High-performance supercapacitor based on MnO/carbon nanofiber composite in extended potential windows

Abstract MnO/carbon nanofiber (CNF) composite is demonstrated as a high-performance electrode material for supercapacitors. LiMn2O4 (LMO) nanoparticle-decorated polyacrylonitrile (PAN) nanofibers are fabricated via electrospinning. Afterwards, LMO is converted to MnO and PAN is fully carbonized under synergistic annealing, resulting in MnO/CNF composite. The composite exhibits electrochemically active in an extended potential window of -1.0 – 0.8 V vs. Ag/AgCl. Moreover, a two-step electrochemical stimulation is observed for MnO at 0.0 V and 0.4 V corresponding to the phase transformations from MnO to Mn3O4 and from Mn3O4 to MnO2, respectively. As a result, the composite presents a high capacitance of 409.7 F g−1 at 1 A g−1 in -0.4 – 0.8 V vs. Ag/AgCl due to the phase transformations of MnO. Also, the composite owns 301.8 F g−1 at 1 A g−1 in -1.0 – 0.2 V vs. Ag/AgCl, which is 2.65 times the value of CNFs owing to the enhanced conductivity and surface redox by incorporating MnO. Finally, a supercapacitor with a working voltage of 1.8 V is realized using MnO/CNF composite as both negative and positive electrodes.