Abstract
A binder-free process for the electrode preparation for supercapacitor application was suggested by drop casting graphene nanoplatelets on a carbon fiber (GnP@CF) followed by electrodeposition of Ni nanoparticles (NPs). The microstructure of the electrode showed that Ni was homogeneously distributed over the surface of the GnP@CF. XRD analysis confirmed the cubic structure of metallic Ni NPs. The Ni-GnP@CF electrode showed excellent pseudocapacitive behavior in alkaline solution by exhibiting a specific capacitance of 480 F/g at 1.0 A/g, while it was 375 F/g for Ni@CF. The low value of series resistance of Ni-GnP@CF (1 Ω) was attributed to the high capacitance. The enhanced capacitance of the electrode could be correlated to the highly nanoporous structure of the composite material, synergetic effect of the electrical double layer charge-storage properties of graphene, and the pseudocapacitive nature of Ni NPs.
Highlights
The supercapacitor (SC) is well-known and promising for energy storage devices because of its high power density, extensive life cycles, and easy fabrication and maintenance [1,2,3,4]
We demonstrated a binder-free process to fabricate Ni-graphene nanoplatelets on a carbon fiber (GnP@CF) electrode by a simple drop coating of Graphene nanoplatelets (GnP) on the CF followed by electrochemical deposition of Ni
The confinement of graphene increased conductivity and allowed dispersion of Ni NPs on its surface. These results demonstrate that Ni-GnP composites can act as a decent electroactive material for SC application, and our results are comparable with previously reported literature (Table 1)
Summary
The supercapacitor (SC) is well-known and promising for energy storage devices because of its high power density, extensive life cycles, and easy fabrication and maintenance [1,2,3,4]. SCs are mainly classified according to the charge storage mechanism; electrochemical double layer capacitors (EDLCs) stores the energy by non-Faradic process by the accumulation of the charges at the electrode–electrolyte interface, while it is done by Faradic process for the pseudo capacitor (a reduction-oxidation based capacitor) as in batteries [5,6] Carbonaceous materials, such as activated carbon, single and multiwalled carbon nanotubes, and graphene, are used as electrode materials in double-layer capacitors [7,8,9,10,11]. Pseudocapacitive materials, such as transition metals and metal oxides, and functionalized or doped graphene, have been studied for use in SCs owing to their larger specific capacitance and higher energy density compared to pristine carbon-based materials [14]. It could be attributed to the highly nanoporous structure, fast reversible redox reaction at Ni surface, strong interconnection between composite material, and synergetic effect of GnP and Ni NPs in the composite
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