considered a microporous membrane.

[0170] B. Coating The coating is not so limited. In some embodiments, the coating can comprise, consist of, or consist essentially of an inorganic component and a wet adhesive polymer. In some embodiments, the coating can comprise, consist of, or consist essentially of an inorganic component and a dry adhesive polymer. Finally, in some embodiments, the coating can comprise, consist of, or consist essentially of an inorganic component, a dry adhesive polymer, and a wet adhesive polymer. In some embodiments, the coating can also further comprise, consist of, or consist essentially of a binder.

[0171] In some embodiments, the inorganic component can comprise, consist of, or consist essentially of a ceramic, a metal oxide, a metal hydroxide, a metal carbonate, a silicate, kaolin, talc, a mineral, a glass, or any combination thereof. In some embodiments, the inorganic component described in this section can include aluminum oxide (Al2O3), boehmite (Al(O)(OH)), titanium oxide (TiO2), silicon oxide (SiO2), zinc oxide (ZnO2), zirconium dioxide (ZrO2), barium sulfate (BaSO4), barium titanium oxide (BaTiO3), aluminum nitride, silicon nitride, calcium fluoride, barium fluoride, zeolite, apatite, kaolin, mullite, spinel, olivine, mica, tin dioxide (SnO2), indium tin oxide, an oxide of a transition metal, or any combination thereof.

[0172] In some embodiments, the amount of inorganic component in the coating is 10% to 99.5% by weight, preferably 20% to 99% by weight, more preferably 80% to 99% by weight, and most preferably 90% to 99% by weight. In some embodiments, the coating is "rich" in inorganic component, meaning that the inorganic component is added in an amount of 50% or greater. Rich in inorganic component can mean that the inorganic component is present in an amount of 50% to 99%, 50% to 90%, 50% to 80%, 50% to 70%, or 50% to 60%.

[0173] The dry adhesive polymers described herein are not so limited and can be any polymer that imparts high or low tack to the coating. A high tack coating is more difficult to separate after contact with another surface where a bond is formed. A low tack coating is easier to separate and reposition after contact with another surface where a bond is formed. A tacky coating can be beneficial for battery separators used in laminated or prismatic battery cells. This helps prevent the separator from moving once in place within the cell.

[0174] The dry adhesive polymers described herein may be characterized by their glass transition temperature. In some embodiments, the dry adhesive polymers have a glass transition temperature of less than 100°C, less than 90°C, less than 80°C, less than 70°C, less than 60°C, less than 50°C, less than 40°C, less than 30°C, or less than 20°C. The minimum glass transition temperature may be 20°C, 10°C, 5°C, or 0°C. Preferably, in some embodiments, the glass transition temperature may be between 20°C and 100°C, between 20°C and 70°C, or between 25°C and 100°C.

[0175] The wet adhesion polymer described herein is not so limited and can be any polymer that absorbs an electrolyte, swells or increases in size upon absorbing an electrolyte, and / or gels upon absorbing an electrolyte. The electrolyte can be any electrolyte suitable for use in a secondary battery, including, but not limited to, electrolytes in which the solvent is DEC, PC, DMC, EC, or combinations thereof. The wet adhesion polymer also increases the adhesion of the coating to the anode or cathode of a secondary battery upon wetting.

[0176] In some embodiments, the wet adhesive polymer can comprise, consist of, or consist essentially of a fluoropolymer. In some embodiments, the fluoropolymer is a PVDF copolymer, such as PVDF-HFP. The HFP content of the PVDF-HFP can be preferably 30 mol% or less, more preferably less than 15 mol%.

[0177] In some embodiments, the wet adhesive polymer is selected from the group consisting of methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, sec-butyl methacrylate, pentyl methacrylate, 2-ethylbutyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, isooctyl methacrylate, isononyl methacrylate, lauryl methacrylate, tetradecyl methacrylate, polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF:HFP), polytetrafluoroethylene (PTFE), polyethylene oxide (PEO), poly(vinyl alcohol) (PVA), polyacrylic acid, acrylic acid esters ... The polymer may comprise, consist of, or consist essentially of polypropylene (PAN), polyacrylamide, polyvinyl acetate, polyvinylpyrrolidone, polytetraethylene glycol diacrylate, isotactic PP, high density PP, ultra-high molecular weight PP, low density PP, polyethylene (PE), including high density PE, ultra-high molecular weight PE, low density PE, polyvinyl acetate, polyvinyl chloride, bisphenol A polycarbonate (BPA-PC), cycloolefin copolymer (COC), polysulfone (PSF), polyetherimide (PEI), polyurethane, acrylonitrile butadiene styrene (ABS), polyimide, polyamide, copolymer of any of the foregoing, or any combination thereof.

[0178] The use of wet adhesive polymers can be useful in batteries where adhesion to the electrodes is important.

[0179] In some embodiments, the coating can include 20% to 80%, 30% to 70%, 40% to 60%, or 50% to 60% wet adhesive polymer, dry adhesive polymer, or a combination thereof. The coating can be rich in wet adhesive polymer, dry adhesive polymer, or a combination of wet adhesive polymer and dry adhesive polymer, meaning that the coating includes 50% or more wet adhesive polymer, dry adhesive polymer, or a combination thereof.

[0180] In some embodiments, the coating can include: 1) an inorganic component, a wet adhesive polymer, and a dry adhesive polymer, 2) an inorganic component and a wet adhesive polymer, or 3) an inorganic component and a dry adhesive polymer. In such embodiments, the particle sizes of the components can be the same or different.

[0181] In some embodiments, the coating may include an inorganic component and a wet adhesive polymer. In some such embodiments, the inorganic component and the wet adhesive polymer may have the same size when the coating is dry, and when the coating is wet, the wet adhesive polymer may swell and become larger than the inorganic component. In some embodiments, the inorganic component does not grow, or does not grow substantially. In these embodiments, the inorganic component may be exposed to the surface of the coating when dry, which may allow for better handling of the separator. In this embodiment, when the separator coating is wet, the wet adhesive polymer swells in the electrolyte, which may allow for adhesion of the coating to the electrodes in a secondary battery. The wet adhesive polymer may be larger than the inorganic component, so the inorganic component may not be exposed to the surface when the wet adhesive polymer swells.

[0182] In some embodiments, the coatings described herein are monolayer or bilayer coatings. As used herein, a monolayer coating is a coating that is one molecule thick, where the molecule is at least one of an inorganic component, a wet adhesive polymer, or a dry adhesive polymer. As used herein, a bilayer is a coating that is two molecules thick, where the molecule is at least one of an inorganic component, a wet adhesive component, and a dry adhesive component.

[0183] In some embodiments, the coating may have a thickness of 1 micron or less, or less than 500 nm. In some embodiments, the coating may be thicker than 1 micron. For example, in some embodiments, the coating may have a thickness of 1 micron to 10 microns, 1 to 9 microns, 1 to 8 microns, 1 to 7 microns, 1 to 6 microns, 1 to 5 microns, 1 to 4 microns, 1 to 3 microns, or 1 to 2 microns. One way to provide a thinner coating is by using smaller inorganic components, wet adhesive polymers, and / or dry adhesive polymers. For example, the inorganic components, wet adhesive polymers, and / or dry adhesive polymers may have particle sizes of less than 1 micron, less than 900 nm, less than 800 nm, less than 700 nm, less than 600 nm, less than 500 nm, less than 400 nm, or less than 300 nm.

[0184] In some embodiments, the coating thickness is 1 micron, 900 nm or less, 800 nm or less, 700 nm or less, 600 nm or less, or 500 nm or less, and is a single-layer or double-layer coating. One way to provide a thinner coating is by using smaller inorganic components, wet adhesive polymers, and / or dry adhesive polymers. For example, the inorganic components, wet adhesive polymers, and / or dry adhesive polymers can have particle sizes less than 1 micron, 900 nm or less, 800 nm or less, 700 nm or less, 600 nm or less, 500 nm or less, 400 nm or less, or 300 nm or less.

[0185] In some embodiments, the coating can be porous or non-porous, so long as it is ionically conductive at typical battery operating temperatures (when wet with electrolyte) during battery use. For example, a PVDF coating can be non-porous (having a high Gurley value when dry) and still be ionically conductive when wet with electrolyte during battery use. Also, very thin, ultra-thin, nano-thin coatings can be non-porous in electrolyte yet still be ionically conductive. Porous or microporous coatings having thicknesses of 1 micron or less, or less than 500 nm, may be preferred.

[0186] In some embodiments, the coating exhibits improved electrolyte wettability compared to conventional ceramic or polymer coatings used in battery separators. In some embodiments, the coating has a contact angle (a measure of electrolyte wettability) of less than 35°, less than about 30°, or less than about 25°. In some embodiments, about 30° is considered to include a contact angle of 28° to 32°. In some embodiments, about 25° is considered to include a contact angle of 23° to 27°.

[0187] In some embodiments, the coatings described herein have a wet adhesion of greater than 30 N / m, greater than 40 N / m, or greater than 50 N / m. In some embodiments, the coatings described herein have a dry adhesion of greater than 10 N / m, greater than 15 N / m, or greater than 20 N / m. In some embodiments, the coatings have a wet adhesion of greater than 30 N / m, greater than 40 N / m, or greater than 50 N / m, and a dry adhesion of greater than 10 N / m, greater than 15 N / m, or greater than 20 N / m.

[0188] In some embodiments, the coatings described herein exhibit enhanced electrolyte absorption compared to conventional ceramic coatings used in battery separators, for example, the coatings may exhibit electrolyte absorption of greater than 2 g / sample after immersion in electrolyte for 60 minutes.

[0189] VIII. Coated separator 3 Also disclosed herein is a battery separator having a coating on one or both sides of a microporous membrane, wherein the coating on one or both sides comprises, consists of, or consists essentially of a polymer that at least one of reduces the surface coefficient of friction of the microporous membrane and reduces the shutdown onset temperature of the microporous membrane.

[0190] A. Microporous membrane The microporous membrane is not particularly limited and can be any microporous membrane suitable for use in a battery separator. The microporous membrane can be any microporous membrane described herein. In some preferred embodiments, the microporous membrane is a microporous membrane made by a dry-stretch process, such as the Celgard® dry-stretch process.

[0191] B. Coating The coatings described herein are not so limited. In some embodiments, the coating comprises, consists of, or consists essentially of a polymer that reduces the coefficient of surface friction of the microporous membrane. This means that the coating has a lower coefficient of surface friction than the uncoated microporous membrane. In some embodiments, the coating comprises, consists of, or consists essentially of a polymer that reduces the shutdown onset temperature of the microporous membrane. This means that the shutdown onset temperature of the coated microporous membrane is lower than the microporous membrane itself or the uncoated microporous membrane. In some embodiments, the coating comprises, consists of, or consists essentially of at least one of a polymer that reduces the coefficient of surface friction of the microporous membrane, a polymer that reduces the shutdown onset temperature of the microporous membrane, or a combination thereof, and an inorganic component. In some embodiments, no inorganic component is present. In some embodiments, a single polymer can reduce the coefficient of surface friction of the microporous membrane and reduce the shutdown onset temperature of the microporous membrane.

[0192] The inorganic component is not so limited and can be any inorganic component, hi some embodiments, the inorganic component is as described herein.

[0193] In some embodiments, the coating comprises a polymer that reduces the surface friction coefficient of the microporous membrane, such that the battery separator has a pin removal force of less than 350 N, less than 325 N, less than 300 N, less than 200 N, or less than 100 N. Low surface friction is an important characteristic in wire-wound cell assembly processes. The coatings described herein significantly reduce film surface friction, thus improving pin removal performance.

[0194] Pin removal properties are quantified using the following procedure, which measures the "pin removal force (g)" where 1 g is 0.01 Newtons.

[0195] A battery winding machine was used to wind the separator (comprising, consisting of, or consisting essentially of a microporous membrane with a coating layer on at least one surface) around a pin (or core or mandrel). The pin is a two-piece cylindrical mandrel with a 0.16 inch diameter and a smooth exterior. Each piece has a semicircular cross section. A separator, described below, is attached to the pin. An initial (tangential) force of 0.5 kgf is applied to the separator, which is then wound at a rate of 10 inches per minute in 24 seconds. During winding, a tension roller engages the separator wrapped around the mandrel. The tension roller consists of a 1 / 3 inch diameter roller located opposite the separator feed roll, a 3 / 4 inch pneumatic cylinder (when engaged) to which 1 bar of air pressure is applied, and a 1 / 4 inch rod interconnecting the roller and cylinder.

[0196] The separator consists of two 30 mm (width) x 10 inch membranes to be tested. Five of these separators are tested, and the results are averaged and reported as the average. Each piece is spliced ​​to the separator feed roll of the winding machine with a 1 inch overlap. Ink marks are made 1 / 2 inch and 7 inches from the free end of the separator, i.e., distal to the spliced ​​end. With the 1 / 2 inch mark aligned with the far side of the pin (i.e., the side adjacent to the tension roller), the separator is engaged between the pieces on the pin and winding begins with the tension roller engaged. When the 7 inch mark is approximately 1 / 2 inch from the jelly roll (separator wrapped around the pin), the separator is cut at that mark and the free end of the separator is secured to the jelly roll with adhesive tape (1 1 / 2 inch wide overlap). The jelly roll (i.e., the pin with the separator wrapped around it) is removed from the winding machine. An acceptable jelly roll will have no wrinkles or stretching.

[0197] The jelly roll is placed in a tensile strength testing machine (i.e., Chatillon Model TCD 500-MS, Chatillon, Greensboro, NC, USA) equipped with a load cell (50 lb (1 lb = 453.59237 g) x 0.02 lb, Chatillon DFGS 50). The strain rate is 2.5 inches per minute, and data from the load cell is recorded at a rate of 100 points per second. The peak force is reported as the pin removal force.

[0198] The static coefficient of friction (COF) is measured according to JIS P8147, entitled "Paper and Paperboard—Method for Measuring Static and Dynamic Coefficients of Friction." In some embodiments, the polymer that reduces the surface coefficient of friction of the microporous membrane and / or the shutdown onset temperature of the microporous membrane is siloxane, silicone resin, fluororesin wax (e.g., paraffin wax, microcrystalline wax, low molecular weight polyethylene, and other hydrocarbon waxes), fatty acid ester (e.g., methyl stearate, stearyl stearate, stearic acid monoglyceride), fatty amide (e.g., stearamide, palmitamide, methylene bisstearamide), or any combination thereof. In some embodiments, the polymer that reduces the surface coefficient of friction of the microporous membrane and the shutdown onset temperature of the microporous membrane is polyethylene. The form of the polyethylene is not particularly limited, and in some embodiments, polyethylene beads may be used.

[0199] In some embodiments, the coating includes a polymer that reduces the shutdown onset temperature of the microporous membrane. In some embodiments, the polymer is a thermoresponsive polymer or a polymer that melts at a predetermined temperature below the temperature at which the microporous membrane melts. In some embodiments, the shutdown onset temperature of a battery separator having a coating described herein is 160°C or less, 150°C or less, 140°C or less, 130°C or less, 120°C or less, 110°C or less, or 100°C or less. Thermoresponsive polymers improve shutdown performance and allow for the ability to tailor the shutdown onset temperature for a wide range of battery applications.

[0200] In some embodiments, the polymer that reduces the shutdown onset temperature of the microporous membrane is a polymer with a melting point in the range of 80°C to 130°C, sometimes in the range of 90°C to 120°C, and sometimes in the range of 100°C to 120°C.

[0201] The polymer that reduces the shutdown temperature of the microporous membrane can be particles having an average particle size in the range of 0.1 to 5.0 microns, 0.2 to 3.0 microns, 0.3 to 1.0 microns, etc. The particles can be coated, uncoated, or partially coated.

[0202] In some preferred embodiments, the polymer that reduces the shutdown temperature of the microporous membrane can be particles comprising wax, oligomers, polyethylene (PE), e.g., low-density PE, etc. These particles can be coated, uncoated, or partially coated. For example, they can be coated with latex and / or a polymer binder.

[0203] IX. Coated separator 4 Also disclosed herein are battery separators comprising, consisting of, or consisting essentially of a single- or double-sided coating of a microporous membrane. The single- or double-sided coating comprises, consists of, or consists essentially of a crosslinked or crosslinkable polymer. In some embodiments, the single- or double-sided coating comprises, consists of, or consists essentially of a crosslinked polymer. In some embodiments, the single- or double-sided coating comprises, consists of, or consists essentially of a crosslinkable polymer. A crosslinkable polymer is a polymer that is not crosslinked but can be crosslinked by light, heat, or any other means. A crosslinkable polymer contains a crosslinker, which is a molecule containing at least two reactive ends for connecting polymer chains. A crosslinked polymer is a polymer that has already been crosslinked. The crosslinked polymer may contain some residual unreacted crosslinker in case the crosslinking reaction did not proceed to 100% completion and left no residual reactants. In some embodiments, the crosslinked polymer contains no more than 2%, no more than 1%, no more than 0.5%, no more than 0.1%, no more than 0.05%, no more than 0.01%, or no more than 0.005% of added crosslinker that remains after the crosslinking reaction to form the crosslinked polymer. The remaining crosslinker reacts to form crosslinks between at least two polymers. The initial amount of crosslinker in the composition (before curing or as-applied) is up to 100,000 ppm or 10%, up to 50,000 ppm or 5%, up to 10,000 ppm or 1%, or up to 5,000 ppm or 0.5% of the total coating composition.

[0204] A. Microporous membrane The microporous membrane is not particularly limited and can be any microporous membrane suitable for use in a battery separator. The microporous membrane can be any microporous membrane described herein. In some preferred embodiments, the microporous membrane is a microporous membrane made by a dry-stretch process, such as the Celgard® dry-stretch process.

[0205] B. Coating The coatings described herein are not so limited. The coatings can include, consist of, or consist essentially of crosslinked or crosslinkable polymers. As previously mentioned, both crosslinked and crosslinkable polymers are intended to include a crosslinking agent. Crosslinkable, for example, is meant to describe the coating as applied, including a crosslinking agent but not yet crosslinked. Crosslinking can be initiated by any means, including, but not limited to, light (e.g., UV light), heat, an initiator, or a combination thereof.

[0206] A crosslinker is a molecule or monomer containing at least two, three, four, five, or more reactive groups capable of linking at least two polymer chains together. The crosslinker is not so limited and can be any molecule containing two or more reactive groups capable of linking at least two polymer chains together. Some examples of crosslinkers include: difunctional acrylates, trifunctional acrylates including pentaerythritol triacrylate, pentaerythritol tetraacrylate, multifunctional acrylates such as ethoxylated (4) pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, and ethoxylated dipentaerythritol hexaacrylate, 1,3-butanediol diacrylate, and the like. Diepoxides including bis[(4-glycidoxy)phenyl]methane and its isomers, 1,4-tanediol diglycidyl ether, 1,2,7,8-diepoxyoctane, diglycidyl 1,2-cyclohexanedicarboxylate, N,N-diglycidyl-4-glycidoxyaniline, tris(2,3-epoxypropyl)isocyanurate and tris(4-hydroxyphenyl)methane triglycidyl ether, dimethacrylates, trimethacrylates, and multifunctional methacrylates.

[0207] In some embodiments, the crosslinker can have a structure as shown in formula (1), (2), or (3):

[0208] [ka]

[0209] [ka]

[0210] [ka]

[0211] wherein R1 is alkyl or aryl containing any atom selected from C, O, N, S, F, or any mixture thereof; R2 is H, or alkyl or aryl containing any atom selected from C, O, N, S, F, or any mixture thereof; X is one or more of R1 and / or R2, and l, m, n, o, p, q; and r is an integer from 1 to 20, 1 to 15, 1 to 10, or 1 to 5.

[0212] The coating may also include at least one polymer containing reactive groups capable of reacting with a crosslinker. For example, the polymer may contain acrylate or methacrylate groups capable of reacting with diacrylate, triacrylate, multifunctional acrylate, dimethacrylate, trimethacrylate, and multifunctional methacrylate crosslinkers. In some embodiments, the polymer may contain nucleophilic groups capable of reacting with a diepoxide or triepoxide crosslinker. The nucleophilic groups may, in some embodiments, include N, O, or S.

[0213] When a crosslinking agent is added, in some embodiments, a catalyst may be added, which may initiate or catalyze, for example, the crosslinking of two polymer chains via the added crosslinking agent. The catalyst may be sensitive to heat, light, or the chemical environment (e.g., pH), for example, the catalyst may initiate or catalyze the crosslinking of one or more polymer chains in the coating composition in response to heating, light irradiation, or a change in pH.

[0214] In some embodiments, the coating may include an inorganic component, and in some preferred embodiments, no inorganic component is added to the coating. The inorganic component described herein is not so limited and may be any inorganic component.

[0215] In some embodiments, the coating may include additional organic components, and in some preferred embodiments, additional organic polymeric components are added to the coating. The organic components described herein are not so limited and may be any organic component.

[0216] In embodiments without the addition of inorganic components, it is possible to form very thin coatings. In some embodiments, without the addition of inorganic components, the thickness of the coated microporous membrane is substantially the same as the thickness of the uncoated microporous membrane. In some embodiments, without the addition of inorganic components, the thickness of the coated membrane compared to the uncoated microporous membrane is an increment of 500 nm or less, 400 nm or less, 300 nm or less, 200 nm or less, 100 nm or less, or 50 nm or less. This is particularly possible in embodiments without the addition of inorganic components, because the coating can partially or completely penetrate the pores of the microporous membrane. In embodiments with the addition of inorganic components, the pores can be blocked or coated, or partially blocked or coated, by the inorganic component.

[0217] In some embodiments, the coated microporous membranes exhibit increased TD tensile strength compared to uncoated microporous membranes, for example, the TD tensile strength of the coated microporous membranes can reach 160%, 150%, 140%, or 130% of the TD tensile strength of the uncoated microporous membranes.

[0218] In some embodiments, the coated microporous membrane may have a reduced standard deviation in TD elongation compared to an uncoated microporous membrane, e.g., the standard deviation in TD elongation of the coated product is 50% or less, 60% or less, 70% or less, or 80% or less of the TD elongation of the uncoated product.

[0219] In some embodiments, the MD shrinkage of the coated microporous membrane after 1 hour at 130° C. is 90% or less, 80% or less, or 70% or less than that of the uncoated microporous membrane. The shrinkage can be measured by preparing a sample of the coated microporous membrane, measuring the MD length before placing it in an oven, placing the sample in an oven at 130° C. for 1 hour, and then measuring the MD length after placing it in the oven.

[0220] In some embodiments, the film thickness of the coated and uncoated products is substantially the same (or within an acceptable film thickness variation, such as ±0.5 microns). In some embodiments, the thickness of the coated product is less than 500 nm, less than 400 nm, less than 300 nm, less than 200 nm, less than 100 nm, or less than 50 nm thicker than the uncoated microporous membrane, i.e., the microporous membrane itself.

[0221] In some embodiments, the loading of the coated film is less than 120% or less than 110% of the loading of the uncoated microporous membrane or the microporous membrane itself.

[0222] In some embodiments, the Gurley value of the coated film is increased compared to the uncoated microporous membrane, ie, the Gurley value of the coated film is 130% or less, 120% or less, or 110% or less of the Gurley value of the microporous membrane itself.

[0223] In some embodiments, the coated film exhibits extended shutdown compared to the microporous membrane itself.

[0224] In some embodiments, the coated film cracks less than the microporous membrane itself. This can mean that if the film is punctured, the resulting opening will not be a slit. If the device used to puncture the film is round, the resulting opening will be round rather than a slit.

[0225] XI. Secondary battery Secondary batteries are described that include any of the battery separators described herein. The secondary batteries are not limited to these. For example, the secondary batteries can be nickel-cadmium, nickel-metal hydride, lithium-ion, sodium-ion, potassium-ion, or nickel-zinc secondary batteries. Typically, secondary batteries include, consist of, or consist essentially of electrodes, separators, and electrolytes.

[0226] In some embodiments, the battery cell can be a prismatic cell, a stacked cell, a cylindrical cell, a button cell, or a pouch cell. Separators with different coatings described herein may have advantages in some types of cells compared to other types. For example, dry adhesion may be beneficial for forming stacked cells but less beneficial for forming cylindrical cells. This may be because adhesion of the separator within the stack is important in stacked cells. It is important that the separator stays in place when placed over the electrodes so that the underlying electrodes are not exposed. In cylindrical cells, dry adhesion can cause problems when removing the winding pins.

[0227] XII. Composite Materials, Vehicles, or Devices The composites, jelly rolls, pancakes, or systems described herein include any of the separators described above and one or more electrodes, e.g., an anode, a cathode, or an anode and a cathode, where the separator is in direct contact with the electrodes. The particular type of electrode can be any electrode type consistent with the objectives of the present disclosure. For example, the electrode can be one suitable for use in a lithium-ion secondary battery.

[0228] A suitable anode can be any anode, preferably having an energy capacity of 372 mAh / g or greater, preferably ≧700 mAh / g, and most preferably ≧1000 mAh / g. The anode can be constructed from lithium metal foil or lithium alloy foil (e.g., lithium aluminum alloy), or mixtures of lithium metal and / or lithium alloy with materials such as carbon (e.g., coke, graphite), nickel, copper, and the like.

[0229] Suitable cathodes may be any cathode compatible with the anode, and may include intercalation compounds, insertion compounds, or electrochemically active polymers. Suitable intercalation materials include, for example, MoS2, FeS2, MnO2, TiS2, NbSe3, LiCoO2, LiNiO2, LiMn2O4, VO 13 , V2O5, and CuCl2. Suitable polymers include, for example, polyacetylene, polypyrrole, polyaniline, and polythiophene.

[0230] The electrolyte may be a liquid (organic or inorganic), a gel, or a polymer. Typically, the electrolyte is primarily composed of a salt and a medium (e.g., in a liquid electrolyte, the medium is referred to as the solvent, while in a gel electrolyte, the medium may be the polymer matrix). The salt may be a lithium salt. Examples of lithium salts include LiPF6, LiAsF6, LiCF3SO3, LiN(CF3SO3)3, LiBF6, LiClO4, BETTE electrolyte (commercially available from 3M Company, Minneapolis, Minnesota, USA), and combinations thereof. Examples of solvents include ethylene carbonate (EC), propylene carbonate (PC), EC / PC, 2-methyltetrahydrofuran (2-MeTHF) / EC / PC, dimethyl carbonate (EC / DMC), dimethylethane (EC / DME), diethyl carbonate (EC / DEC), ethyl methyl carbonate (EC / EMC), EC / EMC / DMC / DEC, EC / EMC / DMC / DEC / PE, PC / DME, and DME / PC. Examples of polymer matrices include polyvinylidene fluoride (PVDF), PVDF:THF (PVDF:tetrahydrofuran), PVDF:CTFE (PVDF:chlorotrifluoroethylene), PVDF:HFP (PVDF:hexafluoropropylene), polyacrylonitrile (PAN), and polyethylene oxide (PEO).

[0231] Any of the separators described above may be incorporated into any battery or cell, such as a lithium primary or secondary battery, a lithium ion battery, a lithium metal battery, etc., for any vehicle, such as a fully or partially battery-powered electronic vehicle, or device, such as a cell phone or laptop, a backup or uninterruptible power supply (UPS), etc. [Example]

[0232] Example 1 Composition of the first layer Table 1 describes the composition and physical properties of an exemplary first layer described in Section I.

[0233] [Table 1]

[0234] Example 2 Composition of the second layer Table 2 sets forth the compositions and physical properties of exemplary second layers described in Section I.

[0235] [Table 2]

[0236] Example 3 An example of a separator coated as described in Section VII, "Coated Separator 2," herein. In this example, the coating includes a ceramic component and PvdF (a wet-sticky polymer). A schematic of this coating is shown in Figure 15. An SEM of this coating is shown in Figure 16.

[0237] The amount of ceramic component in the coating was adjusted to create ceramic-rich and PvdF-rich embodiments. Contact angles of these embodiments were measured and compared to uncoated microporous membranes. Results demonstrating this enhanced electrolyte wettability are seen in Figure 17. The wettability of separators with the coatings described herein was also compared to uncoated microporous membranes (different from those used in Figure 17), a conventional ceramic-coated separator without PvdF (CCS), and a polymer-coated separator without inorganic components (PCS). These results are shown in Figure 18. Separators with the coatings described herein were found to exhibit the best wettability with the electrolyte. The average wet and dry adhesion of the coatings described herein was compared to the average wet and dry adhesion of polymer-coated separators with different polymer loadings. The results are shown in Figures 19 and 20. Figure 20 shows the adhesion of an electrode to the coating after adhesion testing. The electrolyte absorption of separators coated as described herein was measured and compared to separators with polymer coatings, and the results are shown in Figure 21.

[0238] Example 4 In this example, an example of a separator was prepared with a coating as described in Section VIII ("Coated Separator 3"). The shutdown of the coated separator was measured and compared to the shutdown of the microporous membrane or base membrane by itself. The remaining results are shown in Figure 22. The pin removal force of the separator with the coating described herein was measured compared to the uncoated microporous membrane or base membrane, and the results are shown in Figure 23.

[0239] Example 5 In this example, an example of a coated separator was prepared, having a microporous membrane and a crosslinked coating as described in Section IX ("Coated Separator 4"). The separator coating did not contain any inorganic components. Separator properties were tested, including TD tensile, TD elongation, MD shrinkage at 130°C for 1 hour, membrane thickness, load, and Gurley. Figure 24 compares these results with those of an uncoated microporous membrane. The shutdown behavior of the coated separator was also examined and compared to that of an uncoated microporous membrane. These results are shown in Figure 25. Puncture tests were performed on the coated separator and compared to those of an uncoated microporous membrane. These results are shown in Figure 26. Compressive elongation was evaluated. These results are shown in Figure 27. Finally, TMA (MD), TMA (TD), and electrolyte loss were measured. These results are shown in Figure 28, which compares the coated and uncoated microporous membranes. In the electrolyte loss test, the wet film is exposed to air, inducing evaporation of the carbonate electrolyte into the atmosphere. Since the carbonate electrolyte is an organic solvent like acetone, fairly rapid evaporation is expected. The specimens with the coating of the present invention exhibited slower electrolyte loss, meaning that the coating material retains electrolyte longer, thus reducing electrolyte loss.

[0240] Disclosed herein are battery separators comprising microporous membranes and coatings. The coatings can comprise, consist of, or consist essentially of polymeric components, inorganic components, or combinations thereof. The battery separators described herein are, among other things, thinner, stronger, and more electrolyte wettable than some conventional battery separators. The battery separators can be used in secondary or rechargeable batteries, including lithium-ion batteries. The batteries can be used in vehicles or devices, such as cell phones, tablets, laptops, and electronic vehicles.

[0241] The improvement comprising a coated microporous membrane in a battery, capacitor, vehicle, device, textile, garment, filter, medical device, or transdermal patch.

[0242] The new or improved coated microporous membranes, porous substrates, base membranes, and / or thin films, coatings, thin coatings, ultrathin coatings, and / or nanothin coatings, battery separators, capacitor separators, textiles, filters, layers, components, etc., such as batteries, capacitors, vehicles, devices, textiles, clothing, filters, medical devices, and / or transdermal patches, as described, shown, or claimed herein.

[0243] Various embodiments of the present invention have been described to achieve various objectives of the present invention. It should be recognized that these embodiments are merely illustrative of the principles of the present invention. Numerous modifications and adaptations of the present invention will be readily apparent to those skilled in the art without departing from the spirit and scope of the present invention.

Claims

1. A battery separator having a coating on one or both sides of a microporous membrane, the coating comprising 10 to 80% by weight of an inorganic component, a wet adhesive polymer, and a dry adhesive polymer; the coating has a wettability such that a contact angle measured as an angle between an edge of a droplet of electrolyte on the coating film and the coating film is less than 35°; A battery separator wherein the coating has a wet adhesion of greater than 30 N / m.

2. 10. The battery separator of claim 1, wherein said wet adhesion polymer is a fluoropolymer.

3. 10. The battery separator of claim 1, wherein said coating comprises a dry adhesive polymer.

4. 4. The battery separator of claim 3, wherein said dry adhesive polymer has a glass transition temperature of less than 100°C or less than 70°C.

5. 10. The battery separator of claim 1, wherein said coating comprises a wet adhesive polymer and a dry adhesive polymer.

6. The battery separator of any one of claims 1 to 5, wherein said coating has a thickness of 1 micron or less.

7. 6. The battery separator of claim 5, wherein at least one of said inorganic component, said wet adhesive polymer, and said dry adhesive polymer has an average particle size of 500 nm or less.

8. 10. The battery separator of claim 1, wherein said coating has a dry adhesion greater than 16 N / m.

9. 10. The battery separator of claim 1, wherein said coating exhibits an electrolyte absorption of 2 g / sample or greater after 60 minutes.

10. 10. A lithium ion battery comprising the battery separator of claim 1, wherein the battery is a cylindrical, prismatic, or pouch-type battery.

11. A vehicle or device comprising the lithium ion battery of claim 10.

12. 10. The battery separator of claim 1, wherein the coating comprises a polymer that at least one of reduces the surface coefficient of friction of the microporous membrane and reduces the shutdown initiation temperature of the microporous membrane.

13. 13. The battery separator of claim 12, wherein said coating comprises a polymer that reduces the surface coefficient of friction of said microporous membrane, and wherein said battery separator has a pin removal force of less than 350 N.

14. 13. The battery separator of claim 12, wherein said coating comprises a polymer that reduces the shutdown onset temperature of said microporous membrane, said battery separator having a shutdown onset temperature of 160°C or less.

15. A battery separator comprising a microporous membrane coated on one or both sides, the coating comprising 10 to 80% by weight of an inorganic component, a wet adhesive polymer, and a dry adhesive polymer; the coating has a wettability such that a contact angle measured as an angle between an edge of a droplet of electrolyte on the coating film and the coating film is less than 35°; A battery separator wherein the coating has a dry adhesion of greater than 16 N / m.

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