Performance and electrochemical evolution of (Zn0.4Ni0.6)0.95Li0.05O thin film for Li-ion storage electrode

Abstract

To improve the electrochemical performance of thin films based on Zn0.4Ni0.6O (ZNO) solid solution compound (SSC), Li-decorated ZNO [(Zn0.4Ni0.6)0.95Li0.05O, ZNLO] SSC was designed in this work. ZNO and ZNLO nanostructured thin films were prepared by RF magnetron sputtering with related lab-made ceramic targets. Phase composition, element valences, microstructure, electrochemical properties and electrochemically-induced phase evolution of the thin films were investigated. The cells assembled with ZNLO thin films as electrode deliver high reversible specific capacity of 773 mAh g−1 at 200 mA g−1 after 200 cycles, which is extremely superior to that of the ZNO thin film (363 mAh g−1). ZNLO thin film shows a high rate performance with specific capacity of 511 mAh g−1 at 1000 mA g−1 even after 750 cycles. The electrochemically induced phase evolution was studied by transmission electron microscopy, and the results revealed that nearly complete redox conversions of Zn-Ni-O ↔ Ni/Zn and ZnO ↔ Zn took place in ZNLO thin films electrode. The high electrochemical performance owes to the enhanced electrical conductivity of thin film doped with Li-ion and nanostructured characteristics of thin film that provide high specific surface and redox conversion processes.