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In recent years, multi-phase materials capable of multi-ion transport have emerged as attractive candidates for a variety of electrochemical devices. Here, we provide experimental results for fabricating a composite electrolyte made up of a one-dimensional fast sodium-ion conductor, sodium zirconogallate, and an oxygen-ion conductor, yttria-stabilized zirconia. The composite is synthesized through a vapor phase conversion mechanism, and the kinetics of this process are discussed in detail. The samples are characterized using diffraction, electron microscopy, and electrochemical impedance spectroscopy techniques. Samples with a finer grain structure exhibit higher kinetic rates due to larger three-phase boundaries (TPBs) per unit area. The total conductivity is fitted to an Arrhenius type equation with activation energies ranging from 0.23 eV at temperatures below 550 ° C to 1.07 eV above 550 ° C . The electrochemical performance of multi-phase multi-species, mixed Na + and O 2 − conductor, is tested under both oxygen chemical potential gradient as well as sodium chemical potential gradient are discussed using the Goldman-Hodgkin-Kats (GHK) and the Nernst equation.

One and two pseudo-reference electrode proton exchange membrane fuel cell devices were fabricated using composite thin film composed of Nafion and Ag paste as the reference electrode. Three and four-electrode electrochemical studies were performed isolating different parts of the cell. Summing the scans utilizing the reference electrode(s) resulted in good agreement with the two-electrode scan across the entire cell. A DC current was passed through the cell under constant resistive load conditions. The equations necessary to determine the cell and the anode/cathode-reference impedance under constant resistive load are presented. A high frequency depressed arc present in the spectra of the entire cell had contributions from both the anode-reference and the cathode-reference scans. Reactance present in the four-electrode measurements isolating a section of the membrane further suggests that the high frequency depressed semicircle in the cell scan can, at least in part, be attributed to the membrane. The present work shows that by using embedded pseudo-reference electrodes, the polarization behavior of cathode and anode can be investigated independently and unambiguously without the need for de-convolution of spectra across the entire cell.