An ultrahigh-rate electrochemical capacitor based on solution-processed highly conductive PEDOT:PSS films for AC line-filtering

Abstract

Alternating current (AC) line-filters are widely used to attenuate the leftover AC ripples in line-powered devices. However, the commercialized aluminum electrolytic capacitors (AECs) have low specific capacitances, making them usually the largest components in the electronic circuits of miniaturized, portable and/or flexible electronics. Herein, we report a scalable wet-process to fabricate an electrochemical capacitor (EC) using sulfuric acid treated commercially available poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (AT-PEDOT:PSS) as an electrode material and graphite foil as the current collector. It exhibited high areal (994 μF cm⁻²) and volumetric (16.6 F cm⁻³) specific capacitances at 120 Hz, ultrahigh-rate frequency response (phase angle = −83.6° at 120 Hz) with a short resistor–capacitor time constant of 0.15 ms, and an excellent electrochemical stability. Therefore, it is promising to replace AECs for AC line-filtering, and their performance is superior to those of the state-of-the-art ECs for this purpose.