Mechanism for Major Improvement in SOFC Electrolyte Conductivity When Using Lithium Compounds as Anode

Abstract

Recent studies indicate that the electrolyte ionic conductivity in an SOFC can be considerably increased by using lithium compounds as the electrode. We found that the ionic conductivity of Gd0.1Ce0.9O1.95 electrolyte in the Ni0.8Co0.15Al0.05LiO2 anode cell was 10.1 mS/cm only at 550 °C without H2, but it increased to 44.6 mS/cm after feeding H2 to the anode. It was found that LiOH/Li2CO3 moved into the GDC electrolyte from the NCAL anode and formed a three-phase composite electrolyte. A space charge region with a high oxygen vacancy concentration is formed around the interface of LiOH/Li2CO3 and GDC, which increases the ionic conductivity.