Lattice Contraction and Ionic Conductivity Enhancement in LaCl ₃ -Based Solid-State Electrolytes under Moderate Pressure and Heating

It is conventionally believed that pressure below the GPa range has a negligible effect on the structure and properties of solid materials. Here, we challenge this notion by demonstrating that heating at 80 °C under a moderate pressure of 60 MPa induces lattice contraction and Li + redistribution in a LaCl 3 -based solid-state electrolyte. This structural evolution, confirmed by X-ray diffraction and solid-state nuclear magnetic resonance, results in an increase in ionic conductivity from 1.2 to 1.6 mS cm −1 and a decrease in activation energy from 0.27 to 0.19 eV. The one-dimensional ion-transport channels along the c -axis in LaCl 3 feature large intrinsic sizes and weak intermolecular interactions, rendering them susceptible to compression under such moderate conditions. This structural compaction facilitates Li + rearrangement and enhances ion transport, ultimately boosting the electrolyte's overall ionic conductivity.