Improved multilayer microporous separator and related method for lithium-ion secondary batteries

Abstract

To provide an improved multilayer laminate micro porous battery separator for a lithium ion secondary battery and / or a method for manufacturing the separator or a method for using the separator.SOLUTION: A dry process separator of a desirable present invention has a three-layer-lamination micro porous film of polypropylene, polyethylene, and polypropylene having a thickness of 12 μm to 30 μm, the film exhibiting an improved cycle performance of a lithium ion battery and an improved piercing strength and a low electric resistance for the charge performance. Also, a low electric resistance and a high porosity of the separator or the film of a further desirable invention provides an excellent charge rate characteristic of a high-output lithium battery.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] Cross-references to related applications This application is concurrently pending with U.S. Provisional Patent Application No. 62 / 0 filed on November 26, 2014. Claiming priority and interest in Patent No. 84,655. This application is in its entirety as referred to herein. It will be incorporated.

[0002] In at least selected embodiments, the present invention or this application relates to novel or improved batteries. Separators, base films or membranes, and / or such separators, films Or the present invention relates to a method for manufacturing and / or using a film, in at least certain selected embodiments. This invention or application relates to a novel or improved single-layer battery for lithium-ion secondary batteries. or multilayer co-extruded or laminated microporous battery separators, and / or such separators The present invention relates to a method for manufacturing and / or using a data. In at least certain selected embodiments, This invention relates to novel or improved multilayer microporous battery cells for lithium-ion secondary batteries. This relates to a separator, and / or a method for manufacturing and / or using the separator. The dry process separator of the present invention, which may be preferable, improves lithium-ion batteries. It has improved puncture resistance and low electrical resistance for enhanced cycle and charge performance. Three-layer laminated polypropylene / polyethylene / polypropylene with a thickness ranging from 12 μm to 30 μm. It is a pyrene (PP / PE / PP) microporous membrane. Furthermore, a preferred separator of the present invention The low electrical resistance and high porosity of the film contribute to the superior charge rate performance of lithium batteries for high-power applications. Give. [Background technology]

[0003] Various methods for increasing the mechanical strength of microporous separator films for lithium-ion secondary batteries A method exists to improve the mechanical strength of dry-process microporous battery separator films. One such method is discussed in U.S. Patent No. 6,602,593. , based on the use of a blow-up ratio (BUR) of at least 1.5 during the implementation of the Inflation Act. As is known to those skilled in the art, the blow-up ratio method is used to blow up the infras from the annular die. The rate film undergoes radial elongation. Extrusion molding is performed using a blow-up ratio of 1.5 or higher. An increase in the level of crystal structure orientation in the transverse direction (TD) of the film was achieved.

[0004] U.S. Patent No. 8,795,565 describes a controlled longitudinal (MD) relaxation process step. Regarding the biaxial stretching technique involving both MD and TD stretching of dry process precursor films: It is stated that biaxially oriented films have improved mechanical strength in the longitudinal (MD) and TD directions. It possesses excellent strength performance when used as a battery separator film in lithium-ion batteries. This can be predicted.

[0005] U.S. Patent No. 8,486,556 states that the strength as defined by the mixed penetration strength test method has been improved. This invention discloses a multilayer battery separator. This strength prevents short circuits from forming through the separator film. This is a measure of the force required to do so. A polypropylene multilayer separator membrane with a PP / PE / PP three-layer structure. High melt flow index of 1.2 grams / 10 min or less, measured in the pyrene layer. Using molecular weight polypropylene resin, thickness in the range of 21-24.5 μm, 35-37% Porosity in the range of 18-19 seconds (ASTM Guarley = 450-475 seconds) (Same as above), and 2.1-2.3 ohms-cm 2The electric resistance (ER) within the range of (the same as ionic resistance, IR in terms of terminology) of the multilayer separator was manufactured. Similarly, a wet process microporous battery separator that is usually biaxially stretched and can have substantially uniform MD and TD strength characteristics is also known. Examples of microporous membranes manufactured using the wet process may be those of U.S. Patent Nos. 5,051,183, 6,096,213, 6,153,133, and 6,666,969.

[0006] Wet process battery separator membranes usually use extremely high molecular weight polymer resins having a molecular weight exceeding 500,000, more preferably exceeding 1,000,000, and the use of a plasticizer (single or plural) is necessary to enable melt extrusion. Furthermore, components known as plasticizers (single or plural) are typically oils, but they need to be used for melt extrusion of extremely high molecular weight resins. The plasticizer needs to be extracted using a solvent as part of the manufacturing process. The oil plasticizer-containing solvent from the extraction step of the manufacturing process needs to be recycled to make the extraction solvent and oil of usable purity quality. This results in additional high-cost energy consumption. Therefore, compared with a solvent-free, "environmentally friendly", less-impact, and inexpensive dry process method, the wet process is a process that may have environmental issues in some cases and has high-cost solvent handling and waste problems.

[0007] BUR inflation film method, known methods for TD stretching of dry process membranes and biaxially stretched porous membranes of the wet process further have a low electric resistance (ER), 2 ohm-cm

[0008] 2 2 2 2 2 2 2 2 2 2 2 2 2Less than Not only the ER range, but also 1.3 ohms-cm 2 The following are much lower and more preferable ER ranges Even so, it is necessary to achieve excellent strength performance characteristics.

[0009] Therefore, lithium-ion batteries possess excellent cycle performance and safety. A dry process for manufacturing porous battery separators or membranes, which is solvent-free and has a low environmental impact. There is a need for such processes. High-power applications, for example, the electric vehicle (EDV) industry. The battery manufacturer preferably has a thickness in the range of 14 to 30 μm, microporous, and optimal high energy We require a microporous battery separator with a high charge rate (C rate) for optimal performance. They are requesting it. Furthermore, these EDVs and hybrid electric vehicles (HEVs) A dry process microporous battery separator or membrane that meets the requirements of a battery system. It is necessary. [Overview of the project]

[0010] In at least one selected embodiment, aspect, or object, the present invention addresses the above-mentioned need. and / or new or improved battery separators, base films or membranes , and / or methods for manufacturing such separators, films or membranes and / or use Regarding usage, in at least certain selected embodiments, aspects, or objects, the present invention Alternatively, this application relates to novel or improved single-layer or multi-layer lithium-ion secondary batteries. Co-extruded or laminated microporous battery separators, and / or manufacturing of such separators The present invention relates to a method and / or method of use. In at least certain selected embodiments, the present invention is New and This relates to an improved multilayer microporous battery separator, and / or a method for manufacturing this separator. Regarding the method and / or method of use. A potentially preferred dry process separator of the present invention. The regulator has improved transient response for improved cycle performance and charging performance of lithium batteries. Three-layer laminated polypropylene with a thickness ranging from 14 μm to 30 μm, possessing puncture resistance and low electrical resistance. It is a polyethylene / polypropylene (PP / PE / PP) microporous membrane. Furthermore, The low electrical resistance and high porosity of the separator or film of the present invention are desirable for high-power applications (e.g.) This provides excellent charge rate (C-rate) performance for lithium batteries used in EDVs or HEVs. .

[0011] A novel microporous battery separator was developed for use in lithium-ion batteries. The separator film, separator, base film, or film of the present invention, which may be suitable for use, Includes a three-layer structure of polypropylene / polyethylene / polypropylene (PP / PE / PP). It is a multilayer microporous battery separator or film. Multilayer PP / PE / PP is It includes a thermal shutdown function provided by the inner PE layer. Furthermore, the outer PP layer is s It provides excellent oxidation resistance for improving coolant performance and trickle charge performance. Preferred The polypropylene layer is produced by extrusion molding, without the need for plasticizers, resulting in a high level of crystalline structure. High molecular weight and low melt flow are used to produce precursor films with an internal microstructure having melamine orientation. Index polypropylene resin or high molecular weight, low melt flow index polypropylene It is manufactured using a blend of pyrene resin. This high level of crystalline material in the precursor film of the PP layer Lamellar orientation plays a crucial role in the improved mechanical strength performance of the separator porous membrane of the present invention. It can fulfill a role. Furthermore, the degree of crystallinity in the lamellar structure is a key factor in the manufacturing process of microporous separator films. It can play an important role in the formation of micropores during the stretching step of PP / PE / P The pore size and porosity of the porous layer in a P separator or membrane constitute the overall microstructure. It will have a significant impact on the cent.

[0012] The multilayer separator and base film of the present invention (coated or laminated with other layers) The film is constructed in such a way as (CELGARD®) It can be prepared by a dry process, which generally prepares PP and PE non-porous materials. The main body is extruded separately, and the non-porous precursor is joined together in the PP / PE / PP laminated structure. To combine to form a bonded non-porous PP / PE / PP precursor, and to stretch to form a microporous poly The process involves forming a layer film, and pore formation is performed on a non-porous, semi-crystalline extruded polymer. This is achieved by stretching the precursor in the longitudinal (MD) direction.

[0013] The preferred film of the present invention, having low ER, high porosity, low guarley, and high puncture strength, is high output Improved lithium or lithium-ion batteries for use in end-use applications It has a longer lifespan and / or a higher level of safety.

[0014] Transverse (TD) stretching achieved by radial stretching of the inflated extruded precursor film. The improved crystal structure orientation enhances mechanical strength, particularly TD tensile strength and TD elongation. It was revealed that a reduction in longitudinal (MD) delamination of the stretched microporous membrane occurs.

[0015] A typical multilayer film of the present invention having a preferred thickness in the range of approximately 12 to 30 μm is 38% or The above shows high porosity, 1.5 ohms-cm². 2 The following low electrical resistance and less than 320 seconds / 100cc Due to the low JIS Gurley, it offers higher charge rate performance compared to prior art battery separator films. The ER and high porosity of the battery separator contribute to the high level of ionic conductivity of the electrolyte. To facilitate connectivity and / or promote the long cycle life of lithium-ion rechargeable batteries.

[0016] To achieve low ER and high porosity, the multilayer separator film of the present invention has a high molecular weight and low It is preferable to manufacture using melt flow index polypropylene polymer resin. This resin is melt-pressed using a dry process without the use of solvents and extraction steps. When released, it results in a high level of crystalline lamellar content in the precursor film. When a precursor film having crystalline lamellae is stretched to form pores, the resulting microporous film is protruding. It exhibits increased puncture strength, low ER, and high porosity. The separator remains effective throughout the battery's lifespan. It needs to have high mechanical strength to withstand harsh cell assemblies and charge / discharge cycles. The separator of the present invention has a thickness of 14 μm and a strength of 330 gf to 54 μm and a strength of 30 μm. It is preferable to have a puncture strength in the range of up to 9 gf. The dry process microporous electron of the present invention The battery separator membrane is important from the perspective of battery cycle life and safety performance of lithium-ion secondary batteries. Furthermore, is the performance equal between the dry process and the wet process battery separator microporous film? It is preferable that it has better separator performance characteristics.

[0017] In the dry process, the pore formation method in the stretching step includes longitudinal stretching, which is, The layered crystalline lamellar plates are separated, the polymer fibrils are stretched, and rectangular pores are formed. Formed. The amount of crystallinity in the lamellar structure of the non-porous PP layer of the precursor film is determined by the dry process. This may be an important factor in the formation of the internal porous microstructure of stretched microporous membranes. XMZhang , et al. “Oriented Structure and Anisotropy Pr operations of Polymer Blown Films HDPE,LLD "PE and LDPE", in POLYMER 45 (2004) 217-229, S. Tabatabaei, et al. “Microporous Membranes O btained from PP / HDPE Multilayer Films by In "Stretching", JMS 345 (2009) 148-159, the crystalline phase It has been mentioned that the structure strongly influences the mechanical properties of the film. When a precursor film with a high crystalline lamellar content is stretched to form pores, the resulting microporous film is It exhibits increased puncture strength, low ER, and high porosity. Each of these factors From the standpoint of battery cycle life and safety of lithium-ion secondary batteries, the separator film It contributes to high-level performance. [Brief explanation of the drawing]

[0018] [Figure 1] This is a surface SEM micrograph of an etched PP film exhibiting a uniform and ordered lamellar structure. [Figure 2] This is a stress-strain plot of PP and HDPE films. [Figure 3] This is a 20,000x magnification SEM image of the surface of a CE6 microporous film. [Figure 4]This is a 20,000x magnification SEM image of the surface of a CE5 microporous film. [Figure 5] This is a schematic diagram of chain folding and molecular-level polymer structure during folding in polypropylene (see “The Theory of Birefringence”, Cambridge Polymer Group, 2004, CPGAN # 014, www.campoly.com). [Figure 6] This is an SEM micrograph of the surface of the film in Ex.2 of the present invention. [Figure 7] This is an SEM micrograph of a cross-section of the membrane in Ex.2. [Figure 8] This is an SEM micrograph of the surface of the film in Ex.3. [Figure 9] This is an SEM micrograph of the surface of the film in Ex.4. [Figure 10] This is an SEM micrograph of the surface of the film in Ex.5. [Figure 11] This is an SEM image of a cross-section of the membrane in Ex. 5. [Figure 12] This figure shows side-by-side comparisons of surface SEM micrographs of films from Examples Ex.2, 3, 4, and 5 of the present invention. [Figure 13] This is a SEM surface microscope image of CE1. [Figure 14] This is a plot of electrical resistance versus thickness. [Figure 15] This is a plot of puncture strength versus thickness. [Figure 16] This is a plot of % porosity vs. thickness. [Modes for carrying out the invention]

[0019] Typical novel or improved microporous battery separators include lithium-ion batteries and other similar applications. Developed for use in lithium batteries. A potentially preferred separator film of the present invention. This is achieved by extrusion molding (without requiring plasticizers that need to be extracted later), resulting in a high level It produces a precursor film with an internal microstructure having crystalline lamellar orientation, and is high molecular weight and low molecular weight. Flow index polypropylene resin or high molecular weight and low melt flow index Made using a blend of polypropylene resin (at least for the outer layer) This is a PP / PE / PP multilayer microporous battery separator film. Furthermore, it has internal microporous properties. The structure has a high level of uniform crystalline lamellar structure, which is achieved through dry process stretching. This affects the formation of micropores in the step.

[0020] Figure 1 is an SEM micrograph of an etched PP non-porous film. This film is MD-... Alternatively, it has a uniform, ordered, layered crystalline lamellar structure that has not yet undergone TD stretching. The polishing process removes all amorphous regions, allowing for better visualization of the crystalline lamellar structure. This was done to enable it. A well-known method of pore formation in membranes is known, XMZh ang, et al. “Oriented Structure and Anisotropy Properties of Polymer Blown Films HDPE, LLDPE and LDPE”, POLYMER 45(2004)217-229, and S. Tabatabaei et al. “Microporous Membranes Obtained from PP / HDPE Multilayer Films "by Stretching", published in JMS 345 (2009) 148-159. Figure 2 shows a typical stress / strain plot illustrating the response of a non-porous film to applied stress. This shows the separation of the stacked crystalline lamellar plates due to the initial application of stress. Following the initial separation of the lamellar plates, further extraction of polymer chains from the lamellar stacking is performed. This forms an extended polymer chain structure known as a fibril. Figure 2 shows the applied As stress is applied, the polymer fibrils further elongate, creating porous regions within the microstructure. This indicates that.

[0021] Figures 3 and 4 show SEM micrographs of the microporous separator membranes CE6 and CE5. The appearance of the surface at a microscopic scale is shown. The crystalline lamellar and fibril structures are shown at 20,000 It can be clearly seen at x magnification. In the comparison of the crystalline lamellar regions of CE6 and CE5 films: This shows that CE6 has a thicker crystalline lamellar region than CE5.

[0022] Figure 5 shows chain folding in polypropylene crystalline lamellae, as well as molecules within the lamellar structure. A diagram of a level polypropylene polymer chain is shown ("The Theory of Bire fringence”,Cambridge Polymer Group,2004, See CPGAN # 014, www.campoly.com. Melt Flow Index (MFI or MFI) (Under a 2.16 kg load, at 230°C) (Measured by weighing the amount of polypropylene polymer spilled per minute) This is an inherent property of the resin, used in the melt-flow extrusion process, and is related to the molecular weight of the resin. High molecular weight PP has a lower mfi value.

[0023] Table 1 shows the melt flow index values ​​for CE6 and CE5 microporous membranes, as well as the following: This is a list of pore sizes of microporous membranes obtained from resins having a specific MFi value. [Table 1]

[0024] CE6 and CE5 have different molecular weights and melt flow index (mfi) It is manufactured using polypropylene resin. These properties are related to the solvent properties of the precursor film in the dry process. This may be an important factor in the formation of crystalline lamellar regions during melt extrusion.

[0025] CE6 polypropylene resin has an mfi of 5.0 g / 10 min, which is the same as CE5. The resin used in manufacturing has a high melt flow index (mfi) exceeding 3x, and m Changes in fi lead to the generation of crystalline lamellar regions in the microstructure of porous separator films and these This suggests that it may have a significant impact on the uniformity of the crystalline lamellar regions.

[0026] Examples Table 2 shows 12 examples of the present invention Ex.1 to Ex.12 (and 4 comparative examples CE1 to C) The separator performance characteristics of E4) are described. The thickness of the embodiments of the present invention ranges from 14 μm to 30 μm. This range is m, which is the preferred target thickness range for EDV applications. [Table 2]

[0027] The separator film of the present invention is manufactured using a high molecular weight polypropylene resin. When a highly crystalline resin is melt-extruded, the resulting non-porous precursor film has a high level of crystalline properties. It has lamellar orientation. By annealing and stretching the high molecular weight nonporous precursor film, Microporous membranes with improved puncture strength are manufactured with high porosity and lower ER. Figure 6 shows an SEM micrograph of the PP surface of Example Ex.2 of the present invention, which is thicker. As can be seen in the Mela region, compared to Figures 3 (CE6) and 4 (CE5), It shows a level of crystalline lamellar content. Thicker lamellae result in a microporous membrane with higher mechanical strength. It can generate.

[0028] SEM micrographs of Ex.3, Ex.4, and Ex.5 are shown in Figures 8, 9, and 10. The embodiments of the present invention described herein are thermal shutdown microporous films including a PE layer. Figure 11 is a cross-sectional SEM micrograph of the three-layer PP / PE of Ex.2, which embodies the present invention. The / PP configuration is shown, and in this case the thickness of the PP and PE layers are in micrometers. It is marked with a position. The inner PE layer, which enables thermal shutdown at approximately 135°C, is typically It has larger pores than the outer PP layer. Figure 12 shows Examples Ex.2, Ex.3, and E of the present invention. This image shows side-by-side comparisons of SEM micrographs of the x.4 and Ex.5 surfaces, illustrating the fine details of the film's interior. It shows a higher content of crystalline material in the structure. The higher level of crystalline material in the embodiment of the present invention. The uniformity of the lamellae and crystalline lamellae is shown in the SEM micrograph in Figure 12. Image 13 is an SEM micrograph of the surface of Comparative Example 1, showing fewer homogeneous crystalline lamellae.

[0029] The amount and uniformity of crystalline lamellae in the non-porous precursor film of the present invention are related to microporous separators. Along with the pore size and % porosity of the membrane, separators such as electrical resistance, Gurley, and puncture strength are also considered. It can play an important role in performance characteristics. The films Ex.1 to Ex.12 of the present invention are 12 to 30 For thicknesses in the μm range, it has an electrical resistance (ER) value in the range of 0.9 to 1.4, and is for EDV. To provide a high-performance microporous membrane for the application. A preferred microporous membrane of the present invention is a prior art battery. Compared to Parer films, it has low ER and low Gurley. This property is due to EDV and This is important for achieving the excellent high-rate characteristics of lithium batteries for other high-power applications.

[0030] Figure 14 shows the ohms of ER as a function of film thickness (μm) for the films Ex.1 to Ex.12 of the present invention. -cm 2 This is a plot of units. The examples of the present invention are more than comparative examples CE1, 2, 3 and 4. It has a low ER. Furthermore, even if the thickness of the embodiment of the present invention is increased from 12 to 30 μm, ER is 1.5 ohms-cm 2 The following applies: Low ER separator films are lithium-ion batteries. This provides an improved level of lithium-ion conductivity during battery charging and discharging, enhancing the overall performance of the battery. To further improve it.

[0031] Figure 15 shows the puncture strength as a function of film thickness for the separator films Ex.1 to Ex.12 of the present invention. This is a plot. The film of the present invention has a higher puncture strength than comparative examples CE1 to CE4. Ex.7, which is only 2 μm thick, has a higher puncture strength than CE4, which is 16 μm thick. The film of the present invention has the potential to better withstand the harsh winding process of battery assemblies. This is because it provides mechanical strength to protect against dendrite penetration during battery cycling. This leads to an improvement in the degree. The film of the present invention shown in Figure 15 is used throughout the thickness range of 12 μm to 30 μm. It performs better than the comparable technology in terms of higher puncture strength.

[0032] Figure 16 shows a plot of the % porosity as a function of the thickness of the films Ex.1 to Ex.12 of the present invention. The film of the present invention has a thickness range of 12 to 30 μm compared to comparative examples CE1 to CE4. Throughout, it has a higher porosity percentage, and in terms of electrolyte conductivity and electrolyte retention, It will likely perform better in lithium-ion batteries.

[0033] Higher puncture strength, high porosity percentage, and low ER make lithium-ion particularly suitable for high-power applications. In battery-on systems, this contributes to better cycle life and / or safety performance.

[0034] In at least one selected embodiment, aspect, or object, the present invention or this application is intended to be used in accordance with the present invention. Regarding improved separators, membranes, or base films shown or described in the details: and / or the separator is a multilayer separator, film or base film, and the separator The separator is a three-layer separator, membrane, or base film, and the separator is a dry stretched film. The separator is fabricated by a lamination process, and the separator is made with fewer It has a puncture strength (PS) of at least 330 gf and a thickness of at least 14 μm, and separates The material has a puncture strength (PS) of at least 280 gf and a thickness of at least 12 μm. The separator must have a puncture strength (PS) of at least 350 gf and a thickness of at least 16 μm. The separator has a porosity of at least 35%, and the separator has a porosity of more than 37%. It has porosity, and the separator has a porosity of at least 39%, and the separator is approximately 35-6%. The porosity ranges from 5%, and the separator has a porosity range of approximately 39% to 53%. The separator is particularly suitable for power batteries used in electric vehicles, and the separator is 1.5 oz. Room-cm 2 The following ERs have a porosity of at least 35% and are suitable for high C-rate charge / discharge: The separator is a microporous polyolefin made by a dry process, containing at least one type of polyolefin. The film is included, and this dry process extrudes the polypropylene resin so that the film is shaped formed, and the resin has a melt flow index (MFI) of about 0.8 g / 10 min or less relates to an improved separator, membrane or base film.

[0035] In at least select embodiments, aspects or objects, the present invention or this application is an improved multi-layer separator, membrane or base film, including at least one microporous membrane produced by a dry stretching process, wherein in the dry stretching process, a polyolefin resin, mix or blend is extruded to form the membrane, and the resin has a melt flow index (MFI) of about 0.8 g / 10 min or less formed, and the resin has a melt flow index (MFI) of about 0.8 g / 10 min or less has, the separator has a thickness of about 14 μm or more, a porosity of about 35% to about 65%, and an electrical resistance (ER) value of about 1.5 ohm-cm or less, and 2 and optionally, the separator is a three-layer separator or base film, produced by a dry stretching process, produced by a lamination forming process, having a puncture strength (PS) of at least 280 gf and a thickness of at least 12 μm, having a puncture strength (PS) of at least 330 gf and a thickness of at least 14 μm, having a puncture strength (PS) of at least 350 gf and a thickness of at least 16 μm, having a porosity of at least 35%, having a porosity exceeding 37%, having a porosity of at least 39%, having a porosity in the range of about 35% - 65%, having a porosity in the range of about 39% - 53%, particularly suitable for power batteries such as those used in electric vehicles, having an ER of 1.5 ohm-cm or less, having a porosity of at least 35%, and being compatible with high C-rate charge and discharge, produced by a dry process and having a porosity in the range of about 35% - 65%, having a porosity in the range of about 39% - 53%, particularly suitable for power batteries such as those used in electric vehicles, having an ER of 1.5 ohm-cm 2 or less, having a porosity of at least 35%, and being compatible with high C-rate charge and discharge, produced by a dry process and having a porosity of at least 35%, and being compatible with high C-rate charge and discharge, produced by a dry process It contains at least two types of polyolefin microporous membranes, and this dry process allows polypropylene The resin is extruded to form the film, and the resin is melted at a rate of approximately 0.8 g / 10 min or less. It has a flow index (MFI) and is manufactured by a dry process and has at least 3 It contains a variety of polyolefin microporous membranes, and this dry process presses the polypropylene resin. The film is formed by extruding the resin, and the resin melts at a rate of approximately 0.8 g / 10 min or less. It has an INDEX (MFI) and includes at least one type of polyethylene membrane, and at least two types Containing a polypropylene film and / or an improved version superior to previous separators of the same thickness This relates to multilayer separators, films, or base films having puncture strength, etc.

[0036] In at least one selected embodiment, aspect, or subject matter, the present invention or this application is previously The multilayer separators shown and described herein have improved puncture strength superior to those of the same thickness. Regarding multilayer separators.

[0037] In at least one selected embodiment, aspect, or subject matter, the present invention or this application is previously The three-layer separators of the same thickness exhibit improved puncture strength, as shown and described herein. Regarding three-layer separators.

[0038] In at least one selected embodiment, aspect, or subject matter, the present invention or this application is novel. or improved battery separators, base films or membranes, and / or such This relates to a method for manufacturing and / or using separators, films, or membranes. In any specific selected embodiment, aspect, or object, the present invention or this application may be deemed to be lycium Novel or improved single-layer or multi-layer co-extruded or laminated microporous materials for ion secondary batteries Battery separators, and / or methods for manufacturing such separators and / or uses The present invention relates to a method. In at least certain selected embodiments, the present invention relates to a lithium-ion secondary battery Novel or improved multilayer microporous battery separators for use, and / or this separator This relates to a method for manufacturing and / or using a meter. A potentially preferred invention of this model. The iProcess Separator improves the cycle performance and charging performance of lithium-ion batteries. For improved puncture strength and low electrical resistance, thickness in the range of 14 μm to 30 μm. Three-layer laminated polypropylene / polyethylene / polypropylene (PP / PE / PP) microporous It is a membrane. Furthermore, a preferred separator or membrane of the present invention has low electrical resistance and high porosity. This provides excellent charge rate performance for lithium batteries used in high-power applications.

[0039] Improved multilayer microporous battery separators for lithium-ion secondary batteries, and / or A method for manufacturing or using this separator is provided. Preferred method of the present invention The rhodium separator improves the cycle performance and charging performance of lithium-ion batteries. Three thicknesses ranging from 14 μm to 30 μm with improved puncture strength and low electrical resistance. It is a layered polypropylene / polyethylene / polypropylene microporous membrane. Furthermore, The low electrical resistance and high porosity of the separator or film of the present invention are suitable for lithium applications in high-power applications. It provides excellent battery charging rate performance.

[0040] Test method thickness The thickness was determined according to the test procedure ASTMD374 using Embeco Microgage 21. The thickness is measured using a 0-A precision micrometer thickness tester. It is reported in units of cubic meters and micrometers.

[0041] Puncture strength The test samples are first pre-treated at 73.4°C and 50% relative humidity for a minimum of 20 minutes. The puncture strength of the test specimen is measured using an Instron Model 4442. 30 measurements were taken diagonally from end to end on a continuous .25" x 40" specimen, and the average was calculated. The needle has a radius of 0.5 mm. The descent speed is 25 mm / min. The film is A clamping device using an O-ring securely holds the test sample in place. It is fixed and held in place. The diameter of this fixed area is 25 mm. A hole was made by the needle. The displacement of the film (in mm) is relative to the resistance force (in gram force) generated from the test film. It is recorded. The maximum resistance is the puncture strength in gram force (gf) units. A load-displacement plot is generated.

[0042] Pore ​​diameter The pore size is available from Porous Materials, Inc. (PMI) A It is measured using quapore. The pore size is expressed in micrometers (μm).

[0043] Porosity The porosity of the microporous film sample was measured using the ASTM method D-2873, and the microporous properties were determined by the amount of film. It is defined as the percentage of voids in the membrane.

[0044] TD and MD tensile strength Tensile strength along MD and TD was determined according to the ASTM-882 method by Instron. Measurements are taken using Model 4201.

[0045] Meltflow Index (MFI) The melt flow index of polymer resins is measured using ASTM DS1238. For the MFI measurement of polyethylene, the temperature was 190°C and the load was 2.16 kg. For polypropylene, the temperature was 230°C and the load was 2.16 kg. The MFI (Multiplier Factor) was g / 10 min. It is measured as follows.

[0046] Electrical resistance (ER) (also known as ionic resistance or IR) Electrical resistance is measured in ohms-cm² of a separator filled with an electrolyte. 2 Defined as a unit of resistance The unit of electrical resistance is ohms-cm². 2 Therefore, the resistance of the separator is obtained from the finished material. By cutting out small pieces of parator and placing them between two blocking electrodes, The properties are analyzed. The separator is mixed with 1.0 M Li in an EC / EMC solvent in a volume ratio of 3:7. Saturate with battery electrolyte containing PF6 salt. The resistance value of the separator in ohms (Ω), R is Measurement is performed using the 4-probe AC ​​impedance method. Measurement errors at the electrode / separator interface. To reduce the difference, it is necessary to add another separator layer and perform multiple measurements. Based on the measured values, the electrical (ionic) resistance of the electrolyte-saturated separator, R S (Ω) is, formula R S =p S It is calculated by l / A. In the formula, p S This is the ion resistivity of the separator (unit, Ω-cm) is the electrode area (unit: cm²) 2 ), l is the thickness of the separator (unit, c m) p S The ratio of / A is determined by the variation in the resistance value of the separator due to multiple layers (Δδ) (ΔR The gradient calculated for ), where gradient = p S / A is given by ΔR / Δδ.

[0047] In at least one selected embodiment, aspect, or object, a new lithium-ion secondary battery Standard or improved multilayer microporous battery separators, and / or this separator A method for manufacturing and / or using the present invention is provided. The data is an improved cycle performance and trickle charge performance or charge of lithium-ion batteries. Improved puncture strength and low electrical resistance for electrical performance in the 14μm to 30μm range It is a three-layer laminated polypropylene / polyethylene / polypropylene microporous membrane with a thickness of [thickness]. The preferred low electrical resistance and high porosity of the separator or film of the present invention are desirable for high power E Provides excellent charge rate performance for lithium batteries used in DV or HEV applications.

[0048] This invention, without deviating from the spirit and essential attributes of the invention, can be applied in other forms. It is also possible to implement this, and therefore, the scope of the present invention is as described above in the specification. Furthermore, one should refer to the attached claims. In addition, the present invention is appropriately disclosed herein. This can be carried out without any of the elements not specifically disclosed herein.

[0049] The present invention is as follows: [1] Novel or improved separators, membranes, or base films, which are dry stretchable. The invention comprises at least one microporous membrane manufactured by Seth, and the dry stretching process A polyolefin resin, mix, or blend is extruded to form the film, The resin has a melt flow index (MFI) of approximately 0.8 g / 10 min or less. The separator has a thickness of approximately 12 μm or more, a porosity in the range of approximately 35% to approximately 65%, and Approximately 1.5 ohms - cm 2 It has the following electrical resistance (ER) values, and, If necessary, the separator may be a multilayer or triple-layer separator or a base film. It is manufactured by a dry stretching process and by a lamination process, and less Both have a puncture strength (PS) of 280 gf and a thickness of at least 12 μm, and at It has a puncture strength (PS) of 330 gf and a thickness of at least 14 μm, and at least 35 Having a puncture strength (PS) of 0 gf and a thickness of at least 16 μm, and at least 35% It has porosity, has porosity exceeding 37%, has porosity of at least 39%, and is approximately 35 Porosity ranges from % to 65%, and porosity ranges from approximately 39% to 53%, electric vehicles It is particularly suitable for power batteries used in applications such as the 1.5 ohm-cm². 2 The following ER is present: It has a porosity of at least 35%, is suitable for high C-rate charge / discharge, and is suitable for dry processes. It comprises at least two types of polyolefin microporous membranes manufactured in this dry process The film is formed by extruding polypropylene resin, and the amount of resin is approximately 0.8 g / 1 It has a melt flow index (MFI) of 0 minutes or less and is manufactured by a dry process. It also contains at least three types of polyolefin microporous membranes, and in this dry process, polypropylene The resin is extruded to form the film, and the resin is approximately 0.8 g / 10 min or less It has a duct flow index (MFI) and contains at least one type of polyethylene membrane, It includes at least two types of polypropylene films and / or a previous separator of the same thickness. It has superior and improved puncture strength, and combinations thereof, and less of these A novel or improved separator, membrane, or base film having one of the above characteristics. [2] The separator according to [1], which is a multilayer separator, a film, or a base film. [3] The separator according to [1], which is a three-layer separator, a film, or a base film. [4] The separator described in [1], manufactured by a dry stretching process. [5] A separator as described in [1], manufactured by a lamination process. [6] It has a puncture strength (PS) of at least 330 gf and a thickness of at least 14 μm. The separator described in [1]. [7] Having a puncture strength (PS) of at least 350 gf and a thickness of at least 16 μm The separator described in [1]. [8] The separator according to [1], having a porosity of at least 35%. [9] The separator according to [1], having a porosity of more than 37%.

[10] The separator according to [1], having a porosity of at least 39%.

[11] The separator according to [1], having a porosity in the range of approximately 35% to 65%.

[12] The separator according to [1], having a porosity in the range of approximately 39% to 53%.

[13] The separator described in [1] is particularly suitable for power batteries, such as those used in electric vehicles. Ta.

[14] 1.5 ohms-cm 2 It has the following ER, has a porosity of at least 35%, and high A separator suitable for C-rate charging and discharging, as described in [1].

[15] A microporous film manufactured by a dry stretching process, wherein the dry The polypropylene resin is extruded through a stretching process to form the film, and the resin Contains a microporous membrane with a melt flow index (MFI) of approximately 0.8 g / 10 min or less. The separator described in [1].

[16] Novel or improved multilayer separators, films, or base films, A microporous film manufactured by a dry stretching process, wherein the dry The polyolefin resin, mix, or blend is extruded by the stretching process. A film is formed, and the resin has a melt flow index (MFI) of approximately 0.8 g / 10 min or less. It has a microporous membrane having ) and The separator has a thickness of approximately 14 μm or more, a porosity in the range of approximately 35% to approximately 65%, and Approximately 1.5 ohms - cm 2 It has the following electrical resistance (ER) values, and, If necessary, the separator may be a three-layer separator or a base film. Made by a stretching process and a lamination process, at least 330g It has a puncture strength (PS) of f and a thickness of at least 14 μm, and at least 350 gf It has puncture strength (PS) and a thickness of at least 16 μm, and a porosity of at least 35%. It has a porosity of over 37%, at least 39%, and approximately 35-65%. It has a porosity in the range of %, with a porosity in the range of approximately 39% to 53%, and is used in electric vehicles. It is particularly suitable for power batteries such as 1.5 ohms-cm². 2 The following ERs are present, and at least It also has a porosity of 35%, is suitable for high C-rate charge / discharge, and is manufactured by a dry process. This dry process includes at least two types of polyolefin microporous membranes, and the poly The film is formed by extruding polypropylene resin, and the amount of resin is approximately 0.8 g / 10 min or less. It has a melt flow index (MFI) and is manufactured by a dry process. Both contain three types of polyolefin microporous membranes, and this dry process uses polypropylene resin The resin is extruded to form the film, and the resin is melt flowable at a rate of approximately 0.8 g / 10 min or less. - Having an index (MFI), comprising at least one type of polyethylene film, Includes two types of polypropylene films and / or offers superior improvement over previous separators of the same thickness. Novel or improved separators, membranes, or base films having improved puncture strength.

[17] It has improved puncture strength compared to previous multilayer separators of the same thickness, as described in

[16] . A separator.

[18] A three-layer separator with improved puncture strength, superior to previous three-layer separators of the same thickness. A separator, as described in

[16] .

[0050] This application may include the following inventions: [1] Polypropylene (PP) / Polypropylene is formed by laminating a first outer layer, a second outer layer, and an inner layer. Lithium (PE) / Polypropylene (PP) microporous separator A mu-ion secondary battery separator, The microporous separator is made up of a first outer layer, a second outer layer, and an inner layer. This separator is formed by dry stretching a non-porous separator precursor body. , The microporous separator has a thickness of at least 17 μm and a porosity of 41% or more. Electrical resistance (ER) value: 1.5 ohms / cm² 2 The following: The aforementioned microporous separator exhibits a puncture strength (PS) of at least 350 gf. The inner layer of the microporous separator is the first and the It has larger pores than the second outer layer, The first outer layer has a melt flow index (MFI) of 0.8 grams / 10 minutes. It contains polypropylene (PP) and does not contain plasticizers. The aforementioned second outer layer has a melt flow index (MFI) of 0.8 grams / 10 minutes. It contains polypropylene (PP) and does not contain plasticizers. The inner layer is positioned between the first and second outer layers and contains polyethylene (PE). The lithium-ion secondary battery separator has 12 to 16 micrometers of glitter. Having a A lithium-ion secondary battery separator characterized by the following features. [2] The lithium-ion secondary battery separator has a JIS rating of at least 290 seconds / 100cc. A lithium-ion secondary battery separator as described in [1], representing Gurley. [3] A power battery including the lithium-ion secondary battery separator described in [1].

Claims

1. A multilayer separator, film, or base film comprising at least one dry-process microporous film comprising a polyolefin resin, mix, or blend having a melt flow index (MFI) of 0.8 g / 10 min or less, The multilayer separator, film, or base film has a porosity in the range of 35% to 65% and 1.5 ohms-cm². ２ A multilayer separator, film, or base film having the following electrical resistance (ER) values, a puncture strength (PS) of at least 330 gf, and a thickness of at least 14 μm.

2. The multilayer separator, membrane, or base film according to claim 1, wherein the multilayer separator, membrane, or base film is a three-layer separator, membrane, or base film comprising two outer layers and one inner layer, and each of the two outer layers and the inner layer comprises a polyolefin resin, mix, or blend having an MFI of 0.8 g / 10 min or less.

3. The multilayer separator, membrane, or base film according to claim 1, wherein the separator, membrane, or base film is manufactured by a lamination process.

4. The multilayer separator, membrane, or base film according to claim 1, wherein the separator, membrane, or base film has a puncture strength (PS) of at least 350 gf and a thickness of at least 16 μm.

5. The multilayer separator, membrane, or base film according to Claim 1, having a porosity of more than 37%.

6. The multilayer separator, membrane, or base film according to claim 1, having a porosity in the range of 39% to 53%.

7. The multilayer separator, membrane, or base film according to claim 1, wherein the microporous membrane comprises two outer layers and at least one inner layer, each of the two outer layers comprising a polyolefin resin, mix, or blend having a melt flow index (MFI) of 0.8 g / 10 min or less, and the at least one inner layer comprising a polyolefin resin, mix, or blend having an MFI of 0.8 g / 10 min or less.

Images