Journal Article grain boundaries BICUVOX ECRAM Raman spectroscopy electrode materials energy applications freestanding films fuel cells functional oxides high entropy oxides high‐throughput experimentation in situ methodology interface-dominated materials in‐memory computing local nonstoichiometry machine learning manganites mixed ionic-electronic conductors moiré superlattice nanoionics oxide thin film oxide‐ion synaptic transistor oxygen isotope exchange oxygen kinetics perovskite oxides solid oxide fuel cells stacking surface kinetics thin films