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 Li1.3Al0.3Ti1.7(PO4)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 Li1.3Al0.3Ti1.7P3O12 solid electrolytes were synthesized by molten salt assisted synthesis with AlF3 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 LiTiPO5 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 PO43- 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.