High grain boundary density Li 4 Ti 5 O 12 /anatase-TiO 2 nanocomposites as anode material for Li-ion batteries

Li 4 Ti 5 O 12 /TiO 2 nanocomposites are synthesized by a sol-gel method. The size of Li 4 Ti 5 O 12 and TiO 2 particles is of 4–5 and 7–10 nm, respectively. The obtained materials are characterized by XRD, SEM, HRTEM and BET. Ion mobility of the composites and their performance as anode materials for lithium-ion batteries are studied. According to the conductivity and 7 Li NMR data, Li + mobility is much higher in the Li 4 Ti 5 O 12 /TiO 2 nanocomposites as compared with that in pure Li 4 Ti 5 O 12 . For Li 4 Ti 5 O 12 /TiO 2 nanocomposites, marked changes in the charge–discharge curves are observed; charge–discharge rate and effective capacity at a high cycling rate are shown to increase. During the first cycle, charge capacity of these materials surpasses the theoretical capacity of Li 4 Ti 5 O 12 . However, this parameter decreases sharply with cycling, whereas the discharge capacity remains almost unchanged. This phenomenon is attributed to the solid electrolyte interphase formation due to a partial electrolyte reduction on the Li 4 Ti 5 O 12 /TiO 2 composite surface.