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. [ABSTRACT FROM AUTHOR]