Impregnation of Acetylene Black Electrodes with a Polytetrafluoroethylene Binder with an Aqueous Solution and Evaluation of Its Specific Double Layer Capacity

The effect of (0.05 M) tetraalkylammonium salt additions in aqueous 0.5 M KOH on the rate of impregnation of carbon black electrodes with a polytetrafluoroethylene binder (5-20 wt % PTFE) at hydrogen evolution potentials was studied. It was shown that tetraalkylammonium salts facilitate the fast filling of electrodes with electrolyte, and their effect increases with the molecular mass of the cation. Tetramethylammonium bromide showed the weakest effect. In solutions with tetrabutylammonium bromide, the electrodes were completely flooded with 5 wt % PTFE within 15 min. Diethyldibenzylammonium bromide had a similar effect. The influence of the PTFE concentration in the electrodes on their capacity was studied. The specific capacity of acetylene black in acid and alkaline aqueous solutions was evaluated from the electrode surface area determined by low-temperature nitrogen adsorption (BET).