Methods to increase electrochemical activity of lanthanum nickelate-ferrite electrodes for intermediate and low temperature SOFCs

Abstract

In this study the methods to increase electrochemical activity and stability of air electrodes based on LaNi0·6Fe0·4O3-δ (LNF) and Сe0.8Sm0.2O1.9 (SDC) with different collector layers has been developed. The influence of the electrode layers’ composition and sintering conditions on the electrode performance in contact with the SDC electrolyte is considered. The polarization resistance of the electrodes with the LNF collector containing a combined Bi–Cu additive is in a range of 0.60–0.67 Ωcm2 at 600 °C. Appearance of low-melting liquid phases during the collector formation gives rise to both additional sintering and electrochemical activation of the functional layers. The optimized electrodes exhibit a low degradation (13–15%) preserving a polarization resistance level of 0.15–0.21 Ω cm2 at 700 °C after long-term testing for 600 h. To elucidate reasons of the electrode ageing, changes in the electrode performance and microstructure are analyzed using DRT technique and autocorrelation function analysis of SEM images.