Sputtered lithium nickel vanadium oxide (LiNiVO4) films: Chemical compositions, structural variations, target history, and anodic/cathodic electrochemical properties
Résumé
In this paper, we report the chemical compositional variations and target surface history of lithium nickel vanadate material during RF-magnetron sputtering. Amorphous films were characterized by nuclear methods [Rutherford backscattering spectroscopy (RBS) and nuclear reaction analysis (NRA)], Auger electron spectroscopy (AES), X-ray diffraction (XRD), scanning electron microscope (SEM), atomic force microscope (AFM), and high resolution transmission electron microscopy (HTEM) techniques. Various nanostructured/porous LiNiVO4 thin film materials were obtained, depending on the composition of films, total pressure, annealing temperatures, thickness and heating time. Optimum film composition was obtained with the sputtering parameters; oxygen partial pressure (Po2) = 10 mPa, total pressure of (PAr) = 1 Pa, Rf-power = 30 W. Cathodic and anodic electrochemical properties of LiNiVO4 films were evaluated by galvanostatic cycling at constant current and cyclic voltammetry electroanalytical techniques. Electrochemical performance of the LiNiVO4 film deliver a capacity of 780 mA hg−1 (10th cycle), potential range, 0.02–3.0 V (anodic), at a current rate, 75 μA cm−2. In the potential range 1.2–4.5 V, deliver a capacity of 280 mA hg−1, and in the potential window, 3.0–4.8 V (cathodic), 0.6 Li are removed from the host LiNiVO4 lattice.