Abstract: A diffusion membrane is a microporous sheet comprising a blend of an aliphatic polyolefin and a thermoplastic olefin (TPO) elastomer. The blend comprises less than 10 percent by weight of the elastomer. The preferred polyolefins are selected from a group consisting of polyethylene, polypropylene, copolymers thereof, and blends thereof. The preferred TPO elastomers are selected from the group consisting of ethylene-propylene rubbers (EPR), ethylene-propylene-diene terpolymer rubbers (EPDM), and combinations thereof.

Abstract: The present invention is directed to a battery separator. The battery separator comprises a microporous film having a first portion and a second portion. The first portion is bonded to the second portion. The bond has a strength greater than 5 g/in. The film has a thickness less than 1.7 mils, a Gurley of less than 50 sec/10 cc, and a puncture strength of greater than 400 g/mil.

Abstract: A method for removing a pin from a battery assembly by the step of providing a separator comprising: a microporous membrane having an exterior surface portion of polypropylene, the polypropylene including at least 50 ppm of metallic stearate, preferably calcium stearate Static and being adapted to exhibit a pin removal force ≦7100 g.

Abstract: A microporous battery separator is provided having a first co-extruded multilayered portion and a second co-extruded multilayered portion. The two portions are bonded together. In a preferred embodiment, the battery separator has two substantially identical multilayered portions bonded together face-to-face. Each of the two multilayered portions has at least one strength layer and at least one shutdown layer. Methods for making the battery separators are also provided. Preferably, a tubular multilayered film is extruded, and collapsed onto itself to form a multilayered battery separator precursor. The precursor is then bonded and annealed before it is stretched to form a microporous multilayer battery separator.

Abstract: A fusible, structurally stabilized battery separator is disclosed. The separator is formed by extruding a cylindrical parison of a polymer film and quenching the film on both sides with a low temperature fluid stream prior to processing the film to impart microporosity. Most preferably, the film includes at least a polyethylene layer and polypropylene layer.