CPC C08J 5/18 (2013.01) [C08J 7/0423 (2020.01); C08J 7/043 (2020.01); H01M 50/406 (2021.01); H01M 50/417 (2021.01); H01M 50/431 (2021.01); H01M 50/446 (2021.01); H01M 50/449 (2021.01); H01M 50/489 (2021.01); C08J 2323/06 (2013.01); C08J 2409/04 (2013.01); H01M 10/0525 (2013.01); Y10T 428/249955 (2015.04); Y10T 428/249958 (2015.04); Y10T 428/249962 (2015.04)] | 18 Claims |
1. A freestanding polyolefin web, comprising:
a microporous polyolefin membrane having a first major surface, a second major surface opposite the first major surface, and a bulk structure; and
a porous inorganic surface layer comprising fumed inorganic particles and an inorganic acid, wherein the porous inorganic surface layer covers at least a portion of the first major surface and at least a portion of the second major surface of the polyolefin membrane, wherein the fumed inorganic particles form an aggregated network of open chain shaped morphology, the inorganic particles held together by hydrogen bonding provided by the inorganic acid at particle-to-particle contacts, the inorganic acid comprising at least one of phosphoric acid (H3PO4), boric acid (H3BO3), tetraboric acid (H2B4O7), vanadic acid (HVO3), or molybdic acid (H2MoO4);
wherein the inorganic particles are independently selected from a group consisting of silica, alumina, titania, zirconia, and combinations thereof; and
wherein the polyolefin web exhibits in-plane dimensional stability above the melting point of the polyolefin membrane.
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