Enhanced features of Li2CO3 sputtered thin films induced by thickness and annealing time

Abstract

Li₂CO₃ sputtered films of 300 nm have been subjected to physical and electrochemical characterization methods to analyze the influence of annealing treatments at 600 °C for 2 h, 6 h, 12 h and 18 h on the microstructure, surface and conductivity. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), atomic force microscopy (AFM) and electrochemical impedance spectroscopy (EIS) have been used for this purpose. XRD and FT-IR have illustrated the evolution of the microstructure with annealing time. AFM analysis has shown the growth of new Li₂CO₃ particles that increases with annealing time presenting a maximum diameter of 16.8 μm without compromising the continuity of the films. EIS measurements have described a fall in the activation energy of the Li₂CO₃ thin films presenting a minimum around 1.18 eV. The results concerning the activation energy of the films have shown an improvement compared to the results obtained previously for Li₂CO₃. These results serve to understand and optimize the behaviour of the Li₂CO₃ thin films in gas sensors, fuel cells or Li⁺ ion batteries.