SYNTHESIS AND CHARACTERIZATION OF La2Mo2O9-BASED ELECTROLYTES FOR SOLID OXIDE FUEL CELL

Abstract

The global energy demand is increasing at a very steep rate. To fulfill the energy requirements, non-conventional fossil fuels viz., coal, crude oil, petroleum products are significant contributors. But these traditional sources cause a lot of pollution in the past and even in the present and thus having a negative impact on ecology and society. Therefore, it is very much necessary to switch to clean energy sources. In this regard, it is required to develop alternative renewable and clean energy sources like solar, wind, and hydroelectric power and fuel cells intensively at a wide scale. Regarding clean energy sources or energy conversion devices, still, a lot of effort has to be made to make the clean energy generation economical. In the current scenario, progress is being made on a wide scale for a clean energy generation. Solid oxide fuel cells (SOFCs) are considered to be one of the clean energy conversion devices. It has water as its by-product, which can be utilised again in the system to regenerate fuel. A SOFC unit mainly consists of two electrodes: anode, cathode, and a solid electrolyte. The fuel plays an important part in the cell operation and is independent of the SOFC unit as it is often converted into hydrogen through reforming process. The function of the SOFC relies mainly on O2- (oxide) ion transport from cathode to anode side through the electrolyte. The main function of both the electrodes is to initiate the reaction between the reactants (fuel and oxygen) through the electrolyte, without being consumed or corroded during the reaction. The SOFC unit should also bring the three phases, i.e., the electrode, electrolyte, and the fuel into contact of each other. The discovery of LAMOX based electrolytes in the year 2000 has attracted much attention in the SOFC area and may be seen as a potential competitive candidate to traditionally YSZ and GDC based electrolytes. It shows a superior oxygen ion conductivity of (0.06 S/cm and 0.4 S/cm for doped La2Mo2O9 samples at 800 °C) as compared to yttria-stabilised zirconia (YSZ). However, its applicability is limited by its instability in reducing atmosphere, abrupt volume expansion due to the phase transition from monoclinic to cubic phase; high thermal expansion and chemical reactivity towards electrode components.