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Freestanding, heat resistant microporous film for use in energy storage devices

United States Patent

9,896,555
February 20, 2018
View the Complete Patent at the US Patent & Trademark Office
Preferred embodiments of a freestanding, heat resistant microporous polymer film (10) constructed for use in an energy storage device (70, 100) implements one or more of the following approaches to exhibit excellent high temperature mechanical and dimensional stability: incorporation into a porous polyolefin film of sufficiently high loading levels of inorganic or ceramic filler material (16) to maintain porosity (18) and achieve low thermal shrinkage; use of crosslinkable polyethylene to contribute to crosslinking the polymer matrix (14) in a highly inorganic material-filled polyolefin film; and heat treating or annealing of biaxially oriented, highly inorganic material-filled polyolefin film above the melting point temperature of the polymer matrix to reduce residual stress while maintaining high porosity. The freestanding, heat resistant microporous polymer film embodiments exhibit extremely low resistance, as evidenced by MacMullin numbers of less than 4.5.
Pekala; Richard W. (Corvallis, OR), Cherukupalli; Srinivas (Saidabad, IN), Waterhouse; Robert R. (Scio, OR)
Amtek Research International LLC (Lebanon, OR)
13/ 255,868
March 19, 2010
This invention was made with Government support under U.S. Department of Energy Cooperative Agreement No. DE-FC26-05NT42403 awarded by DOE. The Government has certain rights in this invention.