Low Thermal Expansion of Ba0.5Sr0.5Co0.7Fe0.2Mn0.1O3-δ cathode Material

Low thermal expansion Ba0.5Sr0.5Co0.7Fe0.2Mn0.1O3-δ(BSCFM-0.1) material was prepared to improve the thermal compatibility between cathode and electrolyte for intermediate temperature solid oxide fuel cells. The pure perovskite BSCFM-0.1 can be obtained by a combined citrate and EDTA complexing method. The results show that Mn was introduced to replace Co in B-site of Ba0.5Sr0.5Co0.8Fe0.2O3-δ(BSCF) to depress thermal expansion. Thermal expansion coefficient of BSCFM-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 value comparing with BSCF for 15.62×10-6 K-1 at 600oC and 16.76×10-6 K-1 at 700oC. The small difference of thermal expansion is helpful for cathode adhering to the ceria-base electrolyte. As to the single cell, the maximum 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 slowed down to control the concentration of oxygen vacancies in the lattice by Mn partial substitution without reducing electrical properties. The gradual increase of thermal expansion is beneficial to improve the thermal compatibility between cathode and electrolyte for SOFCs.