Instability and growth of nanoscale Ce_(0.8)Gd_(0.2)O_(1.9)/NiO infiltrate in Sr_(0.94)Ti_(0.9)Nb_(0.1)O_3-Zr_(0.84)Y_(0.16)O_(1.92) anodes for solid oxide fuel cells

摘要

Microstructural evolution of Ce_(0.8)Gd_(0.2)O_(1.9)/NiO (CGO/NiO) co-infiltrated nanoparticles in Sr_(0.94)Ti_(0.9)Nb_(0.1)O_3-Zr_(0.84)Y_(0.16)O_(1.92) (STN94-YSZ) anodes for solid oxide fuel cells (SOFCs) is investigated during electrochemical testing in a symmetric cell setup. The CGO/NiO infiltrated symmetric cells were subjected to varying atmospheres of H_2O/H_2 between 650 and 850 ℃ and characterized by electrochemical impedance spectroscopy. Analytical high resolution transmission electron microscopy showed that the CGO/NiO infiltrate was found to coalesce and grow from an indistinguishable CGO/NiO fluorite structure of an average diameter of 5 nm to individual well-connected, but phase-separated, CGO and Ni particles of 50 nm in average. This study confirms that instability and growth of CGO/NiO infiltrates in STN-based SOFC electrodes affect the morphology and can potentially be linked to reported losses in electrochemical performance.