The film growth and electrochemical properties of rf-sputtered LiCoO₂ thin films

In this work, the effect of various sputtering parameters (such as working pressure, O₂ fraction, and rf power) on the film growth of HT-LiCoO₂ on Pt-coated silicon were investigated. The as-deposited films and annealed films show crystalline HT-LiCoO₂ single phase with (1 0 4) preferred orientation under various sputtering parameters. From ICP results, it was observed that the sputtering parameters and annealing process affected the compositions of the films obviously. The annealing process enhanced the crystallinity of HT-LiCoO₂ films. They showed difference in crystallinity and resulted in the variation of Li⁺ diffusion coefficient that was measured and estimated by slow-scan-rate cyclic voltammetry (SSCV) and galvanostatic intermittent titration technique (GITT) techniques. The charge/discharge tests indicated that films exhibit higher D_{L i+} showed better rate capability.