Optimisation of electrochemical performance of Sr(Fe,Sb)O3-δ air electrodes for intermediate-temperature solid oxide cells through spray-pyrolysis processing

Abstract

The effects of replacing iron with cobalt and employing either Pechini or spray pyrolysis synthesis routes have been studied for the perovskite system SrFe0.9-xCoxSb0.1O3-δ (x = 0; 0.45; 0.9) to optimise sustainable air electrodes for intermediate-temperature solid oxide cells. The electrochemical performance of Pechini-prepared compositions improves with increasing cobalt content, attributable to higher electronic conductivity and oxygen-vacancy concentration, and lower processing temperature from 1300 ᵒC, for SrFe0.9Sb0.1O3-δ, to 1200 and 1100 ᵒC, for SrFe0.45Co0.45Sb0.1O3−δ and SrCo0.9Sb0.1O3−δ, respectively, with SrCo0.9Sb0.1O3-δ exhibiting an area specific resistance (ASR) of 0.084 Ω cm2 at 700 °C. The electrochemical stability of Fe-containing Pechini-based compositions is impaired, most likely due to a higher processing temperature. However, the very low processing temperature of 800 °C for spray-pyrolysed electrodes produces similar electrochemical performances for Co-containing and Co-free compositions (ASR≈ 0.065 Ω cm2 at 700 °C for SrFe0.9Sb0.1O3-δ) and high electrochemical stability with practically unaltered electrode polarisation resistance on thermal cycling.