Promotive Effect of MWCNTs on α-NiS Microstructure and Their Application in Aqueous Asymmetric Supercapacitor

Abstract

To synthesize the efficient morphological electrode nanomaterial with a rough surface is a key parameter in high-energy storage devices. The α-NiS microstructure with rough surface nature is synthesized by the most adoptable hydrothermal method and characterized by different characterization techniques. The end product is subjected as electrode material of a supercapacitor, showing good electrochemical performance. To improve the electrochemical performance of the electrode material, α-NiS@MWCNTs is also synthesized. The specific capacitance (C s) of 2057 F g–1 at 1 A g–1 is obtained from α-NiS@MWCNT material, which is found to be higher than solely α-NiS material. Asymmetric supercapacitors (ASCs) show an energy density of 27 W h kg–1 at 362 W kg–1 with a current density of 0.5 A g–1. A kitchen timer, a toy motor fan, and 13 LEDs are also powered from two asymmetric supercapacitors connected in series.

Tailoring the phase composition of carbon-coated nickel sulfides to achieve a high specific capacitance

“…The overall mechanism of an electrode results from the fast capacitive behavior associated with the surface-controlled and ion diffusion. Based on the electrochemical theory, the relationship between the current response and scan rate is shown according to the power law (eqn (1)): 56,57 i = av b where a and b are adjustable parameters. The b value can be calculated from the slope of the plot of log( i ) versus log( v ).…”

Electrode Materials, Structural Design, and Storage Mechanisms in Hybrid Supercapacitors

“…Such materials display a very fast charge/discharge rate to offer high power density. Unfortunately, many battery-type electrodes, such as Ni(OH) 2 [ 22 , 23 ] or other materials, that exhibit faradaic behavior (even those that are electrochemically irreversible) have been considered as pseudocapacitive materials in many reports, which confuses the readers [ 24 , 25 , 26 ]. As suggested by Gogosti et al [ 10 ], it is inappropriate to describe nickel-based oxides, sulfides, and hydroxides as pseudocapacitive electrode materials in alkaline aqueous electrolytes because they undergo faradaic reactions, where their electrochemical signature is analogous to that of a “battery” material.…”