Celgard Inc.

Hoechst Celanese Corporation

Other

Wei-Ching Yu

Shawn E Hux

Ronald W Call

Khuy Van Nguyen

Margaret W Geiger

Pierre C Cook

Carlton F Dwiggins

A continuous method of making dry-stretch microporous membrane battery separators from polypropylene (PP) or polyethylene (PE) or both benefits to the manufacturers in the production efficiency. The precursor-film extrusion in this invention is accomplished by multiple small film-extrusion lines at a compatible line speed with the followed oven processes (annealing and stretching). The overall production process starts continuously from film extrusion to annealing and to stretching. The benefits of the inventive continuous process includes a higher product yield, more effective oven-time usage, no need to handle and manage the intermediate products, less need in labor and machine maintenance, and potentially more stable product quality. The dry-stretch membrane separators made with this inventive continuous method include (1) single-ply PP or PE separators having a thickness ranging from 0.2 mil to 2.0 mil; (2) PP/PE/PP trilayer microporous membrane separators having a thickness ranging from 0.6 mil to 4.0 mil. The PP/PE/PP trilayer can be accomplished in the early extrusion via either co-extrusion or extruding separately and then interposing PE layer between two PP layers, continuously, right before annealing/bonding and stretching process.

Continuous methods of making microporous battery separators

A fusible, structurally stabilized battery separator is disclosed. The separator is formed by extruding a cylindrical parison of a polymer film and quenching the film on both sides with a low temperature fluid stream prior to processing the film to impart microporosity. Most preferably, the film includes at least a polyethylene layer and polypropylene layer.

Structurally stable fusible battery separators and method of making same

A battery separator is made from a microporous polyolefin membrane having a thickness of less than or equal to 0.5 mil. The separator is made by extruding a parison, collapsing the parison to form a flat sheet comprising two plies, annealing the sheet, stretching the sheet, and winding the sheet.

Ultra-thin, single-ply battery separator

A battery separator is made from a microporous polyolefin membrane having a thickness of about 0.33 mills to about 0.5 mils.

A method of making a trilayer, shutdown battery separator has the following steps: extruding a polyethylene precursor; extruding a polypropylene precursor; forming a trilayer precursor, the trilayer precursor having the polyethylene precursor sandwiched between two polypropylene precursors; bonding the trilayer precursor; annealing the trilayer precursor; stretching the trilayer precursor; and forming thereby the battery separator.

Method of making a trilayer battery separator

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.

Shutdown, trilayer battery separator

Continuous seamless cross-plied battery separators are formed by bringing at least two anisotropic with respect to mechanical strength (e.g. uniaxially oriented), microporous plies into adhering face contact such that the uniaxial orientation of one microporous ply is angularly biased relative to the other microporous ply (e.g., between 20.degree. to 90.degree.). This biased relationship between the microporous plies is most preferably achieved by spirally or helically slitting a tubular microporous membrane. The plies are adhered to one another with adhesive and/or by means of heat and pressure. The cross-plied battery separators of this invention exhibit increased puncture strength without significant decrease in permeability. As a result, the battery separators of this invention are especially useful in battery cell configurations whereby the battery separator is sandwiched between anode and cathode sheets to form a composite battery cell structure which is then rolled or folded to be placed in a battery cell can.

Methods of making cross-ply microporous membrane battery separator, and

The present invention is directed to a shutdown, bilayer battery separator and a process for making the same. A first microporous membrane with shutdown capability and a second microporous membrane with strength capability are joined together in face-to-face contact. The face of the first membrane being adhered by calendaring, adhesives, or welding, to the face of the second membrane, and the separator having a thickness of less than 3 mils, and a puncture strength, as measured from the second microporous membrane, of greater than 1900 g-mm, and a peel strength of greater than 1 grams/centimeter.

Growing community of inventors

Charlotte, NC, United States of America

Wei-Ching Yu