Nickel and Nickel-Cerium Alloy Anodes for Direct Borohydride Fuel Cells

The borohydride oxidation reaction (BOR) was studied at nickel and nickel-cerium (Ni-Ce, with 5 and 10 at% Ce) alloy electrodes in alkaline media. The samples were prepared by arc-melting and their microstructure and phase composition were determined by scanning electron microscopy and electron probe microanalysis based on energy dispersive X-ray spectroscopy. BOR was investigated using cyclic voltammetry and chronoamperometry and kinetic parameters such as charge transfer coefficients, number of electrons exchanged and standard heterogeneous rate constants, were evaluated. The three studied electrodes exhibited similar performance for BOR with Ni 95 Ce 5 alloy electrode giving the highest current densities. Direct borohydride-peroxide fuel cell (DBPFC) was constructed employing Ni 95 Ce 5 alloy electrode as anode and main cell parameters (e.g., maximum cell voltage, peak power density) were determined. Influence of temperature on the BOR on Ni and Ni-Ce alloy electrodes, as well as on the DBPFC performance was explored in the 25–45°C range. A peak power density of 110 mW cm −2 was obtained at 45°C for a cell voltage of 0.50 V and current density of 219 mA cm −2 .