Fabrication and Characterization of Ce_(0.8)Sm_(0.2)O_(1.9) Microtubular Dual-Structured Electrolyte Membranes for Application in Solid Oxide Fuel Cell Technology

摘要

Samaria-doped ceria (SDC, Ce_(0.8)Sm_(0.2)O_(1.9)) ceramic powders of submicrometer size were synthesized by a sol-gel auto-combustion method. From these powders microtubes with a dual structure comprising of a dense layer and a porous substrate layer were fabricated in a single step through a phase inversion/ sintering technique. A sintering temperature in excess of 1450℃ is required for SDC to achieve gastight microtubes. The mechanical strength of the SDC microtubes increases with increasing sintering temperature and may attain up to 208 MPa when sintered at 1500℃. Electrical impedance spectroscopy studies indicate that the SDC microtubes have electrical conductivities of 4.46 × 10~(-4)-0.072 S/cm and corresponding activation energy of 81.9 kJ/mol at temperatures between 400° and 800℃. Full fuel cells were fabricated by coating Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3-δ) (BSCF) on to the inner surface and a Ni-SDC cermet on to the outer surface of the gastight microtubes to act as the cathode and the anode, respectively. The resultant BSCF|SDC|Ni-SDC microcells have a stable output maximum of 106 mW/cm~2 at 750℃ when hydrogen and air were used as fuel and oxidant gas, respectively.