Doped Lithium Titanates and their Composites with Carbon Nanotubes as Anodes for Lithium-Ion Batteries

Lithium titanates Li_4+xTi_5–xM_xO₁₂ (M = Sc, Ga, Al, Cr; x = 0, 0.05, 0.1, 0.15) and their composites with carbon nanotubes were synthesized by the sol–gel method and characterized using X-ray powder diffraction, scanning electron microscopy, impedance spectroscopy, and ⁷Li MAS NMR spectroscopy; their electrochemical performance was studied. Doping with trivalent cations leads to a decrease in the mobility of lithium ions in Li_4+xTi_5–xM_xO₁₂, which indicates that lithium transport through vacancies predominates in these materials. The best electrochemical characteristics were found for the Li_4+xTi_5–xM_xO₁₂ composites with carbon nanotubes.