CPC H01M 10/4235 (2013.01) [H01M 10/0525 (2013.01); H01M 50/403 (2021.01); H01M 50/409 (2021.01); H01M 50/411 (2021.01); H01M 50/417 (2021.01); H01M 50/426 (2021.01); H01M 50/449 (2021.01); H01M 50/451 (2021.01); H01M 50/457 (2021.01); H01M 50/491 (2021.01)] | 21 Claims |
1. A multilayer battery separator for a lithium secondary battery that comprises a microporous membrane comprising:
at least three coextruded dry-stretch process polypropylene (PP) layers that each has a thickness of less than or equal to 4 microns; and wherein the microporous membrane has a thickness in the range of 2 to 12 microns and has a ceramic coating or a polymer coating on at least one side thereof; and
wherein one PP layer of the at least three coextruded dry-stretch process PP layers is of a different PP material.
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