Zhenrong Wang

Multilayer tape-casting method for anode-supported planar SOFCs

We have developed a multilayer tape-casting and co-sintering process to fabricate a large-area, anode-supported electrolyte film, which is critical for planar-type, reduced-temperature solid oxide fuel cells (SOFCs). Nickel/yttria-stabilized zirconia (Ni/YSZ), nickel/scandia-stabilized zirconia (Ni/ScSZ) cermets, ScSZ, Ce 0.8 Gd 0.2 O 1.9 (CGO), and La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3δ (LSCF)–CGO were used as materials for anode substrate, anode functional layer, electrolyte, interlayer and cathode, respectively. The powders of these functional layers were ball-milled with organic additives to form slurries, which were assembled together with the multilayer tape-casting procedure to get the green tapes. After drying, the green tape was co-sintered at 1400°C for 4 h in air to get the large-area, anode-supported electrolyte film (thickness 15 μm). For cell preparation, the LSCF–CGO composite cathode was deposited by the screen-printing method and sintered at 1100°C for 3 h. The area-specific resistance (ASR) of the obtained single cell was found to be 0.99 ωcm 2 at 850°C with H 2 /O 2 as the operating gases, and the maximum power density achieved was 0.63 W/cm 2 . The thickness of the (Zr,Ce)O 2 -based solid solution formed at the ScSZ/CGO interface during high-temperature sintering was investigated. The results illustrate that fabrication of an anode-supported electrolyte film for planar SOFCs with a CGO interlayer is possible by the multilayer tape-casting procedure, which is both cost-effective and feasible.

Synthesis and characterization of Ce0.8Sm0.2O1.9 nanopowders using an acrylamide polymerization process

Ce0.8Sm0.2O1.9 (SDC) nanopowders were synthesized by an acrylamide polymerization process. The XRD results showed that SDC powders prepared at 700 °C possessed a cubic fluorite structure. Transmission electron microscopy (TEM) indicated that the particle sizes of powders were in the range of 10–15 nm. A 98.3% of theoretical density was obtained when the SDC pellets were sintered at 1350 °C for 5 h, indicating that the powders had good sinterability. The conductivity of the sintered SDC ceramics was 0.019 S/cm at 600 °C and the activation energy was only 0.697 eV. Furthermore, a unit cell was fabricated from the powders and the maximum power density of 0.169 W/cm2 was achieved at 700 °C with humidified hydrogen as the fuel and air as the oxidant.

Effect of samarium doped ceria nanoparticles impregnation on the performance of anode supported SOFC with (Pr0.7Ca0.3)0.9MnO3−δ cathode

Abstract Solid oxide fuel cell (SOFC) electrodes, after a high temperature sintering, may be impregnated to deposit nanoparticles within their pores to enhance the catalytic function. Samarium doped CeO 2 (SDC) nanoparticles were infiltrated into (Pr 0.7 Ca 0.3 ) 0.9 MnO 3−δ (PCM) cathode of anode supported SOFC cells. The cell with 2.6 mg/cm 2 SDC impregnated in cathode showed the maximum power density of 580 mW/cm 2 compared with 310 mW/cm 2 of the cell without impregnation at 850 °C. The cells were also characterized with the impedance spectra, and the SDC impregnation significantly reduced the polarization resistance. After performance test the cells were characterized with scanning electron microscopy (SEM), and the cathode morphology showed the impregnated SDC particles were nanosized and were deposited on the surface of the PCM framework. The possible mechanism for the performance improvement was discussed.