Celgard Inc.

Ta-Hua Yu

Ken J Harleson

Lie Shi

Ronald W Call

Donald K Simmons

Robert W Callahan

Ron W Call

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

The battery separator for a lithium battery is made from a nonwoven flat sheet material having high temperature melt integrity, a microporous membrane having low temperature shutdown properties, and an adhesive bonding the nonwoven flat sheet to the microporous membrane and being adapted for swelling when contacted by an electrolyte.

High melt integrity battery separator for lithium ion batteries

A split resistant microporous membrane is provided for use in preparing a battery separator. The microporous membrane has a TD tensile strength to MD tensile strength ratio of from about 0.12 to about 1.2, preferably from about 0.5 to about 1. The microporous membrane is made by a process which includes the steps of preparing a film precursor by blown film extrusion at a blow-up ratio of at least 1.5, annealing the film precursor, and stretching the resultant annealed film precursor to form the microporous membrane.

Battery separators with reduced splitting propensity

A trilayer shutdown battery separator is provided having two strength layers sandwiching a shutdown layer that is made by a particle stretch method. The preferred method of making such a trilayer separator comprises: making microporous strength layers; forming a microporous shutdown layer by a particle stretch method; and bonding two microporous strength layers and one microporous shutdown layer into the trilayer battery separator wherein the first and third layers are strength layers, and the second membrane is a microporous shutdown layer made by a particle stretch method.

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Nanuet, NY, United States of America

Ta-Hua Yu