MSE PhD Prospectus Defense of Yanchen Lu

TITLE: Improving Intermediate Temperature Performance of Ni-YSZ Cermet Anodes for Solid Oxide Fuel Cells by Infiltration of Nickel Nanoparticles

ABSTRACT: Liquid infiltration of NiO followed by reduction to form Ni nanoparticle catalysts in solid oxide fuel cell (SOFC) anodes can produce a high density of electrochemical reaction sites. In recent years, electrode architectures utilizing porous oxide substrates with ionic conductivity or mixed ionic-electronic conductivity and connected networks of nickel produced by liquid infiltration have become a popular approach to improve SOFC anode catalytic performance, especially for operating temperatures less than 800°C. However, infiltrated nickel structures suffer from poor durability, demonstrating significant loss in performance during the first 100 hours of use. In contrast, traditional Ni-Yttria Stabilized Zirconia (Ni-YSZ) cermet SOFC anodes exhibit longterm performance stability. However, Ni-YSZ cermet anodes have micron sized structures, and consequently have significantly lower density of electrochemical reaction sites than infiltrated nickel structures, which have dimensions around 100 nm.

In this study, the performance impact of liquid phase infiltration of nickel nanoparticles into Ni-YSZ cermet anode supported SOFCs is studied by measuring the electrochemical behavior of infiltrated cells at 800°C, 700°C, and 600°C, and comparing them to the performance of an uninfiltrated cell. Durability of the nanoparticles after electrochemical testing is also assessed using a method for quantifying particle statistics from fracture cross sections. The particle degradation mechanism has been investigated and the methods to maintain the particle stability have been proposed.

COMMITTEE: Advisor: Soumendra N. Basu, MSE/ME; Uday B. Pal, MSE/ME; Srikanth Gopalan, MSE/ME