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Effect of A/B‐Site Non‐stoichiometry on the Structure and Properties of La 0.9 Sr 0.1 Ga 0.9 Mg 0.1 O 3− δ Solid Electrolyte in Intermediate‐Temperature Solid Oxide Fuel Cells
Author(s) -
Wang Jian Qiu,
Zhou De Feng,
Gao Jin Quan,
Sun Hao Ran,
Zhu Xiao Fei,
Meng Jian
Publication year - 2018
Publication title -
chemelectrochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.182
H-Index - 59
ISSN - 2196-0216
DOI - 10.1002/celc.201701284
Subject(s) - analytical chemistry (journal) , electrolyte , materials science , thermal expansion , thermal stability , dielectric spectroscopy , conductivity , sintering , phase (matter) , scanning electron microscope , electrical resistivity and conductivity , stoichiometry , grain boundary , microstructure , electrochemistry , chemistry , electrode , composite material , physics , organic chemistry , chromatography , quantum mechanics
Abstract (La 0.9 Sr 0.1 ) x (Ga 0.9 Mg 0.1 ) y O 3‐δ [(LS) x (GM) y ] ( x =0.97, 1.00, 1.03; y =1.00 and x =1.00; y =0.97, 1.00, 1.03) electrolyte is prepared through a sol‐gel method followed by sintering at 1300 °C for 10 h. The microstructures of the samples are characterized by using X‐ray diffraction (XRD) and field‐emission scanning electron microscopy (FE‐SEM). The electrical and thermal stability properties are measured by means of electrochemical impedance spectroscopy (EIS) and thermal expansion coefficient (TEC), respectively. It is shown that phase purity could improve by adjusting the non‐stoichiometry of A/B‐site. This, in turn, affects the conductivity and thermal expansion of the solid electrolyte. The samples with B‐site defects [LS(GM) 0.97 ] are found to exhibit the best phase purity and density with minimal grain boundary/total resistances, and superior thermal stability. The conductivity of LS(GM) 0.97 is 1.56 time higher than that of LSGM. The average thermal expansion coefficient of LS(GM) 0.97 at 50–850 °C is 4.13 % lower than that of LSGM. The maximum power density of single cells containing LS(GM) 0.97 electrolyte could reach 0.54 W cm −1 at 800 °C, which is 16.7 % higher than that of cells containing LSGM electrolyte. The stability test for over 120 h at 800 °C indicates a slight decrease in performances during the first 10 h, but no significant differences in electrode polarization are observed even after long‐term operation. These findings suggest the potential applications of LS(GM) 0.97 as a novel electrolyte for intermediate‐temperature solid oxide fuel cells.