Phase formation between La(Sr)Ga(Mg)O3 and Ce(La)O2 for solid oxide fuel cell applications

Abstract

AbstractIn strontium‐ and magnesium‐doped LaGaO3 (LSGM) electrolyte‐based solid oxide fuel cells (SOFC), lanthanum‐doped CeO2 (LDC) is usually used as buffer layer material to prevent reactions between LSGM electrolyte and NiO‐based anode. In literature, based on results for one particular LSGM composition, a fixed buffer layer composition of 40% La‐doped ceria (LDC40) has been used even with electrolytes of different LSGM compositions. In this study, we report the results of a comprehensive study of phase formations between various LSGM and LDC compositions. Our results show that only one LSGM/LDC combination results in no additional phases. For the other combinations, at least one and often two additional phases, LaSrGaO4 and LaSrGa3O7, result. Because LaSrGa3O7 has much lower conductivity, it is necessary to select combinations that avoid this phase. We propose that the combination that results in no additional phase should be considered favorably for SOFCs. For other LSGM compositions, LDC50 should be used as a buffer layer instead of LDC40 as is presently done in SOFC studies. Alternately, if LDC40 is preferred for buffer layer, then lower Sr content LSGM compositions should be used as electrolytes. These combinations are likely to lead to better long‐term SOFC performance.