Electrospun 1D cobalt pyrophosphate porous nanofibers: Redox-active electrode material for asymmetric supercapacitor

The ability of a supercapacitor to store energy is closely tied to the amount of surface area available for elec-troactive reactions. Using 1D nanostructure material not only allows for larger specific surface area compared to that of other nanostructures, but also provides a direct path for the movement of electrons, acting like a "freeway" in the axial direction. Considering the benefits herein, we report the synthesis of Co2P2O7 nanofibers as an electrode material for supercapacitor application using a facile and industrially applicable electrospinning method followed by calcination. The resulting nanofibers have a continuous, uniform, and web-like structure with many small pores, which gives high specific surface area of 234.499 m2 g-1. This high surface area improves the interaction between the Co2P2O7 nanofibers electrode and 3 M KOH electrolyte, thereby enhancing the electrochemical properties of the material. The prepared Co2P2O7 nanofibers electrode has a high specific ca-pacity of 270.7 C g-1 at a high current density 80 A g-1 and good stability of 84.7 % after 3000 continuous cycles. Furthermore, an asymmetric supercapacitor (ASC) device was fabricated using carbon nanofibers (CNF) as another electrode material. The energy density 27.8 Wh kg-1 and power density 1.89 kW kg-1 of ASC at a current density of 2 A g-1 suggests that Co2P2O7 nanofibers could be a viable option as an electrode material for supercapacitors.