Nanoparticles produced by borohydride reduction as precursors for metal hydride electrodes

The performance of electrodes, prepared from amorphous CoxByHz nanoparticles without additives, in 20% KOH solution was tested by means of cyclic voltammetry and chronopotentiometry. Peaks, assigned to hydrogen adsorption and desorption, are observed in the cyclic voltammograms. After charging, hydrogen atoms occupy different types of sites in the substrate, from which electrochemical desorption occurs. An increase in hydrogen content as a result of repeated cycling was established. Discharge capacity of the electrodes, estimated from the chronopotentiometric discharge curves obtained, is about 250 mA h g(-1). The observed changes in hydrogen and boron content, due to electrochemical treatment, indicate that the electrode material is an active participant in the whole electrochemical process. Hypotheses for the reaction mechanism are proposed.