Impact of Lithium Composition on Structural, Electronic and Optical Properties of Lithium Cobaltite Prepared by Solid-state Reaction

Abstract

The lithium-cobalt oxide Li_xCoO₂ is a promising candidate as highly active cathode material of lithium ion rechargeable batteries. The crystalline-layered lithium cobaltite has attracted increased attention due to recent discoveries of some extraordinary properties such as unconventional transport and magnetic properties. Due to layered crystal structure, Li contents (x) in Li_xCoO₂ might play an important role on its interesting properties. LiCoO₂ crystalline cathode material was prepared by using solid-state reaction synthesis, and then Li_xCoO₂ (x<1) has been synthesized by deintercalation of produced single-phase powders. Structure and morphology of the synthesized powders were investigated by X-ray diffraction (XRD), Infrared spectroscopy, Impedance analyzer etc. The influence of lithium composition (x) on structural, electronic and optical properties of lithium cobaltite was studied. Temperature dependent electrical resistivity was measured using four-probe technique. While Li_xCoO₂ with x = 0.9 is a semiconductor, the highly Li-deficient phase (0.75 ? x ? 0.5) exhibits metallic conductivity. The ionic conductivity of Li_xCoO₂ (x = 0.5 1.15) was measured using impedance spectroscopy and maximum conductivity of Li_0.5CoO₂ was found to be 6.5×10^-6 S/cm at 273 K. The properties that are important for applications, such as ionic conductivity, charge capacity, and optical absorption are observed to increase with Li deficiency.

Keywords: Calcination; Characterization; Inorganic compounds; Solid-State reaction; X-ray diffraction.

© 2014 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved.

doi: http://dx.doi.org/10.3329/jsr.v6i2.17900

J. Sci. Res. 6 (2), 217-231 (2014)