Superior ionic conductivity of W-doped NASICON-type Li1.3Al0.3Ti1.7(PO4)3 solid electrolyte

Abstract

NASICON-structured Li1.3Al0.3Ti1.7(PO4)3 (LATP) solid electrolyte has low grain boundary conductivity, which impedes its practical application. Herein, W was adopted to partially replace the Al element in LATP to improve its grain boundary conductivity. The W doping reduces the crystal lattice of the electrolyte, which is detrimental to the grain conductivity. But the doping of W can make the grains closely connect and reduce the voids between the grains, which can greatly enhance the grain boundary conductivity. The LATP sample with the W doping content of 0.03 (LATWP003) exhibits the highest total ionic conductivity of 1.186 mS/cm at 30 ℃, which results from the optimum grain boundary conductivity of 2.315 mS/cm. Moreover, the LATWP003 electrolyte displays a negligible electronic conductivity of 2.01×10−9 S/cm. The LiFePO4/LATWP003/Li battery with PVDF-HFP polymer protective layer can be charged and discharged. Therefore, the W doped LATP sample is a promising electrolyte for lithium-ion batteries.