Provided are electrochemical cells including separators permeable to some materials and impermeable to other materials in electrolytes. Also provide are methods of forming such separators. The selective permeability of a separator is achieved by its specific pore diameter and a narrow distribution of this diameter. Specifically, a species responsible for ion transport in an electrochemical cell are allowed to pass through the separator, while another species is blocked thereby preventing degradation of the cell. For example, a species containing lithium ions is allowed to pass in rechargeable cells, while one or more species containing transition metals are blocked. In some embodiments, a separator may include a membrane layer with at least 90% of pores of this having a diameter of between about 0.1 nanometers and 1.0 nanometer. The membrane layer may be a standalone layer or supported by a membrane support.

Provided are electrochemical cells including separators permeable to some materials and impermeable to other materials in electrolytes. Also provide are methods of forming such separators. The selective permeability of a separator is achieved by its specific pore diameter and a narrow distribution of this diameter. Specifically, a species responsible for ion transport in an electrochemical cell are allowed to pass through the separator, while another species is blocked thereby preventing degradation of the cell. For example, a species containing lithium ions is allowed to pass in rechargeable cells, while one or more species containing transition metals are blocked. In some embodiments, a separator may include a membrane layer with at least 90% of pores of this having a diameter of between about 0.1 nanometers and 1.0 nanometer. The membrane layer may be a standalone layer or supported by a membrane support.

It is an object of the present invention to provide a substrate for lithium ion battery separators which has high adhesion to an inorganic particle layer, can be made thin and is excellent in tensile strength and cuttability and a lithium ion battery separator including the substrate for lithium ion battery separators. The substrate for lithium ion battery separators which contains heat-resistant fibers and synthetic resin short fibers contains fibrillated heat-resistant fibers having a modified freeness of not more than 300 ml as the heat-resistant fibers and has a content of the fibrillated heat-resistant fibers having a modified freeness of not more than 300 ml of not less than 1.0 mass % to less than 5.0 mass % based on the total of all the fiber components contained in the substrate. The modified freeness is a value measured in accordance with JIS P8121-2:2012 except that an 80-mesh wire net having a wire diameter of 0.14 mm and an opening of 0.18 mm is used as a screening plate and the concentration of a sample is 0.1%.

It is an object of the present invention to provide a substrate for lithium ion battery separators which has high adhesion to an inorganic particle layer, can be made thin and is excellent in tensile strength and cuttability and a lithium ion battery separator including the substrate for lithium ion battery separators. The substrate for lithium ion battery separators which contains heat-resistant fibers and synthetic resin short fibers contains fibrillated heat-resistant fibers having a modified freeness of not more than 300 ml as the heat-resistant fibers and has a content of the fibrillated heat-resistant fibers having a modified freeness of not more than 300 ml of not less than 1.0 mass % to less than 5.0 mass % based on the total of all the fiber components contained in the substrate. The modified freeness is a value measured in accordance with JIS P8121-2:2012 except that an 80-mesh wire net having a wire diameter of 0.14 mm and an opening of 0.18 mm is used as a screening plate and the concentration of a sample is 0.1%.

At low cost, a porous film has high thermal film rupture resistance and outstanding battery characteristics. The porous film has a porous layer on at least one surface of a porous substrate, and if the surface porosity of the porous layer is defined as α and the cross-sectional void ratio of the porous layer is defined as β, then α/β does not exceed 90%.

At low cost, a porous film has high thermal film rupture resistance and outstanding battery characteristics. The porous film has a porous layer on at least one surface of a porous substrate, and if the surface porosity of the porous layer is defined as α and the cross-sectional void ratio of the porous layer is defined as β, then α/β does not exceed 90%.

Disclosed are a composition, a composite separator and a preparation method therefor, and a lithium ion battery. The composition includes 10-100 parts of a polymer resin, 0.5-10 parts of a polymer adhesive. 0-50 parts of an inorganic nanoparticle powder, and 0-40 parts of nanowires. The polymer resin includes a low melting point polymer and a high melting point polymer, wherein the low melting point polymer and the high melting point polymer are the same substance: the weight ratio of the low melting point polymer to the high melting point polymer is (5-90): (10-95), the melting point of the low melting point polymer is 145° C. or less, and the melting point of the high melting point polymer is in the range of 146-500° C.

The present invention relates to a composite porous separator, a method of manufacturing the same, and an electrochemical device including the same. Provided is a porous substrate that has excellent heat resistance and heat shrinking properties, a small thickness, and high strength even when a thickness of a coating layer containing inorganic particles is small. Provided are a composite porous separator having significantly reduced heat shrinking and curls according to the present invention, and an electrochemical device using the same.

The present invention relates to a composite porous separator, a method of manufacturing the same, and an electrochemical device including the same. Provided is a porous substrate that has excellent heat resistance and heat shrinking properties, a small thickness, and high strength even when a thickness of a coating layer containing inorganic particles is small. Provided are a composite porous separator having significantly reduced heat shrinking and curls according to the present invention, and an electrochemical device using the same.

A nonaqueous electrolyte secondary battery separator having excellent impact absorbency includes a polyolefin porous film having a full width W at half maximum of a peak of an MD component of not less than 30 degrees. The full width W at half maximum of the peak of the MD component is calculated from an azimuthal profile of a scattering peak on a plane obtained by wide-angle X-ray scattering measurement that is carried out by irradiating a surface of the polyolefin porous film with an X-ray from a direction vertical to the surface of the polyolefin porous film, and/or having a maximum-to-minimum intensity ratio r of not more than 3.6. The maximum-to-minimum intensity ratio r is calculated from a Fourier transformed azimuthal profile obtained by observing the surface of the polyolefin porous film by SEM.