title: ZnO@MnO2Core-Shell Nanofiber Cathodes for High Performance Asymmetric Supercapacitors.
abstract: Asymmetric supercapacitors (ASCs) with aqueous electrolyte medium have recently become the focus of increasing research. For high performance ASCs, selection of cathode materials play a crucial role, and core-shell nanostructures are found to be a good choice. We successfully synthesized, ZnO@MnO2core-shell nanofibers (NFs) by modification of high-aspect-ratio-electrospun ZnO NFs hydrothermally with MnO2nanoflakes. High conductivity of the ZnO NFs and the exceptionally high pseudocapacitive nature of MnO2nanoflakes coating delivered a specific capacitance of 907 Fg-1at 0.6 Ag-1for the core-shell NFs. A simple and cost-effective ASC construction was demonstrated with ZnO@MnO2NFs as a battery-type cathode material and a commercial-quality activated carbon as a capacitor-type anode material. The fabricated device functioned very well in a voltage window of 0-2.0 V, and a red-LED was illuminated using a single-celled fabricated ASC device. It was found to deliver a maximum energy density of 17 Whkg-1and a power density of 6.5 kWkg-1with capacitance retention of 94% and Coulombic efficiency of 100%. The novel architecture of the ZnO@MnO2core-shell nanofibrous material implies the importance of using simple design of fiber-based electrode material by mere changes of core and shell counterparts.
authors.affiliation: Nano Functional Materials Technology Centre, Material Science and Research Centre, Department of Physics, Indian Institute of Technology Madras , Chennai 600036, India.
authors.forename: A V
authors.initials: AV
authors.lastname: Radhamani
authors.affiliation: Conducting Polymer Lab, Department of Physics, Indian Institute of Technology Madras , Chennai 600 036, India.
authors.forename: K M
authors.initials: KM
authors.lastname: Shareef
authors.affiliation: Nano Functional Materials Technology Centre, Material Science and Research Centre, Department of Physics, Indian Institute of Technology Madras , Chennai 600036, India.
authors.forename: M S Ramachandra
authors.initials: MS
authors.lastname: Rao
keywords: ZnO@MnO2 nanofibers; aqueous electrolyte; asymmetric supercapacitor; electrospinning; energy storage