Provided herein is a lithium battery including: a cathode including a cathode active material; an anode including an anode active material; an electrolyte between the cathode and the anode; and a separator impregnated with the electrolyte, wherein the separator includes cellulose nanofibers, and wherein a differential scanning calorimetry (DSC) thermogram of the separator evinces an exothermic reaction peak, represented by a differential value (dH/dT), at a temperature in a range of about 150° C. to about 200° C.

A melt-blown nonwoven fabric includes a fiber containing a thermoplastic resin, wherein apparent density is 0.1 to 0.4 g/cm.sup.3 and KES surface roughness of at least one surface of the fabric sheet is up to 1.2 μm; and a method of producing the fabric includes conveying a web of the nonwoven fabric by sandwiching the web between two belt conveyers each including a belt having a smooth surface, providing a heat treatment zone where a surface of one or both of the belt conveyers has been heated to a temperature not lower than cold crystallization temperature of the thermoplastic resin and not higher than the temperature −3° C. lower than melting temperature of the thermoplastic resin in at least a part of a course between the belts, and heating the nonwoven fabric web in the heat treatment zone by contacting both surfaces of the nonwoven fabric web with the belt.

A polyimide porous film includes: a polyimide porous film body; and at least one of resin particles and a resin porous film, the at least one of the resin particles and the resin porous film adhering to one surface or both surfaces of the polyimide porous film body, and containing a fluorine-based resin or containing a fluorine-based resin and an acrylic resin.

A polyimide precursor film contains a polyimide precursor, in which a total content of a solvent containing water and a solvent other than water in the polyimide precursor film is 5 mass % or more and 40 mass % or less, and a mass ratio of water to the solvent other than water in the polyimide precursor film is 0 or more and 2.5 or less.

This invention provides a multi-layer article comprising a first electrode material, a second electrode material, and a porous separator disposed between and in contact with the first and the second electrode materials, wherein the porous separator comprises a nonwoven consisting essentially of a plurality of fibers of a fully aromatic polyimide. Also provided is a method for preparing the multi-layer article, and an electrochemical cell employing the same. A multi-layer article comprising a polyimide nonwoven with enhanced properties is also provided.

Disclosed are battery separators comprising glass fibers and having a basis weight (gsm), a specific surface area (m.sup.2/g), a density (gsm/mm) and a mean pore size (μm), which satisfy the equation disclosed herein. Also disclosed are batteries comprising the battery separators, and processes for making the separators.

The present invention relates to a porous sheet comprising cellulose fibers having an average fiber diameter ranging from 20 to 500 nm; cut fibers having an average fiber diameter ranging from 1.5 to 20 μm; and a hydrophilic polymer binder, wherein an amount of the cut fibers is 1% by weight or more and 80% by weight or less based on the total weight of the cellulose fibers and the cut fibers, and an amount of the hydrophilic polymer binder is 5 parts by weight or more and 30 parts by weight or less with respect to 100 parts by weight of the total weight of the cellulose fibers and the cut fibers. The porous sheet of the present invention can exhibit a superior strength (in particular, both tear strength and tensile strength), and exhibits a superior performance as a separator for an electrochemical device.

Improved battery separators, base films or membranes, batteries, cells, devices, systems, vehicles, and/or methods of making and/or using such separators, films or membranes, batteries, cells, devices, systems, vehicles, and/or methods of enhancing battery or cell charge rates, charge capacity, and/or discharge rates, and/or methods of improving batteries, systems including such batteries, vehicles including such batteries and/or systems, and/or the like; biaxially oriented porous membranes, composites including biaxially oriented porous membranes, biaxially oriented microporous membranes, biaxially oriented macroporous membranes, battery separators with improved charge capacities and the related methods and methods of manufacture, methods of use, and the like; flat sheet membranes, liquid retention media; dry process separators; biaxially stretched separators; dry process biaxially stretched separators having a thickness range between about 5 μm and 50 μm, preferably between about 10 μm and 25 μm, having improved strength, high porosity, and unexpectedly and/or surprisingly high charge capacity, such as, for example, high 10 C rate charge capacity; separators or membranes with high charge capacity and high porosity, excellent charge rate and/or charge capacity performance in a rechargeable and/or secondary lithium battery, such as a lithium ion battery, for high power and/or high energy applications, cells, devices, systems, and/or vehicles, and/or the like; single or multiple ply or layer separators, monolayer separators, trilayer separators, composite separators, laminated separators, co-extruded separators, coated separators, 1 C or higher separators, at least 1 C separators, batteries, cells, systems, devices, vehicles, and/or the like; improved microporous battery separators for secondary lithium batteries, improved microporous battery separators with enhanced or high charge (C) rates, discharge (C) rates, and/or enhanced or high charge capacities in or for secondary lithium batteries, and/or related methods of manufacture, use, and/or the like, and/or combinations thereof are disclosed or provided.

At least a selected microporous membrane is made by a dry-stretch process and has substantially round shaped pores and a ratio of machine direction tensile strength to transverse direction tensile strength in the range of 0.5 to 6.0. The method of making the foregoing microporous membrane may include the steps of: extruding a polymer into a nonporous precursor, and biaxially stretching the nonporous precursor, the biaxial stretching including a machine direction stretching and a transverse direction stretching, the transverse direction including a simultaneous controlled machine direction relax. At least selected embodiments of the invention may be directed to biaxially oriented porous membranes, composites including biaxially oriented porous membranes, biaxially oriented microporous membranes, biaxially oriented macroporous membranes, battery separators, filtration media, humidity control media, flat sheet membranes, liquid retention media, and the like, related methods, methods of manufacture, methods of use, and the like.

Provided is a separator roll in which deformation is reduced and an external quality is improved. In the separator roll, a separator is wound around a core, and an absolute value of radial stress σ.sub.r applied to the core is not more than a critical stress σ.sub.cr. The critical stress σ.sub.cr is a value obtained by multiplying A by B, where: A is an absolute value, of radial stress σ.sub.r applied to the core, as observed in a case where a maximum value of Von Mises stress σ.sub.m in the core is equal to a yield stress σ.sub.y of a material of the core; and B is a safety factor of 0.5.