Development of lanthanum nickelate as a cathode for use in intermediate temperature solid oxide fuel cells

The performance of lanthanum nickelate, La2NiO4+ δ (LNO), as a cathode in intermediate temperature solid oxide fuel cells (IT-SOFCs) with the electrolyte cerium gadolinium oxide, Ce0.9Gd0.1O2−δ (CGO), has been investigated using AC impedance spectroscopy of symmetrical cells. A significant reduction in the area specific resistance (ASR) was achieved with a layered cathode structure that incorporates a thin compact LNO layer between the dense electrolyte and porous electrode. This decrease in ASR is attributed to improved contact at the electrolyte/cathode interface, facilitating enhanced oxygen ion transfer to the electrolyte. Measurements indicated an ASR of 1.0 Ωcm2 at 700 °C for the layered structure, a substantial improvement compared to an ASR of 7.4 Ωcm2 for cells lacking the compact layer. Furthermore, additional enhancements in cell current collection were observed, suggesting that an optimized symmetrical cell with a layered structure and effective current collection could further lower ASR values.