Bridged Carbon Fabric Membrane with Boosted Performance in AC Line‐Filtering Capacitors

High‐frequency responsive capacitors with lightweight, flexibility, and miniaturization are among the most vital circuit components because they can be readily incorporated into various portable devices to smooth out the ripples for circuits. Electrode materials no doubt are at the heart of such devices. Despite tremendous efforts and recent advances, the development of flexible and scalable high‐frequency responsive capacitor electrodes with superior performance remains a great challenge. Herein, a straightforward and technologically relevant method is reported to manufacture a carbon fabric membrane “glued” by nitrogen‐doped nanoporous carbons produced through a polyelectrolyte complexation‐induced phase separation strategy. The as‐obtained flexible carbon fabric bearing a unique hierarchical porous structure, and high conductivity as well as robust mechanical properties, serves as the free‐standing electrode materials of electrochemical capacitors. It delivers an ultrahigh specific areal capacitance of 2632 µF cm(−2) at 120 Hz with an excellent alternating current line filtering performance, fairly higher than the state‐of‐the‐art commercial ones. Together, this system offers the potential electrode material to be scaled up for AC line‐filtering capacitors at industrial levels.