LSCF nanopowder from cellulose-glycine-nitrate process and its application in intermediate-temperature solid-oxide fuel cells

Nanostructured La_0.6Sr_0.4Co_0.2Fe _0.8O_3-δ (LSCF) oxide powder was synthesized by a facile autocombustion process based on a modified glycine-nitrate process (GNP) using cellulose fiber as micro-reactor. As compared with the normal GNP, this novel process allows the combustion to proceed in a much more environmentally friendly and controllable way. The resulted powder is nanocrystallized with particle size of only 15-20 nm as observed by transmission electron microscopy examination. More importantly, because the metal ions could disperse homogenously in cellulose-GN precursor, SrCO₃ impurity was effectively suppressed. The concentrations of SrCO₃ impurity in LSCF products were determined by carbon dioxide-temperature-programmed desorption technique, which decreased to as low as 1.3 wt% from cellulose-GN process, in contrast to 4.3 wt% from the normal GNP. These features resulted in the attractive improvement of its cathode performance in solid-oxide fuel cells (SOFCs). The interfacial resistances of only ∼0.70 and ∼0.36 Ω·cm² at 600° and 650°C under air, respectively, were observed, which was about two times better than the LSCF cathode derived from the normal GNP. A peak power density of ∼346 mW/cm² was achieved at 600°C with cellulose-GN-derived LSCF cathode based on thin-film Sm_0.2Ce_0.8O_1.9 electrolyte SOFC using 3% humidified H₂ as the fuel.