LiSnZr(PO4)3: NASICON-type solid electrolyte with excellent room temperature Li+ conductivity

Abstract

Development of solid electrolytes with good lithium ion conductivity is one of the key pre-requisites of high performing rechargeable all-solid-state lithium batteries. In this work, NA-Super-Ionic-CONductor (NASICON)-type LiSnZr(PO4)3 ceramics fabricated via a sol-gel route were characterized using Synchrotron x-ray diffraction, Raman Spectroscopy, x-ray photoelectron spectroscopy (XPS) and complex impedance spectroscopy. Stabilization of high Li+ conducting rhombohedral (R3¯c) phase at room temperature was confirmed by the Rietveld refinement of synchrotron x-ray diffraction data. LiSnZr(PO4)3 sample sintered at 1000 °C exhibited an excellent room temperature bulk and total conductivity ∼ 0.1 mScm−1 and 1.45 × 10−5 Scm−1 with associated activation energies of ∼0.36 eV and ∼0.38 eV, respectively. Direct current polarization study confirmed the conductivity of LiSnZr(PO4)3 as predominantly ionic in nature. The role of inductive effect in improving the room temperature ionic conductivity by utilizing the electronegativity of counter-cations in NASICON framework is also discussed.