Carbon electro-catalysis in the direct carbon fuel cell utilising alkali metal molten carbonates: A mechanistic review

The direct carbon fuel cell (DCFC) is a promising technology projected to produce electrical energy from carbon with 100% theoretical efficiency, and realisable efficiencies of 80% observed on the lab scale. Recently this field has gained popularity with the development of a hybrid DCFC system incorporating aspects of both solid oxide and molten carbonate fuel cell systems. Interactions, including chemical and electrochemical reactions that can occur between the various reactants, products and electrolyte mediums in a DCFC; i.e., molten carbonate, carbon and CO2, have been explored in a variety of other literature spheres over the past several decades without careful application of these concepts to a DCFC system. These interactions appear in the fields of molten salts for concentrated solar power, the molten carbonate fuel cell, and alkali metal carbonate catalysed biomass and coal gasification from CO2. This review ties together several key pieces of information not limited to the DCFC literature, leading up to the apotheosis which is a novel electro-catalysis mechanism for the DCFC, which will aid in understanding of the system performance sensitivities as well as potentially catalyst and anode design development.