Improved, coated or treated microporous battery separators, rechargeable lithium batteries, systems, and related methods of manufacture and / or use

Abstract

To provide improved separators that provide high performance of a polyolefin membrane and the wettability of a nonwoven fabric for at least certain battery chemistries or systems, methods of manufacture therefor, and lithium batteries.SOLUTION: A microporous battery separator for a lithium battery, comprises: a polyolefin layer; at least one non-woven layer on each side of the polyolefin layer; and a surfactant coating or surfactant treatment in or on the separator. The surfactant is present in 0.1 to 10.0 weight% (impregnation amount). The separator has at least one of enhanced puncture strength and reduced shrinkage compared to the polyolefin layer alone.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to and the benefit of U.S. Provisional Patent Application No. 62 / 158,582, filed May 8, 2015, and U.S. Provisional Patent Application No. 62 / 297,166, filed February 19, 2016, each of which is incorporated herein by reference in its entirety.

[0002] According to at least selected embodiments, the present application or invention relates to new or improved separator membranes, separators, batteries, cells, systems, and / or methods of making such membranes, separators, batteries, cells, and / or systems, and / or methods of using such membranes, separators, batteries, cells, and / or systems. According to at least some embodiments, the present application or invention relates to new or improved multi-layer or laminated battery separators or membranes, lithium ion batteries including such separators, and / or methods of making and / or using such battery separators and / or lithium batteries (including, but not limited to, rechargeable lithium batteries, secondary lithium ion batteries, and the like). According to at least some specific embodiments, the present invention relates to multi-layer microporous battery separators having at least one nonwoven layer and adapted for use in rechargeable lithium ion batteries, and / or methods related to making and / or using such multi-layer separators. According to at least some selected specific embodiments, the present application or invention relates to new or improved composite, multi-layer or laminated battery separators having at least two nonwoven layers, lithium batteries including such separators, and / or methods of making and / or using such battery separators and / or lithium batteries. According to at least some selected embodiments, the present invention relates to surfactant or material coated, treated or containing microporous battery separator membranes or separators, lithium batteries including such separator membranes or separators, and / or methods of making and / or using such battery separators and / or lithium batteries.In accordance with at least some selected embodiments, the present invention relates to surfactant or wettability enhancing substance coated, treated or containing composite, multi-layer or laminated battery separators having at least one nonwoven layer, and perhaps preferably two nonwoven layers (one on each side), for rechargeable lithium ion batteries, and / or methods of making surfactant coatings for microporous battery separators for rechargeable lithium ion batteries, and / or methods of making and / or using such separators, batteries, and / or the like. According to at least selected embodiments, the present invention relates to novel or improved surfactants, wetting enhancers, coatings, treatments, components, and / or the like, membranes, separators, composite, multi-layer or laminated battery separators for rechargeable lithium batteries having the novel or improved surfactants, wetting enhancers, coatings, treatments, and / or components, separators having at least one nonwoven layer, separators having two nonwoven layers (one on each side), and / or methods of making the novel or improved surfactants, wetting enhancers, coatings, treatments, and / or components, and / or methods of using the novel or improved surfactants, wetting enhancers, coatings, treatments, and / or components, and / or separators, batteries, and / or the like having such novel or improved surfactants, wetting enhancers, coatings, treatments, and / or components therein. [Background technology]

[0003] Lithium batteries (e.g., lithium-ion (Li-ion) batteries) are known for their rapid response Lithium-ion batteries are attractive for stationary energy storage applications due to their high power capability, high efficiency, and long lifespan. The main components of lithium-ion batteries are electrodes (anode and cathode), electrolyte, and porous separator membrane. There are a wide variety of electrode materials, electrolyte, and porous separator membrane materials available for use in rechargeable lithium batteries. Some lithium-ion batteries are made of lithium cobalt oxide (LiCoO), lithium manganese oxide (Li iMn2O4), lithium nickel oxide (LiNiO2), or lithium iron phosphate (L FP or LiFePO4) was used as the cathode active material, while the anode was made of carbon. The electrolyte can be organic or inorganic and can facilitate the transfer of ions during charge and discharge cycles. The separator can be a porous membrane that physically separates the anode and cathode and is ionically conductive (in the electrolyte) and electronically insulating. The electrolyte is in intimate contact with the separator, and the separator's pores should be completely wetted by the electrolyte for efficient ion transfer during charge and discharge cycles. The separator can be a microporous separator membrane made of polyolefin. Polyolefins can be wetted to different degrees by various organic and inorganic electrolytes. Charging capacity and battery performance are enhanced when the separator is readily wetted by the electrolyte.

[0004] Known separators can be microporous and made from polyolefins. Such polyolefin (PO) separators can provide superior performance and safety in battery systems. Some polyolefin separators (e.g., some polypropylene (PP) separators) are hydrophobic and may be less efficient at wetting or electrolyte filling in some inorganic lithium-ion battery systems. Proper wetting of the separator is necessary for efficient ion transfer during cycling. Single-layer nonwoven separators have been utilized in some inorganic battery systems, but these nonwovens are typically too porous and may not adequately prevent short circuits or dendrite growth.

[0005] Chemical treatments may alter the hydrophilicity of the polyolefin separator membrane; however, such treatments may not be permanent and / or non-reactive in the electrolyte and may not be stable to any potential by-products generated during repeated cycling of a rechargeable lithium-ion battery. Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, there is a need for an improved separator that provides the high performance of a polyolefin membrane and the wettability of a nonwoven fabric for at least some battery chemistries or systems. [Means for solving the problem]

[0007] According to at least selected embodiments, aspects, or objectives, the present invention may address one or more of the above-mentioned needs and / or provide new and improved coated and / or treated separator membranes, separators, and / or methods of making such membranes and / or separators, and / or methods of using such membranes and / or separators in lithium batteries (e.g., secondary lithium-ion batteries) for use in products, devices, vehicles, systems, energy storage, and / or the like. According to at least some embodiments, the present invention relates to a microporous separator membrane having at least one nonwoven layer on at least one surface thereof. In some embodiments, the present invention relates to a separator membrane having at least one surfactant coating, treatment, or component. According to at least some embodiments, the present invention relates to a separator membrane or separator having at least one nonwoven layer and at least one surfactant treatment. According to at least some embodiments, a separator, laminate, or composite comprises at least one nonwoven layer laminated or otherwise bonded to at least one porous polyolefin layer or membrane. In some embodiments, the separator, laminate, or composite has an interfacial It may include two porous nonwoven layers (nonwoven / PO membrane / nonwoven), each laminated or otherwise bonded to one side of a porous polyolefin layer or membrane, with or without an active agent treatment. In some embodiments, the polyolefin layer may be a microporous polypropylene or polyethylene monolayer. In other embodiments, the polyolefin layer may be a laminated or coextruded multilayer. In at least some embodiments, the polyolefin layer may be a polypropylene or polyethylene bilayer. In at least some embodiments, the polyolefin layer may be a polypropylene and / or polyethylene trilayer. The layers may be the same or different polyolefins, either laminated or coextruded together. For example, the surfactant-treated separator membrane or separator can include a single layer (e.g., PE, PP, copolymers or blends thereof), or multiple layers or plies (e.g., PE / PE, PP / PP, PE / PP, PP / PE / PP, PE / PP / PE, PE / PE / PE, PP / PP / PP, PP / PE / PE / PP, PE / PP / PP / PE, and even higher order composites, with or without other layers, nonwovens, coatings, and / or the like).

[0008] In some embodiments, a highly preferred separator comprises one or more nonwoven (NW) layers laminated, adhered, or bonded to a microporous polyolefin membrane, base film, or separator. In a highly preferred embodiment, the separator comprises at least one nonwoven or nonwoven (NW) layer laminated, adhered, or bonded to each side of a single or multiple layer or ply of microporous polyolefin membrane, layer, base film, or separator. Such separators with a nonwoven layer or material on each side form a very strong structure. The nonwoven may improve the wettability of the polyolefin layer. In one embodiment, the microporous polyolefin layer can be a single layer of polypropylene (PP) or polyethylene (PE), copolymer, or blend, resulting in a separator with a final structure of NW / PP / NW, NW / PE / NW, or NW / PE-PP / NW. In another embodiment, the polyolefin layer can be multiple layers, for example, NW / PP / PP / NW, NW / PE / PE / NW, NW / PP / PE / NW, NW / PE / PP / PE / NW, or NW / PP / PE / PP / NW. In another embodiment, the polyolefin layer can contain one or more laminated or coextruded tri-layers (NW / PP / PE / PP / NW, NW / PE / PP / PE / NW, or NW / PE / PP / PE / PE / PP / PE / NW, or the tri-layer can be made of several homopolymers or polyolefin copolymers or blends (e.g., NW / PP / PP / PE / PP / PP / PP / NW, NW / PE / PE / PP / PE / PE / PE / PE / NW, NW / PP / PE / PP / PE / PE / PE / PP / NW, NW / PP / PE / PP / PE / PP / PE / NW, or NW / PP-PE / PE-PP / PE-PP / PP-PE / NW).

[0009] According to at least selected embodiments, the present application or invention relates to new or improved separators with one or more surfactant treatments. The surfactant treatments of the present invention can improve the wetting of microporous battery separator membranes, membrane separators, or separators in rechargeable lithium-ion battery systems with various electrolytes, including organic and / or inorganic non-aqueous electrolytes. The hydrophilic or hydrophobic surfactant coatings of the present invention can improve the wetting rate and ability of microporous polyolefin separator membranes with organic and / or inorganic non-aqueous electrolytes. In addition, the surfactant treatments of the present invention can improve the stability of the separator membrane in the electrolyte. The use of the surfactant-coated microporous polyolefin membranes or separators of the present invention in rechargeable lithium-ion batteries can optimize the charging capability of the lithium-ion battery and promote the long-term cycle life performance of lithium-ion batteries in consumer electronics (CE), electric vehicles (EV), and electric or energy storage systems or battery energy storage systems (ESS or BESS), and / or the like.

[0010] The highly preferred treatments of the present invention for polyolefin microporous separator membranes for lithium ion batteries are organic or A surfactant coating allows the membrane to be wetted more easily and more completely by the inorganic electrolyte. It is highly desirable to develop, select, or use a surfactant that is chemically stable in the harsh chemical environment of a lithium-ion battery, stable in overcharge products, and also permanently or stably renders the porous separator membrane hydrophilic or wettable. The separator should be easily wetted in the electrolyte and retain the electrolyte. The former facilitates the electrolyte filling process into the battery assembly, while the latter increases the battery's cycle life. Improving the electrolyte wetting of the separator through surface modification can be important for preparing high-performance lithium-ion batteries. Due to the inherent hydrophobic properties of non-polar polyolefin separators, electrolytes containing high amounts of polar solvents can exhibit poor wetting and electrolyte retention.

[0011] According to selected embodiments, the present invention may relate to a method for manufacturing surfactant-treated separator membranes, membrane separators or separators for rechargeable lithium batteries, and / or surfactant treatments for battery separators for lithium batteries. Additionally, the present invention relates to a method for manufacturing surfactant-treated separator membranes, membrane separators or separators for rechargeable lithium batteries, and / or surfactant treatments for battery separators for lithium batteries. Additionally, the present invention relates to a method for manufacturing surfactant-treated separator membranes, membrane separators or separators for rechargeable lithium batteries, and / or surfactant treatments for battery separators for lithium batteries. Lithium manganese oxide (LiMn2O4), lithium nickel oxide (LiNiO2), lithium iron Electrode materials including phosphates (LFP or LiFePO4), or combinations thereof; 1) an organic or inorganic electrolyte; and 2) a surfactant-treated battery separator membrane.

[0012] According to at least selected embodiments, the surfactant coatings, treatments, or ingredients of the present invention (which may be added to the resin and / or electrolyte) are surfactants, hydrophilic surfactants, water-repellent surfactants, wetting agents, or materials (e.g., lithium dodecylbenzene sulfonate (LiDBS), nonionic fluorosurfactants, lithium stearate, or the like for microporous battery separators) that can improve the wetting of the microporous polyolefin battery separator in rechargeable lithium-ion battery systems by various electrolytes, including organic and / or inorganic nonaqueous electrolytes. When lithium stearate is used, it may be preferable to add it to the resin. The surfactant coatings of the present invention can improve the wetting rate and wetting ability of the microporous polyolefin separator membrane by organic and / or inorganic nonaqueous electrolytes. In addition, the surfactant-coated separator membranes or separators of the present invention may be chemically stable in various electrolytes. The use of the surfactant coated microporous polyolefin separator of the present invention in rechargeable lithium ion batteries can optimize the rechargeability of the lithium ion batteries and promote the long-term cycle life performance of the lithium ion batteries in consumer electronics (CE), electric vehicles (EV), electrical storage systems (ESS or BESS), and / or the like. [Brief explanation of the drawings]

[0013] [Figure 1] 5 is a cross-sectional SEM image at 500x of a separator having a meltblown nonwoven layer laminated on each side of a polyolefin layer. [Figure 2] 1 is a chart demonstrating the improved TD tear strength of a nonwoven membrane composite separator compared to a polyolefin-only separator. [Figure 3] 1 is a graph showing the improved wettability of a nonwoven membrane composite separator compared to a polyolefin-only separator. [Figure 4] Included is a graph depicting surfactant loading or surface density (in mg / cm) for surfactant-treated separators as a function of wt % surfactant in methanol, where the secondary y-axis is wetting time (in seconds) for various surfactant loadings. [Figure 5] 1 includes a graph depicting battery capacity (%) as a function of cycle number for surfactant coated separator membranes compared to uncoated polypropylene microporous separator membranes. DETAILED DESCRIPTION OF THE INVENTION

[0014] In some embodiments, the separator includes at least one nonwoven layer laminated to a polyolefin layer. The polyolefin layer can be a single polyolefin layer or film, or multiple layers or plies of polyolefin laminated or coextruded together. The polyolefin layer can include a polyethylene (PE) layer, a polypropylene (PP) layer, a polymethylpentene (PMP) layer, and mixtures or combinations thereof. Exemplary combinations or multilayer structures for the PO layer include PE / PE, PP / PP, PE / PP, PP / PE / PP, PE / PP / PE, PE / PE / PE, PP / PP / PP, PE / PE / PE / PE, PP / PP / PP / PP, PE / PP / PP / PE, PP / PE / PP / PP, PP / PE / PP / PP, PP / PE / PP / PP, PP / PE / PP / PP, PP / PE / PP / PP, PP / PE / PP / PP, PP / PE / PP / PP, PP / PP / PP / PP, PE / PE / PE / PE / PE, PP / PP / PP / PP, PP / PE ... / PP, PP / PE / PP / PP, PP / PE / PP / PP / PP, PP / PE / PP / PP / PP, PP / PE / PP / PP / PP, PP / PE / PP / PP / PP, PP / PE / PP / PP / PP, PP / PE / PP / PP / PP, PP / PE / PP / PE / PP, PE / PP / PE / PP / PE, PE / PE / PE / PE / PE / PE, PP / PP / PP / PP / PP / PP, PE / PE / PP / PP / PE / PE, PP / PP / PE / PE / PP / PP, PP / PE / PP / PP / PE / PP, PE / P P / PE / PE / PP / PE, PP / PE / PE / PE / PE / PP, PE / PP / PP / PP / PP / PE, PP / PE / PP / PE / PP / PE / PP, PE / PP / PE / PP / PE / PP / PE, or the like.

[0015] Typically, the PO layer or film has a total thickness of about 2-200 μm, about 4-100 μm, about 5-75 μm, about 5-50 μm, about 15-50 μm, about 15-35 μm, about 25-200 μm, about 50-200 μm, about 50-150 μm, or about 75-125 μm. Each layer or ply of the PO film, base film, or layer can be of various thicknesses. For example, in a multilayer film, the PE layer can be of one thickness and the PP layer can be of another thickness.

[0016] Exemplary nonwoven materials include polypropylene, polyethylene, low-density polyethylene, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, polymethylpentene, polystyrene, polyamide, polyimide, polyester, polytetrafluoroethylene (PTFE), PVDF, nylon, glass, and copolymers, combinations, blends, or mixtures thereof. In some embodiments, the nonwoven layer may comprise fibers of polypropylene, polyethylene, or mixtures thereof. In some embodiments, the nonwoven layer is selected from materials having a melting point of less than about 200°C, less than about 190°C, less than about 180°C, less than about 170°C, less than about 165°C, less than about 160°C, less than about 150°C, less than about 140°C, and / or less than about 135°C. In some embodiments, the nonwoven layer is selected from materials having a melting point greater than about 200°C.

[0017] The nonwoven layer can be on one or both sides of the separator membrane, or between two separator membranes. When a nonwoven layer is on both sides, such a membrane is called a sandwich separator.

[0018] The nonwoven layer can be prepared by conventional methods and then laminated to the PO layer. For example, the nonwoven layer can be heat and pressure bonded to the polyolefin layer. In other embodiments, the nonwoven layer can be formed directly on the PO layer by wet-laid or dry-laid methods. The nonwoven can have a random or ordered appearance (e.g., a fibrous wet-laid or electrospun random structure or a mesh or net-like structure).

[0019] Typically, the nonwoven fabric layer has a total thickness of about 2 to 2000 μm, about 5 to 1000 μm, about 5 to 75 μm, about 5 to 50 μm, about 15 to 50 μm, about 15 to 35 μm, about 25 to 200 μm, about 50 to 200 μm, about 50 to 150 μm, or about 75 to 125 μm.

[0020] In some embodiments, the separator membrane includes a surfactant coating or treatment that can increase the surface energy so that the membrane is more easily wetted by organic or inorganic electrolytes. The surfactant treatment can include an alkali metal salt of a linear or branched alkylbenzene sulfonic acid, represented by the following chemical structure:

[0021] [ka]

[0022] wherein R is C, where n is preferably >6, more preferably >8, and most preferably ≥12. n H 2n+1 In some examples, R is an alkyl functional group that can be It may be a branched alkyl functional group as represented by:

[0023] [ka]

[0024] wherein R1 and R2 are independently C, where n is preferably >6, more preferably >8, and most preferably ≥12. n H 2+1 In some embodiments, the alkyl benzene may be a nonylphenyl or dodecylphenyl sulfonate. Preferred examples of alkali metal salts of linear or branched alkyl benzene sulfonic acids include X m+ =Li + The alkylbenzene sulfonate may be a lithium salt of linear or branched alkylbenzene sulfonate,

[0025] In some embodiments, the surfactant may include one or more lithium salts. Exemplary surfactants include lithium salts of alkylbenzenesulfonic acid and lithium salts of fatty acids (e.g., acids having 6, 8, 10, 12, 14, 16, 18, or more than 20 carbon atoms). The fatty acid salts may be saturated or unsaturated. Exemplary saturated fatty acids include caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, and arachidic acid. Exemplary unsaturated fatty acids include myristoleic acid, palmitoleic acid, sapienic acid, oleic acid, linoleic acid, linoleelaidic acid, and arachidonic acid. In some embodiments, the surfactant may be a lithium salt of alkylbenzenesulfonic acid represented by the following chemical structure:

[0026] [ka]

[0027] In the formula, R is C1~ 20 The alkyl group is an exemplary lithium alkyl benzene sulfonate. The lithium salt is 4-dodecylbenzenesulfonate (R=C) which has the following chemical structure: 12 alkyl).

[0028] [ka]

[0029] Lithium salts may be preferred due to their chemical stability in lithium-ion rechargeable batteries. During repeated cycling in lithium-ion rechargeable batteries, decomposition products from the electrolyte and other battery components may decompose the surfactant. Lithium salts react less (or not at all) with overcharge products, thereby enhancing the charge and discharge cycling performance of the battery. The surfactant-treated separators described herein may improve the cycling performance of various batteries containing such separators.

[0030] In some embodiments, the surfactant may include a fluorosurfactant, such as a partially fluorinated or fully fluorinated surfactant (e.g., a perfluorosurfactant). The fluorosurfactant may be anionic, cationic, or nonionic. Exemplary nonionic fluorosurfactants include polyethylene glycol polymers covalently linked to fluorinated or perfluorinated hydrocarbon chains, such as:

[0031] [ka]

[0032] In the formula, n is an integer of 10 to 1000, and R f is the formula C x H y F z where x is an integer from 1 to 20, and y and z, taken together, equal 2x+1, i.e., y+z=2x+1. In some embodiments, x is an integer from 6 to 16. Exemplary perfluorosurfactants include the compounds represented by the following chemical structure: Lithium didecafluorooctanesulfonate is an example.

[0033] [ka]

[0034] Exemplary anionic surfactants include those of the formula: R f Examples of the salts of compounds having -Φ-A include In the formula, R f has the meaning given above, and Φ is a phenyl ring or is absent and A is an acidic moiety (e.g., CO2H, SO3H, or PO3H2). The anionic surfactant may be present as a lithium, sodium, or potassium salt (and lithium salts may be preferred).

[0035] One possible exemplary or useful surfactant may be a fluorinated polyoxyalkylene glycol diester surfactant having the following chemical formula, the formula of which is given in U.S. Pat. No. 8,022,107 B2, which is hereby incorporated by reference.

[0036] [ka]

[0037] Surfactants typically have a hydrophilic (water-loving or lipophobic) end functional group and a hydrophobic or lipophilic (oil-loving or lipophilic) end functional group, and the balance of these functional groups is quantified by the hydrophilic-lipophilic balance (HLB) number, where HLB can have a value between 0 and 60 that can define the affinity of the surfactant for water or oil, and the HLB value can be adjusted by the length of the alkyl chain.

[0038] One or more surfactants can be dissolved or dispersed in a solvent and then applied to a layer present in the separator membrane described above. In some cases, a surfactant-containing solution or suspension can be gravure coated onto a layer, or a layer can be immersed in a surfactant-containing solution or suspension. Surfactants can also be incorporated into layers prior to their formation. For example, surfactants can be added to polyolefin resins before or during extrusion, or surfactants can be added to nonwoven fibers before the spinning process. Surfactants can also be incorporated into multiple layers of a composite separator. For example, a surfactant can be applied to one side of a polyolefin layer or membrane, followed by laminating a nonwoven layer or another polyolefin layer on the coated side. It may be preferable to form membranes and nonwoven structures and then coat or treat them (e.g., by dip coating to treat both sides of the separator or membrane). Surfactants can also be added to the electrolyte. If applied onto the membrane, a lower impregnation amount can be effective. If added to the electrolyte, a larger amount may be required. For example, if 5% is added to the membrane, 10% or more would be needed to provide the same improvement in separator wettability. It may need to be added to the electrolyte.

[0039] When a surfactant treatment is applied to a separator, the separator surface may have a higher surface energy, a lower contact angle, reduced hydrophobicity, and / or may be more easily wetted by or absorb an electrolyte (e.g., propylene carbonate (PC), ethylene carbonate, mixtures thereof, or other electrolytes). Table 1 shows the wetting ability of an untreated separator compared to a surfactant-treated separator. In the table, an uncoated separator (Celgard 4560) could not be wetted on either the nonwoven side or the film side by a particular electrolyte. The surfactant-treated membrane showed a significant improvement in wetting ability, with the film side being completely wetted within 15 seconds and the nonwoven side being completely wetted within 5 seconds.

[0040] [Table 1]

[0041] Table 2 shows a significant decrease in contact angle on both the film and nonwoven sides of the membranes after 3 and 120 seconds of contact time. Compared to the untreated membrane, the surfactant-treated membrane exhibited a contact angle of 0 at 120 seconds, indicating complete wetting. [Table 2]

[0042] Common examples of inorganic electrolytes include, but are not limited to, sulfur-based electrolytes, thionyl chloride-based electrolytes, and sulfur dioxide-based electrolytes. The electrolyte may include one or more conductive salts of alkali metals, particularly lithium, including aluminates, halides, oxalates, borates, phosphates, arsenates, and gallates. These inorganic electrolytes may have difficulty wetting some polypropylene microporous separator membranes and may have higher surface energies than polypropylene.

[0043] An example of a sulfur-based electrolyte is an inorganic electrolyte system that includes LiAlCl4 x SO2, a sulfur dioxide (SO2)-based electrolyte that may contain lithium tetrachloroaluminate conductive salt. The LiAlCl4 x SO2 electrolyte is a material disclosed in U.S. Pat. No. 6,499,499, which is hereby incorporated by reference. It is described in Japanese Patent No. 8410759 and contains SO2 and the conductive salt LiAlCl4, and has the following general chemical structure:

[0044] [ka]

[0045] According to U.S. Pat. No. 8,410,759, the conductive salt may be selected from the group consisting of aluminates, halides, oxalates, borates, phosphates, arsenates and gallates of alkali metals, in particular lithium. An example of a sulfur-based electrolyte is LiAlCl4×S The use of surfactant-treated separators in lithium-ion batteries employing sulfur dioxide-based electrolytes containing conductive salts can optimize the charging capability of rechargeable lithium-ion batteries.

[0046] The surfactants, agents, or materials described above can be more efficient than previously used surfactants for lithium battery separator membranes. By way of example only, in some embodiments, the improved separators described herein can require about 50% less, about 33% less, or about 25% less of the surfactant required to achieve the same amount of improved wetting ability compared to known surfactants for various prior battery separators.

[0047] Use of the separators disclosed herein can optimize the battery capacity of lithium ion batteries and promote the long-term cycle life performance of, for example, LiFePO4 batteries in consumer electronics (CE), electric vehicles (EV) and / or electrical storage systems (ESS).

[0048] Test Methods for Example Data Thickness is measured using an Emveco Microgage 210-A precision micrometer thickness tester according to test procedure ASTM D374. Thickness values ​​are reported in micrometers (μm).

[0049] Wet-out was measured by applying a drop (approximately 0.05 mL) of propylene carbonate electrolyte to the surface of the separator. The time to complete wet-out was measured when the test sample was wet with electrolyte and turned an opaque white color. It is determined visually as the time in seconds for the color appearance to change to a clear, transparent appearance.

[0050] Breaking Strength: Test specimens are first preconditioned at 73.4°C and 50% relative humidity for a minimum of 20 minutes. An Instron Model 4442 is used to measure the breaking strength of the test specimens. 1 Thirty measurements are taken across the diagonal of a 1 / 4 inch x 40 inch continuous specimen and averaged. The needle has a 0.5 mm radius. The descent rate is 25 mm / min. The film is held tightly in place with a clamping device that utilizes an O-ring to hold the test sample firmly in place. The diameter of this clamped area is 25 mm. The displacement (in mm) of the film penetrated by the needle is recorded against the force (in grams-force) exerted by the film being tested. The maximum force is the breaking strength in grams-force (gf). This test method produces a plot of load against displacement.

[0051] Tensile strength along MD and TD is measured using an Instron Model 4201 according to ASTM D-882 method.

[0052] Heat shrinkage tests are measured by placing a 10 cm x 10 cm membrane sample in a manila folder, which is then hung in an oven using clips. Shrinkage was measured in the MD and TD directions with calipers before and after the test sample was placed in the oven at 105°C for 1 hour. Shrinkage was also measured in the MD and TD directions with calipers before and after a second test sample was placed in the oven at 120°C for 1 hour. Shrinkage is expressed as %MD shrinkage and %TD shrinkage using a modified ASTM 2732-96.

[0053] Adhesion was measured using ASTM method D-1876, "Standard test method for peel resistance of adhesives."

[0054] The Gurley number was measured using a Gurley Densometer (Model 4120), ASTM-D726(B)-Gurley. The Gurley number is calculated as the ratio of a 100 ml gas volume to a 6.45 cm3 volume under a 31 cm hydrohead gas pressure. 2 Passing through the area of This was calculated by finding the time it takes for the temperature to rise. Time (t) is the Gurley number.

[0055] High-temperature electrical resistance is a measure of the resistance of a separator film under 50 lb of pressure while the temperature is increased linearly at a rate of 60°C / min. A 3 / 8-inch diameter piece of separator is saturated with electrolyte and sandwiched between two electrode disks made of Al or Cu. The increase in resistance, measured as impedance, corresponds to the collapse or "failure" of the pore structure due to melting of the microporous separator membrane. If a microporous separator membrane has a sustained high level of electrical resistance at high temperatures, this indicates that the separator membrane can prevent electrode shorting within the battery.

[0056] Coating loading or coating surface density is measured in weight percent of the solution or measured using ASTM D3776 and expressed in mg / cm 2 It is expressed as:

[0057] Example 1: NW / PO / NW separator (no surfactant) A triple-layer separator was fabricated by laminating a 60 μm thick PP nonwoven layer to each side of a Celgard® 2500 polypropylene separator using a silicone heated roll (surface temperature 240° F.) and a smooth metal heated roll (surface temperature 250° F.) The two 60 μm PP nonwoven layers were combined with a 25 μm thick microporous Celgard 2500 membrane under 50 psi to produce a 104 μm triple-layer separator.

[0058] Figure 1 shows an example of a nonwoven / membrane / nonwoven triple-layer separator. The outer layers of the separator are 46.3 μm and 35.1 μm thick, with a 26.9 μm polypropylene inner layer. The lamination of two nonwoven layers to the outer surface of the polyolefin layer improves separator performance compared to a similar polyolefin without the nonwoven layer. The sandwich separator shown in Figure 3 has improved wettability of 34 to 38 dynes / cm. This sandwich separator has reduced shrinkage and increased TD tear strength (see Figure 2 and Table 3). The TD tear strength of the sandwich separator is increased from 2.7 gf to 82 gf. The shrinkage percentage is reduced from 9.47% to 3.07% in both cases (MD%, Table 3).

[0059] [Table 3]

[0060] Example 2: Surfactant-treated separator In this example, the control example (CE1) was a commercially available Celgard® 4560 separator (surfactant-free, single-sided nonwoven). Celgard® 4560 is a 110 μm-thick microporous composite separator (nonwoven on only one side, surfactant-free) consisting of a Celgard® 2500 polypropylene membrane (Celgard® 2500 is a 25 μm-thick single-layer polypropylene membrane) laminated to an 85 μm-thick polypropylene nonwoven layer. For the inventive examples, various coatings with varying weight percent pick-up levels and coating surface densities, as well as varying weight percents of surfactant in the methanol-containing coating solutions, were applied to samples of the Celgard® 4560 composite separator. Specifically, the samples were coated with various solutions of lithium 4-dodecylbenzenesulfonate surfactant (LiDBS) in methanol at various concentrations. Table 4 lists the coating data for Examples 1-4, which were coated with solutions of lithium 4-dodecylbenzenesulfonate in methanol at concentrations ranging from 0.5 wt % to 2.0 wt %.

[0061] [Table 4]

[0062] Ex. 1 is a Celgard® 4560 separator with a 4.84 wt. % add-on load that is double-sided dip-coated with a 2.0 wt. % solution of lithium 4-dodecylbenzenesulfonate in methanol. Ex. 2 is a Celgard® 4560 separator with a 3.84 wt. % add-on load that is double-sided dip-coated with a 1.5 wt. % solution of lithium 4-dodecylbenzenesulfonate in methanol. Ex. 3 is a Celgard® 4560 separator with a 2.58 wt. % add-on load that is double-sided dip-coated with a 1.0 wt. % solution of lithium 4-dodecylbenzenesulfonate in methanol. Ex. 4 is a Celgard® 4560 separator with a 1.37 wt. % add-on load that is double-sided dip-coated with a 0.5 wt. % solution of lithium 4-dodecylbenzenesulfonate in methanol. CE1 is an uncoated Celgard® 4560 separator that does not wet out easily, as indicated by an infinite wet out time.

[0063] FIG. 4 shows the wet-out time in seconds of lithium 4-dodecylbenzenesulfonate surfactant applied to Celgard® 4560 laminated polypropylene separator versus surfactant loading in wt % in the coating solution versus mg / cm 2 The correlation between the surface density of the unit This indicates the relationship.

[0064] Propylene carbonate (PC) can be used to evaluate the wettability of membranes by electrolytes. Polypropylene microporous membranes that can be wetted by PC may also be wetted by other electrolytes, such as inorganic electrolytes, including LiAlCl4 × SO2. Typical organic electrolytes for rechargeable lithium-ion batteries can be based on a combination of linear and cyclic alkyl carbonates. Common examples of organic electrolytes include, but are not limited to, propylene carbonate (PC), ethylene carbonate (EC), dimethyl carbonate (DMC), and mixtures thereof. Propylene carbonate has a surface energy of approximately 41 dynes / cm and tends not to wet polypropylene microporous separator membranes, which may have a lower surface energy of approximately 30-36 dynes / cm.

[0065] Table 4 lists the soak times using propylene carbonate as the electrolyte. A soak time of ≦20 seconds is 0.026 mg / cm 2 Lithium 4-dodecylbenzenesulfonate This was observed at a surfactant coating loading of 0.094 mg / cm 2 The latest on coatings The wet-out time was 0.5 seconds, which indicates that the lithium 4-dodecylbenzenesulfonate surfactant coating was 0.094 mg / cm 2 Separator coated with coating density of The zero wetting observed for the uncoated separator membrane compared to the 0.5 second wetting time for the separator demonstrates that electrolyte wetting can be significantly improved. Because this surfactant treatment effectively increases the electrolyte wetting rate of the coated polypropylene microporous separator membrane from virtually no wetting to complete wetting in less than one second, batteries containing the surfactant-treated separator membrane of the present invention have faster electrolyte filling times. Furthermore, the electrolyte wetting rate of less than 1 second indicates greater electrolyte absorption by the coated microporous separator membrane, which may lead to improved capacity performance in lithium-ion batteries.

[0066] Example 3: Battery capacity of surfactant-treated separator In this example, a sample of Celgard® single layer polypropylene membrane approximately 20 microns thick was coated with a solution of lithium 4-dodecylbenzenesulfonate surfactant (LiDBS) according to an embodiment described herein.

[0067] FIG. 5 shows the surfactant-coated electrode of the present invention in a lithium iron phosphate (LiFePO4) battery. Figure 5 shows the battery capacity versus cycle number for a treated Celgard® separator compared to an uncoated sample of the same Celgard® monolayer polypropylene separator membrane, approximately 20 microns thick. Figure 5 shows a clearly evident trend of improved battery capacity (by reducing capacity fade) for the surfactant-coated separator of the present invention compared to the untreated or uncoated separator, which exhibits declining battery capacity and more capacity fade. The battery capacity fade with the untreated membrane would likely continue to decline at higher cycle numbers, which may be undesirable.

[0068] According to at least selected embodiments, aspects, or objects, the present application or invention provides novel or improved separator membranes, separators, batteries, cells, systems, and / or methods of making such membranes, separators, batteries, cells, and / or systems, and / or methods of using such membranes, separators, batteries, cells, and / or systems; novel or improved multi-layer or laminated battery separators or membranes, lithium ion batteries including such separators, and / or methods of making and / or using such battery separators and / or lithium batteries (including, but not limited to, rechargeable lithium batteries, secondary lithium ion batteries, and the like); multi-layer microporous battery separators having at least one nonwoven layer and adapted for use in rechargeable lithium ion batteries and / or methods relating to the making and / or use of such multi-layer separators; novel young separators having at least two nonwoven layers or improved composite, multi-layer or laminated battery separators, lithium batteries containing such separators, and / or methods of making and / or using such battery separators and / or lithium batteries; surfactant or material coated, treated or containing microporous battery separator membranes or separators, lithium batteries containing such separator membranes or separators, and / or methods of making and / or using such battery separators and / or lithium batteries; surfactant or wettability enhancing material coated, treated or containing composite, multi-layer or laminated battery separators having at least one nonwoven layer, perhaps preferably two nonwoven layers (one on each side), for rechargeable lithium ion batteries, and / or methods of making surfactant coatings for microporous battery separators for rechargeable lithium ion batteries, and / or methods of making and / or using such separators, batteries, and / or the like;new or improved surfactants, wetting enhancers, coatings, treatments, components, and / or the like, membranes, separators, composites, multi-layer or laminated battery separators for rechargeable lithium batteries having the new or improved surfactants, wetting enhancers, coatings, treatments, and / or components, separators having at least one nonwoven layer, separators having two nonwoven layers (one on each side), and / or methods of making the new or improved surfactants, wetting enhancers, coatings, treatments, and / or components, and / or methods of using the new or improved surfactants, wetting enhancers, coatings, treatments, and / or components, and / or separators, batteries, and / or the like having such new or improved surfactants, wetting enhancers, coatings, treatments, and / or components therein, and / or the like; According to at least some embodiments, aspects, or objects, the present application or invention addresses or solves the aforementioned problems or issues of poor wettability, hydrophobicity, slow electrolyte wetting or filling, surfactant durability, and / or the like.

[0069] According to at least some embodiments, the present invention relates to a separator membrane, separator, or membrane-based separator. The membrane or separator may include a nonwoven layer, an improved surfactant treatment, or a combination thereof. The separator or membrane is useful in lithium batteries, particularly rechargeable lithium-ion batteries, and provides improved performance, wettability, cyclability, and / or charging efficiency.

[0070] According to at least selected embodiments, the present invention relates to new and improved coated or treated separator membranes, separators, or membrane-based separators for lithium batteries. The membranes or separators may include a nonwoven layer, an improved surfactant treatment, or a combination thereof. The separators or membranes are useful in solvent-electrolyte lithium batteries, particularly rechargeable lithium-ion batteries, and provide improved performance, wettability, cyclability, and / or charging efficiency.

[0071] Exemplary surfactants, agents or substances, according to some embodiments, include: surfactant sodium dodecylbenzenesulfonate (DMS) or sodium dodecyl sulfate (SDS); Non-ionic fluorosurfactants that provide very low surface tension in water-based or solvent-based products, allowing for better wetting; fluorosurfactants or fluorinated surfactants, such as synthetic organic fluorine compounds having multiple fluorine atoms (which can be polyfluorinated or fluorocarbon-based (perfluorinated), and as surfactants, they are more effective at lowering the surface tension of water or polar solvents than comparable hydrocarbon surfactants, which have a fluorinated "tail" and a hydrophilic "head"); A non-ionic fluorosurfactant that provides very low surface tension in water-based or solvent-based products, allowing for better wetting, spreading, leveling, and other beneficial properties, is VOC-free, APEO-free, flame-retardant, and compatible with any ionic class of additives and resins, even at very low concentrations (it can provide very high wetting power and be stable in acidic, basic, saltwater, and hard water environments, making it easy to formulate into a variety of systems); non-ionic fluorosurfactants that are flame retardant, VOC and APEO free, used in solvent-based coatings to reduce defects such as cratering, as wetting and leveling agents, to give coatings weather resistance, stain resistance and UV stability, and as internal lubricants and anti-fog agents for polymers; Fluorosurfactants or fluorocarbon-based surfactants, which are highly effective even when used in very low concentrations (0.001% to 0.1%) and improve wetting, leveling, anti-cratering, dirt pick-up resistance, and oil repellency in many applications; Non-ionic fluorosurfactants that are water repellent (allowing for easier drying before electrolyte injection) or active at very low add-on levels; a water-repellent non-ionic fluorosurfactant or fluorinated glycol ether; and / or Formally classified as a soap (salt of fatty acids), it is a white, soft solid prepared by the reaction of lithium hydroxide and stearic acid, with the formula LiO2C(CH2) 16 Compounds with CH3 Lithium stearate (lithium stearate and lithium 12-hydroxystearate are lithium soaps and components of lithium grease) may be mentioned.

[0072] The present invention may be embodied in other forms without departing from its spirit or essential attributes and, accordingly, reference should be made to the appended claims, rather than the foregoing specification, as indicating the scope of the invention.

Claims

1. 1. A microporous battery separator for a lithium battery, comprising: a polyolefin layer; at least one nonwoven layer on each side of the polyolefin layer; a surfactant coating or surfactant treatment in or on said separator; Including, The surfactant is present at 0.1 to 10.0 wt % (addition amount), and the separator has at least one of improved puncture strength and reduced shrinkage compared to the polyolefin layer alone.

2. 10. The separator of claim 1, wherein the polyolefin layer comprises at least one film of polypropylene.

3. The separator of claim 1 , wherein the nonwoven layer comprises polypropylene.

4. The separator of claim 1 , wherein the nonwoven layer comprises a nonwoven layer having a melting point of less than about 200° C.

5. The separator of claim 1 , wherein the surfactant comprises a lithium salt.

6. The separator of claim 1 , wherein the surfactant comprises a fluorine-containing surfactant.

7. 1. A microporous battery separator for a lithium battery, comprising: a polyolefin layer; at least one nonwoven fabric layer on at least one side of the polyolefin layer; at least one surfactant coating or treatment in or on said separator to enhance wetting of a solvent-based electrolyte; wherein the surfactant is present at about 0.1 to 10.0 wt. % (additive amount). Separator.

8. 8. The separator of claim 7, wherein the polyolefin layer comprises at least one film of polyethylene, polypropylene, or a combination, blend, or mixture thereof.

9. 8. The separator of claim 7, wherein the polyolefin layer comprises multiple layers of polyethylene, multiple layers of polypropylene, or multiple layers of polyethylene and polypropylene.

10. The polyolefin layer has the following multilayer arrangement: PE / PE, PP / PP, PE / PP, PP / PE / PP, PE / PP / PE, PE / PE / PE, PP / PP / PP, PE / PE / PE / PE, PP / PP / PP / PP, PE / PP / PP / PE, PP / PE / PE / PP, PE / PE / PE / PE / PE, PP / PP / PP / PP / PP, PE / PE / PP / PE / PE, PP / PP / PE / PP / PP, PP / PE / PP / PE / PP, PE / PP / PE / PP / PE, PE / PE / PE / PE / PE / PE, PP / PP / PP / PP / PP / PP, PE / PE / PP / PP / PE / PE, PP / PP / PE / PE / PP / PP, PP / 10. The separator of claim 9, selected from one of PE / PP / PP / PE / PP, PE / PP / PE / PE / PP / PE, PP / PE / PE / PE / PE / PP, and PE / PP / PP / PP / PP / PE.

11. The nonwoven fabric layer is made of polypropylene, polyethylene, low-density polyethylene, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, polymethylpentene 8. The separator of claim 7, comprising polystyrene, polyamide, polyimide, nylon, or a combination, blend, or mixture thereof.

12. 8. The separator of claim 7, wherein the nonwoven layer has a melting point of less than about 200°C.

13. The separator of claim 7 , including a surfactant treatment on the surface of the separator.

14. The separator of claim 7 , wherein the surfactant comprises a lithium salt.

15. The separator of claim 7 , wherein the surfactant comprises a fluorine-containing surfactant.

16. laminating at least one nonwoven layer to at least one surface of the polyolefin layer to form a composite; treating the composite material with at least one surfactant to improve wettability of the solvent-based electrolyte; wherein the surfactant is present at about 0.1 to 10.0 wt. % (addition amount).

17. A lithium battery comprising the separator of claim 1.

18. A lithium battery comprising the separator of claim 7.

19. 17. A lithium battery comprising a separator made by the method of claim 16.

20. 1. A lithium battery comprising at least one cell including electrodes, an electrolyte, and a separator between the electrodes, the separator comprising: a polyolefin layer; Nonwoven fabric layer wherein the separator or electrolyte comprises at least one surfactant coating, treatment, or material, the surfactant comprising fluorine atoms, lithium atoms, or both, and the surfactant is present at about 0.1 to 10.0 wt. % (impregnated amount).

21. the polyolefin layer comprises one or more layers, the polyolefin being selected from the group consisting of polypropylene, polyethylene, polymethylpentene, copolymers, blends, combinations, and mixtures thereof; 21. The lithium battery of claim 20, wherein the surfactant coating, treatment, or substance comprises an alkali metal salt of a linear or branched alkylbenzene sulfonic acid, a lithium salt of a linear or branched alkylbenzene sulfonic acid, a non-ionic fluorosurfactant, a water-repellent non-ionic fluorosurfactant, or lithium 4-dodecylbenzene sulfonate, and the battery is a secondary lithium ion battery.

22. 22. The lithium battery of claim 21, wherein the separator is wetted by an organic or inorganic electrolyte in less than 20 seconds.

23. 23. An energy storage system comprising one or more lithium batteries according to claim 22.

24. One or more LiFePOs according to claim 20 4 Energy storage systems, including lithium batteries Tem.

25. 10. The separator of claim 1, comprising one or more LiFePO 4 Energy storage devices, including batteries Warehouse system.

26. 8. One or more LiFePO separators comprising the separator of claim 7. 4 Energy storage devices, including batteries Warehouse system.

27. 21. The lithium battery of claim 20, wherein the separator is wetted by an organic or inorganic electrolyte in less than 5 seconds.

28. 1. A microporous lithium battery separator membrane comprising: at least one polyolefin layer; at least one surfactant coating or treatment in or on said separator membrane to enhance wetting of said membrane by a solvent-based electrolyte; wherein the surfactant is present in an amount of about 0.1 to 10.0 wt. % (wet add-on). Separator membrane.

29. 30. The separator membrane of claim 28, wherein the polyolefin layer comprises at least one membrane of polyethylene, polypropylene, or both.

30. 30. The separator membrane of claim 28, wherein the polyolefin layer comprises multiple layers of polyethylene, multiple layers of polypropylene, or multiple layers of polyethylene and polypropylene.

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