Polydopamine-derived nitrogen-doped carbon-coated NiS nanoparticles as a battery-type electrode for high-performance supercapacitors

A Comparative Study of the Influence of Nitrogen Content and Structural Characteristics of NiS/Nitrogen-Doped Carbon Nanocomposites on Capacitive Performances in Alkaline Medium

“…The resulting curves are distinguishable from the rectangular shape for electric double-layer capacitors, indicating that the energy storage of the NiS electrode is mainly attributed to the reversible Faradic redox reaction of NiS + OH − ↔ NiSOH + e − [ 56 ]. Besides, all CV graphs have stable shapes even as the scan rate increased to 100 mV/sec, showing the outstanding reversible reaction and rapid redox processes [ 57 ]. Especially highlighted is that current densities outputted from the NiS/A-PVP-NC were superior to those of the NiS/PI-NC among the various scan rates, that is, 29.1 A/g vs. 20.4 A/g at 40 mV/sec ( Figure S4a ).…”

“…Especially highlighted is that current densities outputted from the NiS/A-PVP-NC were superior to those of the NiS/PI-NC among the various scan rates, that is, 29.1 A/g vs. 20.4 A/g at 40 mV/sec ( Figure S4a ). However, it is apparent that there is a slight shift at oxidation and reduction peaks towards the positive and negative directions of potential when the scan rate rose, indicating that the charge transfer from the electrolyte to electrode materials and vice versa is the rate-determining step at a high scan rate [ 57 ]. Considering the potential difference (ΔV) between anodic and cathodic peak positions, the ΔV values of NiS/A-PVP-NC shown in Figure S4b were smaller and even better than those of the NiS/PI-NC, especially at 100 mV/sec, that is, 197 mV vs. 227 mV (vs. SCE).…”

“…The specific capacities reported in the present study may not be as high as most of those announced in the literature. However, it is worth mentioning that the capacity retention for the NiS/A-PVP-NC was above that of most cases, for example, CoS/g-C 3 N 4 [ 45 ], NiS/N-doped carbon [ 57 ], CuS/rGO [ 64 ], VS 4 /CNTs/rGO [ 65 ], NiS/N-doped graphene [ 66 ], Ni 3 S 2 /CNFs [ 67 ], and NiS/rGO [ 68 ].…”

Last developments in polymers for wearable energy storage devices

“…In addition, PDA is a biopolymer which gives rise to environmental friendly energy storage devices with a fast and reversible redox activity, developing a remarkable electrochemical performance 149,150 so it is very useful for the obtaining of SC electrodes. As way of illustration, Zhu et al reported some PDA-based polymer electrodes for supercapacitors 129 with NiS particles acting as filler. They obtained the new polymer composite by PDA polymerization on the NiS surface, getting an interconnected network framework and superior N doping, and posterior pyrolysis, improving the specific capacity of the electrodes.…”

“…Both studies 129,130 show great promise for obtaining electrodes for SC based on materials from nature, however, they are rigid materials so they cannot be used in wearable energy storage devices.…”