Nonstoichiometric (La0.95Sr0.05)xGa0.9Mg0.1O3−δ electrolytes and Ce0.8Nd0.2O1.9–(La0.95Sr0.05)xGa0.9Mg0.1O3−δ composite electrolytes for solid oxide fuel cells

• A-site nonstoichiometric LSGM and their composite system NDC–LSGM.
• A-site nonstoichiometry effectively increases the total conductivity of LSGM electrolytes.
• The total conductivity of NDC–LSGM composite electrolyte enhanced greatly.
• Nonstoichiometry have great influence on conductivity of composite electrolytes.

A-site nonstoichiometric electrolytes (La0.95Sr0.05)xGa0.9Mg0.1O3−δ (LSGM, x = 0.97, 1.00, 1.03), and their composites Ce0.8Nd0.2O1.9 (NDC)–LSGM, were synthesized and investigated. The nonstoichiometry efficiently enhanced the total conductivity of LSGM electrolyte, and the A-site deficient composition showed the highest total conductivity above 550 °C (σt,LSGM(x=0.97) = 0.880 S m−1 > σt,LSGM(x=1.03) = 0.808 S m−1 > σt,LSGM(x=1.00) = 0.582 S m−1 at 600 °C). The cubic fluorite and perovskite structures were adopted by all the composites. The LSGM additive significantly promoted the grain growth of the composite electrolyte. The grain boundary conductivities of the composite electrolytes were more or less 5–10 times higher than that of NDC electrolyte at 500 °C. The optimum A-site nonstoichiometry was found to be x = 0.97 in composite electrolytes. This study provides a possible route to design high performance single phase or composite electrolytes for SOFCs.

The total conductivity of the NDC–LSGM composite electrolyte is much higher than that of the NDC electrolytes. The optimum A-site nonstoichiometry was found to be x = 0.97 in both LSGM single phase and NDC–LSGM composite electrolytes.Figure optionsDownload as PowerPoint slide