Continuous PEDOT:PSS nanomesh film: Towards aqueous AC line filtering capacitor with ultrahigh energy density

Filtering capacitors with high energy densities are of critical importance in stabilizing the pulse signal of circuits that require the conversion of alternating current to direct current, which is however far from satisfactory at current stage due to lack of a reasonable design. Here, we report an ultrafast aqueous electrochemical capacitor based on highly conductive and continuously cross-linked poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) nanomesh films fabricated using a rational morphology engineering strategy. The interpenetrating polymer network promoted an efficient electron transfer and provided smooth channels for ion transport while exposing a significant number of accessible interfacial area to electrolyte. In addition to the large phase angle of − 84° at 120 Hz, this polymer-based electrochemical capacitor exhibited an extremely high areal specific capacitance of 1087 μF cm⁻² and areal specific energy density of 544 μF V² cm⁻², far superior to those of most reported aqueous filtering capacitors. Furthermore, it can efficiently smoothen the ripples generated when arbitrary alternating current waveforms were converted into straight signals over a wide frequency range of 1–10,000 Hz. Moreover, it was conveniently integrated with a rotating disk triboelectric nanogenerator for ripple filtering and pulse energy smoothing. This work brings a view for aqueous filtering capacitors with high performance.