Micro-Raman spectrometry and x-ray diffraction (XRD) experiments were performed on the anatase Li_xTiO₂ system (0 ≥ x ≥ 0.6) produced from the electrochemical discharge of a TiO₂ composite cathode in propylene carbonate -LiClO₄ solution at room temperature. Raman spectrum modifications indicate local structural and chemical changes as lithium enters the anatase host lattice. The existence of a tetragonal to orthorhombic phase transition is clearly demonstrated by the Raman and XRD measurements. Moreover, lithium extraction is only partially quantitative for Li uptake ≤0.5, as shown both from structural and electrochemical data in the 3-1.5 V potential range. For the first time, the Raman fingerprint of the lithium titanate (LT) Li_0.5TiO₂ orthorhombic phase is clearly evidenced. A theoretical analysis of the lattice dynamics suggested a complete interpretation of the experimental Raman spectra in the Li _xTiO₂ system, which provided valuable information on the Li atom positions and coordination in LT. Taking into account the possibility of rather short Li-O distances, the complex band structure in the high-wavenumber region is assigned to the Li-O vibrations. Furthermore, spectra simulation offers an explanation for the new shape of the TiO₂ lattice modes observed in the low-wavenumber region.