Technological applications of molten salts: the case of the molten carbonate fuel cell

The particular properties of molten carbonates, oxyanionic salts, allow their application in the promising technological field of fuel cells. A general description of this class of molten salts is presented, outlining the importance of the oxoacidity concept and potential-acidity diagrams to understand the main features of this electrochemical device, dedicated to energy and heat generation. The main characteristics of the molten carbonate fuel cell (MCFC) are reviewed from the single cell, including the matrix electrolyte and the electrode mechanisms, to the stack, with a special attention to the bipolar plates. The factors limiting MCFC lifetime are discussed in order to analyze the potential improvements of the materials presently used. An overview of the principal demonstration prototypes all over the world is given. Finally, some conditions for the introduction of MCFC in the commercial energy market are briefly mentioned.