Amorphous tin oxide films: preparation and characterization as an anode active material for lithium ion batteries

Abstract

Tin oxide thin films were prepared by the electrostatic spray deposition at 400°C, followed by annealing at 500°C in air. X-ray diffraction and X-ray photoelectron spectroscopy revealed that the resulting films were amorphous SnO 2. The electrochemical properties of the SnO 2 films with lithium were studied by in situ conductivity measurements using an interdigitated microarray electrode as well as by cyclic voltammetry, galvanostatic cycling measurements and ac-impedance spectroscopy in 1 M LiClO 4/(PC+EC). The SnO 2 film electrodes exhibited reversible capacities greater than 1300 mA h g −1 when cycled between 0.05 and 2.5 V at 0.2 mA cm −2. However, this capacity faded rapidly after repeated cycling. If the electrode was cycled between 0 and 1.0 V, a reversible capacity of 600 mA h g −1 was maintained for more than 100 cycles. In addition, a stable reversible capacity of about 500 mA h g −1 was obtained even at current density as high as 2 mA cm −2. Thus it is suggested that a higher potential than 1.5 V would cause reformation of tin oxide, which may destroy the stable nanocomposite structure of metallic tin and lithium. These arguments were supported by in situ conductivity measurements with microarray electrodes.