MICROPOROUS MEMBRANES, METHODS FOR MAKING SUCH MEMBRANES, AND THE USE OF SUCH MEMBRANES AS BATTERY SEPARATOR FILM

摘要

The invention relates to microporous membranes having high meltdown temperature, low shutdown temperature, and resistance to heat shrinkage at elevated temperature. The membranes can be produced by stretching a sheet comprising polymethylpentene, polyethylene, and diluent, and then removing the diluent. The membranes can be used as battery separator film in, e.g., lithium ion batteries.