Designing Lithium Superionic Conductors via Polyanion Rotational Dynamics in Isolated Framework

Current strategies to enhance lithium-ion conductivity in solid electrolytes primarily emphasize static structural factors, whereas fundamental principles for designing lithium superionic conductors via dynamic mechanisms remain largely unexplored. Here, we propose a design principle that leverages polyanion rotational dynamics in isolated frameworks to enhance lithium-ion conductivity, where the rotational dynamics can be modulated by structural descriptors such as lithium number density and polyanion moment of inertia. By combining high-throughput computations with ab initio molecular dynamics simulations, we identify two candidate lithium superionic conductors exhibiting polyanion rotation, Li₂VF₆ and LiVF₆, with theoretical room-temperature ionic conductivities of 64.59 and 13.66 mS/cm, respectively. The rotational motion of polyanion couples with lithium-ion translational motion in both vibrational and spatiotemporal properties, thereby dynamically modulating the energy landscape and facilitating lithium-ion migration. These findings provide valuable insights into leveraging polyanion rotational dynamics to rationally design lithium superionic conductors for all-solid-state batteries.