Enhancing triple-phase boundary at fuel electrode of direct carbon fuel cell using a fuel-filled ceria-coated porous anode

• Triple-phase boundary at fuel electrode of DCFC can be significantly improved.
• Solid fuel-filled ceria-coated porous anode was so effective to realize 7-fold increase in power density.
• Ceria coating mainly makes Ni anode wettable and thereby enhance the system performance.
• Ceria does not likely react with Ni supports at least in the current operation condition of DCFC.
• There exists an optimal coating of ceria; too much coating degrades its performance.

A new type of high-temperature fuel cell using solid carbon as a fuel, which is called a direct carbon fuel cell (DCFC), recently attracts scientific and industrial attention due to its excellent electrochemical efficiency, less production of CO2, and no need of CO2 separation. However, the state-of-the-art technology on the DCFC still stays in an idea developing stage, mainly because of fuel-related difficulties: a discontinuous fuel supply and a very limited formation of triple phase boundary. In this study, we focused on how to enhance the formation of triple phase boundary at the fuel electrode: using a porous Ni anode filled with carbon particles to enhance the fuel-electrode physical contact and making the porous anode wettable by ceria coating the anode. We demonstrated for the first time that the two ideas are quite successful, leading to 700% increase in a maximal power density and 500% increase in a maximal current density with respect to the standard case.