A nonwoven fabric and a method of making thereof. The nonwoven fabric includes a plurality of randomly-oriented fibers, the plurality of randomly-oriented fibers including: at least 60 wt% of oxidized polyacrylonitrile fibers; and from to less than 40 wt% of reinforcing fibers having an outer surface comprised of a (co)polymer with a melting temperature of from 100°C to 450°C; and a fluoropolymer binder on the plurality of randomly-oriented fibers; wherein the plurality of randomly-oriented fibers is bonded together to form the nonwoven fabric, optionally wherein the nonwoven fabric has a thickness of one millimeter or less.