RU2766873C1 - Improved membranes, calandrated microporous membranes, battery separators and appropriate methods - Google Patents

Abstract

FIELD: batteries.

SUBSTANCE: inventions group relates to improved microporous single- or multi-layer battery separator membranes, separators, batteries including such membranes or separators, methods for manufacturing such membranes, separators and/or batteries, and/or methods for using such membranes, separators and/or batteries. A method for manufacturing a multilayer polyethylene/polypropylene/polyethylene microporous separator includes stretching in the longitudinal direction followed by stretching in the transverse direction and the subsequent stage of calendering as a means of reducing the thickness of the multilayer microporous membrane to reduce the relative porosity of the multilayer microporous membrane in a controlled increase, and/or for tensile strength in the transverse direction. The result is a thin multi-layer microporous membrane which is easily applied with polymer-ceramic coatings, which has excellent mechanical strength characteristics due to its inner polypropylene layer or layers and thermal shutdown function due to its polyethylene layer or layers.

EFFECT: improving the design and technical characteristics of the battery.

24 cl, 37 dwg, 4 tbl

Description

FIELD OF TECHNOLOGY TO WHICH THE INVENTION RELATES

The present application or invention is directed to new, improved or modified membranes, multilayer membranes, separation membranes, calendered membranes, stretched membranes, stretched and calendered membranes, dry stretched and calendered membranes, membrane separators, coated membranes, membranes with unique structures, membranes with increased productivity, membrane separators, battery separators, disconnecting separators, and / or batteries or cells, including such membranes or separators, and / or methods for manufacturing such membranes, separators, cells and / or batteries, and / or methods for using such membranes, separators, cells and/or batteries. In accordance with at least selected embodiments, the present application or invention is directed to new or improved stretched membranes, calendered membranes, stretched and calendered membranes, biaxially stretched membranes, sequentially biaxially stretched membranes, simultaneously biaxially stretched membranes, biaxially stretched and calendered membranes, dry-formed porous membranes stretched and calendered membranes, dry-formed separation membranes, dry-formed coated membranes, membranes with unique structures, high performance membranes, single or multilayer membranes, microporous membranes, microporous multilayer membranes, thin calendered membranes, thin and strong calendered membranes, thin, strong and/or high performance calendered membranes, dry-processed membranes, dry-processed thin membranes, dry-processed thin calendered membranes, dry-processed thin and strong calendered membranes, thin, strong and/or high-performance dry-processed calendered membranes, dry-processed calendered membranes with unique structures and/or characteristics, dry-processed thin, strong and/or or high performance dry calendered and coated membranes thin, strong and/or high performance stretched and calendered membranes, thin, strong and/or high performance dry stretched, calendered and coated membranes, accumulator membrane separators, accumulator separators, and/or batteries or elements comprising such membranes or separators, such stretched, calendered and/or coated membranes or separators, such biaxially stretched and/or calendered membranes or separators, such biaxially stretched and/or coated membranes or separators, or such biaxially stretched, calendered and/or coated membranes or separators, and/or methods for making such membranes, separators, cells and/or batteries, and/or methods for using such membranes, separators, cells and/or batteries. In accordance with at least some embodiments, the present application or invention is directed to new or improved calendered, single or multilayer membranes, three-layer membranes, reversed three-layer membranes, porous membranes, dry-processed porous multilayer membranes, dry-processed three-layer membranes inverted three-layer membranes, battery separator membranes, battery separators, and/or batteries or cells, including such membranes or separators, and/or methods for manufacturing such membranes, separators, cells, and/or batteries, and/or methods for using such membranes, separators , cells, and/or batteries. In accordance with at least some selected embodiments, the present application or invention is directed to new or improved single or multilayer porous membranes or separators. In accordance with at least some specific preferred embodiments, the present application or invention is directed to new or improved single-layer, multi-layer, three-layer, reversed three-layer, porous membranes, porous multilayer membranes, battery separator membranes, and/or battery separators, such as obtained dry-processed multilayer membrane or separator, dry-processed polyolefin membrane or separator, dry-processed polyolefin multilayer membrane or separator, and/or polyethylene/polypropylene/polyethylene microporous membrane or separator, which are manufactured using the exemplary inventive method described herein, which includes stretching and subsequent calendering steps, such as stretching in the longitudinal direction followed by stretching in the transverse direction (with or without relaxation in the longitudinal direction), and a subsequent calendering step as a possibly preferred means of reducing the thickness of such an expanded membrane, e.g. a multi-layer porous membrane, in a controlled manner, to reduce the relative porosity of such an stretched membrane, e.g. a multi-layer porous membrane, in a controlled manner, and/or to improve strength, properties and/or performance characteristics of such a stretched membrane, e.g., a multi-layer porous membrane, in a controlled manner, such as puncture strength, longitudinal and/or transverse tensile strength, uniformity, wettability, coatability, processability, sealing, springback, tortuosity, permeability, thickness, pin removal force, mechanical strength, surface roughness, hot tip hole propagation, and/or combinations thereof, of such a stretched membrane, such as a multi-layer porous membrane, in a controlled manner, and/ or to obtain a unique structure, porous structure, material, membrane, base film, and/or separator. Single or multi-layer microporous membranes with a thickness of 10 µm or less can be obtained by the process according to the invention. By the method according to the invention, multilayer microporous membranes of 10 µm or less thickness can be obtained, on which polymer-ceramic coatings are easily applied, having excellent mechanical strength characteristics due to their inner polypropylene layer, and/or exhibiting a thermal shutdown effect due to their outer polyethylene layers. The thickness ratio of polypropylene and polyethylene layers in such a multilayer microporous membrane according to the invention can be finely tuned to select, optimize and/or balance its strength, properties and/or technical characteristics such as mechanical strength and thermal shutdown characteristics.

BACKGROUND OF THE INVENTION

A commonly known multi-layer polyolefin separator that can be used in a lithium-ion rechargeable battery is a dry-formed, uniaxially stretched, polyolefin three-layer (or three-layer) separator manufactured by Celgard, LLC in Charlotte, North Carolina, and includes three layers a polyolefin separation membrane or a film configured as a polypropylene/polyethylene/polypropylene (PP/PE/PP-three-layer structure) wherein an inner polyethylene (PE) microporous membrane is sandwiched between two outer layers of a polypropylene (PP) microporous membrane. The inner PE layer in this multilayer microporous separator can act as a thermal shutdown layer in the event of a thermal failure. The use of polypropylene as the outer layers in such a three-layer structure of the battery separator can provide higher mechanical and thermal strength. In some circumstances, the use of polypropylene as the outer layers in a three-layer battery separator may be the preferred configuration. US Patent Publication No. 2007/0148538 proposes a polypropylene/polyethylene/polypropylene (PP/PE/PP) multilayer configuration as a microporous three-layer separator, where polypropylene can be used as outer or outer layers or films due to its higher tensile strength and higher melting point, and polyethylene can be applied as the inner polyethylene layer or film due to its lower melting point and thermal shutdown function. U.S. Patent Nos. 5,952,120, 5,691,077, and 8,486,556 and U.S. Patent Publication Nos. 2014/079980 and 2008/118827 disclose various methods for making dry-manufactured multilayer microporous separators where PP can be used as the outer layers and PE can be used. as inner trip layer in 3-layer microporous PP/PE/PP separator for Li-ion rechargeable battery.

Figure 1 schematically represents a known method for manufacturing a three-layer microporous PP/PE/PP separator as described in US Patent Publication No. 2007/0148538. After extrusion, the non-porous PP and PE layers or films are laminated in a three-layer configuration and laminated using heat and pressure to form a non-porous three-layer PP/PE/PP precursor. Subsequent annealing and longitudinal stretching of the non-porous three-layer PP/PE/PP precursor produces a uniaxially stretched three-layer microporous PP/PE/PP separator. The laminating step can be described as a bonding step, which can be done with heat and pressure using pinch rollers. Lamination and/or bonding can be conventionally used to bond two polymeric materials to each other under heat and pressure.

The thickness of the multilayer microporous separator plays an important role in the design of a lithium-ion battery. A microporous separation membrane or separator that is less than 10 µm thick may be desirable as it may take up less space within the battery and may allow more electrode active material to be accommodated in the battery cell to obtain higher energy density and a higher level of battery capacity.

In addition, thinner microporous membranes may form the preferred microporous substrate for polymer-ceramic coatings. US Patent Publication No. 2014/0045033 discloses aqueous coatings based on polymer-ceramic materials ranging in thickness from 4-7 microns, which can be coated on a microporous PP/PE/PP membrane with a thickness of 12-18 microns. The total thickness of the coated PP/PE/PP membrane can vary from 16 to 25 µm.

For at least some battery applications or technologies, there is still a need for thinner, stronger, more uniform, better performing membranes, dry process membranes, separator membranes, coated membranes, membranes with unique structures, high performance membranes, membrane separators, battery separators, shutdown separators, and/or batteries or cells including such membranes or separators, and/or in methods for manufacturing such membranes, separators, cells and/or batteries, and/or in methods of using such membranes, separators, cells and/or batteries. There is a need for a multilayer microporous cutoff membrane that is less than 10 µm thick for use as a battery separator and/or as a microporous substrate for polymer-ceramic coatings to form a coated battery separator. In addition, there is a need for a multi-layer microporous cut-off membrane with a thickness of less than 10 µm, which can be easily coated with a polymer-ceramic material, where the coating has excellent adhesion to the membrane and excellent adhesion to the electrode. In addition, there is a need for a multi-layer microporous cut-off membrane with a thickness of less than 10 µm, which can be easily coated with a polymer-ceramic material, where the coating thickness can be less than 7 µm. In addition, there is a need for a multi-layer microporous cutoff membrane with a thickness of less than 10 µm, which has excellent tensile strength in the longitudinal (MD) direction and transverse (TD) direction, and which can be easily coated with a polymer-ceramic material.

SUMMARY OF THE INVENTION

At least some embodiments, aspects or objectives of the present application or invention may satisfy the above needs, and/or may provide new, improved or modified membranes, multilayer membranes, separation membranes, calendered membranes, stretched membranes, stretched and calendered membranes obtained dry stretched and calendered membranes, membrane separators, coated membranes, membranes with unique structures, membranes with increased productivity, membrane separators, accumulator separators, trip separators, and/or batteries or cells incorporating such membranes or separators, and/or methods for manufacturing such membranes, separators, cells and/or batteries, and/or methods of using such membranes, separators, cells and/or batteries. In accordance with at least selected embodiments, the present application or invention is directed to new or improved stretched membranes, calendered membranes, stretched and calendered membranes, biaxially stretched membranes, sequentially biaxially stretched membranes, simultaneously biaxially stretched membranes, biaxially stretched and calendered membranes, dry-formed porous membranes stretched and calendered membranes, dry-formed separation membranes, dry-formed coated membranes, membranes with unique structures, high performance membranes, single or multilayer membranes, microporous membranes, microporous multilayer membranes, thin calendered membranes, thin and strong calendered membranes, thin, strong and/or high performance calendered membranes, dry-processed membranes, dry-processed thin membranes, dry-processed thin calendered membranes, dry-processed thin and strong calendered membranes, thin, strong and/or high-performance dry-processed calendered membranes, dry-processed calendered membranes with unique structures and/or characteristics, dry-processed thin, strong and/or or high performance dry calendered and coated membranes thin, strong and/or high performance stretched and calendered membranes, thin, strong and/or high performance dry stretched, calendered and coated membranes, battery seals, battery separators, and/or batteries or elements comprising such membranes or separators, such stretched, calendered and/or coated membranes or separators, such biaxially stretched and/or calendered membranes or separators, such biaxially stretched and/or coated e. membranes or separators, or such biaxially stretched, calendered and/or coated membranes or separators, and/or methods of making such membranes, separators, cells and/or batteries, and/or methods of using such membranes, separators, cells and/or batteries . In accordance with at least some embodiments, the present application or invention is directed to new or improved calendered, single or multilayer membranes, three-layer membranes, reversed three-layer membranes, porous membranes, dry-processed porous multilayer membranes, dry-processed three-layer membranes inverted three-layer membranes, battery separator membranes, battery separators, and/or batteries or cells, including such membranes or separators, and/or methods for manufacturing such membranes, separators, cells, and/or batteries, and/or methods for using such membranes, separators , cells, and/or batteries. In accordance with at least some selected embodiments, the present application or invention is directed to new or improved single or multilayer porous membranes or separators. In accordance with at least some specific preferred embodiments, the present application or invention is directed to new or improved single-layer, multi-layer, three-layer, reversed three-layer, porous membranes, porous multilayer membranes, battery separator membranes, and/or battery separators, such as obtained dry-processed multilayer membrane or separator, dry-processed polyolefin membrane or separator, dry-processed polyolefin multilayer membrane or separator, and/or polyethylene/polypropylene/polyethylene microporous membrane or separator, which are manufactured using the exemplary inventive method described herein, which includes stretching and subsequent calendering steps, such as stretching in the longitudinal direction followed by stretching in the transverse direction (with or without relaxation in the longitudinal direction), and a subsequent calendering step as a possibly preferred means of reducing the thickness of such an expanded membrane, e.g. a multi-layer porous membrane, in a controlled manner, to reduce the relative porosity of such an stretched membrane, e.g. a multi-layer porous membrane, in a controlled manner, and/or to improve strength, properties and/or performance characteristics of such a stretched membrane, e.g., a multi-layer porous membrane, in a controlled manner, such as puncture strength, longitudinal and/or transverse tensile strength, uniformity, wettability, coatability, processability, sealing, springback, tortuosity, permeability, thickness, pin removal force, mechanical strength, surface roughness, hot tip hole propagation, and/or combinations thereof, of such a stretched membrane, such as a multi-layer porous membrane, in a controlled manner, and/ or to obtain a unique structure, porous structure, material, membrane, base film, and/or separator. Single or multi-layer microporous membranes with a thickness of 10 µm or less can be obtained by the process according to the invention. By the method according to the invention, multilayer microporous membranes of 10 µm or less thickness can be obtained, on which polymer-ceramic coatings are easily applied, having excellent mechanical strength characteristics due to their inner polypropylene layer, and/or exhibiting a thermal shutdown effect due to their outer polyethylene layers. The thickness ratio of polypropylene and polyethylene layers in such a multilayer microporous membrane according to the invention can be fine-tuned to select, optimize and/or balance its strength, properties and/or technical characteristics such as mechanical strength and thermal shutdown characteristics.

At least some embodiments, aspects or objectives of the present application or invention may satisfy the above needs for separators, and/or may provide new, improved or modified multilayer membranes, diaphragm seals, battery separators, batteries or cells incorporating such membranes or separators, methods for making such membranes, separators, cells and/or batteries, and/or methods for using such membranes, separators, cells and/or batteries. In accordance with at least selected embodiments, the present application or invention is directed to new or improved calendered, porous or microporous multilayer membranes, battery separator membranes, battery separators, batteries or cells incorporating such membranes or separators, methods of manufacturing such membranes, separators , cells and/or batteries, and/or methods of using such membranes, separators, cells and/or batteries. In accordance with at least some embodiments, the present application or invention is directed to new or improved calendered, inverted three-layer, microporous multilayer membranes, battery separator membranes, battery separators, batteries or cells, including such membranes or separators, methods for manufacturing such membranes, separators, cells and/or batteries, and/or methods of using such membranes, separators, cells and/or batteries. In accordance with at least some selected embodiments, the present application or invention is directed to new or improved reverse three-layer, microporous multilayer membranes, battery separator membranes, or battery separators made from a dry-processed polyethylene/polypropylene/polyethylene microporous membrane or separator, which are made using the method described herein according to the invention, which includes stretching in the longitudinal direction followed by stretching in the transverse direction, and a subsequent calendering step as a means of reducing the thickness of such a multilayer microporous membrane, reducing the relative porosity of the multilayer microporous membrane in a controlled manner, and/or for improve tensile strength in the transverse direction. According to the method according to the invention, a multilayer microporous membrane with a thickness of 10 µm or less can be obtained, which is easy to apply polymer-ceramic coatings, has excellent mechanical strength characteristics due to its inner polypropylene layer, and/or exhibits a thermal shutdown effect due to its outer polyethylene layers. The thickness ratio of the polypropylene and polyethylene layers in such a multilayer microporous membrane according to the invention can be fine tuned to balance mechanical strength and thermal shutdown characteristics.

In accordance with at least selected embodiments, the present application or invention is directed to an improved microporous battery separator membrane, membrane separator, or separator for a lithium rechargeable battery such as a lithium ion battery, a polymer battery, a button cell, a cylindrical cell, a prismatic cell. , large cell, package, module, system, or the like, and various methods of making and/or using such separators or membranes and batteries. The battery separator described herein may be a multilayer polyolefin membrane (or film) comprising polypropylene and polyethylene. Polypropylene (PP) may be polypropylene or a blend or copolymer of two or more propylenes or polypropylenes, and polyethylene (PE) may be polyethylene or a blend or copolymer of two or more ethylenes or polyethylenes.

An optional preferred novel, improved or modified multilayer polyolefin seal membrane for use in a lithium ion rechargeable battery according to the invention may include three layers of a polyolefin seal membrane configured as polypropylene/polyethylene/polypropylene (PP/PE/PP) where the inner polyethylene (PE) the microporous membrane is sandwiched between two outer layers of a polypropylene (PP) microporous membrane, and in which one or more of its layers are stretched, calendered, and optionally coated. A multilayer polyolefin microporous membrane including polypropylene (PP) and polyethylene (PE) may be desirable because it has a thermal shutdown function and can prevent thermal failure in the battery. One example of a known dry-processed membrane comprising polypropylene (PP) and polyethylene (PE) is a uniaxially stretched (MD direction only) laminated three-layer microporous PP/PE/PP membrane separator which is fabricated as shown in Figure 1. The initial step in the manufacture of a three-layer microporous PP/PE/PP membrane is the extrusion of the non-porous PE membrane and the extrusion of the non-porous PP membrane. A non-porous PE membrane and a non-porous PP membrane are layered in a three-layer PP/PE/PP configuration and laminated using heat and pressure to form a non-porous three-layer PP/PE/PP membrane precursor. In subsequent annealing and longitudinal stretching steps of the non-porous 3-layer PP/PE/PP membrane precursor, a uniaxially stretched 3-layer microporous PP/PE/PP membrane is obtained. This uniaxially stretched in the longitudinal direction of the three-layer microporous PP/PE/PP membrane can be used as a precursor, which is stretched in the transverse (TD) direction (preferably with tension release in the longitudinal (MD) direction), or subjected to biaxial stretching, and then calendering.

Yet another method of manufacturing a multilayer PP/PE/PP barrier membrane may involve biaxially stretching the annealed non-porous membrane using longitudinal stretch followed by transverse stretch (preferably with MD release). Stretch in the transverse direction is commonly referred to as TD stretch. TD stretching can increase the tensile strength in the transverse direction, and can reduce the tendency of the microporous polyolefin membrane to delaminate. This biaxially stretched three-layer microporous PP/PE/PP membrane can be used as a stretched precursor which is subjected to calendering and optionally coating.

Figure 2 shows yet another method of manufacturing a dry PP/PE/PP multilayer release membrane, which may include TD stretching of the MD stretched membrane, followed by a calendering step to reduce the thickness of the entire microporous PP/PE/PP membrane as a whole. Calendering may be cold, ambient (room temperature) or hot, and may involve the application of pressure, or the application of heat and pressure, to reduce the thickness of the membrane or film in a controlled manner. In addition, the calendering process can use heat, pressure, and speed to densify heat sensitive material. In addition, the calendering process can use uniform or non-uniform conditions of heat, pressure and/or speed to selectively densify the heat sensitive material, to create uniform or non-uniform calendering conditions (such as using a smooth roll, rough roll, grooved roll, micro-grooved roll , nanogrooved roll, speed change, temperature change, pressure change, humidity change, double roll stage, multiple roll stage, or combinations thereof), to obtain improved, desirable or unique structures, characteristics and/or performance, to provide or control the resulting structures , characteristics and/or performance, and/or the like.

While the typical multilayer microporous PP/PE/PP membrane separator has had great commercial success as a separator in a lithium-ion rechargeable battery, for at least some battery technologies such as automotive and electric vehicle applications, There is a need for a microporous PP/PE/PP membrane separator with a polymer-ceramic coating to further improve the thermal reliability of the battery. Due to the relatively low surface tension of polypropylene (30 to 32 dynes/cm (0.03-0.032 N/m)) compared to polyethylene (34 to 36 dynes/cm (0.034-0.036 N/m)), polyethylene can be easier to coat than PP when the coating is a polymer-ceramic coating. The present invention can solve this problem and improve coating adhesion by TD stretching and calendering the membrane, biaxially stretching and calendering the membrane, placing PE on the outer surface of the membrane (such as PE/PP/PE), and/or adding PE to the outer surface of the membrane, or separator (like PE/PP/PE/PP or PE/PP/PE/PP/PE). Applying or adding PE to the outer surface can also reduce pin removal force compared to some PP outer layers.

When a thinner microporous membrane substrate with a thickness of 10 µm is coated with a polymer-ceramic material with a thickness of 4-7 µm, the total maximum thickness can be between 14 and 17 µm. A 10 µm thick microporous membrane coated with a 7 µm thick polymer-ceramic material may have a total thickness of 17 µm. A porous or microporous membrane that has a thickness of less than 10 µm and a polymer-ceramic coating with a thickness of 4 µm can have an overall thickness of less than 14 µm, more preferably less than or equal to 12 µm, and most preferably less than 10 µm. Optionally, the porous or microporous membrane substrate (or base film) to be coated may be sequentially or simultaneously biaxially stretched and then calendered to a thickness of less than 20 µm, preferably a thickness of less than 15 µm, more preferably a thickness of 10 µm or less, and most preferably a thickness of 5 µm or less. In addition, the coating may be applied to one or both sides of the membrane.

In accordance with at least selected embodiments, calendering can improve the strength, wettability and/or uniformity of the membrane, and reduce surface layer defects that have been created during the manufacturing process. A more uniform membrane can improve coatability. In addition, the use of a textured calender roll can improve the adhesion of the coating to the base membrane.

In accordance with at least selected embodiments, the present application is directed to new or improved microporous multilayer dry-processed battery separator membranes, separators, batteries, including such separators, methods for manufacturing such membranes, separators and/or batteries, and/or methods of application. such membranes, separators and/or batteries, where polyethylene, a compound of various polyethylenes, or a mixture of polyethylene and polypropylene are used as the outer layers of a multilayer microporous membrane, and polypropylene can be used as the inner layer(s). In accordance with at least some embodiments, the present invention is directed to a multilayer polyolefin microporous membrane, where polyethylene, a compound of various polyethylenes, or a mixture of polyethylene and polypropylene are used in one or more outer layers of the multilayer microporous membrane, and polypropylene can be used as one or more inner layers, where the lamination configuration may be, but is not limited to, PE/PP/PE.

In accordance with at least selected embodiments, the present application is directed to, but not limited to, a dry-processed microporous PE/PP/PE membrane that is made using a combination of the steps of longitudinal stretching, transverse stretching and calendering, as shown in Figure 3. The order of these three stages (MD/TD/C) may be important in relation to the overall performance of the microporous PE/PP/PE membrane in the separator and battery. MD stretching can create rectangular slit-shaped micropores, while TD stretching can change the crystallinity and amorphous content of the membrane, resulting in improved TD tensile strength, reduced delamination, and higher relative porosity. The combination of MD and TD stretching followed by a calendering step can create an overall thinner microporous PE/PP/PE membrane. TD stretching can cause an increase in relative porosity in a microporous membrane. The calendering step after TD stretching can be considered as a means of influencing the relative porosity increase that can occur during TD stretching and reducing the overall relative porosity of the MD/TD/calendered microporous membrane. The inventive MD/TD/calendering method for making a microporous PE/PP/PE membrane can provide an inventive approach to 1) overcome the thinness limitation in the MD stretch only method and achieve thicknesses below 10 µm, 2) control the growth of porosity, which may occur during TD stretching, 3) providing a mechanically stronger microporous membrane with improved TD tensile strength, 4) providing a release membrane with higher surface tension to facilitate coating application and enhance coating adhesion, and/or 5) providing a separator with lower pin removal force.

The three-layer microporous PE/PP/PE membrane subjected to "longitudinally stretched/cross stretched/calendered" which has a thickness of less than 10 µm can have a number of advantages that can improve battery design and performance. A multilayer polyolefin microporous separation membrane with a thickness of 10 µm or less can take up less space inside the battery, and can allow more electrode active material to be placed in the battery cell for higher energy density and higher capacity level. Furthermore, the combination of a MD stretching step and subsequent lateral stretching, followed by a calendering step, can create a promising way to achieve a microporous membrane that has excellent MD tensile strength and lateral tensile strength, together with controlled relative porosity. and thermal shutdown function, while at the same time having a thickness of less than 10 microns. The unexpected level of improvement in tensile properties of the inventive microporous PE/PP/PE release membrane produced using MD stretch, TD stretch and calendering as described herein can achieve levels of MD tensile strength and lateral tensile strength. direction, similar to the characteristics of a wet-manufactured multilayer microporous membrane containing PP and/or PE, without the difficulties in terms of solvent or oil removal and recovery, and in terms of the costs associated with the wet-manufacturing process.

A three-layer microporous PE/PP/PE membrane subjected to "longitudinally stretched/lateral stretched/calendered" that has a thickness of less than 10 µm can provide several advantages that can improve battery design and performance. A multilayer polyolefin microporous separation membrane with a thickness of 10 µm or less can take up less space inside the battery, and can allow more electrode active material to be placed in the battery cell for higher energy density and higher capacity level. In addition, the combination of a MD stretching step and subsequent lateral stretching, followed by a calendering step, can provide a promising way to achieve a microporous membrane that has excellent MD tensile strength and lateral tensile strength, and controlled relative porosity and thermal shutdown function, while at the same time having a thickness of less than 10 microns. The unexpected level of improvement in tensile properties of the inventive microporous PE/PP/PE release membrane produced using MD stretch, TD stretch and calendering as described herein can achieve levels of MD tensile strength and lateral tensile strength. direction, similar to the characteristics of a wet-manufactured multilayer microporous membrane containing PP and/or PE, without the difficulties in terms of solvent or oil removal and recovery, and in terms of the costs associated with the wet-manufacturing process.

Single-layer, double-layer, three-layer or multi-layer microporous PP, PP/PP or PP/PP/PP-membrane subjected to "longitudinally stretched/cross stretched/calendered" which has a thickness of less than 10 µm can provide a number of advantages that can improve the design and performance of the battery. A single or multi-layer polyolefin microporous separation membrane of 10 µm or less can take up less space within a battery and can accommodate more active electrode material in a battery cell for higher energy density and higher capacity levels. Furthermore, the combination of a MD stretching step and subsequent lateral stretching, followed by a calendering step, can create a promising way to achieve a microporous membrane that has excellent MD tensile strength and lateral tensile strength, together with controlled relative porosity. and thermal shutdown function, while at the same time having a thickness of less than 10 microns. The unexpected level of improvement in tensile properties of the inventive microporous PP, PP/PP or PP/PP/PP release membrane produced using MD stretching, TD stretching and calendering as described herein can achieve levels of tensile strength in the longitudinal direction and tensile strength in the transverse direction, similar to or better than the characteristics of wet-manufactured multilayer microporous membranes containing PP and/or PE, without difficulties in terms of removal and recovery of solvent or oil and in relation to the costs associated with the wet-manufacturing process, can have better oxidation resistance than PE, may perform at higher temperatures than PE, may have better coating adhesion than typical PP, or combinations thereof.

The present application is directed to new or improved microporous single or multilayer membranes for battery separators, membrane separators, or separators, and/or batteries or cells, including such membranes or separators, and/or methods for manufacturing such membranes, separators, cells and/or batteries, and/or methods of using such membranes, separators, cells and/or batteries. In accordance with at least some embodiments, the present invention is directed to a single-layer or multi-layer, dry-processed polyolefin microporous membrane, membrane separator or separator (such as PP, PE, PP/PP, PE/PE, PP/PE, PP/ PE/PP, PE/PP/PE, PE/PP/PP, PP/PE/PE, PE/PP/PP/PE, PP/PE/PE/PP, PP/PP/PP, PE/PE/PE, PP-PE, PP-PE/PP, PP-PE/PE, PP-PE/PP/PP-PE, PP-PE/PE/PP-PE, or the like), which are produced using the process according to the invention, which includes stretching in the longitudinal direction followed by stretching in the transverse direction (with or without tension release in the longitudinal direction (MD) preferably with MD relaxation, such as 10-90% MD relaxation, 20-80% MD -relaxation, 30-70% MD-relaxation, or 40-60% MD-relaxation, or at least 20% MD-relaxation), and a subsequent calendering step, as a means of reducing the thickness of the membrane, reducing relates porosity of the membrane in a controlled manner, and/or to improve the tensile strength in the transverse direction. By the method according to the invention, a single-layer or multi-layer microporous membrane, separation membrane, base film or separator, with a thickness of 10 µm or less, on which polymer-ceramic coatings having excellent mechanical strength characteristics due to their polypropylene(s) layer(s) can be obtained( -pits), and/or exhibiting a thermal shutdown effect due to their polyethylene(s) layer(s). The thickness ratio of the polypropylene and polyethylene layers in the inventive multilayer microporous membrane can be fine tuned to balance mechanical strength and thermal shutdown characteristics.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic diagram of a method for manufacturing a uniaxially MD-stretched three-layer polypropylene/polyethylene/polypropylene (PP/PE/PP) microporous membrane.

Figure 2 is a schematic diagram of a process according to the invention described herein for manufacturing a biaxially MD/TD-stretched and calendered (MD/TD/C) three-layer polypropylene/polyethylene/polypropylene (PP/PE/PP) microporous membrane.

Figure 3 is a schematic diagram of the method described herein according to the invention for the manufacture of an MD/TD-stretched and calendered three-layer polyethylene/polypropylene/polyethylene (PE/PP/PE) microporous membrane.

Figure 4 is a scanning electron microscope (SEM) micrograph showing the surface of Comparative Example 1 (CE 1) at 20,000 times magnification.

Figure 5 is a scanning electron microscope (SEM) micrograph showing the surface of Comparative Example 2 (CE 2) at 20,000 times magnification.

Figure 6 is a scanning electron microscope (SEM) micrograph showing a cross-sectional view of CE 2 at 3000x magnification.

Figure 7 is a scanning electron microscope (SEM) micrograph showing the surface of Comparative Example 3 (CE 3) at 5000× magnification.

Figure 8 is a scanning electron microscope (SEM) micrograph showing the surface of CE 3 at 20,000x magnification.

Figure 9 is a scanning electron microscope (SEM) micrograph showing a cross-sectional view of CE 3 at 5000x magnification.

Figure 10 is a scanning electron microscope (SEM) micrograph showing the surface of an exemplary inventive Example 1 at 20,000x magnification.

Figure 11 is a graph that contains the thickness values of a three-layer PP/PE/PP structure, including Comparative Example 1, Comparative Example 2, and Comparative Example 3, and a three-layer PE/PP/PE structure, including Comparative Example 4, Comparative Example 5, and Example 1

Figure 12 is a graph that contains the TD tensile strength values of a three-layer PP/PE/PP structure, including Comparative Example 1, Comparative Example 2, and Comparative Example 3, and a three-layer PE/PP/PE structure, including Comparative Example 4, Comparative Example 5 and Example 1.

Figure 13 is a bar graph that includes a comparison of the TD tensile strength of the dry-produced microporous membranes of Comparative Example 4, Comparative Example 5, and Example 1.

Figure 14 is a graph that contains the MD tensile strength values of a three-layer PP/PE/PP structure, including Comparative Example 1, Comparative Example 2, and Comparative Example 3, and a three-layer PE/PP/PE structure, including Comparative Example 4, Comparative Example 5 and Example 1.

Figure 15 is a scanning electron microscope (SEM) micrograph showing the surface of Comparative Example 4 PE/PP/PE after MD stretching at 5000× magnification.

Figure 16 is a scanning electron microscope (SEM) micrograph showing a cross-sectional view of Comparative Example 4 at 1500× magnification.

Figure 17 is a scanning electron microscope (SEM) micrograph showing the surface of Comparative Example 5 PE/PP/PE after MD stretching and TD stretching at 5000× magnification.

Figure 18 is a scanning electron microscope (SEM) micrograph showing a cross-sectional view of Comparative Example 5 at 3000× magnification.

Figure 19 is a scanning electron microscope (SEM) micrograph showing the surface of Example 1 PE/PP/PE after MD stretching, TD stretching and calendering at 5000x magnification.

Figure 20 is a scanning electron microscope (SEM) micrograph showing a cross-sectional view of Example 1 at 5000x magnification.

Figure 21 is start and end scanning electron microscope (SEM) cross-sectional micrographs showing the symmetrical calendering of Comparative Example 5 after TD stretching on the left side (A), and the same membrane after calendering on the right side (B) , at 3000x and 3500x magnification, respectively. Both of the top and bottom polyethylene layers were cut to 1.8 µm. It should be noted that Comparative Example 4 (MD only) may be a precursor to Comparative Example 5 (MD and TD), and that Comparative Example 5 (MD/TD) may be a precursor to Example 1 (MD/TD/C).

Figure 22 is a combined scanning electron microscope (SEM) micrographs with images of cross-sectional views showing asymmetric calendering of Comparative Example 5 after calendering at 6000 times magnification. The top polyethylene layer was reduced to 1.72 µm and the bottom layer to 2.19 µm.

Figure 23 shows respective images of surface irregularities of respective stretched three-layer films at -10% TD and 200% TD stretch, respectively.

Figure 24 shows charts of 3D quantification of surface irregularities of a TD-stretched three-layer film (A) versus a TD-stretched three-layer film (B).

Figure 25 is a graph depicting post removal characteristics after lithium stearate administration.

Figure 26 is a graph depicting post removal performance with 0%, 5%, and 2% injected lithium stearate versus comparative competitive three-layer membranes.

Figure 27 is a series of nine scanning electron microscope (SEM) micrographs showing the surface of three different TD-stretched products. Group 1 (top row from left to right of three SEMs) shows a TD stretched membrane as an EZ2090 product at 5000-, 20000- and 20000-fold magnification. Group 2 (middle row from left to right of three SEMs) shows a TD-stretched membrane as product EZ2090 that has been further TD-stretched at 5,000-, 20,000-, and 20,000-fold magnification. Group 3 (bottom row from left to right of three SEMs) shows a TD-stretched membrane as product EZ2090 that has been further TD-stretched and calendered at 5,000-, 20,000-, and 20,000-fold magnification.

Figure 28 is a series of three scanning electron microscope (SEM) micrographs (A), (B) and (C) showing cross-sectional images of two TD-stretched precursors (A) and (B) at 3000x magnification, and subjected to product calendering (C) at 3500x magnification, and a very schematic representation of thickness and crimp (pore trajectory) shown in at least one PE layer of each membrane.

Figure 29 is a schematic surface view showing the expansion of lamellae to form micropores delimited by bridges or fibrils in a typical dry MD stretch process. The pores are more like slits, and are oriented in the longitudinal (MD) direction (see Figure 4).

Figure 30 is a combination of Figures 19 and 21(B), together with a schematic figure of a three-layer membrane or product, showing that Side A of the surface SEM image of Figure 19 is the top surface layer of Figure 21(B), and that at least the top surface The product has a unique pore structure.

Figure 31 is a modified version of the SEM image of the surface of Figure 19, modified to highlight the pores, pore structure, surface structure, and specific selected areas or pore regions, labeled 1-5.

Figures 32, 33 and 34 are respective enlarged views of portions of the modified surface SEM image from Figure 31.

Figures 35, 36 and 37 are respective enlarged views of portions of the modified surface SEM image from Figure 19.

DETAILED DESCRIPTION OF THE INVENTION

In accordance with at least some embodiments, the present invention is directed to a multilayer polyolefin membrane for a rechargeable lithium battery that is manufactured using a lamination process, a co-extrusion process, or a combination of the two. In at least some embodiments, the multilayer polyolefin membrane may include polypropylene and polyethylene, or a compound, blend, or copolymer of polypropylenes and polyethylenes. Two non-limiting examples of a multilayer polyolefin membrane can be a polypropylene/polyethylene/polypropylene (PP/PE/PP) microporous membrane and a polyethylene/polypropylene/polyethylene (PE/PP/PE) microporous membrane. In addition, variations in the number of PP and PE layers in the multilayer membrane and the alternation of the layered PP and PE layers in the multilayer membrane may be possible.

Figure 2 schematically represents a method for manufacturing a polypropylene/polyethylene/polypropylene (PP/PE/PP) microporous membrane in an embodiment of the membrane described here, where two PP layers and one PE layer are laminated with a PE layer as the inner layer and two PP layers in as outer layers, forming a non-porous three-layer PP/PE/PP membrane. The layered, non-porous, three-layer PP/PE/PP membrane is laminated to bond the layers to each other. The laminated non-porous three-layer structure is then annealed, followed by a longitudinal (MD) stretching step to make the membrane microporous. The microporous trilayer PP/PE/PP membrane according to the invention described herein is obtained by stretching in the transverse (TD) direction of the MD-stretched microporous trilayer PP/PE/PP membrane, after which the subsequent step of calendering the "MD-TD-expanded" microporous trilayer PP is carried out. /PE/PP membranes to reduce membrane thickness, reduce roughness, reduce relative porosity, improve TD tensile strength, improve uniformity, and/or reduce TD delamination. Possible preferred membrane or product can be made using the exemplary inventive process described herein, which includes stretching and a subsequent calendering step, such as longitudinal stretching followed by transverse stretching (with or without longitudinal relaxation), and a subsequent calendering step as a possible preferred means of reducing the thickness of such stretched membrane, e.g., multilayer porous membrane, in a controlled manner, to reduce the relative porosity of such stretched membrane, e.g., multilayer porous membrane, in a controlled manner, and/or to improve strength, properties, and /or the technical characteristics of such a stretched membrane, for example, a multilayer porous membrane, in a controlled manner, such as puncture strength, tensile strength in the longitudinal direction and/or in the transverse direction, uniform wettability, coatability, machinability, compaction, springback, tortuosity, permeability, thickness, pin removal force, mechanical strength, surface roughness, hot tip hole spread, and/or combinations thereof, such a stretched membrane, for example , multilayer porous membrane, in a controlled manner, and/or to obtain a unique structure, porous structure, material, membrane, base film, and/or separator. Single or multi-layer microporous membranes with a thickness of 10 µm or less can be obtained by the process according to the invention. In addition, the calendering process can apply uniform or non-uniform conditions of heat, pressure and/or speed, to selectively densify the heat sensitive material, to create uniform or non-uniform calendering conditions (such as using a smooth roll, rough roll, grooved roll, micro-grooved roll, nano-grooved roll, speed change, temperature change, pressure change, humidity change, double roll stage, multiple roll stage, or combinations thereof), to obtain improved, desirable or unique structures, characteristics and/or performance, to provide or control the obtained structures, characteristics and/or performance, and/or the like.

Figure 3 schematically represents a process for the manufacture of a possibly preferred polyethylene/polypropylene/polyethylene (PE/PP/PE) microporous membrane in an embodiment of the membrane according to the invention described here, where two layers of PE and one layer of PP are laminated with a PP layer as an inner layer and two PE layers as outer layers, forming a non-porous three-layer PE/PP/PE membrane. The layered, non-porous three-layer PE/PP/PE membrane is laminated to bond the layers to each other. The laminated non-porous three-layer structure is then annealed, followed by a longitudinal (MD) stretching step to make the membrane microporous. The microporous trilayer PE/PP/PE membrane according to the invention described herein is obtained by stretching in the transverse (TD) direction of the MD-stretched microporous trilayer PE/PP/PE membrane, after which the subsequent step of calendering the "MD-TD-expanded" microporous trilayer PE is carried out. /PP/PE membranes to reduce membrane thickness, reduce roughness, reduce relative porosity, improve TD tensile strength, improve uniformity, and/or reduce TD delamination. Possible preferred three-layer membrane or product can be made using the exemplary inventive process described herein, which includes stretching and a subsequent calendering step, such as longitudinal stretching followed by transverse stretching (with or without longitudinal relaxation), and a subsequent calendering step as a possible preferred means of reducing the thickness of such stretched membrane, e.g., multilayer porous membrane, in a controlled manner, to reduce the relative porosity of such stretched membrane, e.g., multilayer porous membrane, in a controlled manner, and/or to improve strength, properties and/or performance characteristics of such stretched membrane, e.g. multilayer porous membrane, in a controlled manner, such as puncture strength, tensile strength in the longitudinal direction and/or in the transverse direction , uniformity, wettability, coatability, machinability, compaction, springback, crimp, permeability, thickness, pin removal force, mechanical strength, surface roughness, hot tip hole spread, and/or combinations thereof, of such a stretched membrane, for example, a multi-layer porous membrane, in a controlled manner, and/or to obtain a unique structure, porous structure, material, membrane, base film, and/or separator. Multilayer microporous membranes with a thickness of 10 µm or less can be obtained by the process according to the invention. In addition, the calendering process can apply uniform or non-uniform conditions of heat, pressure and/or speed, to selectively densify the heat sensitive material, to create uniform or non-uniform calendering conditions (such as using a smooth roll, rough roll, grooved roll, micro-grooved roll, nano-grooved roll, speed change, temperature change, pressure change, humidity change, double roll stage, multiple roll stage, or combinations thereof), to obtain improved, desirable or unique structures, characteristics and/or performance, to provide or control the obtained structures, characteristics and/or performance, and/or the like.

Table 1 lists the membrane thickness information along with the performance data of "MD-stretched", "MD-TD-stretched" and "MD-TD-stretched-calendered" dry-processed microporous three-layer PP/PE/PP membranes in comparison examples, and membrane thickness information along with performance data for "MD-stretched", "MD-TD-stretched" and "MD-TD-stretched-calendered" reverse three-layer microporous PE/PP/PE membranes. Comparative Example 1 is a microporous three-layer PP/PE/PP membrane with a thickness of 38 µm, which was only subjected to uniaxial MD stretching. The thickness ratio of PP and PE layers in the three-layer configuration of Comparative Example 1 is 0.33/0.33/0.33 (PP/PE/PP), showing that the PP and PE layers are equivalent in thickness. The MD tensile strength and TD tensile strength of Comparative Example 1 are 1630 kgf/cm ² and 165 kgf/cm ² , respectively, showing that the MD tensile strength is greater than the TD tensile strength. when the membrane is stretched uniaxially in one direction (MD-direction). Figure 4 is a scanning electron micrograph of the surface of Comparative Example 1 showing that the microporous structure can be composed of row-formed crystalline lamellae with chain-like structures of fibrillar bundles connecting the crystalline lamellae. The pores are shaped like rectangular slits, which is a characteristic of dry-processed MD-stretched microporous membranes.

The TD stretch (in the direction perpendicular to MD) of Comparative Example 1 creates Comparative Example 2. Figure 5 is an SEM micrograph of Comparative Example 2 where the microstructure shows that the transverse stretch appears to have a marked effect on the appearance of row-formed crystalline lamellae, where the crystalline lamellae look more elongated in the transverse direction. As a result, the TD tensile strength of Comparative Example 2 is higher, and can be up to 40% higher than the TD tensile strength of Comparative Example 1. This increase in TD tensile strength may be due to the TD tensile strength of the crystalline lamellae and fibrillar structures connecting them. Figure 6 is a sectional view of Comparative Example 2 showing a more open-celled structure of an inner microporous PE layer sandwiched between outer microporous PP layers. The shape of the MD/TD stretched pores of Comparative Example 2 may appear round.

Figure 7 shows an SEM micrograph of the surface of Comparative Example 2 at 5000x magnification.

The method described herein in Figure 2 includes "combined TD stretching and post-calendering" of the MD-stretched microporous membrane of Comparative Example 3 (MD/TD/C), which can be obtained by calendering Comparative Example 2. The calendering process involves heat and pressure, and can reduce the membrane thickness in a controlled manner. The surface of Comparative Example 3 is shown in Figure 8 at 20,000 times magnification. A sectional view of Comparative Example 3 is shown in Figure 9, where the inner PE layer may appear to be compressed and densified compared to Figure 6. The membrane thickness of Comparative Example 3 is reduced from 27.4 µm to 10.3 µm after combined TD stretching and subsequent calendering. A thin microporous membrane is desirable as a separation membrane for a rechargeable lithium ion battery because the thin microporous membrane allows more anode/separator/cathode material to be placed in the battery, providing higher energy and higher power density of the battery.

While the PP/PE/PP multi-layer separation membrane has had great commercial success as a separator in a high energy, high power density lithium-ion rechargeable battery, battery manufacturers for automotive and electric vehicle applications are showing keen interest in applying to microporous sealing membrane containing a polymer-ceramic coating material to improve the thermal reliability of the battery. Due to the relatively low surface tension of polypropylene (30 to 32 dynes/cm (0.03-0.032 N/m)) compared to polyethylene (34 to 36 dynes/cm (0.034-0.036 N/m)), polyethylene can be easier to coat than PP when the coating is a polymer-ceramic coating. In addition, PE is known to have a lower pin removal force than PP during cell winding. The present MD/TD/C method for making PP/PE/PP membrane (or PP-, PP/PP-, or PP/PP/PP-membrane) can improve coating adhesion and reduce pin removal force for outer PP layers or outdoor PP surfaces.

In accordance with at least selected embodiments, the present application is directed to new or improved microporous multilayer dry-processed battery separator membranes, separators, batteries including such separators, methods for making such membranes, separators and/or batteries, and/or methods of application. such membranes, separators and/or batteries, where polyethylene, a compound of different polyethylenes or a mixture of polyethylene and polypropylene are used as the outer layers of a multilayer microporous membrane, and polypropylene can be used as the inner layer(s). In accordance with at least some embodiments, the present invention is directed to multilayer polyolefin microporous membranes, where polyethylene, a compound of various polyethylenes, or a mixture of polyethylene and polypropylene are used as one or more outer layers of a multilayer microporous membrane, and polypropylene can be used as one or multiple inner layers, where the layering configuration may be, but is not limited to, PE/PP/PE.

In accordance with at least selected embodiments, the present application is directed to, but not limited to, a dry-processed microporous PE/PP/PE membrane that is made using a combination of the steps of longitudinal stretching, transverse stretching and calendering, as shown in Figure 3. The order of these three steps is important to ensure the overall performance of the separator and microporous PE/PP/PE membrane battery. MD stretching can create rectangular slit-shaped micropores, while TD stretching can change the crystallinity and amorphous content of the membrane, leading to improved TD tensile strength, reduced susceptibility to delamination, and higher relative porosity. The pore shape achieved in the outer PP layer after biaxial stretching is essentially round pores (Figure 5), while Figure 17 shows the pore shape achieved after biaxial stretching of the outer PE layer (pores that are elliptical). The elliptical pore is characterized by a flattened top and rounded edges. Figure 19 shows what the pores of Figure 17 look like after calendering (MD/TD/C). The compressed ellipticity of the pores of the biaxially stretched and calendered membrane (Figure 19) may contribute to increased compressive strength or reduced resilience. The combination of MD and TD followed by a calendering step can create an overall thinner microporous PE/PP/PE membrane. Figure 21 shows a biaxially stretched 21 µm reverse three-layer porous membrane that has been reduced in thickness to 11.5 µm after calendering, with a 50% reduction in thickness. The thickness of each of the outer polyethylene layers was reduced by about 64% from about 5 microns to about 1.8 microns each. The inner polypropylene layer shrank from about 11 microns to about 7.7 microns. Figure 21 shows a symmetrical reduction in the thickness of the layers, while Figure 22 demonstrates that the reduction in thickness can be selectively asymmetric. In this example, the top polyethylene layer was cut to 1.72 µm and the bottom layer was reduced to 2.19 µm. Asymmetric or controlled calendering can provide optimal or controlled protection against dendritic growth (anode side) and oxidation resistance (cathode side). TD stretching can cause an increase in relative porosity in a microporous membrane. The calendering step after TD stretching can be considered as a means of influencing the increase in relative porosity that may occur during TD stretching and reducing the overall relative porosity of the MD/TD/calendered microporous membrane. Table 1 shows the increase in porosity that occurs after TD stretching and the decrease in porosity after calendering. In the single layer polypropylene examples, after calendering, the porosity returns to the value after MD stretching, from 66% back to 40%.

Table 1

PP monolayer P/E/P E/P/E EZ1290 EZ2590 2340 2340 (B313) X137 X129 Property MD TD TDC MD TD TDC MD TD TDC MD TD TDC MD TD TDC MD TD TDC Thickness 26 eleven 12 56 25 15 39.2 19.8 15 37.6 25.8 13.5 55.3 33.4 24 35.6 25.5 13.2 Porosity 40 76 40 66 41 42.7 59.5 52 43.9 60.4 52.79 38.38 67.3 54.02 43.7 68.81 53 Gurley test 370 35 129 900 60 246 711.8 47.1 89 1015 40 148 1550 70.2 105 563.9 34 51 piercing 488.5 190.2 800 425 440 704.4 226 314 677.5 296 295 629.2 261.7 316 427.5 198.1 201 MD Tensile Strength 1700 677 1900 870 1351 1720.1 682 849 1808.8 621 1127 1955.3 650 1186 1801.7 539.5 927 TD tensile strength 150 535 150 550 687 132.3 440.3 431 140.6 313 528 157 353.4 388 147.4 315.5 473

The inventive MD/TD/calendering method for making a microporous PE/PP/PE membrane can provide an inventive approach to 1) overcome the thinness limitation in the MD stretch only method and achieve thicknesses below 10 µm, 2) control the growth of porosity, which can occur during TD stretching, 3) providing a mechanically stronger microporous membrane with improved TD tensile strength, 4) providing a release membrane with higher surface tension to facilitate coating and enhance coating adhesion, and 5) providing a separator with more lower pin removal force than a separator having outer PP layers, which can achieve higher yields of battery cells in the winding stage when manufacturing a lithium-ion battery using a PE/PP/PE three-layer configuration.

When the membranes are stretched in the MD and TD directions and then subjected to calendering as described herein, the membranes may have some improved characteristics, including increased mechanical strength of a thinner cage. However, some of the resulting membranes may have reduced permeability. The surface roughness can be controlled to prevent the permeability from falling below a desired level. Analysis of membranes with three-layer structures shows a significant degree of surface roughness before TD stretching. The multi-layer construction generally provides increased mechanical strength compared to a single-layer construction. In combination with its inherent surface roughness characteristics, the improved stretched and/or calendered multilayer membrane may also have improved pin removal performance (reduced coefficient of friction (COF)). The analysis also shows that when multilayer membranes are stretched in the TD direction, the membrane surface may become less rough (or have a more uniform surface roughness, which may also reduce pin removal forces, improve thickness uniformity, etc.), and when multilayer membranes are stretched in the TD direction and then subjected to calendering, the membrane surface can become even less rough (or have a more uniform surface roughness or controlled roughness (which can also reduce or control pin removal forces, increase or adjust thickness uniformity, and etc.)). Figures 23 show a 3D laser scanning microscope image of a three layer 2.1xMD stretched film only (-10% TD), and shows a three layer 4.5xTD stretched film (200%). Surface roughness is significantly reduced in TD stretched film. Such films with increased or controlled roughness, either on a milli- or micro-scale, may have improved pin removal characteristics. Figure 24 shows the surface roughness (low compared to high thickness) and the resulting COF value.

table 2

Sample Sa (µm) Sz (µm) COF BUT 0.258 3.14 0.368 IN 0.234 2.77 0.357 X129TD 1.169 13.22 0.231 X129TDC 0.586 7.14 0.281 C 0.272 3.01 0.361

After TD stretching and/or calendering, a reduction in surface roughness may occur. To prevent reduction in permeability after TD stretching, the inventive non-uniform, grooved or roughened calender roll (or controlled uneven calendering) can be used to intentionally modify or control surface roughness, control crimp, control reduction in permeability, control pin removal force or COF, control uniformity, control coatability, control mechanical strength, control compressibility and/or springback, control hot tip hole propagation, control thickness, or combinations thereof. The use of such calender rolls according to the invention can improve the pin removal characteristics and increase the crimpiness of the membranes. When testing and evaluating the High Temperature Melt Integrity (HTMI) performance of TD-stretched and "roughened" calendered membranes, a hot tip hole propagation test can be performed. This test can show that those membranes that have been TD stretched and calendered with grooved calender rolls have a significantly smaller opening resulting from contact with the hot tip. As previously stated, a roughened surface can help improve post removal performance. Table 2 lists the results of COF and roughness measurements. The COF and roughness values correlate with each other. Pin removal performance can also be improved in TD-stretched and calendered membranes by introducing additives into the membrane, onto its surface and/or into the polymer blend. Metal stearates can be added to TD-stretched and calendered films to improve pin removal performance (and reduce COF). Figure 25 shows the effect of injected lithium stearate (LiSt) in membranes. When 5% LiSt is added to the membranes, the pin removal force is reduced by 50 g, 200 g, and 350 g when compared to controls without LiSt. The incorporation of LiSt into single layer membranes shows improved pin removal performance, even when compared to comparative competing triple layer membranes. In TD-stretched and calendered samples with added LiSt, there can be improvements not only in pin removal performance, but also in Gurley score reduction. The introduction of LiSt can also increase the melting point from about 155°C to about 220°C, and expand the melt flow index (MFI) range from about 1.2-1.7 to 0.4-5.0, making the resulting membrane suitable for higher temperatures. In some examples, the introduction of LiSt can also allow the membranes to be extruded at lower temperatures, approximately 10-30° C., depending on the MFI value of the polymer, acting as a plasticizer. Calendering with a rough, grooved, or irregular roll can also improve pin removal performance, wettability, adhesion, and/or the like.

In accordance with selected embodiments, one or more metal stearates (such as lithium, sodium, calcium, magnesium, zinc, and combinations thereof, such as lithium and calcium stearates) may be added. Lithium stearate and/or calcium stearate are preferred. LiSt can serve as a surfactant or wetting agent, and to reduce the effort to remove the pin and/or COF, especially on the surface of the PP layer or membrane. According to selected embodiments, a method can be provided for removing a pin from a battery assembly with the step of using a separator comprising: a microporous membrane having a portion of the outer surface of polypropylene, wherein the polypropylene contains at least 500 ^ppm metal stearate, preferably lithium stearate and/or calcium stearate.

The three-layer microporous "MD stretched/lateral stretched/calendered" PE/PP/PE membrane that has a thickness of less than 10 µm can have certain advantages that can improve battery design and performance. A multilayer polyolefin microporous separation membrane with a thickness of 10 µm or less can take up less space inside the battery and can allow more electrode active material to be placed in the battery cell to obtain higher energy density and a higher level of battery capacity. Moreover, the combination of a MD stretching step and subsequent lateral stretching followed by a calendering step can create a promising way to achieve a microporous membrane that has excellent MD tensile strength and lateral tensile strength, together with controlled relative porosity. and thermal shutdown function, while at the same time having a thickness of less than 10 microns. The unexpected level of improvement in tensile properties of the inventive microporous PE/PP/PE release membrane produced using MD stretch, TD stretch and calendering as described herein can achieve levels of MD tensile strength and lateral tensile strength. direction, similar to the characteristics of a wet-processed PP and/or PE-containing multilayer microporous membrane, without the environmental problems associated with the wet process.

Table 3 lists the specifications of the comparative membranes and membranes according to the invention described herein. Comparative Example 4 is a microporous three-layer PE/PP/PE membrane with a thickness of 32.4 µm, which has been subjected to MD stretching. The thickness ratio of PP and PE layers in the three-layer PE/PP/PE configuration is 0.19/0.63/0.19, indicating that the outer PE layers are thinner than the inner PP layer.

Table 3

CE 1 CE 2 CE 3 Three-layer configuration PP/PE/PP PP/PE/PP PP/PE/PP PP/PE/PP ratio 0.33/0.33/0.33 0.33/0.33/0.33 0.33/0.33/0.33 Thickness, microns 38 27.4 10.3 Gurley JIS test, sec 780 370 176 Strength at MD-tensile, kgf/cm ² 1630 610 1560 Strength at TD-tensile, kgf / cm ² 165 286 665 MD elongation, % 48 54 TD elongation, % 954 103 51 Penetration strength 686 295 179 Specific electrical resistance, Ohm-cm ² 4.3 no data 0.9

Table 3, continued

CE 4 CE 5 Ex. one Ex. 2 Ex. 3 Three-layer configuration PE/PP/PE PE/PP/PE PE/PP/PE PE/PP/PE PE/PP/PE PE/PP/PE ratio 0.19/0.63/0.19 0.19/0.63/0.19 0.19/0.63/0.19 0.19/0.63/0.19 0.19/0.63/0.19 Thickness, microns 32.4 20.9 7.5 9.4 8.8 Gurley JIS test, sec 494 24.8 159 176 126 Strength at MD-tensile, kgf/cm ² 2078 573 1581 1173 1262 Strength at TD-tensile, kgf / cm ² 123 256 543 488 468 MD elongation, % 115 32 345 106 123 TD elongation, % 5.14 2.6 75 8.2 77 Penetration strength TBD (to be determined) TBD 160 165 167 Porosity,% 46 68 40 33 TBD Specific electrical resistance, Ohm-cm ² 1.84 0.51 1.27 0.97 0.6 Calendering temperature, °C no data no data 60 60 60 Calendering pressure, psi (MPa) no data no data 200 (1.38) 125 (0.86) 50 (0.35) Calendering speed, ft/min (m/s) no data no data 80 (0.41) 80 (0.41) 80 (0.41)

The MD tensile strength and TD tensile strength of Comparative Example 4 are 2078 kgf/cm ² and 123 kgf/cm ² , respectively, showing that the tensile strength in the MD direction is greater than the tensile strength in the TD direction when the membrane is stretched uniaxially in one direction (MD-direction).

The TD stretch (in the direction perpendicular to MD) of Comparative Example 4 produces Comparative Example 5. As a result of the TD stretch, the TD tensile strength of Comparative Example 5 can be twice that of the TD tensile strength of Comparative Example 4. This is the increase in TD strength -stretching may be due to the effect of TD-stretching on the crystalline lamellae and the fibrillar structures connecting them.

In at least some embodiments, the TD strength of the inventive membrane can be further improved by adding a calendering step after the TD stretch. The calendering process, which involves heat and pressure, can reduce the thickness of the porous membrane. Figure 10 is an SEM micrograph of the surface of the inventive membrane of Example 1, where the surface of the porous PE/PP/PE membrane appears slightly altered due to the lower melting point of PE during heat and pressure application in the calendering step. However, the calendering step treatment can compensate for the loss in MD and TD tensile strength due to TD tensile strength. In addition, the observed increase in MD and TD tensile strength as a result of calendering can create a more balanced ratio of MD and TD tensile strength, which can be favorable for all mechanical characteristics of the inventive membrane as a whole. Examples 2 and 3 can also be obtained by varying heat and pressure as calendering conditions. Examples 2 and 3 were prepared using the same calendering temperature of 60 degrees Celsius and a line speed of 60 ft/min (0.31 m/s) as in Example 1, while the calendering pressure varied from 50 to 200 psi (0.35 -1.38 MPa). Higher pressure can create a thinner separator.

At least one method according to the invention described herein comprises "combined TD stretching followed by calendering" of an MD stretched microporous membrane. Using the combined TD stretching and subsequent calendering method described herein according to the invention, the thicknesses of the membranes in Example 1, Example 2, and Example 3 are 7.5 µm, 9.4 µm, and 8.8 µm, respectively. A microporous membrane with a thickness of less than 10 µm is desirable as a separation membrane in a rechargeable lithium ion battery, since a thinner separation membrane allows more anode and cathode active material to be accommodated in the battery, resulting in more energy and higher power density of the battery.

In at least some selected embodiments, the improved separator may be a single layer porous membrane that has been biaxially stretched and calendered. Table 4 lists the properties of biaxially stretched single layer polypropylene (MD/TD) versus biaxially stretched and calendered single layer polypropylene (MD/TD/C). The calendered membrane is thinner by up to 50% while maintaining good electrical resistivity (ER) and strength. Figure 27 in group 1 (upper 3 SEMs) shows a biaxially stretched membrane (MD-stretched then TD-stretched with tension release in MD) that has substantially round or spherical pores in a very uniform distribution at least in its outer PP layer. Figure 27, Group 2 (3 medium SEMs) shows a biaxially stretched membrane (MD-stretched, then TD-stretched with tension release in MD, followed by additional TD-stretching) that has a mostly oval or elongated pore shape with an orientation according to TD at least in its outer PP layer. Figure 27, Group 3 (lower 3 SEMs) shows a biaxially stretched and calendered membrane (MD-stretched, then TD-stretched with tension release in MD, followed by additional TD stretching, and then calendering [pressure or compression in Z- direction]), which has pores having an oval or elliptical shape in compressed lamellae across the width at least in the outer or surface PP layer.

Table 4

Properties EZ2090 MDTDC EZ2090 EZ2590 MDTDC EZ2590 Thickness (µm)/standard deviation twenty 10.64/0.37 25 16.4/0.50 Porosity, % 65% 41% 69% 53% Gurley index (JIS), seconds 65 144 66 150 MD/TD shrinkage at 105°C 8.0/0.2 9.0/1.5 4.0/0.5 6.4/0.9 MD/TD shrinkage at 120°C 12/0.5 12.1/2.3 8.5/0.5 8.9/2.2 Puncture strength, grams 380 358 425 480 MD Tensile Strength (kg/cm ² ) 950 1700 870 1252 Tensile Strength TD (kg/cm ² ) 650 1146 550 655 Electrical resistivity (Ohm-cm ² ) 0.7 0.93 0.8 1.0

Figure 11 is a plot of the thickness of three-layer microporous PP/PE/PP and PE/PP/PE membranes using MD-stretch alone, MD-stretch followed by TD-stretch, and the MD-stretch followed by TD method described herein. -stretching, and subsequent calendering to obtain a microporous PE/PP/PE membrane. A reduction in membrane thickness is observed when the MD-stretched membrane is subjected to TD-stretch. In addition, calendering further reduces the thickness of the MD-TD stretched membrane. Calendering can be a reliable way to reduce the thickness of a microporous membrane in a controlled manner.

Figure 12 is a graph of the TD tensile strength of three-layer microporous PP/PE/PP and PE/PP/PE membranes using MD-stretch alone, MD-stretch followed by TD-stretch, and the MD-stretch method according to the invention described herein. stretching followed by TD stretching followed by calendering to obtain a microporous MD/TD/calendered PE/PP/PE membrane. The TD tensile strength of three-layer microporous PP/PE/PP and PE/PP/PE membranes can increase by approximately 4-5 times when the membrane is made using the inventive method described herein, which combines MD tensile followed by TD stretching and subsequent calendering.

Figure 13 shows the overall improvement in TD tensile strength of a dry-processed microporous membrane made using the inventive TD-stretch method described herein followed by calendering of a microporous "MD-stretched" PE/PP/PE membrane. By the dry process of the manufacturing method, which is an environmentally friendly manufacturing method without the use of solvents, an MD/TD/calendered microporous PE/PP/PE membrane can be obtained with a marked increase in TD tensile strength. In at least some selected embodiments, the porous membranes can be MD- and TD-stretched and/or then relaxed sequentially and/or simultaneously. The calendering step may be introduced before or after the stretching steps. Adding calendering to MD/TD stretching and/or relaxation of porous films may increase pore crimp to promote mechanical strength, may reduce effective porosity to a microporosity state, and/or the like.

Figure 14 is a graph of the MD tensile strength of three-layer microporous PP/PE/PP and PE/PP/PE membranes using MD-stretch alone, MD-stretch followed by TD-stretch, and the MD-stretch method according to the invention described herein. stretching followed by TD stretching followed by calendering. There is a reduction in MD tensile strength of three-layer microporous PP/PE/PP and PE/PP/PE membranes. However, subsequent calendering of TD-stretched after MD-stretch membranes may show a return of some of the strength lost during MD-stretch. More importantly, the calendering step created a membrane where the loss in MD tensile strength is compensated for by the gain in TD tensile strength. The inventive membrane described herein has a more balanced MD tensile strength and TD tensile strength, which can be beneficial to the overall performance of the inventive separator in a battery. In addition, the available porosity has been reduced by approximately 40 to 50%. A controlled reduction in relative porosity to a desired range to achieve excellent battery performance can be obtained in the calendering step when it is performed following the TD stretching step. In at least some selected embodiments, to improve the balance of MD and TD tensile strength and improve mechanical strength by varying the temperature conditions of hot and cold stretching.

Due to the thickness of less than 10 µm achievable by the possible preferred MD/TD/calendering process according to the invention, the microporous PE/PP/PE membrane produced by the process described here can form a thin polymer-ceramic coating substrate where the substrate can be coated more easily and has improved adhesion. The configuration of the inventive microporous 3-layer PE/PP/PE membrane results in an excellent polymer-ceramic coating substrate where the coating can have good adhesion and also has excellent adhesion to both the separator and the electrode in a lithium ion rechargeable battery. The thin microporous PE/PP/PE separating membrane, which has a thickness of less than 10 µm, may have a total thickness ranging from 14 to 17 µm, being coated with a cover layer ranging from 4 to 7 µm. In at least some selected embodiments, the calendered porous films may be more uniform and provide an improved coating surface.

Figure 28 is a series of three scanning electron microscope (SEM) micrographs (A), (B) and (C) showing cross-sectional images of two TD-stretched precursors (A) and (B) at 3000x magnification, and subjected to product calendering (C) at 3500x magnification, and a very schematic representation of thickness and crimp (pore trajectory) shown in at least one PE layer of each membrane. SEM (A) is a cross section of a biaxially stretched three-layer PP/PE/PP membrane (see Figure 6). SEM (B) is a cross section of a biaxially stretched three-layer PE/PP/PE membrane (see Figure 18). SEM (C) is a cross section of a biaxially stretched and calendered three-layer PE/PP/PE membrane (see Figures 20 and 21(B)). If the crimp (T) is defined as the length of the path along the tortuous pore of the membrane (Pltp) divided by the length of the path along the straight pore (Plsp, or membrane thickness), then T=1 represents a straight through hole, and then, as a rule, the value of T is preferred is greater than 1 (such as greater than 1, at least 1.5, at least 2.0, at least 2.5, or greater) in the membrane, diaphragm seal, or separator. Generally, a T value greater than 1 is desirable to promote slow dendritic growth or blockage, short circuit prevention, and proper operation as a lithium battery separator. A membrane T value that is too low or too high can create problems. Thus, too much MD-, TD- or biaxial stretching could create some pores with T=1, or an average T of less than 1.5. This could be an undesirable or too low T value. And too little MD-, TD- or biaxial stretching and/or too much calendering (too high pressure or compression) could create some pores with T=10, or an average T value over 9. This could be undesirable or too high T. A very low T value could lead to dendrites or short circuits, while a very high T value could lead to undesirably high resistivity (ER), high Gurley, low conductivity, or the like. In accordance with at least selected embodiments, the crimp, or T value, must be greater than 1, preferably at least 1.5, more preferably at least 2.0, and most preferably at least 2.5, and may be in the range of 1.5 to 9.5, or greater than 1 and less than 10. There are exceptions, such as, but not limited to, the T value of the membrane must be greater than 1 if a gel polymer is used that fills the pores, or if the pores are not very fine (nano) pores (0.001 µm or less), or if the coating on the membrane does not provide an effective T greater than 1.

Figure 29 is a schematic surface view showing microporous lamella propagation in a typical dry-stretched MD-stretched polyolefin microporous membrane (microporous film). The pores are more slit-like MD-oriented rectangles (see Figure 4). In Figure 29, individual elongated openings between adjacent lamellae include numerous slit-like micropores (small group of slit-like pores) defined by lamellae and bridging structures or fibrils, with lamellae extending in transverse direction (TD) and fibrils extending between lamellae in longitudinal direction (MD) direction in a typical dry MD-stretch process, or the Selgard process, to produce polyolefin membranes. Similar structures may be evident in some wet-manufactured MD-stretched polyolefin membranes.

The inventive biaxially stretched and calendered (compressed) membrane of Figure 19 differs from the typical MD-only stretched membrane of Figure 29. Many differences are readily apparent from a glance at Figures 19 and 29. The membrane of Figure 19 has been biaxially stretched and then calendered ( compression). Biaxial stretching creates a membrane precursor structure (such as shown in Figure 17) quite different and unique compared to the MD-stretched membrane of Figure 29 alone. in the TD direction by groups of pores, some broken or missing fibrils, and the like. When the precursor membrane of Figure 17 is calendered, the open network structure contracts, the lamellae are pressed on top of each other in the Z direction, at least the surface lamellae and fibrils flatten, at least some of the adjacent lamellae at or near the surface are layered or folded like a tile , and a less regular, less ordered, more chaotic, densified lamellar scaffold structure with TD-elongated large groups of pores (some without fibrils, some with broken fibrils, some with numerous lamellae, or combinations thereof) is formed (see Figures 19 and 30) -37 in drawings). The membrane according to Figure 19 is one example of a compressed three-layer PE/PP/PE membrane according to the invention. In this example, the respective PE layers are compressed more (higher in % compression) than the PP layer, since the PP layer is less compressible (resists compression). In the example of Figure 19, some of the groups of pores between the lamellae are much larger in the TD direction than in the MD direction. For example, some are 4, 4.9, 6.2, 8.5, or 9.1 times longer in the TD direction than they are wide in the MD direction (maximum TD-length/maximum MD-length) (respectively see references 4, 2, 1, 3 and 5 in Figure 31). Some of the pores (or pockets or cavities) look very deep in the Z direction (measured by membrane thickness), as fibrils are missing or broken, and are open to the lower Z-direction pores made up of packs of two or more groups of pores.

In Figure 31, red coloring is provided to more clearly show the pores (holes, pockets, or cavities) formed between the lamellae and fibrils or bridging structures. Approximate or selected groups of pores between adjacent lamellae are circled in yellow and labeled 1-5, respectively. In addition, in positions or areas 1-5 of Figure 31:

1. Mean number of "bridging structures" or fibrils = ~18 (18.8) (median is 14);

2. The average number of "micropores" (pores, holes, cavities - shaded in red) can = 27.5 (median = 20);

3. White lines represent 1 µm and most micropores are about 0.5-1.2 µm high (in MD) and between about 0.2-0.5 µm wide (in TD); And

4. The lamellae are about 0.8-1.0 µm thick (in MD).

Such surface pore sizes (diameter, length, width) are usually measured in the two-dimensional X-Y plane at the surface. Figure 19 is an SEM of the surface of a calendered or compressed PP layer on one side (Side A) of a compressed three-layer polyolefin (PE/PP/PE) membrane. It is contemplated that a similar calendered or compressed PE porous structure would be evident on each side of a compressed three-layer (PE/PP/PE) membrane, and that a similar calendered or compressed PE porous structure would be evident on each side of a compressed single or multilayer PE membranes (such as PE, PE/PE, PE/PE/PE, etc.), or on the PE side of double or multi-layer membranes with a PE outer layer (such as PE/PP, PE/PP/PP , PE/PE/PP, etc.). The resulting pore structure may be more ordered if the PE layer is thinner or less TD or biaxially stretched, or it may be less ordered if the PE layer is thicker or more TD or biaxially stretched. The pores (pockets, holes or cavities) may be less deep if the PE layer is thinner or less TD- or biaxially stretched, or may be deeper if the PE layer is thicker or more TD- or biaxially stretched.

The desired degree of stretch (MD and/or TD) and/or compression is selected to provide the desired thickness, properties and specifications. Too much compression can result in too high ER or Gurley (too low permeability), while too much stretching can result in too low ER or Gurley (too high permeability) and can reduce battery life or performance. As described herein, dry-processed polyolefin membranes can be formed that perform as well as or better than wet-processed membranes and can provide such performance even though they are thinner than comparative wet-processed membranes. Thin, strong, dry-processed polyolefin (PO) membranes can facilitate the formation of more energy-hungry or higher energy-density cells or batteries.

When stretching and compressing PP layers or membranes that are less elastic, less compressible and typically have smaller pores than similar PE membranes, a more ordered pore structure than that shown in Figure 19 would be expected. dry-formed porous PP membranes have been formed that perform as well as or better than wet-formed membranes and can provide such performance even though they are thinner than comparative wet-formed membranes. Thin, strong, dry-processed PP membranes can facilitate the formation of more energy-hungry or higher energy-density cells or batteries.

Figure 30 is a combination of Figures 19 and 21(B) along with a schematic representation of a three-layer membrane or product, showing that Side A of the surface SEM image of Figure 19 is the top surface layer of Figure 21(B), and that at least the top surface The product has a unique pore structure. Figures 19, 20 and 21(B) are SEM images of a biaxially stretched and calendered three-layer PE/PP/PE membrane. Side A or surface shown in Figure 19 is a calendered PE surface. With reference to Figure 30, the pores in the surface or surface layer (calendered PE layer) tend to be trapezoidal or rectangular with rounded corners, compacted or large lamellae across the width at least in the outer or surface PE layer. And they look less regular or periodic, and less open than the pores in Figure 17.

The micropores formed in the network structure of the lamellae of the outer PE layer in Figures 19, 20, 21(B) and 30 are relatively closed-like structures (see surface view in Figure 19) as a result of the lamella structure being compressed or compressed along thickness direction. The sectional view shows some surface-extended micropores in the membrane (see Figures 20, 21(B) and 30). In addition, Figure 27, group 3 (lower 3 SEM images) can show a similar surface appearance with micropores formed in the network structure of the lamellae of the outer PP layer, which are relatively similar closed structures as a result of the lamella structure being compressed or compressed along direction of thickness (with less closed or compressed, since PP is less compressible and has smaller pores than PE), and some micropores extended in the direction of the membrane surface may be present.

Prior to calendering, the outer PE layer had a reticulated, regular, translucent, open elongated oval pore that could be too open, too porous, too translucent, too weak, too compressible, or a combination of these characteristics. See Figures 17 and 18.

The filler or ceramic coating particles may have an average particle size in the range of about 0.001 micron (μm) to about 5 micron (μm). In another embodiment, the average particle size of the filler may be in the range from about 0.01 micron (μm) to 2 micron (μm). US Pat. No. 6,432,586, which is incorporated herein by reference in its entirety, discloses a variety of ceramic coated separators. In addition, US Patent Publication No. 2014/0045033, which is also incorporated herein by reference in its entirety, discloses a variety of polymeric coatings containing ceramic particles for microporous battery seals.

At least some embodiments, aspects or objectives of the present application may meet the above needs, and/or may provide new, improved or modified membranes, multilayer membranes, separation membranes, calendered membranes, stretched membranes, stretched and calendered membranes, stretched and calendered membranes obtained dry process membranes, sealing membranes, coated membranes, membranes with unique structures, membranes with increased performance, membrane separators, accumulator separators, shut-off separators, and / or batteries or cells incorporating such membranes or separators, and / or methods for manufacturing such membranes, separators, cells and/or batteries, and/or methods of using such membranes, separators, cells and/or batteries. In accordance with at least selected embodiments, the present application or invention is directed to new or improved stretched membranes, calendered membranes, stretched and calendered membranes, biaxially stretched membranes, sequentially biaxially stretched membranes, simultaneously biaxially stretched membranes, biaxially stretched and calendered membranes, dry-formed porous membranes stretched and calendered membranes, dry-formed separation membranes, dry-formed coated membranes, membranes with unique structures, high performance membranes, single or multilayer membranes, microporous membranes, microporous multilayer membranes, thin calendered membranes, thin and strong calendered membranes, thin, strong and/or high-performance calendered membranes, dry-processed membranes, dry-processed thin membranes, dry-processed thin calendered membranes, dry-processed thin and strong calendered membranes, thin, strong and/or high-performance dry-processed calendered membranes, dry-processed calendered membranes with unique structures and/or characteristics, dry-processed thin, strong and/or or high performance dry calendered and coated membranes thin, strong and/or high performance stretched and calendered membranes, thin, strong and/or high performance dry stretched, calendered and coated membranes, battery seals, battery separators, and/or batteries or elements comprising such membranes or separators, such stretched, calendered and/or coated membranes or separators, such biaxially stretched and/or calendered membranes or separators, such biaxially stretched and/or coated e. membranes or separators, or such biaxially stretched, calendered and/or coated membranes or separators, and/or methods of making such membranes, separators, cells and/or batteries, and/or methods of using such membranes, separators, cells and/or batteries . In accordance with at least some embodiments, the present application or invention is directed to new or improved calendered, single or multilayer membranes, three-layer membranes, reversed three-layer membranes, porous membranes, dry-processed porous multilayer membranes, dry-processed three-layer membranes inverted three-layer membranes, battery separator membranes, battery separators, and/or batteries or cells, including such membranes or separators, and/or methods for manufacturing such membranes, separators, cells, and/or batteries, and/or methods for using such membranes, separators , cells, and/or batteries. In accordance with at least some selected embodiments, the present application or invention is directed to new or improved single or multilayer porous membranes or separators. In accordance with at least some specific preferred embodiments, the present application or invention is directed to new or improved single-layer, multi-layer, three-layer, reversed three-layer, porous membranes, porous multilayer membranes, battery separator membranes, and/or battery separators, such as obtained dry-processed multilayer membrane or separator, dry-processed polyolefin membrane or separator, dry-processed polyolefin multilayer membrane or separator, and/or polyethylene/polypropylene/polyethylene microporous membrane or separator, which are manufactured using the exemplary inventive method described herein, which includes stretching and subsequent calendering steps, such as stretching in the longitudinal direction followed by stretching in the transverse direction (with or without relaxation in the longitudinal direction), and the next step of calendering as a possibly preferred means of reducing the thickness of such an expanded membrane, e.g. a multi-layer porous membrane, in a controlled manner, to reduce the relative porosity of such an stretched membrane, e.g. a multi-layer porous membrane, in a controlled manner, and/or to improve strength, properties and/or technical characteristics of such an expanded membrane, for example, a multi-layer porous membrane, in a controlled manner, such as puncture strength, tensile strength in the longitudinal direction and/or in the transverse direction, uniformity, wettability, coatability, processability, sealing, springback, tortuosity, permeability, thickness, pin removal force, mechanical strength, surface roughness, hot tip hole propagation, and/or combinations thereof, of such a stretched membrane, such as a multi-layer porous membrane, in a controlled manner, and/ or to obtain a unique structure, porous structure, material, membrane, base film, and/or separator. Single or multi-layer microporous membranes with a thickness of 10 µm or less can be obtained by the process according to the invention. By the method according to the invention, multilayer microporous membranes of 10 µm or less thickness can be obtained, on which polymer-ceramic coatings are easily applied, having excellent mechanical strength characteristics due to their inner polypropylene layer, and/or exhibiting a thermal shutdown effect due to their outer polyethylene layers. The thickness ratio of polypropylene and polyethylene layers in such a multilayer microporous membrane according to the invention can be finely tuned to select, optimize and/or balance its strength, properties and/or technical characteristics such as mechanical strength and thermal shutdown characteristics.

In at least some embodiments, aspects, or purposes, the present application may address industry concerns, requests, or needs for stronger, thinner, more open, higher C, or higher performance separators, and/or may create new, improved or modified single or multi-layer dry-processed battery seals comprising microporous multi-layer separator membranes containing three layers of polyethylene/polypropylene/polyethylene, the membrane having been stretched in the longitudinal direction followed by stretching in the transverse direction, and then calendered using heat and pressure, and/or where the specified multilayer microporous membrane includes a polyolefin, which may contain polypropylene, polyethylene, a compound of polyolefins, a mixture of polyolefins, one or more polyolefin copolymers, and combinations thereof, and/or with a thermal shutdown function and/or where the ratio of thicknesses of the polyethylene/polypropylene/polyethylene layers varies from 0.05/0.90/0.05 to 0.25/0.50/0.25, and/or having a thickness of less than 20 µm, preferably less than 15 µm, more preferably less than 12 µm, more preferably less than 10 µm, and/or wherein the polyethylene/polypropylene/polyethylene microporous membrane has a relative porosity of preferably 20% to 55%, more preferably 30% to 50%, and most preferably from 35% to 50%, and/or where the polyethylene/polypropylene/polyethylene microporous membrane has a TD tensile strength of over 500 kgf/cm ² ; a ceramic coated microporous membrane as described above, comprising: a multilayer microporous membrane having a first and a second surface, a ceramic coating on at least one surface of said multilayer microporous membrane, said ceramic coating comprising ceramic particles, and may further include a polymeric binder material ; a new, improved or modified method, comprising:

extruding polypropylene to form a non-porous membrane precursor, and

extruding the polyethylene to form a non-porous membrane precursor, and

layering polypropylene and polyethylene in a multilayer polyethylene/polypropylene/polyethylene configuration, and

annealing the multilayer polyethylene/polypropylene/polyethylene non-porous multilayer membrane, and

stretching in the longitudinal direction of the polyethylene/polypropylene/polyethylene non-porous multilayer membrane to form an intermediate uniaxially stretched multilayer microporous membrane, and

stretching in the transverse direction of the intermediate uniaxially stretched polyethylene/polypropylene/polyethylene multilayer microporous membrane to form a second intermediate MD- and TD-stretched polyethylene/polypropylene/polyethylene multilayer microporous membrane, and

calendering a second intermediate MD- and TD-stretched polyethylene/polypropylene/polyethylene multilayer microporous membrane to form a polyethylene/polypropylene/polyethylene multilayer microporous membrane, and/or wherein the calendered MD- and TD-stretched polyethylene/polypropylene/polyethylene multilayer microporous membrane has a thickness less than 20 µm, preferably less than 15 µm, more preferably less than 12 µm, and more preferably less than 10 µm; a polyethylene/polypropylene/polyethylene battery seal made according to the above method, wherein the calendering temperature is less than 90 degrees Celsius; new or improved microporous multi-layer battery separator membrane, separators, batteries, including such separators, methods of making such membranes, separators and/or batteries, and/or methods of using such membranes, separators and/or batteries; a multilayer dry-processed polyethylene/polypropylene/polyethylene microporous separator which is made using a method according to the invention which includes stretching in the longitudinal direction followed by stretching in the transverse direction and a subsequent calendering step as a means of reducing the thickness of the multilayer microporous membrane, reducing the relative porosity of the multilayer microporous membrane in a controlled manner, and improve the tensile strength in the transverse direction; a thin multi-layer microporous membrane, which is easy to apply polymer-ceramic coatings, which has excellent mechanical strength characteristics due to its inner polypropylene layer, thermal shutdown function due to its outer polyethylene layers; the thickness ratio of the polypropylene and polyethylene layers in the inventive multilayer microporous membrane can be fine tuned to balance mechanical strength and thermal shutdown characteristics; and/or combinations thereof.

At least some embodiments, aspects or objectives of the present application or invention may provide new or improved multi-layer single or multi-layer battery separator membranes, separators, batteries, including such membranes or separators, methods for manufacturing such membranes, separators and / or batteries, and /or methods of using such membranes, separators and/or batteries. In accordance with at least some embodiments, a dry-processed polyethylene/polypropylene/polyethylene microporous separator that is made using the process of the invention that includes longitudinal stretching followed by transverse stretching and a subsequent calendering step as a means of reducing the thickness of the multilayer microporous membrane, to reduce the relative porosity of the multilayer microporous membrane in a controlled manner, and/or to improve the tensile strength in the transverse direction. In a very specific embodiment according to the invention, a thin multi-layer microporous membrane is obtained by the method according to the invention, which is easily applied with polymer-ceramic coatings, which has excellent mechanical strength characteristics due to its inner polypropylene layer or layers, and a thermal shutdown function due to its polyethylene layer or layers. The thickness ratio of the polypropylene and polyethylene layers in the inventive multilayer microporous membrane can be fine tuned to balance mechanical strength and thermal shutdown characteristics.

At least some embodiments, aspects or objectives of the present application or invention may meet the needs and/or may provide a new or improved multi-layer cut-off microporous membrane that has a thickness of less than 10 microns for use as a battery separator, and/or as a microporous substrates for polymer-ceramic coatings, to form a coated battery separator, a multi-layer cut-off microporous membrane with a thickness of less than 10 μm, which can be easily coated with polymer-ceramic materials, where the coating has excellent adhesion to the membrane and excellent adhesion to the electrode, a multi-layer switching off microporous membrane with a thickness of less than 10 µm, which can be coated based on polymer-ceramic materials, where the coating thickness can be less than 7 µm, the need for a multi-layer switching off microporous membrane with a thickness of less than 10 µm, which has excellent tensile strength in the longitudinal (MD) direction and transverse (TD) direction, and which can be easily coated with a polymer-ceramic coating, and/or combinations thereof.

The present application is directed to new or improved single or multi-layer battery separator membranes, membrane separators, or separators, and/or batteries or cells, including such membranes or separators, and/or methods for manufacturing such membranes, separators, cells, and/or batteries, and/or methods of using such membranes, separators, cells and/or batteries. In accordance with at least some embodiments, the present invention is directed to single or multilayer dry-processed polyolefin microporous membrane, membrane separator or separator (such as PP, PE, PP/PP, PE/PE, PP/PE, PP/ PE/PP, PE/PP/PE, PE/PP/PP, PP/PE/PE, PE/PP/PP/PE, PP/PE/PE/PP, PP/PP/PP, PE/PE/PE, PP-PE, PP-PE/PP, PP-PE/PE, PP-PE/PP/PP-PE, PP-PE/PE/PP-PE, or the like), which are produced using the method according to the invention, which includes stretching in the longitudinal direction followed by stretching in the transverse direction (with or without tension release in the longitudinal direction (MD) preferably with MD relaxation, such as 10-90% MD relaxation, 20-80% MD -relaxation, 30-70% MD-relaxation, or 40-60% MD-relaxation, or at least 20% MD-relaxation), and a subsequent calendering step, as a means of reducing the thickness of the membrane, reducing relative membrane porosity in a controlled manner, and/or to improve transverse tensile strength. By the method according to the invention, a single-layer or multi-layer microporous membrane, separation membrane, base film or separator having a thickness of 10 µm or less can be obtained, on which polymer-ceramic coatings having excellent mechanical strength characteristics due to their polypropylene(s) layer(s) can be easily applied. -pits), and/or exhibiting a thermal shutdown effect due to their polyethylene(s) layer(s). The thickness ratio of the polypropylene and polyethylene layers in the inventive multilayer microporous membrane can be fine tuned to balance mechanical strength and thermal shutdown characteristics.

TEST METHODS

Thickness

Thickness is measured using an Emveco Microgage 210-A Precision Micrometer Thickness Gauge according to ASTM D374 test method. Thickness values are recorded in units of micrometers, microns.

Gurley exponent

The Gurley index is regulated by the Japanese Industrial Standard (JIS Gurley) JIS P8117, and is an air permeability test measured using an OHKEN permeability tester. The JIS Gurley value is the time in seconds required to force 100 cm ^{3 of} air through one square inch (6.45 cm ² ) of film at a constant pressure of 4.8 inches (12.19 cm) of water.

Penetration strength

The test pieces are preconditioned at 73.4 degrees Celsius and 50% relative humidity for a minimum of 20 minutes. An Instron Model 4442 instrument is used to measure the piercing strength of the test piece. Thirty measurements are taken along the diagonal direction of a 1¼" x 40" (3.17 x 101.6 cm) solid piece and averaged. The tip of the piercing needle has a radius of 0.5 mm. The lowering speed of the piercing needle is 25 mm/min. The film is held tightly in a clamping device that uses an O-ring to hold the test piece firmly in place. The diameter of this fixed area is 25 mm. The displacement (in mm) of the film which is pierced by the penetrating needle is recorded as a function of the resistance force (in gram-force) exerted by the film under test. The maximum drag force is the piercing strength in units of gram-force (gs). As a result of this test method, a load versus displacement plot is plotted.

Porosity

The porosity of a microporous film sample is measured using ASTM D-2873 and is expressed as the percentage of pore space in the microporous membrane.

TD and MD Tensile Strength

Tensile strength along the longitudinal (MD) direction and the transverse (TD) direction is measured using an Instron Model 4201 instrument by the method according to ASTM D-882.

Electrical resistance (ER)

The electrical resistance is defined as the resistance value in ohm-cm ^{2 of} the separator filled with electrolyte. Separator resistance is characterized by cutting off small pieces of separators from the finished material, and then placing them between two blocking electrodes. The separators are saturated with battery electrolyte with a 1.0 M LiPF ₆ salt solution in an EC/EMC (ethylene carbonate/ethyl methyl carbonate) solvent in a 3:7 volume ratio. The resistance R, in ohms (Ω), of the separator is measured by the 4-probe AC impedance method. To reduce measurement error at the electrode/separator interface, multiple measurements are required with the addition of more layers. Based on the measurements on multiple layers, the electrical (ionic) resistance R _S (Ω) of the electrolyte-saturated separator is then calculated by the formula R _s =p _s l/A, where p _s represents the ionic resistivity of the separator in Ω-cm, A represents the electrode area in cm ² and l represents the thickness of the separator in cm. The ratio p _s /A=is the slope of the curve calculated for the change in the resistance of the cage (ΔR) with multiple layers (Δδ), which is given by the expression slope=p _s /A=ΔR/Δδ .

Relative MD and TD elongation in %

The % MD elongation or % MD elongation at break is the percentage expansion in the longitudinal direction of the test piece, measured at the maximum tensile strength required to break the test piece. The % TD elongation or % TD elongation at break is the percentage transverse extension of the test specimen measured at the maximum tensile strength required to break the specimen.

Roughness:

To measure membrane surface characteristics, a Nanovea ST400 3D profilometer was used using a 12 µm (diameter) needle. Scanning is carried out using a non-contact optical linear sensor, and quantification is carried out using an analytical software package.

Coefficient of Friction (COF):

a Rhesca FPR-2000 Friction Player reciprocating slip tester was used to determine the membrane skin friction coefficient.

Hot tip hole propagation test:

In the hot tip hole propagation test, a hot tip probe at 450°C with a tip diameter of 0.5 mm is touched to the surface of the isolating membrane. The hot tip probe approaches the diaphragm at a rate of 10 mm/minute and is brought into contact with the surface of the isolating diaphragm for a period of 10 seconds. The results are recorded using a digital image obtained with an optical microscope showing both the shape of the hole formed by the response of the separation membrane to the touch of the hot tip probe at 450°C and the diameter of the hole in the separator after removal of the hot tip probe. The minimum spread of a seal hole from contact with a hot tip probe simulates the desired response of the seal to a localized hot spot that can occur during an internal short circuit in Li-ion cells.

The present invention may be embodied in other forms without departing from its spirit and essential features, and accordingly, reference should be made to the appended claims rather than to the foregoing description as showing the scope of the invention. Moreover, the invention illustratively disclosed herein may be properly practiced in the absence of any element not specifically disclosed herein.

One embodiment of the invention is a battery separator for a lithium battery, comprising at least one microporous membrane having at least one outer surface or surface layer having/having a unique pore structure, with a pore representing a hole or space between adjacent lamellae, and which may be delimited on one or both sides by a fibril or bridging structure between adjacent lamellae, and wherein at least a portion of the membrane comprises respective groups of pores between adjacent lamellae, the lamellae being oriented substantially along the transverse direction, and the fibrils or bridging structures between adjacent lamellae are oriented essentially along the longitudinal direction, and the outer surface of at least some of the lamellae is essentially flattened or planar, and moreover, the pore structure has at least one of: essentially trapezoidal or rectangular pores, pores with rounded corners lamellae, compressed or massive lamellae along the width or transverse direction, somewhat chaotic or less ordered pores, groups with areas of missing or broken fibrils, densified lamellar framework structure, groups of pores with a TD/MD-length ratio of at least 4, groups of pores with a TD/MD length ratio of at least 6, groups of pores with a TD/MD length ratio of at least 8, groups of pores with a TD/MD length ratio of at least 9, groups of pores with at least 10 fibrils, groups pores with at least 14 fibrils, groups of pores with at least 18 fibrils, groups of pores with at least 20 fibrils, compressed or compressed layered lamellae, uniform surface, slightly non-uniform surface, low COF value, or combinations thereof.

The pore structure is a relatively closed structure as a result of the lamella structure being compressed or compressed in the thickness direction, and some surface-extended micropores may be present in the membrane.

The membrane is a polyolefin microporous membrane.

The membrane is a dry-formed membrane.

The membrane has a thickness of 5 µm to 25 µm, and at least one of:

efforts to remove the pin from 200-900 gram-force,

Gurley index (JIS), seconds, from 50-250,

porosity from 30% -90%,

piercing strength from 150 g-600 g,

tensile strength ratio in MD/TD directions from 1.45-2.2, and

the hole spread value from the hot tip is 2 to 4 mm.

The membrane has at least one of: a surface roughness of 0.0 to 1.5 µm, a crimp greater than 1, a crimp greater than 2, a COF of less than 0.3, a pin removal force of less than 900 gram-force, a pin removal force of less than 800 gram-force, a Gurley index below 200, and a piercing strength of at least 400 g.

The membrane is a dry-formed single or multi-layer microporous polymeric membrane, wherein the membrane has been subjected to longitudinal stretching and transverse stretching, either sequentially or simultaneously, and then calendered using at least pressure.

The roll used for calendering may be smooth, textured, roughened, convex, concave, or otherwise shaped.

The membrane is a polymeric membrane that includes a polyolefin, which may include polypropylene, polyethylene, a polyolefin compound, a polyolefin blend, one or more polyolefin copolymers, and combinations thereof.

The membrane is at least one of: a thermal trip membrane, provides improved battery cycling, has improved uniformity, and may be resistant to springback during battery assembly.

The membrane thickness was reduced by calendering by 2-80%.

The calendering is at least one of symmetrical and asymmetric calendering.

The membrane is a polyethylene/polypropylene/polyethylene membrane, and in which the thickness ratio of polyethylene/polypropylene/polyethylene layers varies from 0.05/0.90/0.05 to 0.25/0.50/0.25.

The polyethylene/polypropylene/polyethylene microporous membrane has a relative porosity of preferably 20% to 75%, more preferably 30% to 70%, and most preferably 35% to 65%.

The membrane has a thickness of less than 20 microns, preferably less than 15 microns, more preferably less than 12 microns, more preferably less than 10 microns.

The membrane has a TD tensile strength of over 400 kgf/cm2.

The diaphragm is a microporous, ceramic-coated isolating diaphragm comprising:

a multilayer microporous membrane having a first and a second surface,

a ceramic coating on at least one surface of said multilayer microporous membrane,

wherein said ceramic coating comprises ceramic particles, and may further comprise a polymeric binder, and wherein at least one layer of said multilayer membrane is an MD-stretched, TD-stretched and calendered membrane.

The membrane is a dry-formed single or multi-layer microporous polymeric membrane comprising at least one microporous polymeric separation membrane, wherein the membrane has been subjected to longitudinal stretching and transverse stretching, either sequentially or simultaneously, and at least then calendered using at least pressure, at least to enhance the crimp.

One of the embodiments of the invention is a battery, including the above separator.

One embodiment of the invention is a vehicle including the above battery.

One embodiment of the invention is a method or process for manufacturing a biaxially stretched and calendered porous polymer single or multilayer membrane for a separator, comprising:

extruding the polymer to form a non-porous membrane precursor, layer or material,

sequential and/or simultaneous biaxial stretching of a non-porous membrane, layer or material to form an intermediate stretched porous membrane, and

calendering the intermediate stretched porous membrane to form a biaxially stretched and calendered membrane,

moreover, the membrane has at least one outer surface or surface layer having/having a unique pore structure, with a pore representing an opening or space between adjacent lamellae, and which can be limited on one or both sides by a fibril or a bridge structure between adjacent lamellae, and moreover, at least part of the membrane contains the corresponding groups of pores between adjacent lamellae, and the lamellae are oriented essentially along the transverse direction, and the fibrils or bridge structures between adjacent lamellae are oriented essentially along the longitudinal direction, and the outer surface of at least some of the lamellae is along essentially flattened or planar, and wherein the pore structure has at least one of: essentially trapezoidal or rectangular pores, rounded pores, compressed or massive lamellae along the width or transverse direction, somewhat chaotic or less ordered pores, groups n with areas of missing or broken fibrils, densified lamellar scaffolding, pore groups with a TD/MD-length ratio of at least 4, pore groups with a TD/MD-length ratio of at least 6, pore groups with a TD/MD-length ratio at least 8, groups of pores with a TD/MD-length ratio of at least 9, groups of pores with at least 10 fibrils, groups of pores with at least 14 fibrils, groups of pores with at least 18 fibrils, groups of pores of at least at least 20 fibrils, compressed or compressed layered lamellae, uniform surface, slightly non-uniform surface, low COF value, or combinations thereof.

One of the embodiments of the invention is a new, improved or modified method, including:

extruding polypropylene to form a non-porous membrane precursor, and

extruding the polyethylene to form a non-porous membrane precursor, and

layering polypropylene and polyethylene in a multilayer polyethylene/polypropylene/polyethylene configuration, and

annealing the multilayer polyethylene/polypropylene/polyethylene non-porous multilayer membrane, and

stretching in the longitudinal direction of the polyethylene/polypropylene/polyethylene non-porous multilayer membrane to form an intermediate uniaxially stretched multilayer microporous membrane, and

stretching in the transverse direction of the intermediate uniaxially stretched polyethylene/polypropylene/polyethylene multilayer microporous membrane to form a second intermediate MD- and TD-stretched polyethylene/polypropylene/polyethylene multilayer microporous membrane, and

calendering a second intermediate MD- and TD-stretched polyethylene/polypropylene/polyethylene multilayer microporous membrane to form a polyethylene/polypropylene/polyethylene multilayer microporous membrane.

The calendered MD- and TD-stretched polyethylene/polypropylene/polyethylene multilayer microporous membrane has a thickness of less than 20 µm, preferably less than 15 µm, more preferably less than 12 µm, and more preferably less than 10 µm

The calendering step may be carried out before stretching.

Ceramic coating is included in the calendering process.

One embodiment of the invention is a polyethylene/polypropylene/polyethylene battery seal made by the method described above, where the calendering temperature is less than 90 degrees Celsius.

One of the embodiments of the invention are new, improved or modified membranes, multilayer membranes, separation membranes, calendered membranes, expanded membranes, expanded and calendered membranes, separation membranes, coated membranes, membrane separators, battery separators, and / or batteries or cells, including such membranes or separators, and/or methods of making such membranes, separators, cells and/or batteries, and/or methods of using such membranes, separators, cells and/or batteries; and/or the like as shown or described here.

One of the embodiments of the invention is a method for manufacturing a biaxially stretched and calendered porous polymeric single-layer or multi-layer membrane for a separator, including:

extruding the polymer to form a non-porous membrane, layer or material precursor,

sequential and/or simultaneous biaxial stretching of a non-porous membrane, layer or material to form an intermediate stretched porous membrane, and

calendering the intermediate stretched porous membrane to form a biaxially stretched and calendered membrane,

wherein the membrane has at least one outer surface or surface layer having/having a unique pore structure with a pore being an opening or space between adjacent lamellae and which may be delimited on one or both sides by a fibril or bridge structure between adjacent lamellae, and moreover, at least a part of the membrane contains the corresponding groups of pores between adjacent lamellae, and the lamellae are oriented essentially along the transverse direction, and the fibrils or bridge structures between adjacent lamellae are oriented essentially along the longitudinal direction, and the outer surface of at least some of the lamellae is essentially flattened or planar, and wherein the pore structure has at least one of: essentially trapezoidal or rectangular pores, pores with rounded corners, compressed or massive lamellae along the width or transverse direction, rather chaotic or less ordered pores, groups of pores with o areas of missing or broken fibrils, compacted lamellar scaffolding, pore groups with a TD/MD-length ratio of at least 4, pore groups with a TD/MD-length ratio of at least 6, pore groups with a TD/MD-length ratio of at least at least 8, groups of pores with a TD/MD-length ratio of at least 9, groups of pores with at least 10 fibrils, groups of pores with at least 14 fibrils, groups of pores with at least 18 fibrils, groups of pores with at least 20 fibrils, compressed or compressed layered lamellae, uniform surface, slightly non-uniform surface, low COF value, or combinations thereof.

The above method is a dry method.

One of the embodiments of the invention is a method for manufacturing a multilayer microporous membrane, including:

extruding polypropylene to form a non-porous membrane precursor, and

extruding the polyethylene to form a non-porous membrane precursor, and

layering polypropylene and polyethylene in a polyethylene/polypropylene/polyethylene multilayer configuration, and

annealing the multilayer polyethylene/polypropylene/polyethylene non-porous multilayer membrane, and

stretching in the longitudinal direction of the polyethylene/polypropylene/polyethylene non-porous membrane to form an intermediate uniaxially stretched multilayer microporous membrane, and

stretching in the transverse direction of the intermediate uniaxially stretched polyethylene/polypropylene/polyethylene multilayer microporous membrane to form a second intermediate MD- and TD-stretched polyethylene/polypropylene/polyethylene multilayer microporous membrane, and

calendering a second intermediate MD- and TD-stretched polyethylene/polypropylene/polyethylene multilayer microporous membrane to form a polyethylene/polypropylene/polyethylene multilayer microporous membrane.

In the above process, the calendered MD- and TD-stretched polyethylene/polypropylene/polyethylene multilayer microporous membrane has a thickness of less than 20 µm, preferably less than 15 µm, more preferably less than 12 µm, and more preferably less than 10 µm.

In the above process, the calendering step may be carried out before stretching.

In the above method, ceramic coating is included in the calendering process.

The above method is a dry method.

One of the embodiments of the invention is a method for manufacturing a biaxially stretched and calendered porous polymeric single-layer or multilayer membrane, including:

extruding the polymer to form a non-porous membrane precursor, layer or material,

sequential and/or simultaneous biaxial stretching of a non-porous membrane, layer or material to form an intermediate stretched porous membrane, and

calendering the intermediate stretched porous membrane to form a biaxially stretched and calendered membrane,

wherein the membrane has at least one outer surface or surface layer having/having a unique pore structure, compressed or compressed layered lamellae, a uniform surface, a slightly non-uniform surface, a low COF value, and/or combinations thereof.

The above method is a dry method.

One of the embodiments of the invention is a method for manufacturing a stretched and calendered porous polymeric single-layer or multilayer membrane, including:

extruding the polymer to form a non-porous membrane precursor, layer or material,

stretching the non-porous membrane, layer or material to form an intermediate stretched porous membrane, and

calendering the intermediate stretched porous membrane to form the stretched and calendered membrane,

wherein the membrane has at least one outer surface or surface layer having/having a unique pore structure, surface roughness, compressed or compressed layered lamellae, a uniform surface, a slightly non-uniform surface, a low COF value, and/or combinations thereof.

The above method is a dry method.

One of the embodiments of the invention is a stretched and calendered porous polymeric single-layer or multi-layer membrane containing:

stretched and calendered porous or microporous polymeric membrane,

wherein the stretched and calendered porous or microporous polymeric membrane has at least one outer surface or surface layer having/having a unique pore structure, surface micro-roughness, compressed or compressed layered lamellae, a macro-homogeneous surface, a slightly non-uniform surface, a low COF value, and/or their combinations.

The stretched and calendered porous or microporous polymeric membrane is a dry-processed membrane.

One embodiment of the invention is a biaxially stretched and calendered porous or microporous membrane having higher puncture strength, TD tensile strength, or MD tensile strength, compared to the same membrane that is biaxially stretched but not calendered.

One embodiment of the invention is a biaxially stretched and calendered porous or microporous membrane having puncture strength, TD tensile strength, and MD tensile strength compared to the same membrane that is biaxially stretched but not calendered.

Claims (53)

1. A battery separator for a lithium battery, comprising: at least one calendered, dry-processed microporous membrane having at least one outer surface having a pore structure with a pore opening between adjacent lamellae, which is bounded on one or both sides by a fibrillar bridge structure between adjacent lamellae; wherein at least a portion of said at least one calendered, dry-produced microporous membrane comprises respective groups of pores between adjacent lamellae, wherein the lamellae are oriented along the transverse direction, and the fibrillar bridge structures between adjacent lamellae are oriented along the longitudinal direction, and the outer surface is at least at least some of the lamellas are planar; the pore structure has at least one of: trapezoidal or rectangular pores, pores with rounded corners, compressed or massive lamellae along the width direction, randomly distributed pores, groups of pores with areas of missing or broken fibrils, compacted lamellar framework structure, groups of pores with a ratio of length in the transverse direction (TD) to length in the longitudinal direction (MD) of at least 4, groups of pores with at least 10 fibrils, the pores are closed slits and arranged as compressed layered lamellae, coefficient of friction (COF) less than 0.3, or combinations thereof. 2. The battery separator of claim 1, wherein the membrane is a polyolefin microporous membrane. 3. Battery separator according to claim 1, in which the membrane has a thickness of 5 microns to 25 microns and at least one of: efforts to remove the pin from 200-900 gram-force, Gurley's JIS indicator, seconds, from 50-250, porosity from 30% -90%, piercing strength from 150 g-600 g, longitudinal (MD)/transverse (TD) tensile strength ratio from 1.45-2.2, and the hole spread value from the hot tip is 2 to 4 mm. 4. Battery separator according to claim 3, wherein the membrane has at least one of: surface roughness from 0.0 to 1.5 µm, crimp over 1, crimp over 2, coefficient of friction (COF) less than 0.3, effort less than 900 gram-force for pin removal, less than 800 gram-force for pin removal, a JIS Gurley score less than 200 seconds, and a piercing strength of at least 400 g. 5. The battery separator of claim 3, wherein the membrane is a single or multi-layer dry-processed microporous polymer membrane, wherein the membrane is longitudinally stretched and transversely stretched, either sequentially or simultaneously, and then calendered using pressure. . 6. The accumulator separator according to claim 5, wherein the roller used for calendering is selected from the group consisting of smooth and textured or rough, which has a convex or concave profile. 7. The battery separator of claim 1, wherein the membrane is a polymeric membrane that contains a polyolefin, which includes polypropylene, polyethylene, a polyolefin compound, a polyolefin blend, one or more polyolefin copolymers, and combinations thereof. 8. The battery separator of claim 1, wherein the membrane has at least one of: a thermally tripping membrane, battery cycling, uniformity, and is resistant to springback during battery assembly. 9. An accumulator separator according to claim 1, wherein the membrane thickness has been reduced by 2-80% by calendering. 10. An accumulator separator according to claim 9, wherein the calendering is at least one of symmetrical and asymmetric calendering. 11. Battery separator according to claim 1, in which the membrane is a polyethylene / polypropylene / polyethylene membrane, and the ratio of the thicknesses of polyethylene / polypropylene / polyethylene layers varies from 0.05 / 0.90 / 0.05 to 0.25 / 0, 50/0.25. 12. The accumulator separator according to claim 11, wherein the polyethylene/polypropylene/polyethylene microporous membrane has a relative porosity of 20% to 75%. 13. Battery separator according to claim 1, wherein the membrane has a thickness of less than 20 microns. 14. The accumulator separator according to claim 1, in which the membrane has a tensile strength in the transverse direction (TD) in excess of 400 kgf/cm ² . 15. The battery separator of claim. 1, in which the membrane is a microporous ceramic-coated separation membrane, containing: a multilayer microporous membrane having a first and a second surface, a ceramic coating on at least one surface of the multilayer microporous membrane, wherein the ceramic coating comprises ceramic particles and a polymeric binder, and wherein at least one layer of the multilayer membrane is a longitudinally stretched (MD), transversely stretched (TD) and calendered membrane. 16. The battery separator of claim. 1, in which the membrane is a dry-made single- or multi-layer battery separator membrane, including at least one microporous polymeric separation membrane, and the membrane has been subjected to stretching in the longitudinal direction and stretching in the transverse direction, or sequentially or simultaneously, and at least then calendered using at least pressure, at least to enhance the crimp. 17. A battery containing a separator according to any one of paragraphs. 1-16. 18. A vehicle containing a battery according to claim 17. 19. A method for manufacturing a biaxially stretched and calendered porous polymeric single-layer or multi-layer membrane for a separator, including: extruding the polymer in the absence of solvent or oil to form a non-porous membrane precursor, sequential or simultaneous biaxial stretching of the non-porous membrane precursor to form an intermediate stretched porous membrane, and calendering the intermediate stretched porous membrane to form a biaxially stretched and calendered membrane, moreover, the biaxially stretched and calendered membrane has at least one outer surface having a pore structure with a pore representing an opening between adjacent lamellae, which is limited on one or both sides by a fibrillar bridge structure between adjacent lamellae, at least a portion of the biaxially stretched and calendered membrane contains respective groups of pores between adjacent lamellae, wherein the lamellae are oriented along the transverse direction, and the fibrillar bridge structures between adjacent lamellae are oriented along the longitudinal direction, and the outer surface of at least some of the lamellae is planar, the pores are closed slits arranged as compressed layered lamellae, coefficient of friction (COF) less than 0.3, or combinations thereof. 20. A method for manufacturing a separator for a lithium battery, including: extruding polypropylene in the absence of solvent or oil to form a first non-porous membrane precursor, extruding polyethylene in the absence of solvent or oil to form a second non-porous membrane precursor, layering polypropylene and polyethylene in a multilayer polyethylene/polypropylene/polyethylene configuration to form a multilayer polyethylene/polypropylene/polyethylene membrane, annealing of multilayer polyethylene/polypropylene/polyethylene membrane, stretching in the longitudinal direction of a multilayer polyethylene/polypropylene/polyethylene membrane with the formation of an intermediate uniaxially stretched multilayer microporous membrane, stretching in the transverse direction of the intermediate uniaxially stretched multilayer microporous membrane to form a second intermediate stretched in the longitudinal (MD) and transverse (TD) directions polyethylene/polypropylene/polyethylene multilayer microporous membrane, and calendering the second intermediate longitudinally (MD) and transversely (TD) stretched polyethylene/polypropylene/polyethylene multilayer microporous membrane to form the final polyethylene/polypropylene/polyethylene multilayer microporous membrane, moreover, the final polyethylene / polypropylene / polyethylene multilayer microporous membrane has a ratio of thicknesses of polyethylene / polypropylene / polyethylene layers from 0.05 / 0.90 / 0.05 to 0.25 / 0.50 / 0.25, and the pores in the polyethylene layers are closed slots arranged in the form of layered lamellae. 21. The method of claim 20 wherein the second intermediate longitudinally (MD) and transversely (TD) stretched polyethylene/polypropylene/polyethylene multilayer microporous membrane has a thickness of less than 20 microns. 22. The method of claim 20, wherein the calendering is performed prior to stretching. 23. The method of claim 20 wherein ceramic coating is included in calendering. 24. A polyethylene/polypropylene/polyethylene battery separator membrane made by the method of claim 20 wherein the calendering temperature is less than 90 degrees Celsius.

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