Structural and compositional analysis of nickel phases at anode/ electrolyte interface using propane/air-oriented syngas.

Syngas produced by catalytic partial oxidation (CPOX) of propane contains hydrogen (21.68%) and carbon monoxide (18.27%). Microtubular solid fuel cells (μT-SOFCs) were fabricated and tested with syngas and pure hydrogen respectively. The open-circuit voltage (OCV) is 1.02 V, and the maximum power (MP) of microtubular solid fuel cell is 7.07 W at 700 °C with syngas/air. After operating in syngas/air for 100 h, the voltage declined 4.5%. A few sites of anode separate from electrolyte, particularly, some few nanometers nickel (Ni) particles have precipitated at the interface of electrolyte/anode. Comparing to Ni grain with 200 nm-1 μm diameter in rest sites of anode, it is easy to explain the loss of Ni and the separation of anode with electrolyte. Meantime obvious carbon deposition is found at the pores after 100 h working in syngas/air. There are other impurity phases discovered by high resolution transmission electron microscopy (HRTEM) at a triple phase boundary (TPB) of electrolyte and anode. • Nano-domains of nickel are expelled as clusters from anode into amorphous oxidized phase. • The loss of nickel causes to the difference of nickel grain size. • The structure of anode is destroyed by the growth of carbon at 700 °C. • The triple phase boundary degenerates towards the double phase boundary for long-term working. [ABSTRACT FROM AUTHOR]