Ion Intercalation in Lanthanum Strontium Ferrite for Aqueous Electrochemical Energy Storage Devices

Abstract

Ion intercalation of perovskite oxides in liquid electrolytes is a very promising method for controlling their functional properties while storing charge, which opens up its potential application in different energy and information technologies. Although the role of defect chemistry in oxygen intercalation in a gaseous environment is well established, the mechanism of ion intercalation in liquid electrolytes at room temperature is poorly understood. In this study, the defect chemistry during ion intercalation of La0.5Sr0.5FeO3−δ thin films in alkaline electrolytes is studied. Oxygen and proton intercalation into the La1–x Sr x FeO3−δ perovskite structure is observed at moderate electrochemical potentials (0.5 to –0.4 V), giving rise to a change in the oxidation state of Fe (as a charge compensation mechanism). The variation of the concentration of holes as a function of the intercalation potential is characterized by in situ ellipsometry, and the concentration of electron holes is indirectly quantified for different electrochemical potentials. Finally, a dilute defect chemistry model that describes the variation of defect species during ionic intercalation is developed.

Deeper mechanistic insights into epitaxial nickelate electrocatalysts for the oxygen evolution reaction

“…Therefore, operando probes for the type and concentration of point defects such as and protons are needed. Tang et al 38 recently developed an operando spectroscopic ellipsometry approach, allowing the tracking of the concentration of holes as a function of the intercalation potential ( Fig. 6h ).…”

“…O , H + incorporation (protonation) can occur more readily in nickelates in aqueous solution since the hydration process is spontaneous and can compensate the total This journal is © The Royal Society of Chemistry 2023 energy cost for protonation reaction. Recent work by Tang et al 38 shows experimental evidence that V…”

“… 37 Compared to , H + incorporation (protonation) can occur more readily in nickelates in aqueous solution since the hydration process is spontaneous and can compensate the total energy cost for protonation reaction. Recent work by Tang et al 38 shows experimental evidence that and H + can co-exist in a perovskite thin film electrocatalyst in alkaline electrolyte. Furthermore, extensive studies show that protonation can be triggered either chemically or electrochemically in nickelate thin films, and that the incorporation of H + can completely change the electrical conductivity (from electronic/metallic to ionic/insulating) and lattice constant of nickelates.…”

“…Furthermore, extensive studies show that protonation can be triggered either chemically or electrochemically in nickelate thin films, and that the incorporation of H + can completely change the electrical conductivity (from electronic/metallic to ionic/insulating) and lattice constant of nickelates. 38 Therefore, the role of point defects as schematically shown in Fig. 1b should be considered when examining the electrocatalytic activity.…”

Properties of Perovskite-like Lanthanum Strontium Ferrite Ceramics with Variation in Lanthanum Concentration

“…Interest in them is also due to the fact that the use of this class of ferrites can help reduce SOFC operating temperatures from high (800-1000 • C) to intermediate and low temperatures (400-800 • C). At the same time, a decrease in operating temperatures will make it possible to achieve an increase in the durability and stability of the SOFC material to degradation, as well as an improvement in thermal compatibility and stability of performance for a long time [11][12][13][14][15].…”