Synthesis and characterisation of a ceria-based cobalt-zinc anode nanocomposite for low-temperature solid oxide fuel cells (LT-SOFCs)

One important factor limiting the development of solid oxide fuel cell is its high operational temperature (700-750 degrees C), significantly hindering its commercialization. Here, for the first time, it is reported that nano -crystalline Co1-x-Znx-Gd0.1Ce0.9O1.95 (x = 0.50, and 0.65) anode powders can provide a practical solution toward Ni-free low temperature SOFCs (LT-SOFCs; 450-550 degrees C) by illustrating strikingly high redox capabilities at temperatures below 400 degrees C. An anode-electrolyte bilayer with tailored electrical conductivity is fabricated by co -sintering a Gd0.1Ce0.9O1.95 disc (as support) and the synthesized Co1-x-Znx-Gd0.1Ce0.9O1.95 anode powder. During co-sintering, the tunable internal Zn supply from the anode composite to the electrolyte support significantly decreases the densification temperature of the GDC electrolyte support (down to 1100-1200 degrees C), while pro-moting the cell efficiency (-7%) by drastically reducing the electron conductivity through the GDC electrolyte layer (open circuit voltage -0.91 V at 650 degrees C). The electrolyte layer shows excellent compatibility with the anode electrode, leading to possible long term thermal cyclability to room temperature. Fuel cell characteriza-tions over a broad range of operating conditions estimate activation energies of 0.49, 0.48, and 0.63 eV for the three identified anodic processes. Zinc can increase the cell power-density by about five times compared to Co -based anode composites.

Automated summary

This study reports for the first time that nano-crystalline Co1-x-Znx-Gd0.1Ce0.9O1.95 (x = 0.50 and 0.65) anode powders can offer a practical solution for Ni-free low temperature solid oxide fuel cells (LT-SOFCs; 450-550 degrees C) by exhibiting high redox capabilities below 400 degrees C. An anode-electrolyte bilayer with tailored electrical conductivity is fabricated by co-sintering a Gd0.1Ce0.9O1.95 disc (as support) and the synthesized Co1-x-Znx-Gd0.1Ce0.9O1.95 anode powder. Zinc can increase the cell power-density by about five times compared to Co-based anode composites.