Investigation of the Fe doping effect on the B-site of the layered perovskite PrBa _0.8 Ca _0.2 Co ₂ O _5+Δ for a promising cathode material of the intermediate-temperature solid oxide fuel cells

Layered perovskites can be considered as promising cathode materials for intermediate-temperature solid oxide fuel cell because of their fast oxygen kinetics compared to simple perovskites. Among them, the cobalt-based layered perovskites are considered as very promising cathode materials due to its high conductivity and fast oxygen kinetics, but they are unstable under operating condition. Doping other transition metal such as Fe, Mn, Cu, and Ni can be considered to solve the instability of the cobalt-based layered perovskites. In this paper, we investigated Fe doped cobalt-based layered perovskite, PrBa _0.8 Ca _0.2 Co _2-x Fe _x O _5+δ (x = 0, 0.5, and 1.0), as prospective cathode materials in terms of their crystal structures, thermal expansion behavior, electro- and electro-chemical properties. The PrBa _0.8 Ca _0.2 Co _1.5 Fe _0.5 O _5+δ shows improved maximum power density of 1.89 W cm ⁻² and polarization resistance of 0.080 Ω cm ² at 600 °C as compared with un-doped PrBa _0.8 Ca _0.2 Co ₂ O _5+δ while maintaining suppressed thermal expansion. Based on these results, PrBa _0.8 Ca _0.2 Co _1.5 Fe _0.5 O _5+δ can be considered as a promising cathode material for intermediate-temperature solid oxide fuel cell.