Electrospun lignin-derived carbon nanofiber mats surface-decorated with MnO2 nanowhiskers as binder-free supercapacitor electrodes with high performance

The aim of this study is to explore innovative materials for the development of next-generation super capacitor electrodes. The hypothesis is that, upon the surface-decoration with appropriate amount of MnO2 nanowhiskers, freestanding and highly graphitic electrospun carbon nanofiber (ECNF) mats (with fiber diameters of similar to 200 nm and BET specific surface areas of similar to 583 m(2) g(-1)) derived from a natural product of lignin would be binder-free supercapacitor electrodes with high performance. To test the hypothesis, the ECNF mats have been prepared first; thereafter, the acquired ECNF mats have been surface-decorated with varied amounts of MnO2 nanowhiskers to prepare three types of ECNF/MnO2 mats. The morphological and structural properties of ECNF and ECNF/MnO2 mats are characterized by SEM, TEM and XRD, the weight percentages of MnO2 nanowhiskers in three ECNF/MnO2 mats are determined by thermal gravimetric analysis; while the electrochemical performance of each mat/electrode is evaluated by cyclic voltammetry, galvanostatic charge/discharge method, and electrochemical impedance spectroscopy. This study reveals that, all of the three ECNF/MnO2 mats/electrodes have significantly enhanced electrochemical performances compared to the ECNF mat/electrode; while the ECNF/MnO2 (1:1) mat/electrode exhibits the highest gravimetric capacitance of 83.3 F g(-1), energy density of 843 W h kg(-1), and power density of 5.72 kW kg(-1). (C) 2016 Elsevier B.V. All rights reserved.