We have investigated the conjugated polymer poly(3,4-ethylenedioxythiophene) as electrode material in electrochemical supercapacitor. The conjugated polymer is prepared by chemical polymerization in the form of thin films on nonconducting plastic substrates. One film is electrochemically reduced to the neutral state, while the other is kept in the as-prepared, doped state. The films are thin immersed in a liquid organic electrolyte. In the charged state the supercapacitor cell voltage is 0.8 V and the energy density is measured to 1 to 4 Wh/kg of active electrode material, depending on the current density used during discharge. The power density (delivered energy/discharge time) also depends on the current density and at the highest current densities investigated (1 mA/cm2) it reaches 2.5 kW/kg of active electrode material.) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see ABSTRACT The reaction of potassium, sodium, and lithium permanganate in water at 170°C leads directly to potassium, sodium, and lithium manganese dioxides, A,MnO ' nHO, with a R3m rhombohedral structure. These crystalline layered structures after dehydration readily and reversibly react with lithium through an intercalation mechanism. The capacity for lithium is a function of the alkali ion present, and the larger potassium ion maintains the capacity best. For lithium there is a tendency to convert to the spinel structure which leads to loss of capacity.
The change in electrical conductivity of poly(3,4-ethylenedioxythiophene) (PEDOT) when going from the oxidized state to the neutral state was measured using impedance spectroscopy. The electrical conductivity is reduced by nearly three orders of magnitude upon dedoping, a value much less than usually reported for conjugated polymers. The high conductivity in the neutral state (-10_i S/cm) explains the fast switching of PEDOT even when deposited on a nonconducting substrate. The doping process is also studied using rapid in situ optical spectroscopy of a solid-state electrochemical cell having PEDOT as one electrode. The absence of a conducting current collector enables studies of the propagation of the reaction front from the electrical contact throughout the polymer film. Optical and electrical measurements support earlier suggestions that the doping process consists of two processes occurring at different potentials.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.