A binder-free wet chemical synthesis approach to decorate nanoflowers of bismuth oxide on Ni-foam for fabricating laboratory scale potential pencil-type asymmetric supercapacitor device

The present study involves the synthesis of a bismuth oxide (Bi₂O₃) electrode consisting of an arranged nano-platelets for evolving a flower-type surface appearance on nickel-foam (Bi₂O₃-Ni-F) by a simple, inexpensive, binder-free and one-step chemical bath deposition (CBD) method, popularly known as a wet chemical method. The as-prepared Bi₂O₃ on Ni-foam, as an electrode material, demonstrates 557 F g^-1 specific capacitance (SC, at 1 mA cm^-2), of which 85% is retained even after 2000 cycles. With specific power density of 500 kW kg^-1, the Bi₂O₃-Ni-F electrode documents a specific energy density of 80 Wh kg^-1. Furthermore, a portable asymmetric supercapacitor device, i.e. a pencil-type cell consisting of Bi₂O₃-Ni-F as an anode and graphite as a cathode in 6 M KOH aqueous electrolyte solution, confirms 11 Wh kg^-1 and 720 kW kg^-1 specific energy and specific power densities, respectively. An easy and a simple synthesis approach for manufacturing a portable laboratory scale pencil-type supercapacitor device is a major outcome of this study, which can also be applied for ternary and quaternary metal oxides for recording an enhanced performance. In addition, we presented a demonstration of lighting a light emitting diode (LED) using a home-made pencil-type supercapacitor device which, finally, has confirmed the scaling and technical potentiality of Bi₂O₃-Ni-F in energy storage devices.