A high-performance cobalt-free Ruddlesden-Popper phase cathode La1·2Sr0·8Ni0·6Fe0·4O4+δ for low temperature proton-conducting solid oxide fuel cells

Abstract

Ruddlesden-Popper typological (R-P type) layered material La2NiO4 is known for the excellent ionic conductivity and fast oxygen kinetics, but limited by its electronic conductivity as a single-phase cathode for low-temperature proton-conducting solid oxide fuel cells (LT H-SOFC). Cobalt-doping can improve the electro-catalytic capability, accompanied with an increased thermal expansion coefficient (TEC), which would lead to the delamination at the cathode/electrolyte interface. In this assignment, strontium and iron co-doped R-P phase cathode La1·2Sr0·8Ni0·6Fe0·4O4+δ (LSNF), exhibiting fine oxygen conduction, sufficient electronic conductivity and compatible TEC with the electrolyte, is investigated thoroughly. The single cell with LSNF cathode based on BaZr0·1Ce0·7Y0·2O3-δ (BZCY) electrolyte achieves a maximum power density (MPD) of 781 mW cm−2 with the low interfacial polarization resistance (Rp) of 0.078 Ω cm2 at 700 °C. Interestingly, the single cell can also possess an eximious power output of 138.5 mW cm−2 at relatively low temperature of 500 °C. Moreover, the excellent long-term stability with no observable performance degradation for almost 100 h at 600 °C could also indicate that the single-phase R-P layered material LSNF is a preeminent cathode candidate for LT H-SOFC.