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Infiltrating nanoparticle electrocatalysts into solid oxide fuel cells (SOFCs) has been shown to improve their intermediate-temperature performance by increasing the density of reaction sites, known as triple phase boundaries (TPBs), in the electrode. By increasing TPB density with infiltration, anode activation polarization is mitigated and cell performance improves relative to an uninfiltrated cell, especially at low temperatures. In this study, electrochemical impedance spectroscopy and distribution of relaxation times analyses were performed on baseline and Ni-infiltrated NiYSZ anode symmetric cells. A transmission line model (TLM) was used to deconvolute the electrode processes. The effects of temperature and humidity on TLM parameters, and the relative polarization contributions of various charge transfer processes will be discussed.

Electrochemical performance in reversible solid oxide cells is influenced by the microstructure and dimensions of the components and the transport properties of the constituent materials. In this work, we consider oxygen electrodes in the Nd2NiO4+ δ- Nd0.5Ce0.5O2- δ materials system. Optimization of the oxygen electrodes in this system has been achieved by considering the tradeoffs in the microstructure and dimensions of the active layer and the current collecting layer. Detailed electrochemical analysis of the symmetrical cells using impedance spectroscopy has led us to an optimized architecture with significantly reduced ohmic and polarization resistance. The optimized architecture, based on symmetrical cells, has been translated into single, complete reversible solid oxide cells. Significant performance improvement has been achieved in both fuel cell and electrolysis mode compared to baseline materials and electrode architecture material.