Shutdown, trilayer battery separator
AssigneeHoechst Celanese Corporation
InventorWei-Ching Yu
Life of this patent
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Abstract
The present invention is directed to a shutdown, trilayer battery separator. The separator has a first and a third microporous membranes sandwiching a second microporous membrane. The first and the third membranes have a greater puncture strength than the second membrane. The second membrane has a lower melting temperature than either the first or the third membranes.
Claims20
A shutdown, trilayer battery separator comprising a first and a third microporous polypropylene membranes sandwiching a microporous polyethylene membrane.
A shutdown battery separator comprising a first and a third microporous polypropylene membranes sandwiching a microporous polyethylene membrane, said separator having:
- a thickness in the range of about 0.5 mils to about 1.5 mils;
- a puncture strength greater than or equal to about 450 grams;
- and a peel strength of greater than 4 grams per inch.
A method for making a microporous membrane having a thickness less than about 0.5 mils comprises the steps of:
- extruding a parison;
- collapsing the parison onto itself to form a flat sheet comprising two plies;
- annealing the flat sheet;
- stretching the flat sheet;
- and
- winding up the flat sheet, an adhesion force between the two plies being less than 8 grams per inch.
A shutdown, trilayer battery separator comprising a first and a third microporous polypropylene membrane sandwiching a microporous polyethylene membrane and having a thickness of less than 3 mils.
A battery separator comprising a first and a third microporous polypropylene membrane sandwiching a microporous polyethylene membrane and having a thickness of less than 3 mils.
Dependencies are inferred from the claim text.