Electrochemical and structural influence on BaZr0.8Y0.2O3-δ from manganese, cobalt, and iron oxide additives

Proton conductive BaZr0.8Y0.2O3-delta (BZY20) is a promising electrolyte candidate with perspective application in electrochemical devices, including fuel cells, electrolyzer cells. Mn, Fe, and Co are commonly incorporated into BZY20, to improve the sinterability (CoO), or due to possible inter-diffusion by calcining with cathode materials (eg, La1-xSrxMnO3-delta, La1-xSrxCo1-yFeyO3-delta) for cell preparation. This work was performed to investigate the influence of Mn, Fe, and Co on the structural and electrochemical properties of BZY20. As reported in literature, the sinterability of BZY20 was improved by adding CoO. XANES analysis shows that Mn, Fe, and Co are possibly incorporated into the perovskite crystal structure of BZY20, and are partially reduced when the samples were exposed to hydrogen at 600 degrees C for 24 hours. However, through electrochemical analysis, we found that all these three elements decrease both the proton conductivity and transport numbers of proton conduction of BZY20. Therefore, the BZY20 electrolyte should be carefully handled to avoid the incorporation of these transition metal elements, to fabricate the cells with high performance.