Improved ionic conductivity in NASICON-type Sr2+ doped LiZr2(PO4)(3)

Abstract

Lithium ion conducting ceramics Li1 + 2xZr2 − xSrx(PO4)3 with x = 0–0.2 were synthesized via a sol-gel method using citric acid. The effects of Sr2 + substitution on the structure, microstructure, and conductivity of LiZr2(PO4)3 ceramics were studied. Rietveld refinement of powder XRD patterns showed that 5% of Sr2 + substitution for Zr4 + in LiZr2(PO4)3 stabilizes the rhombohedral (space group R3̅c) phase at room temperature. Sr2 + doped LiZr2(PO4)3 samples exhibited significantly improved ionic conductivity with Li1.2Zr1.9Sr0.1(PO4)3 showing highest conductivity of 0.34 × 10− 4 Ω−1 cm− 1 at room temperature. Activation energy was found to decrease from 0.56 eV for LiZr2(PO4)3 to 0.40 eV for Li1.4Zr1.8Sr0.2(PO4)3. Li+ transference number determined by DC polarization for Li1.2Zr1.9Sr0.1(PO4)3 was close to 1 confirming the ionic nature of conductivity.