Abstract

A new type of CuO/Cu/graphene quantum dots (GQDs) triaxial nanowires (referred as CCG) has been designed and successfully fabricated using a two-step electrochemical process followed by annealing. The synergistic combination of high-capacity metal oxide CuO and conductive layers of Cu and GQDs exerts an enhanced electrochemical performance for Li ion storage. The triaxial nanowire CCG electrode shows an improved reversible capacity (ca. 760 mAh g^-1 cycled at 1/3 C) and rate capability (~60 % capacity retention cycled at 10 C) compared with nanowires without GQDs coating. A relatively high initial coulombic efficiency (~87 %) is obtained for the CCG anode as a result of the Cu and GQDs double layers. Meanwhile, the CCG anode showed high capacity retention in long cycles reached up to 1000 cycles. This ultrastability can be ascribed to the GQDs shell which provides an elastic protection for the nanowires and conductive path for electrons. Our results demonstrate the effectiveness of GQDs coating in improving the electrochemical performance and stability of nanostructured electrodes for Li ion batteries and possibly also for other electrochemical devices.

© 2015 Optical Society of America