engleski

Ruthenium oxide/polyaniline/binder composites as active electrode material for supercapacitors

Ruthenium oxide is one of the most promising materials for supercapacitors due to various oxidation states, good reversibility, high cycle life and good stability. The energy storage/delivery process within ruthenium oxide generally follows the equation: HxRuOy ↔ Hx-zRuOy + zH+ + ze- Capacitive performance of ruthenium oxide depends on proton and electron conductivity and usually only thin layer in contact with electrolyte is active resulting in a poor utilization of material. It is therefore of high importance to improve utilization of oxide material and achieve higher gravimetric energy and power densities. In order to improve capacitive properties of ruthenium oxide different attempts were made including the optimization of proton and electron conductivity [1], addition of other oxides [2] or ruthenium oxide nanostructures were formed on carbon support [3]. Another promising group of material for supercapacitors are conductive polymers [4]. Advantage of these materials is low price and quite simple methode of preparation. The aim of this paper was to increase utilization of ruthenium oxide by dispersion of the oxide micro-particles within the polymer matrix and by the deposition of polyaniline that will interconnect ruthenium oxide particles and increase overall capacitance. In this work ruthenium oxide was mixed with two different polymer binders, Nafion and PVDF. The composite materials were formed on glassy carbon electrode by casting a homogenized suspension of ruthenium oxide in solution of NafionTM in isopropyl alcohol or solution of poly(vinylidene fluoride) (PVDF) in N-methyl-pyrrolidone. The electrodes were dried in the case of NafionTM in open air and in the case of PVDF in vacuum through 24 hours. Polyaniline was subsequently deposited by electrochemical polymerization from solution of 0.1 mol dm-3 aniline in 0.5 mol dm-3 H2SO4. The electrochemical properties of materials were tested by means of cyclic voltammetry and electrochemical impedance spectroscopy in 0.5 mol dm-3 H2SO4. It was found that capacitive properties strongly depend on the type and amount of binder. Polyaniline deposition increased the capacitance of the composite, but the overall electrochemical behaviour was affected by the binder used.

ruthenium oxide; polyaniline; Nafion; PVDF

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