Synthesis and characterization of sdc-bcs composite electrolyte for solid oxide fuel cells

Solid oxide fuel cells (SOFCs) attracted a great deal of consideration among the promising fuel cell systems for energy conversion. In SOFC, electrolyte plays a vital role in increasing the efficiency of energy conversion. The main hurdle for fuel cell is its higher operating temperature (1000°C) which results in design limitation and higher fabrication cost. Current trend in SOFC have attracted the young researcher to develop a suitable oxygen ion conducting solid electrolytes for electrochemical energy conversion with high efficiency, low cost, more sustainable and environmentally friendly in nature. In SOFC electrolyte is considered as a main component with high performance rate by means of high oxide ion diffusion for the conversion of required ionic conductivity (0.1S cm-1). Anode and cathode are the supporting electrodes, where the half cell reaction takes place. So far 8 mol% of Yttria Stabilized Zirconia (YSZ) has been a considered as a potential candidate for high ionic conductivity with negligible electronic conduction at 1000°C [1]. YSZ has shown sustained ionic conduction in both oxidizing and reducing atmosphere. But the main problem associated with these Zirconia based electrolyte is its thermal mismatch, instability at high temperature and higher cost which limits its niche commercial requirements. In order to overcome the above stated problems, the operating temperature of solid electrolyte must be reduced to intermediate temperature (600-800°C) [2, 3]. Ceria based electrolytes with fluorite structure have became a possible oxygen ion conducting electrolyte to replace Yttria Stabilized Zirconia (YSZ) with high ionic conductivity at intermediate temperature (600°C-800°C). But pure ceria is not a good oxygen conductor. Doping of an aliovalent cation into ceria lattice is an effective approach to facilitate the creation of oxygen vacancies thereby improving the ionic conductivity. However, these doped ceria materials exhibits its low open cell voltage(OCV) with partially increased electronic conduction and acts as a n-type conductor due to the reduction of Ce to Ce [4 ,5]. That is the formation of oxide defect at high temperature results in instability of oxygen partial pressure during fuel cell operation and in turn reduces its OCV [6,7]. Another class of pervoskite type oxide (ABO3) structures such as barium cerate, strontium cerate, barium zirconate are considered as best solid electrolytes [8,9] with required high ionic conductivity at intermediate temperature with the reduced electronic conduction. But, these undoped BaCeO3 Pervoskite structure shows some instability in CO2 atmosphere, due to the formation of BaCO3, which in turn provide poor mechanical strength and to decrease the Abstract