Preparation and electrochemical properties of Li₄Ti₅O₁₂ thin film electrodes by pulsed laser deposition

Spinel Li₄Ti₅O₁₂ thin film anode material for lithium-ion batteries is prepared by pulsed laser deposition. Thin film anodes are deposited at ambient temperature, then annealed at three different temperatures under an argon gas flow and the influence of annealing temperatures on their electrochemical performances is studied. The microstructure and morphology of the films are characterized by XRD, SEM and AFM. Electrochemical properties of the films are evaluated by using galvanostatic discharge/charge tests, cyclic voltammetry and a.c. impedance spectroscopy. The results reveal that all annealed films crystallize and exhibit good cycle performance. The optimum annealing temperature is about 700 °C. The steady-state discharge capacity of the films is about 157 mAh g^-1 at a medium discharge/charge current density of 10 μA cm^-2. At a considerably higher discharge/charge current density of 60 μA cm^-2 (about 3.45 C) the discharge capacity of the films remains steady at a relative high value (146 mAh g^-1). The cycleability of the films is excellent. This implies that such films are suitable for electrodes to be used at high discharge/charge current density.