Li0.625Al0.125H0.25Cl0.75O0.25 Superionic Conductor with Disordered Rock-Salt Structure

Authors

Abstract

Solid-state Li-ion conductors are of broad interest in electrochemical energy storage, especially in solid-state Li batteries that serve as a promising alternative for the next-generation safe and high-energy-density batteries. Exploring solid-state superionic conductors is significant for the development of solid-state Li batteries with high performance. Herein, we report a disordered rock-salt (A1B1)-structured solid electrolyte (Li0.625Al0.125H0.25)(Cl0.75O0.25) (abbr. LAHCO) that was synthesized using Li2OHCl and LiAlCl4 as precursors. Neutron diffraction reveals that Li, Al, and H atoms occupy the A sites and O and Cl atoms occupy the B sites in the A1B1 structure for pure LAHCO. The LAHCO compound with excess LiAlCl4 shows the highest Li+ ionic conductivity of 104 S cm1 at room temperature due to the disordering induced by configurational entropy as well as the entropy of mixing. Moreover, LAHCOLiAlCl4 solid electrolyte exhibits a stable polarization voltage under a current density of 550 A cm2 in Li symmetric cells. This work not only explicates the importance of Li-ion conductors with a rock-salt structure but also contributes toward the development of solid-state Li-ion conductors for broad applications.