Molten salt assisted synthesis and structure characteristic for high conductivity fluorine doped Li1.3Al0.3Ti1.7P3O12 solid electrolytes

To address the safety concerns surrounding liquid electrolyte lithium-ion batteries, the development of a safe and reliable solid electrolyte with high ionic conductivity is of utmost importance. In recent years, the NASICON-type Li _1.3Al _0.3Ti _1.7(PO ₄) ₃ solid electrolyte has garnered increasing attention due to its impressive room temperature ionic conductivity and excellent chemical stability. However, its preparation is usually completed in high temperature up to 1000 ℃, which is high energy consumption. Herein, F-doped Li _1.3Al _0.3Ti _1.7P ₃O ₁₂ solid electrolytes were synthesized by molten salt assisted synthesis with AlF ₃ as the precursor and flux, which were prepared at 800 ℃ with relative density of 95.39% and room temperature lithium ionic conductivity of 1.14 × 10 ⁻³ S cm ⁻¹ . XRD results show that F doping can inhibit the formation of impurity phase LiTiPO ₅ to a certain extent, and is beneficial to improve the conductivity and density of LATP solid electrolyte. FT-IR spectra show that the addition of F changes the structural peak of PO4 ^3- and increases the number of bridge oxygen, thus enhancing the structural stability of LATP solid electrolyte. The SEM results show that the addition of F can promote the growth of grain at low temperature, increase the density of LATP electrolyte, and reduce the energy consumption. EDS, XPS and TEM results show that F has been successfully doped into LATP solid electrolyte crystals.