A New Lithium-Ion Conductor LiTaSiO₅: Theoretical Prediction, Materials Synthesis, and Ionic Conductivity

Owing to the nonleakage and incombustibility, solid electrolytes are crucial for solving the safety issues of rechargeable lithium batteries. In this work, a new class of solid electrolyte, acceptor-doped LiTaSiO₅, is designed and synthesized based on the concerted migration mechanism. When Zr⁴⁺ is doped to the Ta⁵⁺ sites in LiTaSiO₅, the high-energy lattice sites are partly occupied by the introduced lithium ions, and the lithium ions at those sites interact with the lithium ions placed in the low-energy sites, thereby favoring the concerted motion of lithium ions and lowering the energy barrier for ion transport. Therefore, the concerted migration of lithium ions occurs in Zr-doped LiTaSiO₅, and a 3D lithium-ion diffusion network is established with quasi-1D chains connected through interchain channels. The lithium-ion occupation, as revealed by ab initio calculations, is validated by neutron powder diffraction. Zr-doped LiTaSiO₅ electrolytes are successfully synthesized; Li_1.1Ta_0.9Zr_0.1SiO₅ shows a conductivity of 2.97 × 10⁻⁵ S cm⁻¹ at 25 °C, about two orders of magnitude higher than that of LiTaSiO₅, and it increases to 3.11 × 10⁻⁴ S cm⁻¹ at 100 °C. This work demonstrates the power of theory in designing new materials.