K. Giza

Effect of preparation method of metal hydride electrode on efficiency of hydrogen electrosorption process

Abstract The preparation of negative electrodes for nickel–metal hydride batteries using LaNi4.3Co0.4Al0.3 alloy is presented. The constant current discharge technique is employed to determine the discharge capacity, the exchange current density and the hydrogen diffusion coefficient of the studied electrodes. The electrochemical performance of metal hydride electrode is strongly affected by preparation conditions. The results are compared and the advantages and disadvantages of preparation methods of the electrodes are also discussed.

Hydrogen sorption and corrosion properties of La2Ni9CoSn0.2 alloy

Abstract The hydrogenation and corrosion behaviour of La2Ni9 · CoSn0.2 alloy was analysed in respect of its use in Ni–MH batteries. It has been proved that the presence of tin in the alloy causes a decrease in hydrogen equilibrium pressure. In the electrochemical studies several techniques, such as chronopotentiometry, multi-potential steps, linear sweep voltammetry and the potentiokinetic polarization were applied to characterize the electrochemical properties of a La2Ni9CoSn0.2 powder composite electrode. During long cycling, powder particles undergo micro-cracking or other forms of surface development causing a progressive increase in the exchange current density of the H2O/H2 system, but, on the other hand, this increase favours corrosion processes such as the electrode materials oxidation. This is also reflected in the capacity loss values.

Influence of H3PW12O40 on electrochemical properties of LaCo4.8Bi0.2 alloy

The effect of the surface treatment by H3PW12O40 solution on electrochemical properties of the LaCo4.8Bi0.2 alloy was investigated. A significant increase of hydrogen absorption and a distinct increase of exchange current density was obtained for LaCo4.8Bi0.2 alloy activated with tungstophosphoric acid. Potentiokinetic polarization curves show that the anodic currents increase with the amount of absorbing hydrogen.Graphical abstract