In this work, the entire composition phase space of a state-of-the-art ion- and electron-conducting solid oxide fuel cell cathode material (La0.6Sr0.4Co1-xFexO3-δ) is examined with unprecedented compositional resolution (x=0 to x=1 with Δx=0.05). Gradient pulsed laser deposition was employed to obtain a compositionally graded thin film on a (100)-oriented 8 mol% Y2O3-ZrO2 electrolyte substrate. The film was patterned using photolithography and ion milling to obtain electronically isolated circular microdot electrodes ranging from 80-500 µm in diameter. Microelectrode impedance spectroscopy was performed with a robotic scanning probe in an environmental chamber to obtain relevant electrochemical parameters. The measured impedance spectra are consistent with a two-phase boundary electrochemical pathway including bulk ionic conduction through the oxide. A monotonic increase in electrochemical resistance is observed from La0.6Sr0.4CoO3–δ (LSC) to La0.6Sr0.4FeO3–δ (LSF) along with a decrease in chemical capacitance corresponding to a decrease in reducibility and oxygen vacancy concentration. This case study demonstrates the rich insights that can be gleaned from this high-throughput approach and its promising application toward searching for new high-performance solid oxide fuel cell electrode materials.
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