A Ruddlesden–Popper oxide as a carbon dioxide tolerant cathode for solid oxide fuel cells that operate at intermediate temperatures

Abstract

Solid oxide fuel cells (SOFCs) that operate at intermediate temperatures of 600 to 800 °C have recently received increased attention due to their improved durability, more rapid startup and shutdown, better sealing and lower cost than their counterparts operate at high temperatures. Nevertheless, intermediate-temperature SOFCs (IT-SOFCs) with popular perovskite cathodes contain alkaline-earth elements, which are prone to reaction with carbon dioxide (CO2), even when the CO2 content is comparatively low. In this work, an alkaline-earth metal-free Ruddlesden–Popper oxide, Nd1.8La0.2Ni0.74Cu0.21Ga0.05O4+δ (NLNCG), is developed for IT-SOFC cathodes. The cell is based on an electrolyte with 8 mol% Y2O3-stabilized ZrO2 (8YSZ). The NLNCG cathode exhibits an excellent CO2 tolerance, as proven by thermogravimetry analysis (TGA), in situ X-ray diffraction (XRD), I-V-P test, and electrochemical impedance spectroscopy (EIS), and stability measurements. The anode-supported single-cell NiO-YSZ|YSZ|NLNCG outputs a peak power density (PPD) of 0.522 W·cm-2 at 800 °C. These findings suggest that NLNCG could be a highly suitable cathode material with CO2 tolerance for IT-SOFCs.