Zinc Oxide Based Nanocomposite Thin Film Electrodes and the Effect of D.C. Plasma Oxidation Power on Discharge Capacity for Lithium Ion Batteries

Abstract

Zinc oxide based thin films have been grown on glass and stainless steel substrates in two steps; thermal evaporation from high purity metallic zinc and D.C. plasma oxidation. X-ray diffraction has shown that the films were polycrystalline nature and small predominant orientation at some specific planes. Analysis showed that plasma oxidation starts from the thermally evaporated leaf-like surfaces and produces a core-shell structure of ZnO on the metallic Zn. Increasing plasma oxidation power causes increased amount of ZnO volume and resistivity. Coin-type (CR2016) test cells were assembled in an argon-filled glove box and cyclically tested. The electrochemical performance of the films has been studied by cyclic voltammetry. The dependence of converted Li-ions on voltage profile of the films has been determined. It was found that the Zn/ZnO films exhibited highest the number of converted Li-ions at 175 W plasma oxidation conditions. Discharge capacity measurements revealed the double phase structures of Zn/ZnO exhibited significantly high reversible capacities. The high capacity and low capacity fade values were attributed to the high electrical conductivity and buffering ability of metallic Zn in the anodes.