Superionic materials are a class of materials that simultaneously present properties that are characteristic of solids and liquids. Essentially, a set of ions in these materials exhibits liquid-like mobility, even if the materials’ underlying atomic structure maintains a solid-like order.

Due to their unique ionic conductivity patterns, superionic materials could be promising for developing solid-state batteries. These are batteries that contain electrolytes based on solid materials instead of liquid electrolytes.

While various past studies have explored the potential of superionic materials as solid-state electrolytes, the physics underpinning their rapid ionic diffusion is not yet fully understood. Specifically, it is unclear whether this property results from liquid-like motion in the material or from the conventional lattice phonons (i.e., atom vibrations) in the material.