Probing the Cost-Effective Sodium Doped Strontium Silicate (Sr1-xNaxSiO3-0.5x) as Solid Electrolytes for IT-SOFC

Abstract

The urgency for clean and secure energy has stimulated a global resurgence in searching foradvanced electrical energy conversion systems. Solid oxide fuel cells (SOFC) have been considered as one of the most promising electro-chemical energy conversion technologies due to their high efficiency, low emission, and excellent fuel flexibility. The most widely used electrolyte materials are fluorite structured yttria stabilized zirconia (YSZ). However, use of YSZ is limited because of the limiting magnitude of the electrical conductivity and its high operating temperature over 800 °C. Recently, the sodium doped strontium silicate (Sr1-xNaxSiO3-0.5x) is gathering attentions as a fast ion conductor [1]. And Wei et al. confirmed a good SOFC performance using this electrolyte material at 500 and 600 °C [2]. In this study, we investigated this promising material to get the optimal fabrication conditions with composition and to minimize degradation problems and also enhance the stability on this material. From this study, we found out the optimal fabrication conditions (sintering at 900 °C for 10 h) for 40 % sodium doped strontium silicate electrolyte which was known as the best ionic conductor. Thermal behaviour of the compositions has also been investigated for the applicability as solid electrolyte. Moreover, for the higher doping concentration (>40 %); a decrease in the electrical conductivity is observed. This decrease in the conductivity may be due to the formation of impurity phases of sodium silicate. Keywords: SOFC; Electrical conductivity; solid electrolyte; strontium silicate.