Lithium lanthanum titanate (LLTO, CAS number: 12031-66-2) is a perovskite solid-state electrolyte. The general formula of LLTO is Li3xLa2/3-xTiO3, where x typically ranges from 0.05 to 0.33. The lithium and lanthanum contents impact the ionic conductivity and structural stability of the electrolyte. Increasing the lithium content generally enhances the ionic conductivity but can reduce structural stability. LLTO typically exhibits ionic conductivity in the range of 10−4 to 10−3 S/cm.
Lithium lanthanum titanate has been used in lithium sulfur batteries, all solid-state batteries, and supercapacitors. A lithium sulfur battery with a configuration of lithium/LLTO/polysulfide exhibits a high charge-storage capacity of 1429 mAh/g and electrochemical efficiency exceeding 99%. In solid-state capacitors, LLTO combined with 6% ionic liquid enables at least 10,000 charge–discharge cycles at an operating voltage of 2 V and a discharge current of 1.13 A/g (2 mA), achieving an outstanding Coulombic efficiency of 99%.