Facile fabrication of cuprous oxide nanocomposite anode films for flexible Li-ion batteries via thermal oxidation

In the present work, nanostructured Cu2O films are directly grown from a Cu metal foil by means of a rapid thermal oxidation process. The structural characteristics of the films are investigated by field emission scanning electron microscopy, X-ray diffraction and attenuated total reflectance Fourier-transformed infrared spectroscopy. The electrochemical behaviour is investigated in both lithium (liquid electrolyte) and all-solid lithium polymer cells. At a discharge/charge rate of C/5, the films can provide a specific capacity greater than 220 mAh g−1 in the all-solid configuration, with excellent cycling stability and capacity retention after prolonged cycling. High surface area, short diffusion path and good conduction of the Cu2O films are considered to be responsible for the good electrochemical performance, along with the use of the polymeric electrolyte which is directly formed in situ on the electrode film surface. The present findings can provide a new and easy approach to fabricate nanocomposite films with interesting performance as negative electrode particularly for the next generation of flexible all-solid-state Li-ion microbatteries.