Celgard Inc.

Donald K Simmons

Ronald W Call

Joseph G Yaritz

Zhengming Zhang

Pankaj Arora

Khuy Van Nguyen

Tien Dao

Robert A Nark

Xiangyun Wei

Shizuo Ogura

Ta-Hua Yu

J Robert Dees

Mark W Ferebee

A membrane is a microporous sheet made of a blend of a first ultra high molecular weight polyolefin and a second ultra high molecular weight polyolefin. Each polyolefin has a molecular weight, both of those molecular weights are greater than 1 million, and one molecular weight is greater than the other. Additionally, the intrinsic viscosity (IV) of the membrane may be greater than or equal to 6.3.

Membrane made of a blend of UHMW polyolefins

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.

Multilayer battery separators

A battery separator is a microporous membrane. The membrane has a major volume of a thermoplastic polymer and a minor volume of an inert particulate filler. The filler is dispersed throughout the polymer. The membrane exhibits a maximum Z-direction compression of 95% of the original membrane thickness. Alternatively, the battery separator is a microporous membrane having a TMA compression curve with a first substantially horizontal slope between ambient temperature and 125&#xb0; C., a second substantially horizontal slope at greater than 225&#xb0; C. The curve of the first slope has a lower % compression than the curve of the second slope. The curve of the second slope is not less than 5% compression. The TMA compression curve is graphed so that the Y-axis represents % compression from original thickness and the X-axis represents temperature.

Battery separator with Z-direction stability

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.

Battery separator

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 &lE;7100 g.

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Fayetteville, GA, United States of America

Donald K Simmons