Low Thermal Expansion of Ba_0.5Sr_0.5Co_0.7Fe_0.2Mn_0.1O_3-δ cathode Material

摘要

Low thermal expansion Ba0.5Sr0.5Co0.7Fe0.2Mn0.1O3-?(BSCFM-0.1) material was prepared to improvethe thermal compatibility between cathode and electrolyte for intermediate temperature solid oxidefuel cells. The pure perovskite BSCFM-0.1 can be obtained by a combined citrate and EDTAcomplexing method. The results show that Mn was introduced to replace Co in B-site ofBa0.5Sr0.5Co0.8Fe0.2O3-?(BSCF) to depress thermal expansion. Thermal expansion coefficient ofBSCFM-0.1 is 14.24×10-6 K-1 at 600oC, and 14.97×10-6 K-1 at 700oC, respectively. It is a smaller valuecomparing with BSCF for 15.62×10-6 K-1 at 600oC and 16.76×10-6 K-1 at 700oC. The small difference ofthermal expansion is helpful for cathode adhering to the ceria-base electrolyte. As to the single cell, themaximum power density is 110 mW cm-2 at 600oC, which is slightly higher than that of BSCF cathode(102 mW cm-2 at 600oC). The results imply that the rate of lattice oxygen release has been sloweddown to control the concentration of oxygen vacancies in the lattice by Mn partial substitution withoutreducing electrical properties. The gradual increase of thermal expansion is beneficial to improve thethermal compatibility between cathode and electrolyte for SOFCs.