Hybrid Fuel Cells with Carbonate/Oxide Composite Electrolytes: An Electrochemical and Theoretical Insight

Abstract

In view of increasing SOFCs’ lifetime, lowering the working temperature is probably the most convenient solution. The targeted range is 400-600°C, low enough to minimize the degradations kinetics while keeping rather good electrochemical performances. Carbonate/oxide composites are promising materials as electrolyte in hybrid fuel cells, which could operate at lower temperature than the usual MCFC or SOFCs. The aim of this paper is to get a deeper understanding on the origins of such improved performances by combining both experimental and modeling approaches. Experimentally, systematic studies dealing with the impact of molten salts composition, oxide phase conductivity and environmental parameters are performed by impedance spectroscopy. In parallel, Density Functional Theory calculations are carried out to provide insights into the transport mechanisms and the species involved, by first determining the most stable surface structures for both phases, separately, before building different carbonate/oxide interfaces and investigating the operating principles of these cells.