Chemical and electrochemical behaviour of Ni-Ti in the cathodic conditionsused in molten carbonate fuel cells

The chemical and electrochemical behaviour of nickel-titanium alloys is inv estigated in molten Li2CO3 + Na2CO3 at 650 degreesC under the usual MCFC ca thode conditions. XPS, XRD and SIMS analyses show that Ni-Ti alloy is mostl y covered by a TiO2 inner layer and by a Li2TiO3 or LixNayTiO3 outer layer. Only traces of nickel species can be detected. Ocp and conductivity measur ements confirm general behaviour closer to titanium than to nickel compound s. An intercalation/deintercalation phenomenon involving the alkali titanat e present at the surface of a Ni-Ti electrode was analysed by cyclic voltam metry. It can be noted that nickel compounds have a positive effect on the conductivity, but their influence on the surface characteristics of the all oy is difficult to analyse precisely. (C) 2001 Elsevier Science B.V. All ri ghts reserved.