Chemical and electrochemical behaviour of Ni–Ti in the cathodic conditions used in molten carbonate fuel cells

The chemical and electrochemical behaviour of nickel–titanium alloys is investigated in molten Li2CO3+Na2CO3 at 650°C under the usual MCFC cathode conditions. XPS, XRD and SIMS analyses show that Ni–Ti alloy is mostly 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 measurements confirm general behaviour closer to titanium than to nickel compounds. An intercalation/deintercalation phenomenon involving the alkali titanate present at the surface of a Ni–Ti electrode was analysed by cyclic voltammetry. It can be noted that nickel compounds have a positive effect on the conductivity, but their influence on the surface characteristics of the alloy is difficult to analyse precisely.