A comparison of anodically grown CuO nanotube film and Cu2O film as anodes for lithium ion batteries

CuO nanotube film and Cu2O film were anodically grown on Cu substrates through direct oxidation and electrochemical anodic reduction, respectively. The microstructure and morphology of the films were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The obtained CuO is monoclinic crystallization, and the diameters of tubes are about 100-300 nm, while the as-prepared Cu2O has a typical structure with a space group Pn3m and consists of compact faceted crystals. As anodes for Li-ion batteries, the electrochemical properties of the nanostructured CuO and Cu2O films were investigated by cyclic voltammogram and galvanostatic charge-discharge tests. An "apparent charge capacity" was introduced to describe the electrochemical performance. The initial apparent discharge capacity of the CuO and Cu2O film electrode reached to 911 and 570 mAh/g, respectively. Although they exhibited large irreversible capacities attributed to the formation of solid electrolyte interface (SEI) during the first cycle, the CuO nanotube film and Cu2O film had good cyclability and delivered the apparent capacity of 417 and 219 mAh/g after 30 cycles, respectively.