Development of paper-based flexible supercapacitor: Bismuth ferrite/graphene nanocomposite as an active electrode material

In this work, a lightweight and efficient supercapacitor on a flexible paper has been developed. Flexible electrodes of bismuth ferrite (BFO)/graphene nanocomposite have been fabricated by a simple drop casting method. The mechanical stability of the electrodes was tested by bending the supercapacitor. The BFO/graphene electrode with its porous structure has more electrolyte accessibility and the graphene nanosheets act as an effective conductive pathway for charge transportation between the electrode material and the current collector. The electrode exhibited excellent electrochemical performance in terms of specific capacitance and cycle stability. The electrode demonstrated specific capacitance of 9 mF/cm2determined from cyclic voltammetry test at a scan rate of 10 mV/s in the potential window of 0–0.9 V. It can deliver specific power of 0.5–3.5 kW/kg with moderate energy density. The electrode retains 98% capacitance over 1000 cycles and 95% after 5000 cycles. The BFO/graphene nanocomposite electrode demonstrated good mechanical stability towards flexible supercapacitor application. X-ray diffraction, Raman spectroscopy, and field emission scanning electron microscopic analyses revealed the formation of BFO/graphene nanocomposite. The electrochemical results such as cyclic voltammetry and galvanostatic charging/discharging suggested that BFO/graphene nanocomposite electrode has a significant potential for flexible energy storage system.