Abstract: The present invention provides a battery separator comprising a nonwoven web of first and second fibers having a mean diameter of about 15 .mu.m or less, wherein the first fibers comprise at least about 60 wt. % of a first polyolefin having a first melting temperature and no more than about 40 wt. % of a second polyolefin having a second melting temperature which is lower than the first melting temperature, the second fibers comprise a third polyolefin having a third melting temperature which is higher than the second melting temperature, the nonwoven web has two sides, one of which sides has been contacted with a heated surface such that the nonwoven web has been subjected to a temperature higher than the second melting temperature and lower than the first and third melting temperatures so as to render the contacted side more smooth than the other side, the battery separator is spontaneously wettable by an electrolyte, the battery separator has a thickness of at least about 50 .mu.