Fuels for direct carbon fuel cells: present status and development prospects

The direct carbon fuel cell (DCFC) has been considered an efficient way to mitigate the energy crisis and environmental pollution issues, owing to its high energy conversion efficiency, low pollution, and abundant and readily available resources, but its performance is closely related to the fuel used. We give a brief introduction to the development of DCFCs and a review of the current status of DCFC fuels, with an emphasis on the impact of different carbonaceous materials, such asgraphite, coal, activated carbon, solid waste, and cokeon DCFC performance. We also systematically analyze the relation between the electrochemical reaction activity of the fuels and their characteristics. For carbonaceous fuels, defects in the crystal structure and surface oxygen functional groups can promote the anodic electrochemical reaction, and their wettability by the electrolyte. Their pore structure, conductivity and particle size can affect mass transfer and charge transfer in the anodic electrochemical reaction. We discuss the function of anodic catalysts in the DCFC, which accelerate the conversion of carbon from solid to gas and improve the anodic electrochemical reaction rate. Based on the current research on DCFC fuels, we forecast development trends and key issues relating to DCFC fuels.