Nb and Pd co-doped La<inf>0.57</inf>Sr<inf>0.38</inf>Co<inf>0.19</inf>Fe<inf>0.665</inf>Nb<inf>0.095</inf>Pd<inf>0.05</inf>O<inf>3-d</inf>as a stable, high performance electrode for barrier-layer-free Y<inf>2</inf>O<inf>3</inf>-ZrO<inf>2</inf>electrolyte of solid oxide fuel cells

Abstract

© 2017 Elsevier B.V. La 0.6 Sr 0.2 Co 0.2 Fe 0.8 O 3-d (LSCF) is the most intensively investigated high performance cathode for intermediate temperature solid oxide fuel cells (IT-SOFCs), but strontium segregation and migration at the electrode/electrolyte interface is a critical issue limiting the electrocatalytic activity and stability of LSCF based cathodes. Herein, we report a Nb and Pd co-doped LSCF (La 0.57 Sr 0.38 Co 0.19 Fe 0.665 Nb 0.095 Pd 0.05 O 3-d , LSCFNPd) perovskite as stable and active cathode on a barrier-layer-free anode-supported yttria-stabilized zirconia (YSZ) electrolyte cell using direct assembly method without pre-sintering at high temperatures. The cell exhibits a peak power density of 1.3 W cm -2 at 750 °C and excellent stability with no degradation during polarization at 500 mA cm -2 and 750 °C for 175 h. Microscopic and spectroscopic analysis show that the electrochemical polarization promotes the formation of electrode/electrolyte interface in operando and exsolution of Pd/PdO nanoparticles. The Nb doping in the B-site of LSCF significantly reduces the Sr surface segregation, enhancing the stability of the cathode, while the exsoluted Pd/PdO nanoparticles increases the electrocatalytic activity for the oxygen reduction reaction. The present study opens up a new route for the development of cobaltite-based perovskite cathodes with high activity and stability for barrier-layer-free YSZ electrolyte based IT-SOFCs.