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

摘要

The performance of lanthanum nickelate, La_2NiO _(4 + δ) (LNO), as a cathode in IT-SOFCs with the electrolyte cerium gadolinium oxide, Ce_(0.9)Gd_(0.1)O_(2-δ) (CGO), has been investigated by AC impedance spectroscopy of symmetrical cells. A significant reduction in the area specific resistance (ASR) has been achieved with a layered cathode structure consisting of a thin compact LNO layer between the dense electrolyte and porous electrode. This decrease in ASR is believed to be a result of contact at the electrolyte/cathode boundary enhancing the oxygen ion transfer to the electrolyte. An ASR of 1.0 Ω cm~2 at 700 °C was measured in a symmetrical cell with this layered structure, compared to an ASR of 7.4 Ω cm~2 in a cell without the compact layer. In addition, further improvements were observed by enhancing the cell current collection and it is anticipated that a symmetrical cell consisting of a layered structure with adequate current collection would lower these ASR values further.