Effect of Composition Ratios on the Performance of Graphene/Carbon Nanotube/Manganese Oxide Composites toward Supercapacitor Applications

Herein, we describe the preparation and characterization of graphene/carbon nanotube (CNT)/MnOv composites and the effects of chemical composition and phase transformation on the properties of the corresponding electrode film. In general, the effect of graphene-to-CNT ratio (G/C ratio) and the manganese (Mn) content on the morphology, chemical state, crystallization properties, and microstructure of the composite material was examined by scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and selected area electron diffraction. The bonding mechanism between MnOv and graphite-based materials, that is, graphene and CNTs, is discussed. The influence of the composition of the composites on the performance of the electrode was investigated using charge–discharge curves. The faradically active MnOv also functioned as a considerable cobinder and allowed for a reduced amount of polymeric binder, which enhanced the conductivity and capacitance of the electrode. The optimized electrode composition was obtained based on our present graphene and CNT specifications. In summary, the results discussed in this article provide significant background information for future applications of graphene/CNT/MnOv composite electrodes.