Hierarchical porous MnO 2 /carbon nanofiber composites with hollow cores for high-performance supercapacitor electrodes: Effect of poly(methyl methacrylate) concentration

Hierarchical porous MnO2/carbon nanofiber composites with hollow cores (MnPMCNFs) are fabricated by a simple electrospinning method using poly(methyl methacrylate) (PMMA) for electrochemical capacitor electrodes. The introduction of PMMA into the PAN solution aids the uniform dispersion of the amorphous MnO2 particles as a stabilizer and increases the specific surface area with numerous hollow cores, thereby aiding the electrolyte diffusion from the exterior into the interior of the electrode material. Electrochemical measurements of the MnPMCNFs reveal a maximum specific capacitance of 228 Fg−1 with a capacitance retention of 88% and high energy densities of 27–18 Whkg−1 in the power density range of 400 to 10,000 Wkg−1 in aqueous KOH electrolyte. This impressive electrochemical performance of the MnPMCNF electrode highlights the importance of incorporating the MnO2 nanostructure and hierarchical structure into the composite, owing to the synergistic contribution of the redox pseudocapacitance and the electric double layer capacitance.