Intermediate Temperature Solid Oxide Fuel Cells (IT-SOFCs) are envisaged as one of the most powerful devices for providing clean energy with high efficiency. Today, an important challenge for their development as eco-friendly technology is to obtain a cathode material with high oxygen reduction ability below 800°C. Perovskite-type compounds, like Ba0.5Sr0.5Co0.8Fe0.2O3-? (BSCF), with cubic structure, and La1-xSrxCo1-yFeyO3-? (LSCF), with orthorhombic (y>0.5) or rhombohedral (y<0.5) structure, are among the most promising cathode compositions. Solution combustion synthesis (SCS) is an efficient methodology for the single-step synthesis of nanostructured and ultra-fine perovskite-type compounds with complex compositions and targeted microstructural properties. Herein, a Ba, La, Sr, Co and Fe-containing all-perovskite nanocomposite, here named "biperovskite", was created by SCS dissolving the metal nitrates precursors in water with a sucrose-polyethylene glycol fuel mixture and characterized for application as IT-SOFCs cathode materials. After annealing at 900°C, Rietveld analysis applied to XRD patterns and HR-TEM disclosed a nanostructured powder composed by a BSCF-type (Pm-3m) and a LSCF-type (R-3c) structure. The sucrose-polyethylene glycol eco-friendly mixture granted that all the metals remained trapped in the correct positions forming a gel network characterized by a cage-like structure. As evidenced by TGA, H2-TPR and XPS measurements, the high reducing power of sucrose-polyethylene glycol fuel mixture promoted an oxygen vacancy-rich configuration, which is essential for an optimal oxygen exchange with air and a suitable ionic transport. Electrochemical characterization performed by impedance spectroscopy, on a symmetrical membrane electrode assembly with a Ce0.8Sm0.2O2-x electrolyte, revealed area specific resistance (ASR) values of 0.0177 ohm*cm2 at 780°C and 0.0187 at 600°C, which are competitive with those of perovskite-type cathode materials reported in the literature.
Biperovskite nanocomposites prepared by solution combustion synthesis: a new concept for IT-SOFCs innovative materials
Chiara Aliotta;Leonarda Francesca Liotta;Valeria La Parola;Francesca Deganello
2018
Abstract
Intermediate Temperature Solid Oxide Fuel Cells (IT-SOFCs) are envisaged as one of the most powerful devices for providing clean energy with high efficiency. Today, an important challenge for their development as eco-friendly technology is to obtain a cathode material with high oxygen reduction ability below 800°C. Perovskite-type compounds, like Ba0.5Sr0.5Co0.8Fe0.2O3-? (BSCF), with cubic structure, and La1-xSrxCo1-yFeyO3-? (LSCF), with orthorhombic (y>0.5) or rhombohedral (y<0.5) structure, are among the most promising cathode compositions. Solution combustion synthesis (SCS) is an efficient methodology for the single-step synthesis of nanostructured and ultra-fine perovskite-type compounds with complex compositions and targeted microstructural properties. Herein, a Ba, La, Sr, Co and Fe-containing all-perovskite nanocomposite, here named "biperovskite", was created by SCS dissolving the metal nitrates precursors in water with a sucrose-polyethylene glycol fuel mixture and characterized for application as IT-SOFCs cathode materials. After annealing at 900°C, Rietveld analysis applied to XRD patterns and HR-TEM disclosed a nanostructured powder composed by a BSCF-type (Pm-3m) and a LSCF-type (R-3c) structure. The sucrose-polyethylene glycol eco-friendly mixture granted that all the metals remained trapped in the correct positions forming a gel network characterized by a cage-like structure. As evidenced by TGA, H2-TPR and XPS measurements, the high reducing power of sucrose-polyethylene glycol fuel mixture promoted an oxygen vacancy-rich configuration, which is essential for an optimal oxygen exchange with air and a suitable ionic transport. Electrochemical characterization performed by impedance spectroscopy, on a symmetrical membrane electrode assembly with a Ce0.8Sm0.2O2-x electrolyte, revealed area specific resistance (ASR) values of 0.0177 ohm*cm2 at 780°C and 0.0187 at 600°C, which are competitive with those of perovskite-type cathode materials reported in the literature.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
