Ultrahigh-Conductivity Polymer Hydrogels with Arbitrary Structures

A poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) hydrogel is prepared by thermal treatment of a commercial PEDOT:PSS (PH1000) suspension in 0.1 mol L⁻¹ sulfuric acid followed by partially removing its PSS component with concentrated sulfuric acid. This hydrogel has a low solid content of 4% (by weight) and an extremely high conductivity of 880 S m⁻¹. It can be fabricated into different shapes such as films, fibers, and columns with arbitrary sizes for practical applications. A highly conductive and mechanically strong porous fiber is prepared by drying PEDOT:PSS hydrogel fiber to fabricate a current-collector-free solid-state flexible supercapacitor. This fiber supercapacitor delivers a volumetric capacitance as high as 202 F cm⁻³ at 0.54 A cm⁻³ with an extraordinary high-rate performance. It also shows excellent electrochemical stability and high flexibility, promising for the application as wearable energy-storage devices.