Polymer-Derived Electrospun Co<sub>3</sub>O<sub>4</sub>@C Porous Nanofiber Network for Flexible, High-Performance, and Stable Supercapacitors
Rasmita Barik, Avinash Raulo, Shwetambara Jha, Bhanu Nandan, Pravin P. Ingole
Abstract
1D nanofibers with higher surface area, small pore size, high porosity, good electrical conductivity, and relatively high production rate with high fiber interconnectivity have gained attention as energy materials. In the present study, citrate-stabilized 1D cobalt oxide nanofibers are prepared by the electrospinning technique using polyvinylpyrrolidone (PVP) polymer followed by annealing at 500 °C where PVP acts as the carbon source leading to highly porous 1D Co3O4@C nanofibers exhibiting enhanced specific capacitance. Microscopic and structural characterization illustrates that the rod-shaped Co3O4 is interlinked with each other through polymer-derived carbon in the form of a nanofiber network. The electrospun Co3O4@C nanofibers demonstrate a specific capacitance of 731.2 F g–1 at a current density of 8 A g–1 in the 0.1 M KOH electrolyte. Furthermore, the Co3O4@C nanofibers show better cyclic stability with an excellent capacity retention of 100% after 3000 continuous GCD cycles at a current density of 9 A g–1. Again, the asymmetric supercapacitor system with the PVA–KOH electrolyte was fabricated and showed a specific capacitance of 120. 8 F g–1 (12.08 mF cm–2) with an energy density of 37.75 Wh kg–1 (3.77 mWh cm–2) and power density of 1800 W kg–1 (180 mW cm–2) at 0.6 A g–1 (0.06 mA cm–2) current density. The symmetric supercapacitor shows 100% retention in specific capacitance after 4000 GCD cycles. The enhanced supercapacitor performance of 1D Co3O4@C nanofibers was attributed to their unique nanofibrous structure with greater active surface area provided by the in situ carbon, facilitating a faster ion and electron transfer.