Characterization of amorphous LiNiVO4 thin-film anode grown by pulsed laser deposition

Abstract

LiNiV O4 thin-film anode deposited under 8 mTorr of O2 and room temperature by pulsed laser deposition has been characterized by electrochemical tests and physical analyses. A retainable capacity as high as 410 μAh cm2 μm with only 10.4% of initial irreversible capacity loss was achieved, corresponding to more than 7 lithium ions intercalated per LiNiV O4 formula unit. The linear dependence of peak current on the square root of scan rates by cyclic voltammogram (CV) gave an apparent Li+ diffusion coefficient of 1.9× 10-12 cm2 s. Alternating current (ac) impedance revealed a small charge transfer resistance of 52 Ω at 1.32 V, indicating that lithium ion is easily inserted in and extracted from the as-deposited LiNiV O4 film anode. Ex situ X-ray photoelectron spectroscopy (XPS) analysis on the as-deposited and lithiated films confirmed that vanadium cations were reduced to some extent with the lithium intercalation. The cathodic peaks at 1.71 and 0.53 V with a shoulder around 0.95 V in CV scans may correspond to the different reduction processes of vanadium. The as-deposited film was mainly amorphous and smooth, with a surface roughness of only 2.835 nm. The lithiated film remained amorphous and had only a minor change in surface topography. © 2006 The Electrochemical Society. All rights reserved.