Crosslinked Polyolefin Separator and Manufacturing Method Therefor

A crosslinked polyolefin separator which has gels with a longer side length of 50 μm or more in a number ranging from 0 to 3 per 1 mof the separator, and shows a standard deviation of absorbance ratio between the center of the separator and the side thereof ranging from 0.01 to 0.5 is provided. A method for manufacturing the crosslinked polyolefin separator is also provided. The method includes (S) preparing a polyolefin porous membrane, and (S) applying a coating solution containing an initiator and alkoxy group-containing vinylsilane onto at least one surface of the porous membrane. The coating solution can permeate even to the inside of exposed pores. Thus, it is possible to provide a crosslinked polyolefin separator in which silane crosslinking occurs uniformly even inside of the pores.