This University of Wisconsin project will focus on advancing the fundamental understanding of how solid oxide fuel cell cathodes operate such that their performance can be improved. This project will center around the role of material interfaces in determining electrochemical performance. Advanced physical characterization tools will be employed in support of a coordinated approach consisting of ab initio modeling and a unique electrochemical characterization technique called Non-Linear Electrochemical Impedance Spectroscopy. The results will be interpreted to determine the operation mechanisms and identify new material architectures thereby enabling improved fuel cell performance.