Triggering electrode multi-catalytic activity for reversible symmetric solid oxide cells by Pt-doping lanthanum strontium ferrite

Abstract

Among the up-and-coming technologies, reversible solid oxide cells (r-SOCs) represent a highly efficient way to store and convert energy using a single device. The interchangeability between SOFC and SOEC operation is the key aspect, though for its technological advancement the development of performing, versatile and robust electrodes must be pursued. A multi-purpose catalyst would allow for the design of a reversible symmetric cell (r-SSOC), greatly reducing fabrication and maintenance costs. However, such a flexible electrode material must comply with the requirements of both SOC electrodes, namely ensuring high performance in a wide pO2 range: catalytic activity towards fuel oxidation and H2O/CO2 reduction, electronic and ionic conductivity, long-term stability, tolerance to carbon deposition. In this work, platinum doping at the B-site of a lanthanum strontium ferrite (LSFPt) endowed the parent perovskite with superior versatility, making it able to operate as oxygen exchange catalyst as well as fuel electrode material. 5-mol% Pt inclusion enhanced the ORR/OER activity, lowering the LSF area-specific resistance by 29% and approaching the state-of-the-art LSCF performance. After reduction, Pt-Fe finely distributed exsolution provided the fuel electrode with catalytically active sites. LSFPt-symmetric H2-SOFCs and CO2-SOECs, displayed 720 mW∙cm−2 power density and 1.66 A·cm−2 current density at 1.6 V, respectively, at 850 °C. Endurance tests on LSFPt-based r-SSOCs demonstrated a remarkably stable SOFC/SOEC cyclability and a steady current density output for over 370 h in 50:50 CO2:CO at 850 °C.