Sintering and grain growth of (La,Sr)MnO 3 electrodes of solid oxide fuel cells under polarization

Abstract

The grain growth and sintering behavior of (La 0.8Sr 0.2) x MnO 3( x = 1.0, 0.9 and 0.8) of solid oxide fuel cells (SOFC) are studied under polarization and open circuit conditions at 1000 °C for 1600 h. The LSM electrodes with A-site non-stoichiometry show a much higher sinterability than that with the A-site stoichiometric composition. It has been found that under cathodic polarization at a constant current density of 500 mA cm −2 and 1000 °C in air, the grain growth of LSM electrodes is significantly smaller than that under open circuit at the same temperature for all the compositions studied. The hindrance of sintering under cathodic polarization has been attributed to the elimination of the cation vacancies at the A-sites, thus increasing the resistance to the sintering process. The reduced sinterability of LSM electrodes under cathodic polarization is consistent with the observed high performance stability of LSM cathodes under SOFC operation conditions.