International Partnership Brings an Important Breakthrough in Fuel Cell Research
3D charge redistribution around the oxygen vacancy in BSCF perovskite with respect to neutral O atom. Blue and red isosurfaces (0.0025e/A3) correspond to excess and deficiency of the electron density, respectively. Oxygen vacancy (center) is surrounded by two B-metals - Co (top) and Fe (bottom), as well as four oxygen atoms from both sides.
UMD researchers Dr. Yuri A. Mastrikov and Prof. Maija M. Kuklja in partnership with Max-Plank Institute?s researchers Prof. Eugene A. Kotomin and Prof. Joachim Maier have demonstrated by means of large scale computer modeling that the vacancy formation energy in (Ba,Sr)(Co,Fe)O3 complex perovskites is much smaller than in other perovskites which means orders of magnitude larger defect concentrations and thus fast oxygen transport in mixed electronic-ionic conductors for numerous applications. An article, First-principles modeling of complex perovskite (Ba1-xSrx)(Co1-yFey)O3-d for solid oxide fuel cell and gas separation membrane applications describing details of this work was published last week in Energy & Environmental Science.
Solid oxide fuel cells (SOFC) are promising devices generating energy in an environmentally friendly way, by a direct conversion of fossil and renewable fuels into electricity and high-quality heat. A major challenge in the SOFC improving is to reduce the operating temperature down to 500?600 C. This needs search of complex perovskites combining high O vacancy concentration (non-stoichiometry) and high vacancy mobility at moderate temperatures, as well as long-term cubic structure stability against transformation and degradation in polluted atmosphere. As we have demonstrated recently, the optimal strategy for developing new SOFC cathode should be based on the combination of key experimental data on oxygen incorporation into material and first-principles thermodynamics/kinetics of oxygen reduction and related processes. In this way, we were able to identify the atomistic mechanisms of key reactions for (La,Sr)MnO3 (LSM) with the emphasis on the rate-determining steps. Based on the present study, we plan to perform similar analysis for BSCF and related complex perovskites. This work is supported in part by NSF.
August 17, 2010