Evaluation of LaNi0.6M0.4O3 (M = Fe, Co) cathodes in LSGM-electrolyte-supported solid-oxide fuel cells

Abstract

We evaluated the electrochemical performances of LaNi0.6Fe0.4O3 (LNFO) and LaNi0.6Co0.4O3 (LNCO) perovskites as cathodes in La0.8Sr0.2Ga0.83Mg0.17O2.815 (LSGM) electrolyte-supported solid oxide fuel cell. Both samples show excellent chemical compatibility with the LSGM electrolyte up to 900 °C, and exhibit small-polaron type electrical conduction with a high conductivity σ ≈ 510 (430) S·cm−1 at 800 °C and a small activation energy Eae = 54.9 (44.4) meV for LNFO (LNCO). The oxygen-reduction reaction evaluated in a symmetric LNFO(LNCO)|LSGM|LNFO(LNCO) cell gives a polarization resistance Rp ≈ 0.51 (0.34) Ω·cm2 at 800 °C in air and an activation energy EaO = 1.61 (1.87) eV. For a single cell composed of LNFO (LNCO) cathode, 300-μm-thick LSGM electrolyte, and a composite Ni + Gd-doped ceria anode, the maximum power densities reach Pmax = 490 (650) and 850 (1015) mW·cm−2 at 800 and 850 °C, respectively. These results demonstrated that LNFO and LNCO are promising cathode materials for the IT-SOFCs.