Fabrication of TiNb2O7 thin film electrodes for Li-ion micro-batteries by pulsed laser deposition

Pulsed laser deposited TiNb2O7 thin films are demonstrated as anode materials in rechargeable Li-ion micro-batteries. The monoclinic and chemically pure TiNb2O7 films in different morphologies were successfully deposited at 750 degrees C. The single phase formation was confirmed by grazing incident X-ray diffraction, micro-Raman spectroscopy, high resolution transmission electron microscopy, field emission scanning electron microscopy and X-ray photoelectron spectroscopy. The oxygen partial pressure during the deposition significantly influenced the properties of TiNb2O7 films. The TiNb2O7 thin films exhibited excellent stability with fast kinetics reversible reaction. The TiNb2O7 films showed initial discharge specific capacity of 176,143 mu Ah mu m(-1) cm(-2) at 30, 50 mu A cm(-2) current densities respectively with 92% coulombic efficiency in a non-aqueous electrolyte consisting of Li+ ions. The high discharge specific capacity of TiNb2O7 thin films may be attributed to nanometer grain size with high roughness which offers high surface area for Li-diffusion during charge and discharge process. (C) 2016 Elsevier B.V. All rights reserved.