Structural and electrochemical properties of LiMoO 2

Abstract

In this paper, we revisit the structural and electrochemical properties of lithium molybdenate, LiMoO 2, synthesized by a carbothermal method using citric acid as a chelating agent. Free-impurity microcrystalline powders were grown by a two-step synthesis with a final thermal treatment at 800 °C for 72 h in air. LiMoO 2 was characterized by means of X-ray diffractometry (XRD), Fourier transform infrared (FTIR) and Raman scattering (RS) spectroscopy and by nuclear magnetic resonance (NMR). Analyzing the data from the above experiments, we determine that LiMoO 2 crystallizes in the monoclinic system ( C2/ m S.G.) instead of the rhombohedral structure ( R 3 ¯ m S.G.) such as reported previously. The electrochemical performance of the synthesized products was evaluated in Li cells using non-aqueous solution 1 mol L −1 LiPF 6 in EC–DMC as electrolyte. The charge–discharge profiles of the monoclinic-phase LiMoO 2 display two plateaus and show the suitability of this electrode for electrochemical applications delivering a specific capacity 185 mAh g −1 in the potential range 3.7–2.0 V vs. Li 0/Li +. The chemical diffusion coefficient of Li + ions into the LiMoO 2 framework has been studied as a function of Li concentration; results show values in the range 10 −11–10 −12 cm 2 s −1.