Premium
Phase Transition of a Cobalt‐Free Perovskite as a High‐Performance Cathode for Intermediate‐Temperature Solid Oxide Fuel Cells
Author(s) -
Jiang Shanshan,
Zhou Wei,
Niu Yingjie,
Zhu Zhonghua,
Shao Zongping
Publication year - 2012
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201200264
Subject(s) - cathode , perovskite (structure) , tetragonal crystal system , cobalt , materials science , dielectric spectroscopy , electrochemistry , electrolyte , phase transition , oxide , phase (matter) , inorganic chemistry , analytical chemistry (journal) , chemistry , chemical engineering , electrode , crystallography , metallurgy , thermodynamics , physics , organic chemistry , chromatography , engineering
Abstract It is generally recognized that the phase transition of a perovskite may be detrimental to the connection between cathode and electrolyte. Moreover, certain phase transitions may induce the formation of poor electronic and ionic conducting phase(s), thereby lowering the electrochemical performance of the cathode. Here, we present a study on the phase transition of a cobalt‐free perovskite (SrNb 0.1 Fe 0.9 O 3− δ , SNF) and evaluate its effect on the electrochemical performance of the fuel cell. SNF exists as a primitive perovskite structure with space group P 4mm (99) at room temperature. As evidenced by in situ high‐temperature X‐ray diffraction measurements over the temperature range of 600 to 1000 °C, SNF undergoes a transformation to a tetragonal structure with a space group I 4/m (87). This phase transition is accompanied by a moderate change in the volume, allowing a good cathode/electrolyte interface on thermal cycling. According to the electrochemical impedance spectroscopy evaluation, the I 4/m phase exhibits positive effects on the cathode’s performance, showing the highest oxygen reduction reaction activity of cobalt‐free cathodes reported so far. This activity improvement is attributed to enhanced oxygen surface processes.