Microporous membranes and methods for producing and using such membranes
AssigneeToray Tonen Specialty Separator Godo Kaisha
InventorsKotaro Takita, Junko Takita, Yoichi Matsuda, Sadakatsu Suzuki
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Abstract
The invention relates to microporous polymeric membranes suitable for use as battery separator film. The invention also relates to a method for producing such membranes, batteries containing such membranes as battery separators, methods for making such batteries, and methods for using such batteries.
Claims22
A monolayer microporous membrane comprising a polyolefin having an Mw>1.0×106, the membrane having a normalized air permeability ≦4.0×102 seconds/100 cm3/20 μm, and a heat shrinkage at 130° C. of ≦15% in at least one planar direction.
A method for manufacturing a microporous membrane, comprising:
- (a) stretching an extrudate in at least one of MD or TD, the extrudate comprising diluent and a polyolefin having an Mw>1.0×106, and then removing at least a portion of the diluent from stretched extrudate to form a membrane having a first length along MD and a first width along TD;
- (b) stretching the membrane in MD from the first length to a second length larger than the first length by a first magnification factor in the range of from about 1.1 to about 1.5 and stretching the membrane in TD from the first width to a second width that is larger than the first width by a second magnification factor in the range of from about 1.1 to about 1.3;
- and then
- (c) reducing the second width to a third width, the third width being in the range of from the first width to about 1.1 times larger than the first width.
(canceled)
A battery comprising an anode, a cathode, an electrolyte, and a monolayer microporous membrane comprising polypropylene having an Mw>1.0×106, the membrane having a normalized air permeability ≦4.0×102 seconds/100 cm3/20 μm, and a heat shrinkage at 105° C. in at least one planar direction ≦2.5%;
- wherein the microporous membrane separates at least the anode from the cathode.
22-23. (canceled)
Dependencies are inferred from the claim text.