Effects of Soaking Duration on the Properties of LSCF–SDCC for Low-Temperature SOFC

摘要

Solid oxide fuel cells (SOFCs) offer the advantages of high efficiency, low pollution emission, and low processing cost. SOFC quality is strongly influenced by the preparation process. Composite La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ) (LSCF) samarium-doped ceria carbonate (SDCC) cathode for low-temperature SOFCs was developed, and the effect of sintering soaking time on the physical properties of an LSCF–SDCC composite cathode was studied. Composite cathode powders with 50 wt% LSCF and 50 wt% SDCC were mixed before undergoing calcination and uniaxial pressing process. The pressed samples were sintered at 600°C and soaked at 1, 2, and 3 hr. The porosity and density results obtained by the Archimedes method showed a decrement of porosity from 24.92% to 19.62% and an increment of density from 4.03 g cm~(-1) to 4.15 g cm~(-1) under 1 hr to 3 hr of soaking time. Scanning Electron Microscopy reveals that the grain size of the composite cathode surface increases with increasing soaking time. X-ray diffraction results demonstrate that the diffraction angles at 33° and 59° exhibit a decreasing SDCC peak because of the increasing grain size. However, the new peak of lithium chromium oxide (Li_2CrO_4) appears at an angle of 21.66° for 3 hr soaking time. The findings proved that soaking time influences the microstructure of the composite cathode.