Fabrication of MnO2‑carbonized cotton yarn derived hierarchical porous active carbon flexible supercapacitor electrodes for potential applications in cable-type devices

Abstract

MnO2 has received immense consideration for supercapacitors; however, its performance in energy storage is limited by its low electroconductivity and agglomeration during the charge-discharge process. This necessitates the fabrication of flexible supercapacitor with excellent electrochemical properties for application in cable-type devices. In the current study, we have fabricated a self-standing carbonized cotton yarn (CCY) and the MnO2-based electrode by using a cotton yarn derived carbon fiber as a substrate. The electrode with hierarchical porous architecture was obtained through a redox reaction between CCY and potassium permanganate (KMnO4). Field emission scanning electron microscopy showed the deposition and uniform distribution of MnO2 nanoparticles on the surface of CCY. The electrode showed excellent capacity performance and electrochemical stability. In the electrode, the combination of MnO2 nanoparticles and CCY offered enhanced kinetics, a large surface area which resulted in high energy density (16.88 μWh/cm2) and high-power density (4770 μW/cm2). Further, the fabricated electrode showed a specific area capacity of 182.94 mF/m2 at 20 mV/s. Moreover, three flexible supercapacitors were connected in series and parallel to get higher working voltage and higher capacity, respectively, which demonstrated its potential for broad-spectrum applications in flexible devices, these results demonstrate the potential of MnO2/CCY for diverse applications in the development of cable-type devices.