| CPC H01M 50/403 (2021.01) [H01M 50/409 (2021.01); H01M 50/417 (2021.01); H01M 50/449 (2021.01); H01M 50/491 (2021.01); H01M 50/489 (2021.01)] | 19 Claims |

|
1. A polyolefin separator, comprising:
a polyolefin porous substrate comprising a plurality of fibrils and pores formed by the fibrils draped across one another; and
coating layers surrounding an outer side of the fibrils contained in the polyolefin porous substrate and the coating layers comprising a crosslinked polymer,
wherein the coating layers surround the outside of the fibrils not only on the polyolefin separator surface but also inside the polyolefin separator, and are not separate coating layers differentiated from the porous substrate but are layers formed on the surface of each of the fibrils, and
wherein the polyolefin separator having the coating layers has a change in air permeability of 20% or less and a change in basis weight of 4% or less, as compared to the polyolefin porous substrate.
|