LAUSR

Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) is one of the most widely studied conductive polymers due to its excellent electrical, optical, and mechanical properties, with various applications such as organic electrochemical transistors, electrochromics, and flexible/stretchable supercapacitors. The charging mechanism of PEDOT:PSS supercapacitors has been traditionally believed to be faradaic, which involves the transfer of charge across the electrode/electrolyte interface. In the present work, however, robust experimental evidence suggests that the PEDOT:PSS supercapacitors mainly store and deliver charge non-faradaically. The various electrochemical properties of the PEDOT:PSS electrical double layer capacitors (EDLCs) are clearly distinguishable from those of the polyaniline (PANI) pseudocapacitors, which store charge faradaically. Owing to the non-faradaic mechanism, the frequency response of the PEDOT:PSS supercapacitors is even comparable to that of state-of-the-art ultrafast EDLCs with carbon-based electrodes, making them suitable for high-frequency applications such as 60-Hz AC line filtering. This result is of great importance for the fundamental understanding of the charging mechanism of mixed ionic-electronic conducting polymers such as PEDOT:PSS, and is expected to greatly contribute to the development of various electrochemical devices based on this type of material.