Enhancing Anodic Catalytic Activity at High Fuel Utilization By Infiltration of Ni Nanoparticles
The performance of SOFCs degrades with increasing fuel utilization, since the fuel oxidation reaction faces increased competition for the triple-phase-boundary (TPB) sites in the anode from adsorbed water vapor species. Introduction of addition TPB sites by infiltration of Ni nanoparticles into the anode is an effective way to alleviate this problem. Both liquid and vapor phase infiltration of Ni nanoparticles into commercially available Ni/YSZ cermet anodes have been explored. The microstructure of the anode before infiltration has been examined by FIB/SEM 3-D reconstruction to quantify the TPB length. Infiltrated and un-infiltrated cells have been electrochemically characterized by I-V and electrochemical impedance spectroscopy (EIS) techniques in a temperature range of 600°C-800°C at varying water vapor partials pressures. The infiltrated Ni nanoparticles have been characterized by image analysis of SEM micrographs from fracture cross-sections, before and after electrochemical testing. The effects of the nanoparticles on cell electrochemical performance as a function of temperature and anode input water vapor content, the stability of the nanoparticles, as well as the thermodynamics of vapor phase infiltration of Ni are presented.