Optimisation of high-performance, cobalt-free SrFe1-xMoxO3-d cathodes for solid oxide fuel cells prepared by spray pyrolysis

Strontium-ferrite-based perovskites as cobalt-free cathodes for intermediate-temperature solid oxide fuel cells (IT-SOFCs) have been analysed employing structural, stability and electrochemical studies. Neutron diffraction of SrFeO3-delta and SrFe0.9Mo0.1O3-delta prepared by a Pechini method confirmed that SrFeO3-delta undergoes a phase transition from tetragonal to cubic symmetry at 300-400 & DEG;C, whereas Modoping stabilises cubic symmetry in the range RT-90 0 & DEG;C. Spray-pyrolysed electrodes offered significantly lower area-specific resistances of 0.2 and 0.11 omega cm(2) for SrFeO3-delta and SrFe0.9Mo0.1O3-delta at 700 & DEG;C, respectively, in comparison to their analogues synthesised by the Pechini method (0.55 and 0.42 omega cm(2)), and lower grain size, as confirmed by scanning electron microscopy. Thermal cycling and ageing studies indicated a more robust response for the spray-pyrolysed electrodes, in particular the Mo-doped phase, which achieved a stable electrode-polarisation resistance < 0.1 omega cm(2) for 10 heating/cooling cycles and 100 h of ageing at 700 & DEG;C. Anode-supported single cells with a thin Ce0.9Gd0.1O2-delta electrolyte produced performances of 0.5 and 0.9 W cm(-2) at 700 and 800 & DEG;C, respectively. SrFe0.9Mo0.1O3-delta deposited by spray pyrolysis is, thus, proposed as a promising cobalt-free cathode for IT-SOFC based on its good structural stability and highly competitive electrochemical performance.(c) 2021 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).