Porous highly conductive PEDOT film for high-performance supercapacitors

Thick and highly conductive poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate films with ideal porous structure are fulfilling as electrodes for supercapacitors. However, the homogeneous micro-structure without the aid of templates or composite presents a significant obstacle, due to the intrinsic softness of the dominant PSS component. In this study, we have successfully developed a porous configuration by employing a solvothermal approach with ethylene glycol (EG) as the solvent. The synergistic action of elevated pressure and temperature was crucial in prompting EG to tailor the microstructure of the PEDOT:PSS films by removing non-conductive PSS chains and improving PEDOT crystallinity, and the formation of a porous network. The resulting porous PEDOT:PSS films exhibited a high conductivity of 1644 ​S ​cm⁻¹ and achieved a volumetric capacitance record of 270 ​F ​cm⁻³, markedly exceeding previous records. The flexible all-solid-state supercapacitor assembled by the films had an outstanding volumetric capacitance of 97.8 ​F ​cm⁻³ and an energy density of 8.7 ​mWh cm⁻³, which is best one for pure PEDOT:PSS-based supercapacitors. Grazing-incidence wide-angle X-ray scattering, X-ray photo-electron spectroscopy, and other characterizations were carried out to characterize the structure evolution. This work offers an effective novel method for conducting polymer morphology control and promotes PEDOT:PSS applications in energy storage field.