Structural and electrochemical properties of LiMoO2

In this paper, we revisit the structural and electrochemical properties of lithium molybdenate, LiMoO2, 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. LiMoO2 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 LiMoO2 crystallizes in the monoclinic system (C2/m   S.G.) instead of the rhombohedral structure (R3¯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 LiPF6 in EC–DMC as electrolyte. The charge–discharge profiles of the monoclinic-phase LiMoO2 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. Li0/Li+. The chemical diffusion coefficient of Li+ ions into the LiMoO2 framework has been studied as a function of Li concentration; results show values in the range 10−11–10−12 cm2 s−1.

► We revisit the structural and electrochemical features of the LiMoO2 phase.
► LiMoO2 crystallizes with the monoclinic structure (C2/m   S.G.) instead of (R3¯m S.G.).
► Charge–discharge profiles of LiMoO2 displays 2 plateaus related to the 2 sites occupied by Li ions.