Surface-treated microporous membrane and electrochemical device prepared thereby

Disclosed is a porous film comprising: (a) a porous substrate having pores; and (b) a coating layer formed on at least one region selected from the group consisting of a surface of the substrate and a part of the pores present in the substrate, wherein the coating layer comprises styrene-butadiene rubber. An electrochemical device using the porous film as a separator is also disclosed. The porous film is coated with a styrene-butadiene polymer, whose rubbery characteristics can be controlled, and thus provides improved scratch resistance and adhesion to other substrates. When the porous film is used as a separator for an electrochemical device, it is possible to improve the safety of the electrochemical device and to prevent degradation in the quality of the electrochemical device.