Enhancing purity and ionic conductivity of NASICON-typed Li_1.3Al_0.3Ti_1.7(PO₄)₃ solid electrolyte

Increasing demand for safe energy storage and portable power sources has led to intensive investigation for all-solid state Li-ion batteries and particularly to solid electrolytes for such rechargeable batteries. One of the most promising types of solid electrolytes is NASICON-structured Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP) due to its relatively high ionic conductivity and stability towards air and moisture. Here, the work is aimed on implementing the steps to hinder formation of impurity phases reported for various synthesis routes. Consequently, the applied modifications in the preparation strategies alter a crystal shape and size of prepared material. These two parameters have an enormous impact on properties of LATP. Fabrication of larger particles with a cubic shape significantly improves its ionic conductivity. As a result, LATP preparation methods such as a solution chemistry and molten flux resulted in the highest ionic conductivity samples with the value of ~10⁻⁴ S cm⁻¹ at room temperature. Other LATPs obtained by solid-state reaction, sol-gel and spray drying methods depicted the ionic conductivity of ~10⁻⁵ S cm⁻¹. The activation energy of lithium ion transfer in LATP varied in a range of 0.25–0.4 eV, which is in well agreement with the previously reported data.