Nanostructured Lscf-GDC Cathodes Via a Sol–Gel Method for High Performance Solid Oxide Fuel Cells

Abstract

Cobaltite-based perovskite materials such as La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF), Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF) which have rapid surface activation and mixed ionic and electronic ionic conductivity (MIEC) usually mixed with ionic conducting electrolyte material to lower cathodic polarization resistance. Moreover, decreasing the particulate size of the cathode at nanoscale can effectively enhance the ORR activity of the cathode by extending the electrochemically active sites due to its high surface area. However, due the high surface energy, the nanoparticles easily aggregate before mixing into homogeneous heterophase nanoparticles, resulting in significant coarsening between adjacent particles during high-temperature sintering. In this study, GDC and LSCF-GDC composite powders were synthesized via advance sol-gel method. The physicochemical properties such as sintering behavior, phase stability, etc. of the synthesized nanopowders were investigated. The optimal sintering conditions of GDC nanopowders were evaluated based on the relative density and total conductivity of the sintered GDC pellets. Furthermore, the electrochemical performances of the LSCF-GDC nanocomposite cathodes were measured by the electrochemical impedance spectroscopy (EIS). The microstructural characteristics of the LSCF-GDC nanocomposite cathode were quantified via a 3D reconstruction techniques and related to electrochemical performance of the Ni-YSZ anode supported SOFC single cell.