Ionic Conduction of Ceramic/Molten Salt Composite Electrolyte in Fuel Cell with Lithium Compound as Electrode

The ionic conduction of GDC electrolyte in a ceramic fuel cell (CFC) with NCAL as symmetrical electrode was investigated. Under the test condition of hydrogen concentration cell with pure hydrogen and 3% H₂ + 97% Ar flowing into both sides of the cell, the open circuit voltage (OCV) of the cell with NCAL as the symmetrical electrode reaches 57 mV at 550 °C, while the OCV of the cell using Pt symmetrical electrode is close to 0 V，indicating that there is proton conduction in the cell with NCAL as the symmetrical electrode. The characterization results of SEM, XPS and TOF-SIMS indicate that the internal phase composition of the electrolyte of the as-prepared cell changes from pure GDC to GDC/LiOH + Li₂CO₃ + Li₂O composite after the test of hydrogen concentration cell. Combined with the composition of the GDC/LiOH + Li₂CO₃ + Li₂O composite electrolyte and the variation law of proton transference numbers at different temperatures, it is speculated that the carriers of the composite electrolyte formed during the test of CFC using NCAL symmetrical electrode in H₂ may include OH⁻ and/or O²⁻ in addition to proton.