A separator substrate include a substrate having a bulk portion and a surface portion, the surface portion having at least one porous area with a net charge; and ionic particles coupling to at least a part of the at least one porous area. The ionic particles have a net charge of an opposite sign to the net charge of the at least one porous area. The coupling between the part of the at least one porous area and the ionic particles may result in at least one of a good electrochemical performance, chemical stability, thermal stability, wettability, and mechanical strength of the separator substrate.