Metal (manganese) oxide based nano-architectures and supercapacitor materials in energy storage applications

This study describes the growth mechanism, magneto-capacitance enhancement and separator-free design of a-MnO2 on super-aligned electrospun carbon nanofibers (SA-ECNFs) as electrode materials for supercapacitor energy storage. The morphology of the SA-ECNFs/MnO2hybrid electrodes were investigated by scanning electron microscope (SEM). The composite and crystal information was characterized by X-ray photoelectron spectroscopy (XPS), Energy-dispersive X-ray spectroscopy (EDX) and X-Ray Diffraction Spectroscopy (XRD). The energy storage performance was tested by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charging/discharging techniques. A time-dependent MnO2 film growth analysis suggests a three-step kinetics mechanism for the electrodeposition of MnO2 on SA-ECNFs and a self-cessation ending. The SA-ECNFs/MnO2 hybrid electrodes provide with high specific capacitance energy storage. The MnO2-modified ECNFs electrode presents mT magneto-energy storage enhancement ability due to the polarization of unpaired electrons’ contribution in increased pseudocapacitance. Manipulation of the thickness of MnO2 film suggests an ultra-thick MnO2 coating capable for separator-free configuration for a supercapacitor. A bi-functional model of the MnO2 film is proposed to explain its potential to assemble a device without the use of separator, which, for the first time, demonstrates the supercapacitance energy storage.