Electrical and electrochemical properties of molten-salt-synthesized 0.05 mol Zr- and Si-doped Li4Ti5O12 microcrystals

Abstract

This work emphasizes the structural, morphological, electrical, and electrochemical properties of 0.05 mol Zr- and Si-doped Li4Ti5O12 synthesized using the molten salt method and applied to negative electrodes in Li-ion batteries. Formation of the spinel phase with face-centered cubic structure in the nominally pure and Zr- and Si-doped samples are revealed from X-ray powder diffraction technique. Lattice parameters refined by full-profile Rietveld method are in accordance with the literature data for the Li4Ti5O12 (Li1.333Ti1.667O4) spinel structure. The presence of possible functional groups is identified using Fourier transform infra red spectroscopy. The field emission scanning electron microscopic images indicate the formation of micron-sized (1.5–2 μm) randomly distributed polyhedral-shaped particles. The electrical conductivity studies demonstrate the grain-conducting behavior of the material. The maximum DC conductivity of 2 × 10−5 S cm−1 is observed for Zr-doped Li4Ti5O12 at room temperature. The galvanostatic charge–discharge studies show that Zr-doped Li4Ti5O12 exhibits a high discharge capacity of about 325 mAh g−1 at 0.01 °C, higher than Si-doped Li4Ti5O12 (200 mAh g−1), and also that the cycling stability of Zr-doped Li4Ti5O12 is enhanced.