Experimental and numerical studies of a bifunctional proton conducting anode of ceria-based SOFCs free from internal shorting and carbon deposition.

A proton conducting anode NiO-BaZr 0.1 Ce 0.7 Y 0.2 O 3-δ (BZCY) is investigated to play a dual role in avoiding internal shorting and carbon deposition of ceria-based SOFCs by experimental and numerical methods. The electronic barrier layer Ba x Ce 1−y Sm y O 3-δ (BCS) can be in-situ formed at the interface of anode and electrolyte, which improves the open-circuit voltage (OCV) and the peak power density. To deeply analyze the electron-blocking effect and optimize the thickness ratio of the BCS layer, electronic conductivities, leakage current densities and cell efficiencies considering the internal shorting and polarization are calculated by a mathematic model. Importantly, this ceria-based cell with the proton conducing anode also shows superior electrochemical performance and stability using wet methane as fuel. A thermodynamic equilibria calculation considering the water adsorption capacity of the anode is performed to predict the equilibrium composition and carbon deposition boundaries, which quantitatively explains the excellent carbon-tolerance of the cell. The superior bifunctional proton conducting anode enables ceria-based electrolytes to be promising electrolyte candidates toward the application of low temperature SOFCs and provides an efficient path for avoiding carbon deposition. [ABSTRACT FROM AUTHOR]