Bismuth oxide self-standing anodes with concomitant carbon dots welded graphene layer for enhanced performance supercapacitor-battery hybrid devices

Abstract

To meet the energy storage demand of developing electronic information technology, the supercapacitor-battery hybrid devices based on Bi2O3 have attracted much attention due to their superior energy storage characteristics. However, the poor cycling stability limits its application. Herein, through the nano-welding technique induced by the microwave thermal effect of graphene, the carbon nanotube film-supported Bi2O3 electrode with a graphene/carbon dots encapsulation structure is fabricated. The as-prepared composite electrode delivers a remarkable capacity of 1.90 mAh cm−2 at 1 mA cm−2 as well as high rate performance (1.57 mAh cm−2 at 100 mA cm−2). Assembled device with above composite electrode as anode and the carbon nanotube loaded nickel cobalt as cathode exhibits a maximum energy density of 589.3 μWh cm−2 (98.2 Wh kg−1) at power density of 0.8 mW cm−2 and maintain 288.3 μWh cm−2 (48.1 Wh kg−1) at 57.1 mW cm−2. Most notably, by virtue of the flexible confinement of graphene, the device exhibits impressive cycle stability (80.1% capacity retention after 8000 cycles, ∼4.5 times than that of a device assembled with a raw anode). This work opens a new pathway to the design and fabrication for high energy density and durable cyclic stability energy storage devices.