Electrochemical Characterisation Of Activated Carbon Particles Used In Redox Flow Battery Electrodes

摘要

The Faradaic and non-Faradaic characteristics of a series of activated carbon particles (used to produce composite carbon-polymer electrodes for redox flow cells) have been determined using aqueous electrolytes (sulfuric acid and sodium polysulfide) at 295 K. The particles were mounted as a circular section (ca. 0.80cm~2) shallow packed bed of 2.5 mm thickness in the direction of electrolyte flow (mean linear flow velocity ≈ 6 mm s~(-1)). Cyclic voltammetry in deaerated, 1 mol dm~(-3) H_2SO_4 at 295 K indicated a specific capacitance in the range of 50-140 Fg~(-1). Linear sweep voltammetry and galvanostatic step studies in an alkaline sodium polysulfide electrolyte (1.8 mol dm~(-3) Na_2S_(2.11)) have demonstrated marked differences amongst various types of activated carbon. Such differences are highlighted during galvanostatic charge-discharge cycling of half-cell electrodes in the polysulfide electrolyte. The electrochemical characteristics are compared to those based on (N_2 adsorption) gas porosimetry measurements.