Detailed electrochemical performance and microstructural characterization of nickel - Yttria stabilized zirconia cermet anodes infiltrated with nickel, gadolinium doped ceria, and nickel - Gadolinium doped ceria nanoparticles

Infiltration of nickel nanoparticles into nickel - yttria-stabilized-zirconia (Ni-YSZ) cermet anodes improves anode performance by reducing the average nickel feature size of the electrode, thus increasing the density of triple phase boundaries (TPBs). However, the TPBs of nickel nanoparticles are not fully utilized because there is no conductive pathway between nanoparticles, and nickel nanoparticles suffer from rapid coarsening during operation. This work explores the infiltration of Gd0.1Ce0.9O2-delta (GDC) as a material for connecting and stabilizing infiltrated nickel nanoparticles. Anodes were infiltrated with Ni, GDC, and Ni-GDC to study their stability and electrochemical performance. Measurements show that the simultaneous infiltration of nickel and GDC results in a greater performance improvement than either nickel or GDC alone. From this result, it is speculated that GDC provides a conducting pathway between nickel nanoparticles, better utilizing their TPBs. Fitting of electrochemical impedance spectra with an equivalent circuit model is used to measure individual cell resistances, revealing that infiltration of GDC reduces the activation energy of the anodic charge transfer reaction from 1.29 eV to 0.74 eV. The Ni-GDC nanoparticles are also more durable than nickel nanoparticles, demonstrating microstructural stability after 120 h of constant current at 800 degrees C, while nickel alone shows extensive coarsening.