Electrochemical Characteristics of Al2O3-Doped ZnO Films by Magnetron Sputtering

Al2O3-doped ZnO (AZO) films have been prepared by radio frequency (rf) magnetron sputtering. The electrical properties and electrochemical behavior are investigated by Hall measurements, galvanostic cycling, and cyclic voltammograms. The result demonstrates that doping with a small amount of Al2O3 (<3 wt %) can improve the electrochemical performance of ZnO significantly. Among all of the AZO films, AZO2 (2 wt % Al2O3) film shows the best behavior with a large reversible specific capacity around 590 mAh g(-1) and excellent capacity retention. High-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) measurements confirm the formation of LiAl and nanosized Al2O3 during the first discharge and charge processes, respectively. The electrochemical reaction mechanism of AZO with lithium is proposed. It is believed that the nanosized Al2O3 formed after the charge process in AZO films plays an important role in the improvement of electrochemical performance.