Lattice vibrations of materials for lithium rechargeable batteries II. Lithium extraction-insertion in spinel structures

摘要

Lithiated spinel manganese oxides with various amounts of lithium have been prepared through solid-state reaction and electrochemical intercalation and deintercalation. Local structure of the samples are studied using Raman scattering and Fourier transform infrared spectroscopy. We report vibrational spectra of lithiated manganese oxides Li_xMn_2O_4 as a function of lithium concentration in the range 0.1 ≤ x ≤ 2.0. Raman and Fourier transform infrared (FTIR) spectral results indicated multiple-phase reactions when the lithium content is modified in the spinel lattice. Lattice dynamics of lithiated spinel manganese oxides have been interpreted using either a classical factor-group analysis or a local environment model. The structural modifications have been studied on the basis of vibrations of LiO_4 tetrahedral and MnO_6 octahedral units when Li/Mn ≤ 0.5, and LiO_4, LiO_6, and MnO_6 structural units when Li/Mn > 0.5.