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

Abstract

Abstract The aim of this study is to explore innovative materials for the development of next-generation supercapacitor electrodes. The hypothesis is that, upon the surface-decoration with appropriate amount of MnO 2 nanowhiskers, freestanding and highly graphitic electrospun carbon nanofiber (ECNF) mats (with fiber diameters of ∼200 nm and BET specific surface areas of ∼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 MnO 2 nanowhiskers to prepare three types of ECNF/MnO 2 mats. The morphological and structural properties of ECNF and ECNF/MnO 2 mats are characterized by SEM, TEM and XRD, the weight percentages of MnO 2 nanowhiskers in three ECNF/MnO 2 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/MnO 2 mats/electrodes have significantly enhanced electrochemical performances compared to the ECNF mat/electrode; while the ECNF/MnO 2 (1:1) mat/electrode exhibits the highest gravimetric capacitance of 83.3 F g −1 , energy density of 84.3 W h kg −1 , and power density of 5.72 kW kg −1 .