Electrochemical behaviour of Ni-BZO and Ni-BZY cermet anodes for Protonic Ceramic Fuel Cells (PCFCs) – A comparative study

• Cermet anodes Ni-BaZrO3 (Ni-BZO) & Ni-BaZr0.85Y0.15O3-δ (Ni-BZY) were synthesised
• Resultant microstructure of both cermet anodes shown to be similar
• Minimum Rp in Ni-BZY in 10%H2/N2 with matrix phase of higher proton conductivity.
• Strong links shown between R2 and proton conduction in cermet matrix phase.
• Magnitude of R3 lower for Ni-BZO than for Ni-BZY under similar conditions.

The matrix phase of protonic ceramic fuel cell (PCFC) cermet anodes potentially plays a vital role in hydrogen oxidation kinetics. The present work aims to investigate such involvement by selecting ceramic-oxide matrices with widely dissimilar levels of proton conduction. The materials chosen were that of the proton conducting phase BaZr0.85Y0.15O3-δ and the nominal composition BaZrO3 of negligible proton conduction. Cermet anodes Ni-BaZrO3 and Ni-BaZr0.85Y0.15O3-δ were synthesized by the acetate-H2O2 combustion method for Ni contents of 40 vol%. The microstructure and electrochemical performance of the cermet anodes were investigated by scanning electron microscopy (SEM) and electrochemical impedance measurements (EIS) respectively. The polarisation behaviour of the two nickel cermet anodes was studied as a function of temperature, hydrogen partial pressure (pH2) and water vapor partial pressure (pH2O). The results confirm that polarisation resistance is highly sensitive to the composition of the ceramic phase of the cermet anode and that the higher frequency electrode response exhibits strong links to levels of proton transport in the ceramic-oxide matrix.