Correlating Proton Diffusion in Perovskite Triple-Conducting Oxides with Local and Defect Structure

Abstract

Triple-conducting oxides are considered to be next-generation materials for renewable and green energy as parts of fuel cells, electrolyzers, and membrane reactors. The electrochemical properties of any material are tightly correlated with its structural features. Because all ionic transport in oxides is related to point defects, it is crucial to understand their location and surroundings. In this work, we use total X-ray and neutron scattering to investigate how the introduction of Co into a proton-conducting oxide La0.9Sr0.1Sc1–xCoxO3−δ influences the local structural disorder and location of protons. Using non-constant force field molecular dynamics, we investigate the proton trapping effect and point out a way of avoiding it. Under an applied voltage, we observe proton diffusion anisotropy, which significantly improves the proton conductivity of oxide membranes. We show that the introduction of cobalt into a proton-conducting oxide can increase the number of incorporated protons compared to previous expectations. This, coupled with the absence of proton trapping and proton conductivity anisotropy, means that the potential of A3+B3+O3 perovskites could be much greater than considered so far. Our computational results will improve our understanding of the features of proton transport by updating the model of proton conductivity in triple-conducting oxides.