Electrochemical evaluation of double perovskite PrBaCo_2-xMn_xO_5+Δ (x = 0, 0.5, 1) as promising cathodes for IT-SOFCs

Mn-substituted double perovskites, PrBaCo_2-xMn_xO_5+δ (x = 0, 0.5, 1), are evaluated as cathode materials for intermediate-temperature solid oxide fuel cells. The effects of Mn substitution content on their structural and electrochemical properties including crystal structure, thermal expansion coefficient, and cathodic interfacial polarization resistance are investigated. The PrBaCo_2-xMn_xO_5+δ samples exhibit structural changes with increasing Mn contents from tetragonal (x = 0) to cubic (x = 0.5 and 1.0) symmetry. The thermal expansion coefficient decreases with the increasing Mn content while the cathodic performance increases with the increment of Mn content from x = 0 to x = 0.5 then decreases with the further increment of Mn content from x = 0.5 to x = 1.0. When using La_0.8Sr_0.2Ga_0.8Mg_0.15Co_0.05O₃ with 300 μm thickness as electrolyte and Sr₂Fe_1.4Ni_0.1Mo_0.5O_6-δ as anode, the maximum powder density of the x = 0.5 composite is 0.638 W cm⁻², which is higher than that of the other two samples with x = 0 (0.474 W cm⁻²) and x = 1.0 (0.371 W cm⁻²) at 800 °C.