Preparation and characterization of Ceo.8Smo.201.9(SDC)-carbonates composite electrolyte via molten salt infiltration

摘要

Ce_0.8Sm_0.2O_1.9 (SDC)-carbonates composite electrolytes for SOFCs have been prepared for the first time via molten salt infiltration approach by infiltrating LiNaCO_3 molten carbonates into porous SDC ceramic. A range of techniques including XRD, SEM, Mercury Porosimeter and A.C. impedance, have been employed to characterize SDC and composite electrolytes. It has been found that the porous SDC shows a monomodal pore size distribution with average pore size of 300 nm. SDC-carbonates composite electrolytes via molten salt infiltration show a kind of SDC/carbonates co-continuous composite structure, with one SDC ceramic skeleton of bonded grains surrounded by carbonates phase. Both phases provide a continuous pathway for ionic transport and a large interfacial surface area. SDC-carbonates composite electrolytes prepared by molten salt infiltration have a higher mechanical strength than that of mixing-pressing composite electrolytes. Moreover, they show higher conductivity and lower activation energy than that of mixing-pressing composite electrolytes according to the measurements of AC impedance in the temperature range of 350 ℃-650 ℃.