Hydrogen transport between proton conducting oxide and hydrogen storage metal

We constructed an electrochemical cell consisting of proton conducting oxid e as a electrolyte and hydrogen storage metal as a negative electrode. Hydr ogen transport between the proton conducting oxide and the hydrogen storage metal, which induced by the gradient of electric potential or the hydrogen concentration, were studied by the measurements of electromotive force (EM F) and proton flux across the electrolyte. The transport of protons from Sr Ce0.95Yb0.05O3-alpha proton conducting oxide to the hydrogen storage metals of V and Zr induced by the electric potential was investigated from the me asurement of proton flux which flow in the negative electrode, where the pr oton flux was determined from the time evolution of the hydrogen content in the electrode material which could be obtained by the d.c. current and the ERDA measurements. From the relations between the hydrogen flux and the to tal electric current across the electrolyte, we evaluated the proton transp ort numbers and the proton diffusivity for SrCe0.95Yb0.05O3-alpha oxide-use d as the electrolyte. As for the hydrogen transport from the hydrogen stora ge metal to the proton conducting oxide, we observed the temporal evolution of the voltage between the electrodes. The temperature dependence of the e lectromotive force revealed that the protons emitted from the hydrogen stor age metals such as V, Zr, Nb and LaNi5 had entered into the proton conducti ng oxide. This result indicated that the hydrogen storage metals has a poss ibility to use as the negative hydrogen electrode of the hydrogen-air fuel cell. (C) 1999 Elsevier Science S.A. All rights reserved.