In operando optical study of active three phase boundary of nickel-yttria stabilized zirconia solid-oxide fuel cell anode under polarization

Abstract

Degradation of solid oxide fuel cell (SOFC) anode always takes place during long-term high temperature operation because of the decrease in three phase boundary (TPB) density and loss of nickel (Ni) network percolation due to Ni coarsening. In the present study, for the first time, an in operando observation technology using optical laser microscope is developed to demonstrate the real-time local morphological change of Ni at active TPB under polarization conditions. The local morphological change, which is determined by the competition between the mechanisms of enhanced Ni wettability on yttria-stabilized zirconia (YSZ) surface and thin Ni-film break up caused by Ni coarsening are observed. In operando observation reveals the reason of rapid performance degradation of SOFC anode under sever operation conditions. It is expected that the in operando observation of Ni morphological change can largely enrich our understanding of the SOFC anode microstructure change, which may further supply precious opportunities to investigate sever degradation mechanisms.