Characterization of Cuprate based Cathode Structures by AC Impedance

Abstract

Composites containing the cuprate Nd1.8Ce0.2CuO4+δ (NCCO) have been shown to have promising behaviour for SOFC cathode applications, with performances similar to those of standard LSM based composites. It is hoped that the n-type conductivity exhibited by the NCCO may confer further operational advantages when operating at high oxygen utilizations or high cell polarisations where the local cathode oxygen partial pressure is reduced. Also, as it contains neither Mn nor Sr (both of which have been implicated in nucleating Cr deposition) it may also have benefits in terms of Cr tolerance. Candidate structures were assessed in a symmetrical half cell arrangement using both AC impedance and SEM examination. So far the best results have been obtained using the in-situ fired current collector Rp values of 0.10Ωcm2 and 0.115 Ωcm2 at around 750{degree sign}C have been observed for cathode structures with the CGO interface or CGO electrolyte respectively.