Enhanced lithium-ion conductivity in a LiZr 2 (PO 4 ) 3 solid electrolyte by Al doping

Abstract The fast Li-ion conducting Na + super ionic conductor (NASICON) lithium zirconium phosphate LiZr 2 (PO 4 ) 3 with a rhombohedral phase is only stable above 50 °C. It is triclinic at room temperature with σ Li ≈ 10 −8 S cm −1 . Substitution of Zr by Al in LiZr 2 (PO 4 ) 3 stabilizes the high conducting rhombohedral phase at room temperature, decreases the intensity of impurity phase and increases Li-ion concentration through the addition of additional Li + ions into the unit cell. This gives a high total Li-ion conductivity at room temperature. With different amounts of Al doped into the Li 1+x Al x Zr 2−x (PO 4 ) 3 system, its total Li-ion conductivity reaches 3.1 × 10 −6 S cm −1 when x = 0.275. This is as high as that of the rhombohedral high-temperature phase of LiZr 2 (PO 4 ) 3 at about 50 °C.