Scalable Electrostatic‐Induced Control of Marangoni Deposition of Uniform 3D‐Porous PEDOT Electrodes for Ultrafast AC‐Line Filtering and High Areal/Volumetric Capacitance

Abstract With the miniaturization of integrated circuits driving increased demand for high‐frequency alternating current (AC)‐line filtering capacitors, portable electrochemical capacitors (ECs) must reconcile two persistent challenges: i) the inherent contradiction in synergistic enhancement between areal capacitance ( C A ) and volumetric capacitance ( C V ) at the condition of high frequency response, and ii) developing scalable fabrication methods. To address these issues, an electrostatic‐induced Marangoni assembly process is introduced, which enables large‐area, rapid deposition of poly(3,4‐ethylenedioxythiophene) (PEDOT) films with a uniform, 3D fibrous porous network. By pre‐treating the PEDOT:poly(styrenesulfonate) (PSS) ink with a polar solvent and applying an electrostatic field, Marangoni flows align microdroplets into a continuously interconnected 3D architecture. This structure not only facilitates ultrafast ion transport but also provides abundant storage sites, yielding a sultaneous enhancement in C A (1.72 mF cm⁻ 2 ) and C V (13.2 F cm⁻ 3 ), as well as an exceptional phase angle of −82.9° at 120 Hz. These metrics surpass those of most reported carbon‐ and PEDOT‐based filtering capacitors. Moreover, the method accommodates high‐loading of pseudocapacitive materials, demonstrating its versatility for composite electrode engineering. Subsequent AC‐line filtering tests confirm the practical applicability of these electrodes, offering a scalable route to miniaturized capacitors with synergistically optimized C A and C V .