Effect on ionic conductivity of Na3+xZr2-xMxSi2PO12 (M=Y, La) by doping rare-earth elements

NASICON structure solid electrolyte with the composition of Na3+xZr2-xMxSi2PO12 (M = La, Y) were prepared by solid-state method. The effects of La and Y doping on the density and ionic conductivity of NASICON solid electrolyte were investigated. The results show that the doping of La and Y can improve the ionic conductivity of NASICON structure solid electrolyte because of the higher carrier concentration, migration efficiency, and higher density. The Na3.3Zr1.7La0.3Si2PO12 has the highest ionic conductivity of 6.7 × 10−3 S/cm at 25 °C.