Polyimide coated separator for lithium battery or capacitor

Abstract

This article relates to a polyimide coating, separator membrane, or separator for lithium batteries, such as high-energy or high-voltage rechargeable lithium batteries, and the corresponding battery. The separator includes a porous or microporous polyimide coating or layer on at least one side of a microporous polymer layer, membrane, or film. The polyimide coating or layer may include other polymers, additives, fillers, or the like. The polyimide coating may be configured, for example, to provide oxidation resistance, inhibit dendrite growth, add dimensional and / or mechanical stability, reduce shrinkage, add high-temperature performance (HTMI functionality), prevent electrical shorting at temperatures above 200°C, and / or the like.

Description

[Technical field]

[0001] The present disclosure or invention preferably relates to a polyimide coating, separator membrane, or separator for lithium batteries, such as high energy or high voltage rechargeable lithium batteries, and the corresponding batteries. The separator preferably includes a porous or microporous polyimide coating or layer on at least one side of a microporous polymer layer, membrane, or film. The polyimide coating or layer may include other polymers, additives, fillers, or the like. The polyimide coating may be configured, for example, to provide oxidation resistance, inhibit dendrite growth, add dimensional and / or mechanical stability, reduce shrinkage, add high temperature performance (HTMI function), prevent electrical shorts above 200° C., and / or the like. The microporous polymer base layer may be configured to at least retain a liquid, gel, or polymer electrolyte, allow ions to flow, and / or prevent ion flow between the anode and cathode during thermal runaway (shutdown function). Polyimide coated separators may be configured, for example, to separate electrodes at elevated temperatures, provide oxidation resistance, inhibit dendrite growth, add dimensional stability, reduce shrinkage, add high temperature performance (HTMI functionality), prevent electrical shorts above 200° C., increase breakdown strength, and / or inhibit ion flow between the anode and cathode during thermal runaway (shutdown functionality). Although use in lithium secondary batteries is preferred, the polyimide coated films of the present invention may also be used as layers or components in batteries, cells, primary cells, capacitors, fuel cells, textiles, filters, and / or composites, and / or other applications, devices, and / or the like.

[0002] In at least selected embodiments, objects or aspects, the present disclosure or invention relates to a polyimide coating, separator membrane or separator for lithium secondary batteries, such as high energy or high voltage rechargeable lithium ion batteries, polymer batteries or metal batteries, and corresponding batteries. The separator preferably comprises a porous or microporous polyimide coating or layer on at least one side of a microporous polymer layer, membrane or film. The polyimide coating or layer may comprise other polymers, additives, fillers, or the like. The polyimide coating may be adapted, for example, to provide oxidation resistance, inhibit dendrite growth, add dimensional and / or mechanical stability, reduce shrinkage, add high temperature performance (HTMI function), prevent electrical shorts above 200°C, and / or the like. The microporous polymer base layer may be adapted to at least retain a liquid, gel or polymer electrolyte, allow ions to flow, and / or prevent ion flow between the anode and cathode during thermal runaway (shutdown function). The polyimide coated separator may be adapted, for example, to separate electrodes at elevated temperatures, provide oxidation resistance, inhibit dendrite growth, add dimensional stability, reduce shrinkage, add high temperature performance (HTMI function), prevent electrical shorts above 200° C., increase breakdown strength, and / or inhibit ion flow between the anode and cathode during thermal runaway (shutdown function).

[0003] A separator for a high energy or high voltage rechargeable lithium battery and a high energy or high voltage rechargeable lithium battery are disclosed herein. According to at least certain embodiments, objects or aspects, the disclosure or invention relates to a polyimide coated separator for a high energy or high voltage rechargeable lithium battery and the corresponding battery. The separator preferably comprises a porous polyimide coating or layer on at least one side of a microporous polymer layer, membrane or film. The polyimide coating or layer may comprise other polymers, additives, fillers, or the like. The polyimide coating may be adapted, for example, to provide oxidation resistance, inhibit dendrite growth, add dimensional stability, reduce shrinkage, add high temperature performance (HTMI function), prevent electrical shorts above 200°C, and / or the like. The microporous polymer layer may be adapted to at least retain liquid electrolyte, allow ions to flow, and / or prevent ion flow between the anode and cathode during thermal runaway (shutdown function).

[0004] The polyimide of the polyimide coating or layer may be a polyimide, a copolyimide, a soluble polyimide, a solvent soluble polyimide, a water soluble polyimide, a soluble copolyimide, a solvent soluble copolyimide, a water soluble copolyimide, and combinations, mixtures or blends thereof. [Background technology]

[0005] High energy rechargeable lithium batteries may have anodes with an energy capacity of at least 372 milliamp hours per gram (mAh / g). Such anodes may include, for example, lithium metal, lithium alloys (e.g., lithium aluminum), and mixtures of lithium metal or lithium alloys and materials such as carbon, nickel, and copper.

[0006] High voltage rechargeable lithium batteries may have a voltage of at least 4.5 V, 4.7 V or higher. Such batteries may have an anode that includes a lithium intercalation or insertion compound.

[0007] The commercial success of certain high energy and high voltage secondary or rechargeable lithium ion batteries has been hindered by difficult cycling or safety issues or problems.

[0008] A common solution is the ceramic coated separator (CCS), as described, for example, in U.S. Patent No. 6,432,586, the contents of which are fully incorporated herein by reference. Difficulties associated with the use of certain CCS in selected batteries or cells include ceramic particles flaking off during cell manufacturing, ceramic coatings being abrasive and difficult to slit, which can wear down equipment and slitter blades, increased thickness, cost, complexity, and the like associated with ceramic coatings.

[0009] Some have suggested using gel or polymer electrolytes instead of CCS. These gel or polymer electrolytes may not have sufficient dimensional stability (cannot maintain shape) and may not have good ionic conductivity. Liquid electrolytes may have 10X the conductivity of gel or polymer electrolytes.

[0010] Gel or polymer electrolytes also cannot prevent dendrite shorts. Lithium dendrite growth can occur after repeated charge-discharge cycles. Although dendrite growth is a potential problem for all lithium batteries, it becomes more severe when used with high-energy anodes (e.g., metal, metal alloy, or simple carbon intercalation anodes). When lithium dendrites grow and penetrate the separator, they cause an internal short circuit in the battery (any direct contact between the anode and cathode is called an "electrical short" and contact caused by dendrites is one type of electrical short circuit). Some short circuits caused by very small dendrites (i.e., soft short circuits) only reduce the cycling efficiency of the battery. Other short circuits, such as hard short circuits, can also cause thermal runaway in lithium batteries, which is a serious safety issue for lithium rechargeable batteries. Summary of the Invention [Problem to be solved by the invention]

[0011] Therefore, a need exists for improved separators for high energy or high voltage rechargeable lithium batteries. [Means for solving the problem]

[0012] In accordance with at least selected embodiments of the present invention or disclosure, a new or improved inventive separator can address the needs, problems or issues noted above, and / or provide a polyimide coating, separator or separator membrane suitable for use as a layer or component in batteries, cells, primary batteries, secondary batteries, high energy or high voltage rechargeable lithium batteries, capacitors, fuel cells, textiles, filters, and / or composites, and / or other applications, devices and / or the like.

[0013] The present disclosure or invention preferably relates to a polyimide coating, separator membrane or separator for lithium batteries, such as high energy or high voltage rechargeable lithium batteries, and the corresponding batteries. The separator preferably comprises a porous or microporous polyimide coating or layer on at least one side of a microporous polymer layer, membrane or film. The polyimide coating or layer may comprise other polymers, additives, fillers, or the like. The polyimide coating may be adapted, for example, to provide oxidation resistance, inhibit dendrite growth, add dimensional and / or mechanical stability, reduce shrinkage, add high temperature performance (HTMI function), prevent electrical shorts above 200°C, and / or the like. The microporous polymer base layer may be adapted to at least retain a liquid, gel, or polymer electrolyte, allow ions to flow, and / or prevent ion flow between the anode and cathode during thermal runaway (shutdown function). The polyimide coated separator may be adapted, for example, to separate electrodes at elevated temperatures, provide oxidation resistance, inhibit dendrite growth, add dimensional stability, reduce shrinkage, add high temperature performance (HTMI functionality), prevent electrical shorts above 200° C., increase breakdown strength, and / or inhibit ion flow between the anode and cathode during thermal runaway (shutdown functionality). Although use in lithium secondary batteries is preferred, the polyimide coated films of the present invention may also be used as layers or components in batteries, cells, primary batteries, capacitors, fuel cells, textiles, garments, filters, and / or composites, and / or other applications, devices, and / or the like.

[0014] In at least selected embodiments, objects or aspects, the present disclosure or invention relates to a polyimide coating, separator membrane or separator for lithium secondary batteries, such as high energy or high voltage rechargeable lithium ion batteries, polymer batteries or metal batteries, and corresponding batteries. The separator preferably comprises a porous or microporous polyimide coating or layer on at least one side of a microporous polymer layer, membrane or film. The polyimide coating or layer may comprise other polymers, additives, fillers, or the like. The polyimide coating may be configured, for example, to provide oxidation resistance, inhibit dendrite growth, add dimensional and / or mechanical stability, reduce shrinkage, add high temperature performance (HTMI function), prevent electrical shorts above 200° C., and / or the like. The microporous polymer base layer may be adapted to at least retain a liquid, gel or polymer electrolyte, allow ions to flow, and / or prevent ion flow between the anode and cathode during thermal runaway (shutdown function). The polyimide coated separator may be adapted, for example, to separate electrodes at elevated temperatures, provide oxidation resistance, inhibit dendrite growth, add dimensional stability, reduce shrinkage, add high temperature performance (HTMI function), prevent electrical shorts above 200° C., increase breakdown strength, and / or inhibit ion flow between the anode and cathode during thermal runaway (shutdown function).

[0015] The polyimide of the polyimide coating or layer may be a polyimide, a copolyimide, a polyimide mixture or blend, a soluble polyimide, a solvent soluble polyimide, a water soluble polyimide, a soluble copolyimide, a solvent soluble copolyimide, a water soluble copolyimide, a polyamide-imide, and combinations, mixtures or blends thereof.

[0016] A separator for a high energy or high voltage rechargeable lithium battery and a high energy or high voltage rechargeable lithium battery are disclosed herein. According to at least certain embodiments, objects or aspects, the disclosure or invention relates to a polyimide coated separator for a high energy or high voltage rechargeable lithium battery and the corresponding battery. The separator preferably comprises a porous polyimide coating or layer on at least one side of a microporous polymer layer, membrane or film. The polyimide coating or layer may comprise other polymers, additives, fillers, or the like. The polyimide coating may be adapted, for example, to provide oxidation resistance, inhibit dendrite growth, add dimensional stability, reduce shrinkage, add high temperature performance (HTMI function), prevent electrical shorts above 200°C, and / or the like. The microporous polymer layer may be adapted to at least retain liquid electrolyte, allow ions to flow, and / or prevent ion flow between the anode and cathode during thermal runaway (shutdown function).

[0017] According to at least certain embodiments, the present disclosure or invention relates to a new or improved separator for high energy or high voltage rechargeable lithium batteries and corresponding batteries. The separator of the present invention includes at least one polyimide layer, treatment, material, deposition, or coating and at least one microporous polymer-based layer. The polyimide-coated separator is adapted to at least inhibit dendrite growth and prevent electrical shorts. The polymer-based layer is adapted to inhibit ion flow between the anode and cathode at least during thermal runaway.

[0018] The general chemical formula for polyimide is:

[0019] [ka]

[0020] Polyimide (sometimes abbreviated as PI) is a polymer made of imide monomers. Polyimides have high heat resistance. A typical polyimide is Kapton®, which is produced by condensing pyromellitic dianhydride and 4,4'-oxydianiline.

[0021] Polyimide 2D structure: 2D representation of this compound

[0022] [ka]

[0023] Polyamide-imides are either thermosetting or thermoplastic amorphous polymers with exceptional mechanical, thermal and chemical resistance properties. Polyamide-imides are prepared from isocyanates and TMA (trimellitic anhydride) in N-methyl-2-pyrrolidone (NMP). A well-known distributor of polyamide-imides is Solvay Specialty Polymers, which uses the trademark Torlon®.

[0024] Polyamide-imides exhibit a combination of properties from both polyamides and polyimides, such as high strength, melt processability, exceptional heat capacity, and broad chemical resistance.

[0025] Soluble polyimides with high glass transition temperatures (Tg) can be prepared, for example, from four commercially available aromatic dianhydrides (i.e., BPDA, OPDA, 6FDA, and BPADA) and a rigid aromatic diamine containing t-butyl groups (3,3'-di-t-butylbenzidine).

[0026] Examples of soluble polyimides include MATRIMID XU5218 available from Ciba-Geigy, ULTEM 1000P available from General Electric, or LaRC-CP1, LaRC-CP2, and LaRC-Si available from Imitec, Inc. (Schenectady, NY).

[0027] Matrimid® 5218 is a soluble thermoplastic polyimide. It is fully imidized during manufacture and does not require high temperature processing. Matrimid 5218 can be dissolved in a variety of common solvents. Evaporation of these solvents leaves behind a strong, durable and tough coating.

[0028] Nexolve CP1 fluorinated polyimide can provide excellent physical and electrical properties over a wide temperature range and in many hostile environments. This fluorinated polyimide can be readily dissolved in many solvents including MIBK, DMF, THF and others for use in a variety of applications.

[0029] The polyimide 1-BPDA, which has a rigid structure and a high Tg, can also be dissolved in NMP, DMAc, and m-cresol at 60° C. If the concentration of this polyimide solution is diluted by two times, it can also be dissolved in DMAc and m-cresol at room temperature.

[0030] Certain soluble polyimides may be soluble in organic solvents, and the precursors of the polyimides may also be soluble in organic solvents, so that the soluble polyimides can be prepared in a one-step process.

[0031] Selected soluble polyimides with side chains on the PI backbone may be a useful approach to improve solubility because the side chains effectively prevent the coplanarity of the aromatic rings and reduce the packing efficiency of the main chain.

[0032] Selected highly soluble polyimides can be synthesized from various aromatic tetracarboxylic dianhydrides and aromatic diamines containing t-butyl pendant groups [4,4'-methylenebis(2-t-butylaniline)]. Such polyimides may exhibit good solubility in common solvents such as chloroform, tetrahydrofuran, and dioxane at room temperature.

[0033] Certain soluble polyimides having polyalicyclic structures can be prepared by reacting 2,3,5-tricarboxycyclopentylacetic dianhydride (TCA-AH) with aromatic diamines (two-step polymerization system).

[0034] According to one or more preferred possible processes, the insoluble polyimide is converted to a soluble polyimide using one or more strong solvents, acids, or the like. The soluble polyimide is then mixed with a solvent and particles to form a coating slurry, which is coated onto a base film and dried, and the particles are then removed from the dried coating to form a preferred porous polyimide coated base film or separator.

[0035] According to one or more preferred possible processes, the insoluble polyimide is converted to a soluble polyimide using one or more strong solvents, acids, or the like. The soluble polyimide is then mixed with a solvent and particles to form a coating slurry, which is coated onto a base film and dried, with or without removing the particles from the dried coating to form a polyimide-coated base film or separator. For example, the particles may be dissolved in the electrolyte, absorbed or adsorbed into the electrolyte, wetted by the electrolyte, and / or the like.

[0036] A separator for a high energy or high voltage rechargeable lithium battery and a high energy or high voltage rechargeable lithium battery are disclosed herein. According to at least certain embodiments, objects or aspects, the present disclosure or invention relates to a polyimide coated separator for a high energy or high voltage rechargeable lithium battery and the corresponding battery. The separator preferably comprises a porous polyimide coating or layer on at least one side of a microporous polymer layer, membrane or film. The polyimide coating or layer may comprise other polymers, additives, fillers, or the like. The polyimide coating may be adapted, for example, to provide oxidation resistance, inhibit dendrite growth, add dimensional stability, reduce shrinkage, add high temperature performance (HTMI function), prevent electrical shorts above 200°C, and / or the like. The microporous polymer layer may be adapted to at least retain liquid electrolyte, allow ions to flow, and / or prevent ion flow between the anode and cathode during thermal runaway (shutdown function).

[0037] The polyimide of the polyimide coating or layer may be a polyimide, a copolyimide, a soluble polyimide, a solvent soluble polyimide, a water soluble polyimide, a soluble copolyimide, a solvent soluble copolyimide, a water soluble copolyimide, and combinations, mixtures or blends thereof. For the purpose of illustrating the invention, there is shown in the drawings a form of the invention which is preferred, it being understood, however, that the invention is not limited to the precise arrangements and precise devices shown. [Brief description of the drawings]

[0038] [Figure 1] FIG. 1 is a cross-sectional view of an exemplary inventive separator 100 having a porous substrate 1 with a polyimide coating 20 on one side 10 of the substrate. [Diagram 2]FIG. 2 is a cross-sectional view of another exemplary inventive separator 101 having a substrate 1 having a first polyimide coating 20a on one side 10 of the porous substrate 1 and a second polyimide coating 20b on the other side 11 of the porous substrate 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0039] A typical lithium battery (or cell) comprises a lithium metal or alloy anode, a cathode, a separator disposed between the anode and cathode, all packaged inside a can or pouch in a cylindrical or "jelly roll" cell, or a prismatic or stacked cell. The invention is not limited to a particular battery or cell configuration and may be suitable for button cells, polymer cells, and the like. Additionally, the electrolyte may be a liquid (organic or inorganic) or a gel (or polymer). For convenience, the invention is described in terms of a cylindrical cell with a liquid organic electrolyte, but is not limited thereto and may be used in other cell types (e.g., energy storage systems, capacitors, composite cells, and capacitors) and configurations.

[0040] Potentially preferred anodes should have high energy or high voltage performance or capacity, preferably 372 mAh / g or greater, preferably 700 mAh / g or greater, and most preferably 1000 mAH / g or greater. Preferred anodes may be constructed of lithium metal or lithium alloy foils (e.g., lithium aluminum alloys), or mixtures of lithium metal and / or lithium alloys with materials such as carbon (e.g., coke, graphite), nickel, copper, and the like. The anodes may also include lithium-containing intercalation compounds or lithium-containing insertion compounds.

[0041] The cathode may be any cathode compatible with the anode and may include an intercalation compound, an insertion compound, or an electrochemically active polymer. Suitable intercalation materials include, for example, MoS2, FeS2, MnO2, TiS2, NbSe3, LiCoO2, LiNiO2, LiMn2O4, VO 13 , V2O5, and CuCl2. Suitable cathode polymers include, for example, polyacetylene, polypyrrole, polyaniline, and polythiopene.

[0042] The electrolyte may be a liquid or a gel (or polymer). Typically, the electrolyte consists primarily of a salt and a medium (e.g., in a liquid electrolyte, the medium may be called a solvent, and in a gel electrolyte, the medium may be a polymer matrix). The salt may be a lithium salt. The lithium salt may include, for example, LiPF6, LiAsF6, LiCF3SO3, LiN(CF3SO3)3, LiBF6, and LiClO4, BETTE electrolyte (commercially available from 3M Corp., Minneapolis MN), and combinations thereof. The solvent may include, for example, ethylene carbonate (EC), propylene carbonate (PC), EC / PC, 2-MeTHF (2-methyltetrahydrofuran) / EC / PC, EC / DMC (dimethyl carbonate), EC / DME (dimethylethane), EC / DEC (diethyl carbonate), EC / EMC (ethyl methyl carbonate), EC / EMC / DMC / DEC, EC / EMC / DMC / DEC / PE, PC / DME, and DME / PC. The electrolyte polymer matrix may include, for example, PVDF (polyvinylidene fluoride), PVDF:THF (PVDF:tetrahydrofuran), PVDF:CTFE (PVDF:chlorotrifluoroethylene), PVDF-HFP, PAN (polyacrylonitrile), and PEO (polyethylene oxide).

[0043] With reference to Figures 1 and 2, an exemplary separator includes at least one polyimide coating or layer on at least one surface of at least one microporous polymer layer, base film, or membrane. In a battery, the polyimide coating or layer must be sufficiently ionically conductive to provide ionic flow between the anode and cathode so that the cell generates the desired amount of electrical current. The coating and base film should adhere well to each other. The coating and base film layer may be formed by lamination, coextrusion, film forming, or coating methods. The polyimide coating may be a coating or a separate layer, both having a thickness ranging from 0.001 μm to 50 μm, preferably 0.01 μm to 15 μm or less. The microporous polymer layer is preferably a separate membrane having a thickness ranging from 5 μm to 50 μm, preferably 4 μm to 12 μm or more. The thickness of the entire separator is in the range of 5 μm to 100 μm, preferably 6 μm to 25 μm.

[0044] The polyimide coating may be porous, microporous, or non-porous (preferably porous, although it should be understood that a non-porous coating layer can become ionically conductive when wetted or immersed in an electrolyte, depending on the material that constitutes the coating layer).

[0045] The microporous polymer base film may be any commercially available separator microporous membrane (e.g., monolayer or multilayer), such as Celgard® dry process products manufactured by Celgard, LLC (Charlotte North Carolina), or Hipore® wet process products manufactured by Asahi Kasei Corporation (Tokyo Japan). The base film may have a porosity in the range of 20-80%, preferably 30-60%, an average pore size in the range of 0.02-2 μm, preferably 0.05-0.5 μm, and a Gurley number in the range of 5-150 seconds, preferably 15-60 seconds. (Gurley number is the number of pores per 10 cm of water at 31 cm (12.2 in) water column.) 3 6.4cm of air 2 (time required for the fluid to pass through one square inch of membrane) and is preferably polyolefin-based. Preferred polyolefins include polyethylene and / or polypropylene. Polypropylene may be the most preferred (high temperature polymer, oxidation resistant).

[0046] The foregoing separators are designed primarily for use in high energy or high voltage rechargeable lithium batteries, but may be used in other battery systems where dendrite growth is a problem.

[0047] The base film or coating substrate can in some instances comprise a semi-crystalline polymer, such as a polymer having a crystallinity in the range of 20-80%.

[0048] In some embodiments, the substrates described herein can include a single layer, a bilayer, a trilayer, or a multilayer. For example, a trilayer or multilayer substrate can include two outer layers and one or more inner layers. In some embodiments, the substrate can include one, two, three, four, five, or more inner layers. Each of these layers can be coextruded and / or laminated together, as described in more detail below.

[0049] The substrates described herein can be made by a dry stretch process (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 singly extruded, in which case the layer is extruded by itself without any sublayers (layers), or each layer can include multiple coextruded sublayers. For example, each layer can include multiple sublayers, such as a coextruded two-sublayer, three-sublayer, or multi-sublayer substrate, each of which can be collectively considered a "layer." The number of sublayers in a coextruded two-layer is two, the number of layers in a coextruded three-layer is three, the number of sublayers in a coextruded multi-layer substrate can be two or more, three or more, four or more, five or more, etc. The exact number of sublayers in a coextruded layer is dictated by the mold design, and not necessarily by the materials that are coextruded to form the coextruded layers. For example, a coextruded two-, three-, or multi-sublayer substrate may be formed using the same material in each of the two, three, four, or more sublayers, which would still be considered separate sublayers even though each sublayer is made from the same material.

[0050] In some embodiments, the three-layer or multi-layer substrates described herein can include two outer layers (such as a first outer layer and a second outer layer) and a single or multiple inner layers. The multiple inner layers can be monoextruded layers or coextruded layers. A lamination barrier can be formed between each of the inner layers and / or between each of the outer layers and one of the inner layers. A lamination barrier 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.

[0051] In some embodiments, the substrates described herein are the following: 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,The laminate may have the following non-limiting configurations: PE / PE / PP / PP / PP / PP / PP / PP / PP / PP / PE / PE, PP / PP / PP / PE / PE / PP / PP / PP / PP / PP / PE, or PE / PE / PE / PP / PP / PP / PE / PE / PE / PE / PP / PP / 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, a designation of PP / PE refers to a bi-layer substrate having a polypropylene (PP) layer and a polyethylene (PE) layer.

[0052] Each individual layer in the substrate may have multiple sublayers, which may be formed by coextrusion or by combining individual sublayers to form each individual layer of the multilayer substrate. With a multilayer substrate having the structure PP / PE / PP, each individual PP or PE layer may include two or more coextruded sublayers. For example, when each individual PP or PE layer includes three sublayers, each individual PP layer may be represented as PP=(PP1,PP2,PP3) and each individual PE layer may be represented as PE=(PE1,PE2,PE3). Thus, the structure PP / PE / PP may be represented as (PP1,PP2,PP3) / (PE1,PE2,PE3) / (PP1,PP2,PP3). The composition of each of the sublayers PP1, PP2, and PP3 may be the same, or each sublayer may have a different polypropylene composition than one or both of the other polypropylene sublayers. Similarly, the composition of each of the sublayers PE1, PE2, and PE3 may be the same, or each sublayer may have a different polyethylene composition than one or both of the other polyethylene sublayers. This rule also applies to other multilayer substrates having layers that are roughly the same as the exemplary three layer substrate described above.

[0053] In some embodiments, the substrates described herein have a total thickness of 1 μm to 60 μm, 1 μm to 55 μm, 1 μm to 50 μm, 1 μm to 45 μm, 1 μm to 40 μm, 1 μm to 35 μm, 1 μm to 30 μm, 1 μm to 25 μm, 1 μm to 20 μm, 1 μm to 15 μm, 1 μm to 10 μm, 5 μm to 50 μm, 5 μm to 40 μm, 5 μm to 30 μm, 5 μm to 25 μm, 5 μm to 20 μm, 5 μm to 10 μm, 10 μm to 40 μm, 10 μm to 35 μm, 10 μm to 30 μm, or 10 μm to 20 μm.

[0054] In some embodiments, the thickness of each layer in a two-layer, three-layer, or multi-layer substrate may be equal to, or less than, or greater than, the thickness of the other layers. For example, when the substrate is a three-layer substrate with the structure PP / PE / PP (polypropylene / polyethylene / polypropylene) or PE / PP / PE (polyethylene / polypropylene / polyethylene), the thickness of the polypropylene layer may be equal to, less than, or greater than the thickness of the polyethylene layer.

[0055] In some embodiments, the substrates described herein may be triple layer laminated PP / PE / PP (polypropylene / polyethylene / polypropylene) or PE / PP / PE (polyethylene / polypropylene / polyethylene) substrates. In some examples, the structural ratios of these layers of the substrate include 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 ... / 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%.

[0056] The substrates described herein may further include fillers, elastomers, wetting agents, lubricants, flame retardants, nucleating agents, antioxidants, colorants, and / or other additional components not inconsistent with the objectives of the present disclosure. For example, the substrate 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, and the like, or combinations thereof. Elastomers may include ethylene-propylene (EPR), ethylene-propylene-diene (EPDM), styrene-butadiene (SBR), styrene isoprene (SIR), ethylidene norbornene (ENB), epoxies, and polyurethanes, or combinations thereof. Wetting agents may include ethoxylated alcohols, primary polymeric carboxylic acids, glycols (such as polypropylene glycol and polyethylene glycol), functionalized polyolefins, and the like.

[0057] The lubricants may include silicones, fluoropolymers, oleamide, stearamide, erucamide, calcium stearate, lithium stearate, or other metal stearates. The flame retardants may include brominated flame retardants, ammonium phosphate, ammonium hydroxide, alumina trihydrate, and phosphate esters. The nucleating agents may include any nucleating agent not inconsistent with the objectives of the present disclosure, such as the β-nucleating agents for polypropylene disclosed in U.S. Patent No. 6,602,593.

[0058] The substrate described in some of the embodiments herein can be made by dry stretching process in some examples. Substrate should be understood to be a thin, flexible, polymer membrane, film, sheet, foil, or substrate that has a plurality of pores extending therethrough. In some cases, porous substrates are made by dry stretching process (also known as CELGARD® dry stretching process), which refers to the pore formation caused by stretching non-porous, semi-crystalline, extruded polymer precursor in the machine direction (MD), transverse direction (TD), or both MD and TD. See, for example, Kesting, Robert E., Synthetic Polymeric Membranes, A Structural Perspective, Second Edition, John Wiley&Sons, New York, NY, (1985), pages 290-297, the contents of which are incorporated herein by reference. Such dry stretching process is different from wet process and particle stretching process. In the wet process, also known as the phase inversion process, extraction process, or TIPS process, generally, the polymeric feedstock is mixed with a process oil (sometimes called a plasticizer), the mixture is extruded, and the pores are formed when the process oil is removed. These wet process substrates can be stretched before or after the oil is removed, but the principle of the pore formation mechanism is the use of the process oil. See, for example, Kesting, Ibid. pages 237-286, the contents of which are incorporated herein by reference. In the particle stretching process, particles such as silica or calcium carbonate are used as pore formers. The polymeric feedstock is mixed with the particles, the mixture is extruded, and the pores are formed when the particles are removed. These particle-filled substrates can be stretched before or after the particles are removed, but the principle of the pore formation mechanism is the use of the particles. The porous substrates described herein may in some instances preferably be all Celgard® polyolefin porous separator substrates available from Celgard, LLC (Charlotte, NC).

[0059] The porous substrate may be a macroporous substrate, a mesoporous substrate, a microporous substrate, or a nanoporous substrate. The porosity of the substrate may be any porosity consistent with the goals of the present disclosure. For example, any porosity capable of forming an acceptable battery separator is acceptable. In some embodiments, the porosity of the porous substrate is 20-90%, 20-80%, 40-80%, 20-70%, 40-70%, 40-60%, greater than 20%, greater than 30%, or greater than 40%. Porosity is measured using ASTM D-2873 and is defined as the percentage of hollow space, such as pores, in a given area of ​​the porous substrate, measured in the machine direction (MD) and the transverse direction (TD) of the substrate. In some embodiments, the pores are slit-shaped, circular, elliptical, trapezoidal, or ovoid with a sphericity of 0.25-8.0.

[0060] The substrate can have any gurley not inconsistent with the objectives of this disclosure, such as a gurley acceptable for use as a battery separator. Gurley is a Japanese Industrial Standard (JIS) gurley and can be measured using an air permeability tester, such as an OHKEN air permeability tester. JIS Gurley is the permeability of a 100 cm2 gas column at a constant pressure of 12.4 cm (4.9 inches) water. 3 6.4cm of air 2 (1 square inch) of substrate. In some embodiments, the porous film or substrate described herein has a JIS Gurley (sec / 100 cc) 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.

[0061] The substrate, in its uncoated state, can have a breaking strength of 200 gf or more, 210 gf or more, 220 gf or more, 230 gf or more, 240 gf or more, 250 gf or more, 260 gf or more, 270 gf or more, 280 gf or more, 290 gf or more, 300 gf or more, 310 gf or more, 320 gf or more, 330 gf or more, 340 gf or more, 350 gf or more, or up to 400 gf or more.

[0062] 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 may include more than one additive, such as two, three, four, five or more additives. The additives may be present in one or both of the outermost layers of the porous substrate, in one or more inner layers, in all of the inner layers, or in both all of the inner layers and the outermost layer. 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 over time, and the additive supply of the outermost layer may be replenished by migrating the additives of the inner layers to the outermost layer. In some embodiments, each layer of the substrate may include a different additive or combination of additives than adjacent layers of the substrate.

[0063] In some embodiments, the additive comprises a functionalized polymer. As will be understood by one of ordinary skill in the art, a functionalized polymer is a polymer having functional groups originating from the polymer backbone. In some embodiments, the functionalized polymer is a maleic anhydride functionalized polymer. In some embodiments, the maleic anhydride modified polymer is a 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, very low density polyethylene.

[0064] In some embodiments, the additive comprises an ionomer. An ionomer is a copolymer that contains both ionic and nonionic repeating groups, as understood by one of ordinary skill in the art. The ionic repeating groups may sometimes comprise less than 25%, less than 20%, or less than 15% of the ionomer. In some embodiments, the ionomer may be a Li-based, Na-based, or Zn-based ionomer.

[0065] In some embodiments, the additive comprises cellulose nanofibers.

[0066] In some embodiments, the additive comprises inorganic particles with a narrow particle size distribution. For example, the difference between the distribution D10 and D90 is less than 100 nm, less than 90 nm, less than 80 nm, less than 70 nm, less than 60 nm, less than 50 nm, less than 40 nm, less than 30 nm, less than 20 nm, or less than 10 nm. In some embodiments, the inorganic particles are selected from at least one of SiO2, TiO2, or a combination thereof.

[0067] In some embodiments, the additive comprises a lubricant. The lubricants or glidants described herein may be any lubricant not inconsistent with the objectives of the present disclosure. As will be understood by one of ordinary skill in the art, a lubricant is a compound that acts to reduce friction between a variety of different surfaces, including the following: polymer:polymer, polymer:metal, polymer:organic material, and polymer:inorganic material. Specific examples of the lubricants or glidants described herein are compounds containing siloxy functional groups, including siloxanes and polysiloxanes, and fatty acid salts, including metal stearates.

[0068] The lubricants described herein may be compounds containing 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, or 10 or more siloxy groups. Siloxanes, as understood by those skilled in the art, are a class of molecules that contain alternating silicon (Si) and oxygen (O) atom backbones, where each silicon atom may have a bonded hydrogen (H) or a saturated or unsaturated organic group, such as -CH3 or C2H5. Polysiloxanes are polymerized siloxanes, and typically have a high molecular weight. In some embodiments described herein, the polysiloxanes may have a high molecular weight, such as ultra-high molecular weight polysiloxanes. In some embodiments, the high or ultra-high molecular weight polysiloxanes may have a weight average molecular weight ranging from 500,000 to 1,000,000.

[0069] The fatty acid salt described herein may be any fatty acid salt not inconsistent with the objectives of the present disclosure. In some examples, the fatty acid salt may be any fatty acid salt that acts as a lubricant. The fatty acid of the fatty acid salt may be a fatty acid having 12 to 22 carbon atoms. For example, the metal fatty acid may 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 may be any metal not inconsistent with the objectives of the present disclosure. In some examples, the metal is an alkali metal or an alkaline earth metal, such as Li, Be, Na, Mg, K, Ca, Rb, Sr, Cs, Ba, Fr, and Ra. In some embodiments, the metal is Li, Be, Na, Mg, K, or Ca.

[0070] The fatty acid salt may be lithium stearate, sodium stearate, lithium oleate, sodium oleate, sodium palmitate, lithium palmitate, potassium stearate, or potassium oleate.

[0071] Lubricants containing fatty acid salts described herein may have a melting point of 200° C. or more, 210° C. or more, 220° C. or more, 230° C. or more, or 240° C. or more. Fatty acid salts such as lithium stearate (melting point 220° C.) or sodium stearate (melting point 245-255° C.) have such melting points.

[0072] In some embodiments, the additives can include one or more nucleating agents. As will be appreciated by one of ordinary skill in the art, nucleating agents are materials, inorganic, that in some embodiments, that aid in increasing or enhancing polymer crystallization, including semi-crystalline polymers.

[0073] In some cases, the additive may include a cavitation promoter, which is a material that forms, assists in the formation, increases the formation, or enhances the formation of bubbles or hollow spaces in a polymer, as would be understood by one of ordinary skill in the art.

[0074] The additive may, in some instances, include a fluoropolymer, such as the fluoropolymers detailed herein.

[0075] In some embodiments, the additive may include a crosslinking agent.

[0076] The additive described herein may in some embodiments include an X-ray detectable material. The X-ray detectable material may be any X-ray detectable material that is not inconsistent with the objectives of this disclosure, such as those disclosed in U.S. Patent No. 7,662,510, which is incorporated herein by reference in its entirety. A suitable amount of X-ray detectable material or component is also disclosed in U.S. Patent No. 7,662,510, but in some embodiments, is 50% by weight or less, 40% by weight or less, 30% by weight or less, 20% by weight or less, 10% by weight or less, 5% by weight or less, or 1% by weight or less based on the total weight of the porous film or substrate that can be used. In some embodiments, the additive is barium sulfate.

[0077] In some embodiments, the additive may include a lithium halide. The lithium halide may be lithium chloride, lithium fluoride, lithium bromide, or lithium iodide. The lithium halide may be lithium iodide, which is ionically conductive and electrically insulating. In some examples, the ionically conductive and electrically insulating material may be used as part of the battery separator.

[0078] In some embodiments, the additives may include polymer processing agents. As will be appreciated by those skilled in the art, polymer processing agents or additives are added to improve the processing efficiency and quality of polymeric compounds. In some embodiments, the polymer processing agent may be an antioxidant, stabilizer, lubricant, processing aid, nucleating agent, colorant, antistatic agent, plasticizer, or filler.

[0079] In some embodiments, the additive may include a high temperature melt index (HTMI) polymer. The HTMI polymer may be any HTMI polymer not inconsistent with the objectives of the present disclosure. In some examples, the HTMI polymer may be at least one selected from the group consisting of PMP, PMMA, PET, PVDF, aramid, syndiotactic polystyrene, polyimide, polyamide, and combinations thereof.

[0080] 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 typically added by battery manufacturers, particularly lithium battery manufacturers, to improve battery performance. The electrolyte should also be miscible, such as miscible with the polymer used for the polymeric porous substrate or compatible with the coating slurry. The compatibility of the additive may also be aided 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 LiPF6 salt stabilizer, an overcharge protectant, an aluminum corrosion inhibitor, a lithium deposition agent or improver, or a solvation enhancer, an aluminum corrosion inhibitor, a wetting agent, and a thickener. In some embodiments, the electrolyte may have more than one property, such as being a wetting agent and a thickener.

[0081] 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 nonafluorobuyl 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 protectants include xylene, cyclohexylbenzene, biphenyl 2,2-diphenylpropane, and phenyl t-butyl carbonate. Exemplary lithium deposition improvers include AlI3, SnI2, cetyltrimethylammonium chloride, perfluoropolyethers, and tetraalkylammonium chlorides with long alkyl chains. Exemplary ion solvation enhancers include 12-crown-4, TFPPB (tris(pentafluorophenyl)). Exemplary Al corrosion inhibitors include borates such as LiBOB, LiODFB, etc. Exemplary wetting agents and viscosity reducers include cyclohexane and P2O5.

[0082] In some embodiments, the electrolyte additive is air stable or resistant to oxidation. Battery separators containing the electrolyte additives disclosed herein may have a shelf life of several weeks to several months, such as, for example, one week to 11 months.

[0083] In some embodiments, the additive may include 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 containing the additive.

[0084] The substrate described herein may be MD or TD stretched to make the substrate porous. In some examples, the substrate is made by performing TD stretching on a MD stretched substrate or performing MD stretching on a TD stretched substrate. In addition to sequential MD-TD stretching (with or without relaxation), the substrate may be simultaneously subjected to biaxial MD-TD stretching (with or without relaxation). Furthermore, the simultaneous or sequential MD-TD stretched porous substrate may be subjected to subsequent stretching, reaxing, heat setting, or calendaring steps to reduce the thickness of the substrate, reduce roughness, reduce the percentage of porosity, increase the TD tensile strength, increase uniformity, and / or reduce TD splittiness.

[0085] In some embodiments, the substrate has a thickness of 0.01 nm to 1 μm, 0.01 μm to 1 μm, 0.02 μm to 1 μm, 0.03 μm to 1 μm, 0.04 μm to 1 μm, 0.05 μm to 1 μm, 0.06 μm to 1 μm, 0.07 μm to 1 μm, 0.08 μm to 1 μm, 0.09 μm to 1 μm, 0.1 μm to 1 μm, 0.2 μm ~1μm, 0.3μm~1μm, 0.4μm~1μm, 0.5μm~1μm, 0.6μm~1μm, 0.7μm~1μm, 0.8μm~1μm, 0.9μm~1 μm, 0.01μm~0.9μm, 0.01μm~0.8μm, 0.01μm~0.7μm, 0.01μm~0.6μm, 0.01μm~0.5μm, 0.01μm m~0.4μm, 0.01μm~0.3μm, 0.01μm~0.2μm, 0.01μm~0.1μm, 0.01μm~0.09μm, 0.01μm~0.08 μm, 0.01μm~0.07μm, 0.01μm~0.06μm, 0.01μm~0.05μm, 0.01μm~0.04μm, 0.01μm~0.03μm, It may contain pores having an average pore size of 1 μm, 0.9 μm, 0.8 μm, 0.7 μm, 0.6 μm, 0.5 μm, 0.4 μm, 0.3 μm, 0.2 μm, 0.1 μm, 0.09 μm, 0.08 μm, 0.07 μm, 0.06 μm, 0.05 μm, 0.04 μm, 0.03 μm, 0.02 μm, or 0.01 μm.

[0086] In embodiments, porous substrates may be produced using exemplary processes including a stretching process and a subsequent calendering process, such as longitudinal stretching followed by transverse stretching (with or without longitudinal relaxation) and a subsequent calendering process, to reduce the thickness of such stretched substrates, e.g., multi-layer porous substrates, in a controlled manner, and / or to improve the strength, properties and / or performance of such stretched substrates, e.g., multi-layer porous substrates, in a controlled manner, such as breaking strength, longitudinal and / or transverse tensile strength, uniformity, wettability, coverage, runnability, compression, spring back, tortuosity, permeability, thickness, pin removal force, mechanical strength, surface roughness, hot tip hole propagation and / or combinations thereof, of such stretched substrates, e.g., multi-layer porous substrates, in a controlled manner, and / or to produce unique structures, pore structures, materials, substrates, base substrates, and / or separators.

[0087] In some cases, the TD tensile strength of the multilayer substrate can be further improved by adding a calendaring step after the TD stretching step. The calendaring step typically requires heat and pressure that can reduce the thickness of the porous substrate. The calendaring step can restore the loss of MD and TD tensile strength due to TD stretching. Furthermore, the increase observed in MD and TD tensile strength due to the calendaring step makes the MD and TD tensile strength ratio more balanced, which is beneficial to the overall mechanical performance of the multilayer substrate.

[0088] The calendering process can use uniform or non-uniform heat and / or speed to selectively compress the heat-sensitive material, to provide uniform or non-uniform calendering conditions (such as by using smooth rolls, rough rolls, patterned rolls, micropatterned rolls, nanopatterned rolls, speed changes, temperature changes, pressure changes, humidity changes, double roll steps, multiple roll steps, or combinations thereof), to create improved, desirable or unique structures, properties and / or performance, to engineer or control the resulting structure, properties and / or performance, and / or the like. In embodiments, calender pressures of 5-200 psi, calender temperatures of 50° C.-70° C., and line speeds of 40-80 ft / min can be used. In some instances, higher pressures can provide thinner separators and lower pressures can provide thicker separators.

[0089] In some embodiments, the porous substrates or membranes described herein may comprise a coating located on a first surface, a second surface, or both the first and second surfaces of the porous substrate, as shown in Figures 1 and 2. In some embodiments, the coating may comprise a first layer and a second layer. In some instances, the first layer of the coating may be located on the first surface of the substrate, on the second surface of the substrate, or on both the first and second surfaces of the substrate. When the first layer is located on the first and / or second surface of the substrate, the second layer of the coating may be located on one or both of the first layer of the coating.

[0090] In some embodiments, the second layer of the coating may be located on the first side of the substrate, on the second side of the substrate, or on both the first and second sides of the substrate. When the second layer is located on the first and / or second sides of the substrate, the first layer of the coating may be located on one or both of the second layers of the coating.

[0091] In a further embodiment, a first layer of the coating may be located on one of the first or second sides of the substrate, and a second layer of the coating may be located on the other of the first or second sides of the substrate. In this embodiment, the first layer on one of the sides of the substrate may optionally be covered with the second layer, and the second layer on the other side of the substrate may optionally be covered with the first layer, such that the first and second sides have an opposing arrangement of coating layers.

[0092] Still further, in other embodiments, a first layer may be located on both the first and second sides of the substrate, with only one of the two first layers of the substrate further covering a second layer of the coating.Similarly in other examples, a second layer may be located on both the first and second sides of the substrate, with only one of the two second layers of the substrate further covering a first layer of the coating.

[0093] The first layer and the second layer may each have any thickness not inconsistent with the objectives of the present disclosure. In some cases, the first layer has a thickness of 10 nm to 20 μm, 500 nm to 15 μm, 500 nm to 10 μm, 500 nm to 5 μm, or 500 nm to 1 μm. The second layer has a thickness of 500 nm to 20 μm, 500 nm to 15 μm, 500 nm to 10 μm, 500 nm to 5 μm, or 500 nm to 1 μm. The thicknesses of the first layer and the second layer may be the same or different.

[0094] In another aspect, a method for preparing a coated separator as described above includes coating a first side, an opposing second side, or both the first side and the second side of a porous substrate comprising a layer, a first layer, and / or a second layer.

[0095] According to one or more preferred possible processes, the insoluble polyimide is converted to a soluble polyimide using one or more strong solvents, acids, or the like. The soluble polyimide is then mixed with a solvent and particles to form a coating slurry, which is coated onto a base film and dried, and the particles are then removed from the dried coating to form a preferred porous polyimide coated base film or separator.

[0096] According to one or more preferred possible processes, the insoluble polyimide is converted to a soluble polyimide using one or more strong solvents, acids, or the like. The soluble polyimide is then mixed with a solvent and particles (or other pore formers) to form a coating slurry, which is coated onto a base film and dried, and the particles (or other pore formers) are then optionally removed from the dried coating to form a preferred porous polyimide coated base film or separator.

[0097] According to at least one embodiment, the coating (or coating slurry) and the base film or separator may be co-extruded.

[0098] According to at least one embodiment, the coating or layer can be deposited or precipitated onto the base film or separator, such as by evaporation, PVD, CVD, or laser sputtering.

[0099] According to one or more potentially preferred embodiments, there is provided a polyimide and / or polyamide-imide coating configured for use in high energy or high voltage rechargeable lithium batteries, batteries, cells, primary batteries, secondary batteries, capacitors, fuel cells, textiles, garments, filters, and / or composites, and / or other applications, devices, and / or the like, comprising: Microporous base layer, membrane or film and A polyimide and / or polyamide-imide coated membrane comprising a polyimide and / or polyamide-imide coating or layer, preferably a polymeric layer, more preferably a polyolefin-based layer, and most preferably a dry stretch process polyolefin-based layer, on at least one surface of the microporous base layer, membrane or film.

[0100] According to one or more potentially preferred embodiments, a polyimide and / or polyamide-imide coating is provided, comprising: Microporous polymer layers, membranes or films and A polyimide and / or polyamide-imide coating comprising a polyimide and / or polyamide-imide coating or layer on at least one side of a microporous polymeric layer.

[0101] According to one or more potentially preferred embodiments, layers or components of batteries, cells, primary batteries, capacitors, fuel cells, textiles, garments, filters, and / or composites, and / or other applications, devices, and / or the like, comprise or include the above-described polyimide and / or polyamide-imide coating layers, membranes or films.

[0102] According to one or more potentially preferred embodiments, the polyimide coating or layer is at least partially covered by another coating or layer, such as an adhesive or tacky coating.

[0103] According to one or more potentially preferred embodiments, the separator further comprises another coating or layer, such as an adhesive or tacky coating, on at least one surface thereof.

[0104] According to one or more potentially preferred embodiments, the polyimide coating and / or the adhesive or cohesive coating contains or comprises PVDF or a PVDF copolymer.

[0105] The present disclosure or invention preferably relates to a polyimide coating, separator membrane, or separator for lithium batteries, such as high energy or high voltage rechargeable lithium batteries, and the corresponding batteries. The separator preferably includes a porous or microporous polyimide coating or layer on at least one side of a microporous polymer layer, membrane, or film. The polyimide coating or layer may include other polymers, additives, fillers, or the like. The polyimide coating may be configured, for example, to provide oxidation resistance, inhibit dendrite growth, add dimensional and / or mechanical stability, reduce shrinkage, add high temperature performance (HTMI function), prevent electrical shorts above 200° C., and / or the like. The microporous polymer base layer may be configured to at least retain a liquid, gel, or polymer electrolyte, allow ions to flow, and / or prevent ion flow between the anode and cathode during thermal runaway (shutdown function). Polyimide coated separators may be configured, for example, to separate electrodes at elevated temperatures, provide oxidation resistance, inhibit dendrite growth, add dimensional stability, reduce shrinkage, add high temperature performance (HTMI functionality), prevent electrical shorts above 200° C., increase breakdown strength, and / or inhibit ion flow between the anode and cathode during thermal runaway (shutdown functionality). Although use in lithium secondary batteries is preferred, the polyimide coated films of the present invention may also be used as layers or components in batteries, cells, primary batteries, capacitors, fuel cells, textiles, garments, filters, and / or composites, and / or other applications, devices, and / or the like.

[0106] The present invention may be embodied in other specific forms without departing from its spirit or essential attributes, and therefore, reference should be made to the appended claims, drawings, and specification as indicating the scope of the invention.

Claims

1. 1. A polyimide coated separator for a high energy or high voltage rechargeable lithium battery comprising: a microporous polymer layer formed from polypropylene and / or polyethylene; a polyimide coating or layer comprising polyimide on at least one surface of the microporous polymer layer; Equipped with the polyimide contained in the polyimide coating or layer is a water-soluble polyimide; The water-soluble polyimide is synthesized from an aromatic tetracarboxylic dianhydride and an aromatic diamine containing t-butyl pendant groups [4,4'-methylenebis(2-t-butylaniline)].

2. 10. The separator of claim 1, wherein the polyimide coating or layer provides oxidation resistance, inhibits dendrite growth, adds dimensional stability, reduces shrinkage, adds high temperature capability (HTMI functionality), or prevents electrical shorts at temperatures above 200°C.

3. 3. The separator of claim 1 or 2, wherein the microporous polymer layer is adapted to retain liquid electrolyte, conduct ions, and / or prevent ion flow between the anode and cathode of a cell or battery during thermal runaway (shutdown function).

4. The separator of any one of claims 1 to 3, wherein the polyimide coating or layer is porous, microporous, mesoporous, macroporous and / or nanoporous.

5. 5. The separator of claim 4, wherein the polyimide coating or layer is rendered porous by removing plasticizers, pore formers, and / or particles from a coating formulation consisting of at least polyimide and at least one of plasticizers, pore formers, and / or particles.

6. 6. The separator of claim 5, wherein the polyimide coating or layer is rendered porous by removing particles from a coating formulation consisting of at least polyimide and particles.

7. The particles include silica, calcium carbonate, sodium chloride, kaolin, barium sulfate, SiO ２ , Al ２ O ３ , CaCO ３ , TiO ２ , SiS ２ , SiPO ４ 7. The separator of claim 5 or 6, wherein the salt is selected from the group consisting of: salt, NaCl, and / or mixtures or blends thereof.

8. The separator of any one of claims 5 to 7, wherein the particles are removed by one or more solvents.

9. The one or more solvents may be water, oil, a hydrocarbon, an ester, an ether, an alcohol, a freon, N,N-methylpyrrolidinone (NMP), γ-butyrolactone, a carboxylic acid having the formula R １ R ２ N-SO ２ -NR ３ R ４ wherein R １ , R ２ , R ３ and R ４ 9. The separator of claim 8, wherein R is an alkyl having 1 to 6 carbon atoms and / or an oxyalkyl having 1 to 6 carbon atoms, a sulfamide, and / or blends or combinations thereof.

10. The separator according to any one of claims 5 to 7, wherein the particles are solvent-soluble particles.

11. 6. The separator of claim 5, wherein the polyimide coating or layer is rendered porous by removing a plasticizer from a coating formulation consisting of at least a polyimide and a plasticizer.

12. 6. The separator of claim 5, wherein the polyimide coating or layer is pore-formed by removing a pore-former from a coating formulation consisting of at least a polyimide and a pore-former.

13. The separator of any one of claims 1 to 12, wherein the polyimide coating or layer comprises other polymers, additives, and / or fillers.

14. The separator according to any one of claims 5 to 10, wherein the particles comprise 20% to 80% by weight of the mixture of polyimide and particles before being removed.

15. 15. The separator of claim 1, wherein the microporous polymer layer has a porosity in the range of 20-80%, an average pore size in the range of 0.02-1.0 μm, and a Gurley number in the range of 5-300 seconds.

16. The separator according to claim 5, 6 or 7, wherein the particles have an average particle size in the range of 0.001 to 10 μm.

17. an anode, a cathode, and the separator according to any one of claims 1 to 16 disposed between the anode and the cathode; an electrolyte in ionic communication with the anode and the cathode through the separator; 1. A high energy or high voltage rechargeable lithium battery comprising:

18. an anode containing lithium metal, or a lithium alloy, or a mixture of lithium metal and / or a lithium alloy and another material, a cathode, a separator according to any one of claims 1 to 16 disposed between the anode and the cathode; an electrolyte in ionic communication with the anode and the cathode through the separator; A high energy rechargeable lithium battery comprising:

19. The separator of any one of claims 1 to 13, wherein the polyimide coating or layer is at least partially covered by an adhesive or sticky coating.

20. The separator of any one of claims 1 to 13, wherein the polyimide coated separator further comprises an adhesive or tacky coating on at least one surface thereof.

21. 21. The separator of claim 19 or 20, wherein the polyimide coating, adhesive coating, and / or cohesive coating comprises PVDF or a PVDF copolymer.

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