Battery separator, lithium ion battery, separator membrane, and dry microporous polymer membrane

Abstract

To provide a battery separator improved in tensile strength and dielectric breakdown strength.SOLUTION: Provided is a battery separator for lithium batteries, which comprises a dry coextruded polyolefin microporous separator sub-membrane including three or more dry polymer micro-layers each having a thickness of less than 2 μm, where the dry coextruded polyolefin microporous separator sub-membrane is laminated with another dry coextruded polyolefin microporous separator sub-membrane that also includes a plurality of dry polymer micro-layers each having a thickness of less than 2 μm.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 Serial No. 62 / 253,932, filed November 11, 2015, which is hereby incorporated by reference in its entirety.

[0002] The present disclosure or invention relates to novel or improved membrane layers, membranes or separator membranes, battery separators including such membranes, and / or related methods. According to at least selected embodiments, the present disclosure or invention relates to novel or improved porous membranes or separator membranes, battery separators including such membranes, and / or related methods. According to at least certain embodiments, the present disclosure or invention relates to novel or improved microporous membranes or separator membranes, microlayer membranes, multilayer membranes including one or more microlayer membranes, battery separators including such membranes, and / or related methods. According to at least certain selected embodiments, the present disclosure or invention relates to one or more novel or improved outer and / or inner layers, multilayer microporous membranes or separator membranes having an outer layer and an inner layer, microlayer membranes, multilayer microporous membranes having an outer layer and an inner layer, or separator membranes, some of which layers are made by coextrusion and all of which layers are laminated together to form a novel, optimized or improved membrane or separator membrane. In some embodiments, a layer comprises a homopolymer, a copolymer, and / or a polymer blend.

[0003] The invention also relates to methods of making such membranes, separator membranes or separators, and / or methods of using such membranes, separator membranes or separators, for example as lithium battery separators. According to at least selected embodiments, the present application or invention relates to new or improved multilayer and / or microlayer porous or microporous membranes, separator membranes, separators, composites, electrochemical devices, batteries, methods of making such membranes, separators, composites, devices and / or batteries. According to at least certain selected embodiments, the invention relates to new and improved separator membranes that are multilayer, where one or more layers of the multilayer structure are made in a multilayer or microlayer coextrusion die with multiple extruders. The improved membranes, separator membranes or separators can preferably exhibit improved shutdown, improved strength, improved dielectric breakdown strength, and / or reduced tendency to cracking. [Background technology]

[0004] Methods for reducing cracking in microporous battery separator membranes and certain split- or tear-resistant microporous membranes are provided in U.S. Patent No. 6,602,593, which describes, among other things, a method for extruding a film precursor by a blown film process and using a blow-up ratio (BUR) of at least about 1.5 during blown film extrusion.

[0005] US Patent No. 8,795,565 describes, among other things, a biaxial stretching technique involving both MD and TD stretching of a dry-process precursor membrane with a controlled MD relaxation treatment step. Biaxially stretched membranes, such as those shown in Figures 1-3 of the '565 patent, may have some reduced cracking or tearing. When biaxially stretched microporous membranes are strength tested using a puncture strength test method, the puncture site of the test specimen may be a round hole as opposed to an elongated crack.

[0006] U.S. Patent No. 8,486,556 discloses, among other things, a multi-layer battery separator membrane having increased strength. A high molecular weight polypropylene resin having a melt flow index was used to manufacture the multi-layer separator described in U.S. Patent No. 8,486,556.

[0007] Wet-laid microporous battery separator membranes have also been described, typically uniaxially or biaxially stretched and having balanced MD and TD strength properties. Examples of microporous membranes made using wet-laid processes are described in U.S. Patent Nos. 6,666,969; 5,051,183; 6,096,213; and 6,153,133.

[0008] Various known methods for producing microporous multilayer membranes, such as for use as battery separator membranes, include laminating or gluing two or more monolayer precursors together, or coextruding two or more membrane layers simultaneously using a coextrusion die. The above-mentioned methods may not fully optimize the balance of strength and / or performance properties for reuse in applications such as certain primary and / or secondary batteries, such as lithium ion rechargeable batteries. Summary of the Invention [Problem to be solved by the invention]

[0009] Thus, there is a need for new or improved coextruded or laminated multi-layer microporous membranes, base films or battery separators that have various improvements such as improved tensile strength and improved dielectric breakdown strength.

[0010] According to at least selected embodiments, the present application or invention may address the above needs or problems and may address the need for new or improved coextruded or laminated, multi-layer porous, macroporous, mesoporous, microporous or nanoporous membranes, base films, or battery separators having various improvements such as improved tensile strength and improved dielectric breakdown strength, and / or may provide new or improved coextruded and / or laminated multi-layer, and / or multi-microlayer (or multi-nanolayer), microporous membranes, base films, or battery separators having various improvements such as perhaps and preferably improved shutdown, mechanical strength, porosity, air permeability, cracking (reduced cracking), tensile strength, oxidation resistance, adhesion, wettability, and / or dielectric breakdown strength, and / or new or improved membrane layers, membranes or separator membranes, battery separators including such membranes, and / or related methods. [Means for solving the problem]

[0011] According to at least selected embodiments, the disclosure or invention relates to novel or improved porous or separator membranes, battery separators including such membranes, and / or related methods. According to at least certain embodiments, the disclosure or invention relates to novel or improved microporous or separator membranes, microlayer membranes, multilayer membranes including one or more microlayer membranes, battery separators including such membranes, and / or related methods. According to at least certain selected embodiments, the disclosure or invention relates to separator membranes, microlayer membranes, multilayer microporous membranes, or novel, optimized, or improved microporous or separator membranes having one or more novel or improved outer and / or inner layers, some of which are formed by coextrusion, and all of which are laminated together to form the novel, optimized, or improved membrane or separator membrane. In some embodiments, a layer comprises a homopolymer, a copolymer, and / or a polymer blend.

[0012] The invention also relates to methods of making such membranes, separator membranes or separators, and / or methods of using such membranes, separator membranes or separators, for example, as lithium battery separators. , new or improved multilayer and / or microlayer porous or microporous membranes, separator membranes, separators, composites, electrochemical devices, batteries, methods of making such membranes, composites, devices and / or batteries. According to at least certain selected embodiments, the present invention relates to new and improved separator membranes that are multilayer, where one or more layers of the multilayer structure are produced in a coextrusion die having one or more extruders (typically one extruder per layer or microlayer) feeding the multilayer or microlayer die. The improved membranes, separator membranes and / or separators may preferably exhibit improved shutdown, improved strength, improved dielectric breakdown strength, and / or reduced propensity to crack.

[0013] According to at least certain embodiments, the present application or invention may address the above needs or problems and / or provide new or improved porous membranes or substrates, separator membranes, separators, composites, electrochemical devices, batteries, methods of making such membranes or substrates, separators, and / or batteries, and / or methods of using such membranes or substrates, separators, and / or batteries. According to at least certain embodiments, the present battery separators may include one or more coextruded multilayer membranes of similar and / or distinct polymers or copolymers laminated or adhered to another membrane.

[0014] For example, and not by way of limitation, in certain embodiments, an inventive battery separator may comprise at least two coextruded multi-layer films of similar and / or distinct polymers or copolymers laminated or adhered to each other or to another polymer film (single or multi-layer films of similar and / or distinct polymers or copolymers).

[0015] For example, a battery separator in one embodiment can include, but is not limited to, a polyethylene / polyethylene / polyethylene (PE / PE / PE) coextruded trilayer laminated to a polypropylene (PP) monolayer, and in some embodiments, laminated to another PE / PE / PE coextruded trilayer to form the following structures: [PE / PE / PE] / PP / [PE / PE / PE] or [PE / PE / PE] / PP or PP / [PE / PE / PE] / PP or [PE / PE / PE] / PP / PP or [PE / PE / PE] / [PE / PE / PE] / PP, or other multilayer structures, with each of the individual coextruded polymer layers preferably being μm or nanometers (nm) in thickness (microlayer or nanolayer).

[0016] In other embodiments, the PE / PE / PE coextruded trilayer is laminated to a coextruded PP / PP / PP trilayer, and in some embodiments, to another PE / PE / PE or PP / PP / PP coextruded trilayer to form the following structures: [PE / PE / PE] / [PP / PP / PP] / [PE / PE / PE] or [PP / PP / PP] / [PE / PE / PE] / [PP / PP / PP] or [PE / PE / PE] / [PP / PP / PP] or [PE / PE / PE] / [PE / PE / PE] / [PE / PP / PP / PP] or [PE / PE / PE] / [PE / PE / PE] / [PP / PP / PP] or [PE / PE / PE] / [PP / PP / PP] / [PP / PP / PP] or other multilayer structures, with each of the individual coextruded polymer layers preferably being μm or nanometers (nm) in thickness (microlayer or nanolayer).

[0017] In yet another embodiment, the PP / PE / PP or PP / PP / PP or PE / PE / PE or PE / PP / PE or PP / PP / PE or PE / PE / PP coextruded trilayer film may be laminated to a coextruded PP / PP / PP or PE / PE / PE or PP / PE / PP or PE / PP / PP or PP / PP / PE or PE / PE / PP trilayer film, which in some embodiments is further laminated to another PP / PP / PP or PE / PE / PE or PP / PE / PP or PP / PP / PP or PE / PP / PE or PP / PP / PE or PE / PE / PP coextruded trilayer film having the following structure: [PP / PE / PP] / [PP / PP / PP] / [PE / PE / PE] or [PP / PE / PP] / [PE / PE / PE] / [PP / PP / PP] or [PP / PP / PP] / [PE / PE / PE] / [PP / PP / PP] or [PP / PE / PP] / [PP / PE / PP] / [PP / PE / PP] or [PE / PE / PE] / [PE / PE / PE] / [PE / PE / PE] or [PE / PE / PE ] / [PE / PE / PE] or [PE / PE / PE] / [PP / PP / PP] or [PP / PP / PP] / [PP / PP / PP] or [PP / PP / PP] / [PP / PP / PP] / [PP / PP / PP] or [PE / PE / PE] / [PE / PE / PE] / [PP / PP / PP] or [PP / PP / PP] / [PP / PP / PP] / [PE / PE / PE] or [PE / PE / PP] / [PP / PP / PP] or [PP / PP / PP] / [PP / PP / PE] or [PE / PP / PP] / [PP / PP / PP] / [PP / PP / PE] or [PE / PE / PP] / [PP / PE / PE] or [PP / PP / PP] / [PP / PP / PP] / [PP / PE / PE] or other combinations or multi-layer structures, each of the individual coextruded polymer layers preferably being μm or nanometers (nm) in thickness (microlayer or nanolayer).

[0018] In yet another embodiment, other coextruded trilayer films of PP / PE / PP, PP / PP / PP or PE / PE / PE or PE / PP / PE or PE / PP / PP or PE / PE / PP or PP+PE / PP / PP or PP+PE / PP / PP+PE or PP+PE / PP / PP+PE or PP+PE / PP / PE or PP+PE / PP / PE or PP+PE / PP / PE or PP, PE or PP+PE are PP / PE / PP or PP / PP / PP or PP / PE / PP or PE / PP / PE or PE / PP / PP or PE+PE / PP / PP or PP+PE or PP / PP+PE or PP+PE / PP+PE / PP+PE or PP+PE / PE / PE or PP+PE / PP / PE or PP+PE / PE / PP or PP+PE / PE / PP or other tri-layer films of PP, PE, or PP+PE, and in some embodiments may be further laminated to another PP / PE / PP or PP / PP / PP or PE / PE / PE or PE / PP / PE or PE / PP / PP or PE / PP / PP or PE+PE / PP / PP or PP+PE / PP / PP or PP+PE / PP / PP+PE or PP+PE / PP / PP+PE or PP+PE / PP / PP+PE or PP+PE / PP / PE or PP+PE / PP / PE or other co-extruded tri-layer films of PP, PE, or PP+PE, having the following structure: PP / PE / PP] / [PP / PP / PP] / [PE / PE / PE]または[PP / PP / PP] / [PE / PE / PE]または[PP / PE / PP] / [PP / PE / PP]またたPE / PE / PE] / [PE / PE / PE]または[PE / PE / PE] / [PP / PP / PP]または[PP / PP / PP] / [PP / PP / PP]または[PP / PP / PP] / [PP / PP / PP] / [PP / PP / PP]または[PE / PE / PP] E] / [PE / PE / PE] / [PP / PP / PP]または[PP / PP / PP] / [PP / PP / PP] / [PE / PE / PE]または[PP / PE / PE] / [PE / PE / PE]または[PP / PP / PE] / [PE / PE / P E]または[PE / PP / PP] / [PP / PP / PE]または[PP+PE / PP / PP] / [PP / PP / PP+PE]または[PP / PE / PP] / [PP / PP / PP] / [PE / PE / PE] [PE / PE / PE] / [PP / PP / PP] / [PE / PE / PE] / [PP / PP / PP]または[PP / PE / PP] / [PP / PE / PP] / [PP / PE / PP]または[PE / PE / PE] / [PE / PE / PE] / [PE / PE / PE] / [PE / PE / PE]または[PP / PP / PP] / [PP / PP / PP] / [PP / PP / PP]または[PE / PE / PE] / [PE / PE / PE] / [PP / PP / PP]または[PP / PP / PP] / [PP / PP / PP] / [PE / PE / PE]または[PP / PE / PE] / [PE / PE / PE] / [PE / PE / PP]または[PP / PP / PE] / [PE / PE / PE] / [PE / PP / PP]または[PE / PP / PP] / [PP / PP / PP] / [PP / PP / PE]または[PP+PE / PP / PP] / [PP / PP / PP] / [PP / PP / PP+PE]または[PP / PE / PP] / [PP / P coextruded polymer layers may be formed in a variety of combinations or subcombinations (blends, mixtures or copolymers) of PP, PE, or PP+PE layers, microlayers, nanolayers, or combinations thereof, or other multilayer structures, with each of the individual coextruded polymer layers preferably being in the range of μm or nanometers (nm) in thickness (microlayers or nanolayers).

[0019] While certain multi-layer polymeric film embodiments (bi-layer, tri-layer, quadruple layer, penta-layer, etc.) are preferred, (and one or more layers, treatments, materials, or coatings (CT), and / or nets, meshes, mats, wovens, or nonwovens (NW) may be added to both sides, or within the multi-layer film, which may include one or more coextruded layers or sub-layers (CX), such as, but not limited to, CT / M, NW / M, CT / M / CX, CT1 / M / CT2, CT / CX1 / CX2 / NW, CT1 / CX1 / CX2 / CX3 / CT2, CT / CX1 / CX2, CX1 / CX2, CX1 / CX2, NW1 / CX1 / CX2 / CX3 / NW2, CT / and / or combinations or subcombinations of NW / CX1 / CX2, CX1 / NW / CX2, CX1 / CT / CX2, and / or M, CX, CT, and / or NW) that comprise a single layer or monolayer or multilayer film (M) or embodiment (and one or more coatings (CT) and / or nonwovens (NW) consisting of one or more micro- or nanolayers of PP, PE, or PE+PP (preferably more than one), including, but not limited to, CT / M, NW / M, CT / M / CX, CT / CX / NW, CT1 / CX / CT2, NX1 / CX / NW2, CT / CX / NW / CT, NW1 / CX / NW2 / CT,CT1 / NW / CX / CT2, and / or combinations or subcombinations of M, CX, CT and / or N are expected to be added to one or both sides of the film (M or CX), and one or more other films (extruded or co-extruded) PP or PE or PE+PP or PP / PE or PP / PP or PE / PE or PP+PE / PP or PP+PE / PP+PE or PP+PE / PP or PP / PE / PP or PP / PP / PP or PE / PE / PE or PE / PP / PP or PE / PP / PP or PE / PP / PP or PE / PP / PP or PE+PE / PP / PP or PP+PE / PP / PP or PP+PE / PP / PP+PE or PP+PE / PP+PE / PP+PE Or PP+PE / PE / PE or PP+PE / PP / PE or PP+PE / PP / PP or PP+PE / PP+PE or PP+PE / PP or PP / PE / PP or PP / PE / PP or PP / PE / PP or PE / PE / PE or PE / PP / PP or PE / PE / PE or PE / PP / PP or PE / PP / PP or PE / PE / PP or PE / PP / PP or PE / PP / PP or PP+ ...PE / PP / PP or PP+PE / PE / PP / PP or PP+PE / PE / PP / PP or PP+PE / PE / PP / PP or PP+PE / PE / PP / PP or PP+PE / PE / PP / PP.

[0020] It is in some embodiments laminated to yet another PP or PE or PE+PP or PP / PE or PP / PP or PE / PE or PP+PE / PP or PP+PE / PP+PE or PP+PE / PP or PP / PE / PP or PP / PP / PP or PE / PE / PE or PE / PP / PP or PE / PP / PP or PE / PP / PP or PE / PP / PP or PE / PP / PP or PP+PE / PP / PP or PP+PE / PP / PP or PP+PE / PP / PP+PE or PP+PE / PP / PP+PE or PP+PE / PP / PP or PP+PE / PP / PP or PP+PE / PE / PP / PP film(s) to give the following structure: PP or PE or PE+PP or PP / PE or PP / PP or PP / PE or PP / PE or PP+PE / PP or PP+PE / PP or PP+PE / PP+PE or PP+PE / PP+PE or PP+PE / PP / PP or PP+PE / PE / PP film(s) PE / PP] / [PP / PP / PP]または[PP / PE / PP] / [PE / PE / PE]または[PP / PP / PP] / [PE / PE / PE]または[PP / PE / PP] / [PP / PE / PP] ]または[PE / PE / PE] / [PE / PE / PE]または[PE / PE / PE] / [PP / PP / PP]または[PP / PP / PP] / [PP / PP / PP]または[PP / PP / PP] / [ PP / PP / PP] / [PP / PP / PP]または[PE / PE / PE] / [PE / PE / PE] / [PP / PP / PP]または[PP / PP / PP] / [PP / PP / PP] / [PE / PE / P E]または[PP / PE / PE] / [PE / PE / PE]または[PP / PP / PE] / [PE / PE / PE]または[PE / PP / PP] / [PP / PP / PE]または[PP+PE / PP / P P] / [PP / PP / PP+PE]ま[PP / PE / PP] / [PP / PP / PP] / [PE / PE / PE]または[PP / PE / PP] / [PE / PE / PE] / [PP / PP / PP]または[ PP / PP / PP] / [PE / PE / PE] / [PP / PP / PP]または[PP / PE / PP] / [PP / PE / PP] / [PP / PE / PP]または[PE / PE / PE] / [PE / PE / P E] / [PE / PE / PE]または[PE / PE / PE] / [PE / PE / PE]または[PP / PP / PP] / [PP / PP / PP] / [PP / PP / PP]または[PE / PE / PE] / [P E / PE / PE] / [PP / PP / PP]または[PP / PP / PP] / [PP / PP / PP] / [PE / PE / PE]または[PP / PE / PE] / [PE / PE / PE] / [PE / PE / PP][PP / PP / PE] / [PE / PE / PE] / [PE / PP / PP] or [PE / PP / PP] / [PP / PP / PP] / [PP / PP / PE] or [PP+PE / PP / PP] / [PP / PP / PP] / [PP / PP / PP+PE] or [PP / PE / PP] / [PP / PE / PE] or [PE / PP / PE] / [PE / PP / PP] or [PE / PE / PP] / [PP / PE / PE] or [PP+PE / PP / PP] / [PP / PP / PP+PE] or [PP+PE / PP / PP+PE] / [PP+P [PP+PE / PP+PE] or [PP+PE / PE / PE] / [PP+PE / PP / PE] or [PP+PE / PE / PE] / [PP+PE / PP / PE] / [PP+PE / PE / PP] or other such combinations of PP, PE, or PP+PE (blend, mixture or copolymer) layers, or subcombinations, microlayers, nanolayers, combinations thereof, or other layered structures, with each of the individual coextruded polymer layers preferably being μm or nanometers (nm) in thickness (microlayer or nanolayer).

[0021] Each of the micro- or nano-layers may preferably be a polyolefin (PO) such as PP or PE or PE+PP blends, mixtures, copolymers, etc., although other polymers (PY), additives, materials, fillers, and / or particles (M), and / or the like may be added or used to form layers, micro-layers, nano-layers, or films such as PP+PY, PE+PY, PP+M, PE+M, PP+PE+PY, PE+PP+M, PP+PY+M, PE+PY+M, PP+PE+PY+M, or blends, mixtures, copolymers and / or the like thereof, and it is expected that such layers or films may be used in combination with one or more PP or PE or PE+PP layers or films.

[0022] Also, layers, microlayers, nanolayers or membranes of the same, similar, separate or different PP or PE or PE+PP polymers, homopolymers, copolymers, molecular weights, blends, mixtures, copolymers, etc., may be used in many different combinations and subcombinations to form layers, sublayers, membranes or submembranes. For example, the same, similar, separate or different molecular weight PP, PE and / or PP+PE polymers, homopolymers, copolymers, multipolymers, blends, mixtures and / or the like may be used in each layer or membrane or each individual layer, microlayer, nanolayer or membrane.

[0023] Thus, the structures are PP, PE, PP+PE, PP1, PP2, PP3, PE1, P The various combinations, subcombinations of E2, PE3, PP1+PP2, PE1+PE2, PP1+PP2+PP3, PE1+PE2+PE3, PP1+PP2+PE, PP+PE1+PE2, PP1 / PP2, PP1 / PP2 / PP1, PE1 / PE2 PE1 / PE2 / PP1, PE1 / PE2 / PE3, PP1+PE / PP2, or other combinations or structures may be included. For example, the properties of the membranes or separators of the present invention may be improved, modified or optimized by tailoring the outer layer or membrane surface, for example, by using specific polymers, blends, molecular weight polymers, etc., only in the outer layer or membrane surface.

[0024] As non-limiting examples, an outer PE or PP+PE surface or layer may have improved pin removal (lower COF), a high molecular weight (MW) polymer surface or layer (PP or PE) may have improved puncture strength, a PP or PP+PE surface or layer may have improved oxidation resistance, expensive raw materials (expensive polymers) may be used in limited layers to reduce costs, etc. Additionally, while each of the layers or micro- or nano-layers may preferably be polyolefins (PO) such as PP or PE or PE+PP blends, mixtures, copolymers or the like, it is expected that other polymers (PY), additives, drugs, materials, fillers and / or particles (M), etc. may be added or used, and may be used in combination with one or more PP or PE or PE+PP layers or membranes to form layers, micro-layers, nano-layers, or membranes, such as different outer or surface layers, which may have added coatings (CT) or nonwovens (NW).

[0025] The production of single or multi-layer porous, microporous, or nanoporous membranes according to various inventive embodiments herein may enable improved properties such as improved shutdown, mechanical strength, porosity, air permeability, oxidation resistance, pin removal, wettability, and / or cracking (reduced cracking).

[0026] In one embodiment of the invention, the multilayer film can be extruded in the form of PE homopolymer / PE homopolymer or PP homopolymer / PP homopolymer, or one or more layers of such a multilayer film can comprise a blend of two polymers, such as a PE(s) / homopolymer PE blend.

[0027] The microlayer membrane precursors may be bonded together by lamination or adhesion. The possibly preferred battery separators described herein have a total thickness of less than about 30 μm, less than about 25 μm, less than about 20 μm, less than about 16 μm, less than about 15 μm, less than about 14 μm, or less than about 10 μm. 0 μm, less than about 9 μm, less than about 8 μm, or less than about 6 μm (depending on the number of layers), and may exhibit surprisingly increased strength performance as defined by reduced cracking or reduced tendency to crack compared to known battery separators of the same (or greater) thickness, particularly when compared to known dry battery separators of the same (or greater) thickness.

[0028] The improvement in cracking or crack resistance can be quantified by the test method disclosed herein as Composite Crack Index (CSI), and the new or improved separators described herein can have an improvement in CSI, and may exhibit other improvements as well, such as improved Gurley, improved puncture strength, etc.

[0029] In at least one embodiment, the membranes of the present invention can be constructed from many microlayers or nanolayers, where the final product can include 50 or more individual microlayer or nanolayer layers. In at least certain embodiments, the microlayer or nanolayer technology can be created by a pre-encapsulation feedblock prior to entering the cast film or blown film die.

[0030] In at least selected embodiments, the microlayer or nanolayer membranes include three or more layers of individual coextruded microlayers or nanolayers and can have improved strength, improved cycling, greater flexure, and favorable compression resistance and / or recovery.

[0031] In at least selected embodiments, the microlayer or nanolayer membranes include three or more layers of individual coextruded microlayers or nanolayers and may have improved strength, improved cycling, greater flexure, and / or favorable compression resistance and / or recovery.

[0032] In at least selected embodiments, the microlayer or nanolayer membrane may include nine or more layers of individual coextruded microlayers or nanolayers and may have improved strength, improved cycling, greater flexure, and / or favorable compression resistance and / or recovery.

[0033] In at least selected embodiments, the microlayer or nanolayer membrane may include five or more layers of individual coextruded microlayers or nanolayers and may have improved strength, improved cycling, greater flexure, and / or favorable compression resistance and / or recovery.

[0034] In at least certain select embodiments, the microlayer membranes include three or more layers of individual coextruded microlayers or nanolayers and may have improved strength, improved cycling, greater flexure, and / or favorable compression resistance and / or recovery.

[0035] In at least certain select embodiments, the multilayer film may include two or more layers of individual coextruded microlayers laminated together and may have improved strength, improved cycling, greater flex and / or favorable compression resistance and / or recovery.

[0036] In at least certain select embodiments, the multilayer film may include three or more layers of individual coextruded microlayers laminated together and may have improved strength, improved cycling, greater flex and / or favorable compression resistance and / or recovery. [Brief description of the drawings]

[0037] [Figure 1] FIG. 1 is a partial cross-sectional scanning electron micrograph at 2,500x magnification of an exemplary laminated trilayer or triple trilayer microporous membrane of the invention trilayer / trilayer / trilayer (having nine coextruded microlayers per trilayer layer, and three microlayers per each PP or PE sublayer of each trilayer layer) (at least the outer PP layer of each layer is microporous). [Diagram 2]FIG. 2 is a partial cross-sectional scanning electron micrograph (SEM) at 15,000 times magnification of a portion of the polypropylene surface sublayer (three microlayers of PP) of the surface tri-layer component or submembrane of the composite laminate membrane of FIG. [Diagram 3] FIG. 3 is a partial cross-sectional scanning electron micrograph (SEM) at 15,000x magnification of one polyethylene sublayer (three microlayers of PE) of the nine microlayer trilayer of the three-layer membrane of FIG. [Figure 4] FIG. 4 is a graph illustrating the improved cycling behavior of an exemplary inventive structure compared to EH1211. [Diagram 5] FIG. 5 is a graph illustrating the compressive elasticity results of certain constructions compared to EH1211. [Figure 6] FIG. 6 is a graph illustrating Mix P penetration test results of certain structures in comparison with EH1211. [Figure 7] FIG. 7 is a schematic diagram illustrating how microlayers can be built in a feedblock by layer augmentation. [Figure 8] FIG. 8 is a schematic diagram showing how the microlayers are created by delamination. [Figure 9] FIG. 9 is a cross-sectional scanning electron micrograph (SEM) at 5000x magnification of an exemplary inventive trilayer or trilayer (9 microlayers total with three triple microlayer sublayers laminated together) of a PP / PE / PP microporous membrane (at least the outer PP sublayer is microporous). [Figure 10] Figure 10 is a surface scanning electron micrograph (SEM) at 3,000x magnification of the surface of the polypropylene surface sub-layer (surface PP microlayer) of the nine microlayer, three-layer membrane of Figure 9. This nine microlayer membrane could be used as one layer of a three-layer membrane as shown in Figure 1. [Figure 11] FIG. 11 is a surface scanning electron micrograph (SEM) at 10,000× magnification of a portion of the surface of the polypropylene surface sub-layer (surface PP microlayer) of the nine microlayer layer, three-layer membrane of FIG. [Figure 12]FIG. 12 is a surface scanning electron micrograph (SEM) at 30,000 times magnification of a portion of the surface of the polypropylene surface sub-layer (surface PP microlayer) of the nine microlayer, three-layer membrane of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] In accordance with at least selected embodiments, aspects or objectives, the present application or invention may address the above needs or problems and / or may provide new or improved membrane layers, porous membranes or substrates, separator membranes, separators, composites, electrochemical devices, batteries, methods of making such membranes or substrates, separators and / or batteries, and / or methods of using such membranes or substrates, separators and / or batteries.

[0039] According to at least certain embodiments, the battery separator comprises one or more coextruded microlayers or microlayer films laminated or adhered to another polymer film. For example, in some examples, the battery separator can comprise, but is not limited to, a polyethylene / polyethylene / polyethylene (PE / PE / PE) coextruded micro trilayer film laminated to a polypropylene (PP) monolayer micro or nanolayer film, and in some embodiments, further laminated to another PE / PE / PE coextruded micro trilayer film, forming the following structure: [PE / PE / PE] / PP / [PE / PE / PE].

[0040] In selected embodiments, a membrane, membrane precursor, submembrane, layer, or sublayer may be composed of one or more microlayers. A microlayer is defined herein as a layer or individual layer, e.g., of a polymer or copolymer blend, preferably less than about 5 μm, more preferably less than about 4 μm, even more preferably less than about 3 μm, and perhaps most preferably less than about 2 μm. In selected embodiments, a membrane, membrane precursor, submembrane, layer, or sublayer may be composed of one or more nanolayers. A nanolayer is defined herein as a layer or individual layer, e.g., of a polymer or copolymer blend, preferably less than about 1 μm, more preferably less than about 0.5 μm, even more preferably less than about 0.3 μm, and perhaps most preferably less than about 0.2 μm.

[0041] A novel microporous battery separator has been developed for use in lithium ion secondary batteries. In some embodiments, the possibly preferred inventive separator film, separator, base film, or membrane may comprise a polyethylene / polyethylene / polyethylene (PE / PE / PE) co-extruded microlayer (PE microtrilayer) membrane, which is laminated to another membrane, such as a polypropylene (PP) monolayer membrane, and optionally further laminated to another PE / PE / PE co-extruded membrane, forming the following structure: [PE / PE / PE] / PP / [PE / PE / PE].

[0042] A possibly preferred separator, membrane or base film thickness may range from 5 μm to 30 μm. FIG. 1 shows a nine microlayer coextrusion structure for each of the three layers of the membrane (the three layers are laminated together to form the membrane). Each of the nine microlayer polymer sublayers has In the coextrusion process, there are three microlayers that create a PP or PE sublayer. Figures 2 and 3 show close-up views of the three layers highlighting the continuity between each of the microlayers in each layer. Figure 3 shows the continuity between the polypropylene and polyethylene microlayers. The microlayers in at least each of the nine microlayer coextrusion layers in Figures 1-3 have undefined adjacent microlayer interfaces, and this seamless interface between the microlayers may contribute to improved cycling, increased surface area, and higher flexurality. EXAMPLES

[0043] In the examples, various membranes were prepared with the structure [PE / PE / PE] / PP / [PE / PE / PE], and their properties are shown in Table 1 immediately below. Various membranes produced as examples of the present invention, Example 1, Example 2, and Example 3, show improved puncture strength and dielectric breakdown (DB) over the control Comparative Example 1 (as shown in Table 1 below).

[0044] [Table 1]

[0045] In accordance with at least certain embodiments, the present invention relates to a multi-layer battery separator or separator film, the exterior surface of which in some instances comprises multiple coextruded layers, such as a polyethylene (PE) homopolymer coextruded multi-layer film, which is adhered or laminated to an additional multi-layer coextruded multi-layer film comprising a polypropylene monolayer and a polyethylene homopolymer.

[0046] In accordance with at least certain embodiments, the present invention relates to multi-layer battery separators or separator membranes, and performance may be further improved, optimized, selected, controlled, etc.

[0047] In accordance with at least certain embodiments, the present invention relates to a multi-layer battery separator or separator membrane, the exterior surface of which includes a plurality of layers, one or more of which contain a polyethylene (PE) blend and / or PE copolymer, which is adhered or laminated to a polypropylene monolayer and an additional multi-layer coextruded multilayer membrane, one or more of which contain a polyethylene blend and / or PE copolymer.

[0048] In accordance with at least certain embodiments, the present invention provides a multi-layer battery separator or separator. Regarding the membrane, the outer surface of which comprises multiple layers, one or more of which contain polyethylene (PE) homopolymer while one or more of which contain polyethylene blends and / or PE copolymers, which is adhered or laminated to a polypropylene monolayer and an additional multilayer coextruded membrane, one or more of which contain polyethylene homopolymer while one or more of which contain polyethylene blends and / or copolymer blends.

[0049] Other possibilities for such structures are also encompassed by the present invention, where at least one coextruded multilayer film is laminated to at least one other film to form a multilayer structure combining a side of the coextruded film with a side of the laminated film.

[0050] The multi-layer polyolefin film is designed to provide an exterior surface with low pin removal force, faster wetting, good coating adhesion, tunable shutdown, etc. Each layer of polymer is laminated or coextruded with the resulting film having significant improvements in many properties. The invention described herein utilizes both coextrusion and lamination of one or more multi-layer films to improve surface properties. According to at least certain embodiments, the invention can provide an exterior surface with improved shutdown function, improved longitudinal strength, and increased dielectric breakdown.

[0051] The polymers or copolymers that may be used in the battery separator of the present invention are extrudable polymers or copolymers. Such polymers are typically referred to as thermoplastic polymers. Exemplary thermoplastic polymers, blends, mixtures or copolymers include, but are not limited to, polyolefins, polyacetals (or polyoxymethylenes), polyamides, polyesters, polysulfides, polyvinyl alcohols, polyvinyl esters, and polyvinylidenes (and may include PVDF, PVDF:HFP, PTFE, PEO, PVA, PAN, etc.). Polyolefins include, but are not limited to, polyethylenes (including, for example, LDPE, LLDPE, HDPE, UHDPE, UHMWPE, etc.), polypropylenes, polybutylenes, polymethylpentenes, copolymers thereof, and blends thereof. Polyamides (nylons) include, but are not limited to, polyamide 6, polyamide 66, nylon 10,10, polyphthalamide (PPA), copolymers thereof, and blends thereof. Polyesters include, but are not limited to, polyester terephthalate, polybutyl terephthalate, copolymers thereof, and blends thereof.

[0052] Polysulfides include, but are not limited to, polyphenylsulfides, copolymers thereof, and blends thereof. Polyvinyl alcohols include, but are not limited to, ethylene-vinyl alcohol, copolymers thereof, and blends thereof. Polyvinyl esters include, but are not limited to, polyvinyl acetate, ethylene vinyl acetate, copolymers thereof, and blends thereof. Polyvinylidenes include, but are not limited to, polyvinylidene fluorides (e.g., polyvinylidene chloride, polyvinylidene fluoride), copolymers thereof, and blends thereof. Various materials can be added to the polymer. These materials are added to modify or enhance the performance or properties of individual layers or the separator as a whole. Such materials can include, but are not limited to, materials that lower the melting temperature of the polymer. Typically, multi-layer separators contain layers designed to close their pores at a given temperature to block ion flow between the electrodes of the battery. This function is commonly referred to as shutdown.

[0053] Figure 4 shows the cycling performance of the microlayer membranes compared to EH1211. In each sample, the microlayer structure showed either maintenance or improvement in cycling performance.

[0054] In at least selected embodiments, the microlayer or nanolayer may contain various additives in one or more layers, for example to reduce pin removal force, without affecting the adhesion between PP and PE in micro trilayer applications. In certain cases, additives may be applied to the outer microlayer. The outer microlayer may contain or consist of PP with siloxane additive / homopolymer PP / homopolymer PP. Additives may contain anything that may affect the surface properties of the film, some examples include PE, calcium stearate, lithium stearate and / or siloxane.

[0055] In accordance with at least selected embodiments, aspects or objectives, the present application or invention relates to battery separators, or separator membranes, including one or more coextruded multilayer films laminated or adhered to another polymeric film and / or to another coextruded multilayer film, and / or may provide improved strength, e.g., improved puncture strength, especially at a particular thickness, and / or such separators may exhibit improved shutdown and / or reduced propensity to crack.

[0056] In accordance with at least certain embodiments, aspects or objectives, the present application or invention relates to battery separators or separator membranes comprising one or more coextruded multilayer microlayer and / or nanolayer membranes, and / or such separators may exhibit improved strength, e.g., improved puncture strength, particularly at a particular thickness, and / or improved shutdown and / or reduced tendency to crack.

[0057] In accordance with at least certain embodiments, aspects or objectives, the present application or invention relates to a battery separator or separator membrane comprising one or more coextruded multilayer microlayer and / or nanolayer membranes that are coextruded and laminated or adhered to another polymeric membrane and / or another coextruded multilayer membrane, and / or such separators may exhibit improved strength, e.g., improved puncture strength, particularly at a particular thickness, and / or improved shutdown and / or reduced tendency to crack.

[0058] Table 2 shows a comparison of the 9 microlayer 12 μm membrane with a more conventionally constructed 12 μm trilayer membrane (EH1211). When compared to the conventional trilayer, the microlayer 12 μm membrane of the present invention showed increased mechanical strength and a significant reduction in shrinkage. Figure 6 shows Mix P or mix penetration test results for the 9 microlayer 12 μm microporous membrane. The microlayer membrane of the present invention showed the greatest penetration resistance at a force of 650 N.

[0059] [Table 2]

[0060] Table 3 shows a comparison of the nine microlayer 12 μm membrane (R0384) with a conventional 12 μm dry process membrane (EH1211). The microlayer structure provides greater compression recovery than a comparable wet process membrane. In certain applications, less shatter and / or better compression recovery may be desired.

[0061] [Table 3]

[0062] Figure 5 and Table 3 show the compression profiles of various porous membranes. Compared to other 12 μm membranes, the microlayer structure shows a balanced compression recovery profile, while being able to compress, but provide significant recovery in certain battery applications. In selected embodiments, the microlayer or nanolayer technology may consist of more than 50 layers.

[0063] These layers may be created in a pre-encapsulated feedblock prior to first entering either a cast film die or a blown film die. Microlayers may be created in the feedblock by layer accretion (an example in FIG. 7) or layer splitting (an example in FIG. 8). When used to produce porous membrane precursors, these techniques can further improve strength and flex crack resistance. These precursors can be laminated, annealed, and stretched, and the resulting membranes can show improved strength and toughness. Furthermore, by utilizing these techniques, the need to use polymers with molecular weights greater than 1M, which can be very difficult to process, can be reduced, especially in dry-process membranes.

[0064] In other selected specific embodiments, the microlayers can be used to produce modified trilayer membranes. In this embodiment, the microlayers include or consist of alternating polymers, and the resulting membrane is PP / PE / PP / PE / PP / PE / PP / PE / PP. Precursor membranes can be extruded with microlayers of PP / PE / PP and PE / PP / PE, and these microlayer precursors can then be laminated together and then stretched to achieve the desired porosity. The polypropylene can be any homopolymer PP, copolymer PP and / or polymer blend. The polyethylene used can be high density polyethylene (HDPE) or any polyethylene, copolymer and / or polymer blend with comonomers.

[0065] [Table 4]

[0066] Additionally, certain inventive microlayer or nanolayer structures may create greater surface area. Cross-sectional SEMs of Figures 1-3 may show columns, pillars, columnar, column-like, columned or substantially vertical crystalline polymer structures. These columns or pillars of crystalline polymer may provide added strength, improved DB, etc.

[0067] In accordance with at least selected embodiments, aspects or objects, the present application or invention provides According to at least selected embodiments, the present disclosure or invention relates to new or improved porous membranes or separator membranes, battery separators including such membranes, and / or related methods.

[0068] According to at least some embodiments, the disclosure or invention relates to new or improved microporous or separator membranes, microlayer membranes, multilayer membranes containing one or more microlayer membranes, battery separators including such membranes, and / or related methods. According to at least certain selected embodiments, the disclosure or invention relates to new, optimized or improved microporous or separator membranes having one or more new or improved outer and / or inner layers, microlayer membranes, multilayer microporous membranes, or separator membranes having outer and inner layers, where some layers are formed by coextrusion and all of the layers are laminated together to form the new, optimized or improved membrane or separator membrane.

[0069] In some embodiments, certain layers include homopolymers, copolymers, and / or polymer blends. The invention relates to methods of making such membranes, separator membranes, or separators, and / or methods of using such membranes, separator membranes, or separators, for example, as lithium battery separators. According to at least selected embodiments, the present application or invention relates to new or improved multilayer and / or microlayer porous or microporous membranes, separator membranes, separators, composites, electrochemical devices, batteries, methods of making such membranes, separators, composites, devices, and / or batteries. According to at least certain selected embodiments, the invention relates to new and improved separator membranes that are multilayered, where one or more layers of the multilayer structure are made in a multilayer or microlayer coextrusion die with one or more extruders feeding the die (typically one extruder per layer or microlayer). The improved membranes, separator membranes, and / or separators may preferably exhibit improved shutdown, improved strength, improved dielectric breakdown strength, and / or reduced cracking tendency.

[0070] The present disclosure or invention may relate to a novel or improved membrane or separator membrane, a battery separator including such membrane, and / or related methods. According to at least selected embodiments, the present disclosure or invention relates to a novel or improved porous membrane or separator membrane, a battery separator including such membrane, and / or related methods. According to at least certain embodiments, the present disclosure or invention relates to a novel or improved microporous membrane or separator membrane, a microlayer membrane, a multilayer membrane containing one or more microlayer membranes, a battery separator including such membrane, and / or related methods. According to at least one selected embodiment, the present disclosure or invention relates to a novel, optimized or improved separator membrane having one or more novel or improved microporous membranes, or an outer layer and / or an inner layer, a microlayer membrane, a multilayer microporous membrane, or a separator membrane having an outer layer and an inner layer, some of which layers are produced by coextrusion, and all of which layers are laminated together to form the novel, optimized or improved membrane or separator membrane. In some embodiments, a particular layer comprises a homopolymer, a copolymer, and / or a polymer blend.

[0071] The invention also relates to methods of making such membranes, separator membranes or separators, and / or methods of using such membranes, separator membranes, or separators, for example, as lithium battery separators. According to at least selected embodiments, the present application or invention provides new or improved multi-layer and / or micro-layer porous or microporous membranes, separator membranes, separators, composites, electrochemical devices, batteries, such membranes, separators, composites, The present invention relates to methods of making materials, devices and / or batteries. In accordance with at least certain selected embodiments, the present invention relates to new or improved multi-layer separator membranes, where one or more layers of the multi-layer structure are produced in a multi-layer or micro-layer co-extrusion die having multiple extruders. The improved membranes, separator membranes or separators may preferably exhibit improved shutdown, improved strength, improved dielectric breakdown strength, and / or reduced tendency to crack.

[0072] In accordance with at least selected embodiments, the battery separator or separator film comprises one or more coextruded multi-microlayer films, optionally laminated or adhered to another polymer film. The separators described herein can provide improved strength, such as improved puncture strength, particularly at a particular thickness, and can exhibit improved shutdown and / or reduced tendency to crack.

[0073] (Test Method) (Gurley) Gurley is defined herein as the Japanese Industrial Standard (JIS Gurley) and is measured using an OHKEN air permeability tester. JIS Gurley is defined as the time in seconds required for 100 cc of air to pass through 1 square inch of film at a constant water pressure of 4.9 inches.

[0074] (Thickness) Thickness is measured in μm using an Emveco Microgage 210-A micrometer thickness tester and test procedure ASTM D374.

[0075] (Tensile strength) Machine direction (MD) and transverse direction (TD) tensile strength are measured using an Instron Model 4201 according to ASTM-882 procedure.

[0076] (stretch) % MD elongation at break is the percent of the elongation of a test sample along the machine direction of the test sample measured at the ultimate tensile strength required to break the sample. TD % Elongation at Break is the percent of the elongation of the test sample along the transverse direction of the test sample measured at the ultimate tensile strength required to break the sample.

[0077] (Puncture strength) Puncture strength is measured using an Instron Model 4442 based on ASTM D3763. Measurements are taken across the width of the microporous membrane and puncture strength is defined as the force required to puncture the test sample.

[0078] (Heat shrinkage rate) Shrinkage is measured by placing a test sample between two pieces of paper and hanging the sample in an oven with the sample sandwiched between the papers. For the "105°C 1 hour" test, the specimen is placed in a 105°C oven for one hour. After the specified heating time in the oven, each sample is removed and taped to a flat opposing surface using double-sided adhesive tape to flatten and smooth the sample for accurate length and width measurements. Shrinkage is measured in both the machine direction (MD) and transverse direction (TD) and is expressed as %MD shrinkage and %TD shrinkage.

[0079] (hole size) Pore ​​size is measured using Aquapore, available from Porous Materials, Inc. (PMI). Pore size is expressed in μm.

[0080] (porosity) The porosity of the microporous film samples was measured using ASTM method D-2873 and is defined as the percentage of voids in the microporous membrane, measured in both the machine direction (MD) and the transverse direction (TD). (Dielectric breakdown (DB)) A voltage is applied to the separator film until dielectric breakdown of the sample is observed. A strong separator exhibits a high DB. Non-uniformity in the separator film reduces the DB value.

[0081] (Compressive elastic modulus) The compressive modulus was evaluated using a TMA Q400 and a hemispherical probe. A 5 mm x 5 mm sample was subjected to a compression force of 1 N (568 N / cm 2 ) and then release the pressure back to 0 N at a constant rate at ambient temperature. The percentage of dimensional change during compression and recovery is estimated based on the initial thickness of the sample.

[0082] (Mixed invasion) Mixed penetration is the force required to short through a separator when placed between cathode and anode materials. This test is used to indicate the tendency of a separator to short during battery assembly. Details of this method are described in US2010 / 209758.

[0083] (cycling) All cycling was performed in constant current (CC) mode. The cathode used is 523NMC. The anode used is fine graphite. The electrolyte used was 1M LiPF6 salt in 3:7v:vEC:EMC solvent. The voltage window is 3.0-4.3V. Cycles 1-5 have charge and discharge rates of C / 10. Cycles 6-10 have charge and discharge rates of C / 5. Cycles 11-15 have charge rates of C / 5 and discharge rates of C / 2. Cycles 16-20 have charge rates of C / 5 and discharge rates of 1C (charge and discharge rate capacity; 1C is the rate of full charge or discharge in 60 minutes). Cycles 21-25 have charge rates of C / 5 and discharge rates of 5C. Cycles 26-30 have charge rates of C / 5 and discharge rates of 10C. Cycles 31-35 have charge and discharge rates of C / 10.

Claims

1. a dry co-stretched polyolefin microporous separator sub-membrane comprising three or more dry polymer microlayers, each microlayer having a thickness of less than 2 μm; A battery separator for a lithium battery, wherein the dry co-extended polyolefin microporous separator sub-membrane is laminated to another dry co-extended polyolefin microporous separator sub-membrane comprising a plurality of dry polymer microlayers, each microlayer having a thickness of less than 2 μm.

2. 10. The battery separator for a lithium battery according to claim 1, wherein three or more layers of said dry co-extended polyolefin microporous separator sub-membranes are laminated together.

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

4. A lithium ion battery comprising the lithium battery separator of claim 1.

5. A lithium ion secondary battery comprising the battery separator for a lithium battery according to claim 1.

6. 1. A battery separator comprising one or more dry coextruded polymeric multi-layer micromembranes, the micromembranes having a thickness of less than 2 μm, The dry coextruded polymer multi-layer microfilm having a thickness of less than 2 μm is laminated to two or more other dry coextruded polymer multi-layer microfilms having a thickness of less than 2 μm; The battery separator has at least one of the following properties: improved strength, improved shutdown, or reduced tendency to crack.

7. A separator membrane comprising one or more layers of a dry coextruded polymeric multi-layer micromembrane laminated to other dry polymeric membranes, each of which is another dry coextruded polymeric multi-layer micromembrane, The separator membrane has at least one of the following properties: improved puncture strength, improved shutdown, or reduced tendency to crack.

8. 7. A lithium ion battery comprising the battery separator of claim 6.

9. A lithium ion battery comprising the separator membrane of claim 7.

10. A multi-layer dry microporous polymeric membrane comprising one or more dry coextruded microporous multi-layer micromembranes, the micromembranes having a thickness of less than 2 μm, A multi-layer dry microporous polymer membrane laminated to two or more layers of other dry polymer membranes, each of said other dry polymer membranes being a multi-layer dry microporous polymer membrane comprising a dry coextruded microporous multi-layer micromembrane, each micromembrane having a thickness of less than 2 μm.

11. A dry, microporous polymeric membrane comprising one or more dry, coextruded, multi-layer polymeric membranes laminated to at least one other dry, coextruded, multi-microlayer polymeric membrane.

12. 11. The multi-layer dry microporous polymer membrane of claim 10, comprising a polyolefin dry microporous polymer membrane.

13. 12. The dry microporous polymer membrane of claim 11, comprising a polyolefin dry microporous polymer membrane.

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