Rational Design of NiCo₂S₄ Nanosheet Arrays Modified by Nitrogen-Doped Graphene Quantum Dots with Enhanced Charge Storage Performance for Flexible Supercapacitors

Abstract

In this work, nitrogen-doped graphene quantum dots (N-GQDs) are introduced into the honeycomb structure of NiCo2S4 nanoarrays on a carbon cloth by electrodeposition, which significantly enhances the electrochemical performances of NiCo2S4 as an electrode of hybrid supercapacitors. The honeycomb framework structure of NiCo2S4 nanosheets not only increases more active sites but also improves the structural stability of the electrode material. At the same time, the introduction of N-GQDs improves the wettability of NiCo2S4 and effectively reduces its internal resistance. As an electrode material, the NiCo2S4/N-GQDs@CC composite shows outstanding capacitive properties with an areal capacity of 1803 mC cm–2 at 3 mA cm–2. In addition, the assembled symmetric supercapacitor device can provide a high energy density of 127 μWh cm–2 at a power density of 1000 μW cm–2, good rate performance, and cycle stability. After 2500 cycles, the capacity retention rate can still reach 83%. The outstanding charge storage capability may be due to the synergistic effect between its unique honeycomb structure, high porosity, and improved electrical properties of N-GQDs. This simple and controllable synthesis strategy provides a reference for energy storage applications.

Flexible High-Energy-Density 4.3 V Supercapacitor Based on a Trimetallic Sulfide Cathode and a Bimetallic Sulfide-Polypyrrole Anode with an Ionic Liquid Gel Polymer Electrolyte

“…Ni 2 FeS 4 -PPy, the final anode material, was manufactured. 24 Both synthesis schematics are represented in Figures S2 and S3 in the Supporting Information (SI). Supporting Information related to this article includes the employed material, characterization, electrochemical investigation, manufacturing of electrodes, extensive discussion of crystallography, Nyquist plot, Hirshfeld surface map, details of Mott−Schottky measurements, and needed formulas.…”

“…Ni 2 FeS 4 -PPy, the final anode material, was manufactured. 24 Both synthesis schematics are represented in Figures S2 and S3 in the Supporting Information (SI).…”

“…Before electrochemical characterization, the produced electrodes were allowed to dry without rinsing in deionized water. Ni 2 FeS 4 -PPy, the final anode material, was manufactured . Both synthesis schematics are represented in Figures S2 and S3 in the Supporting Information (SI).…”

Review of NiCo2S4-Based Electrode Nanomaterials for Supercapacitors

“…In addition, in situ, growth or heterogeneous binding of NiCo 2 S 4 using carbon nanomaterials or their derivatives as collector constructs has been widely reported by researchers, and the direct construction of NiCo 2 S 4 nanoarrays on the nanoscale from carbon nanomaterials remains poorly investigated due to the easily stackable nature of carbon nanomaterials and the challenge of designing composites on the nanoscale. For example, Jia et al 96 recently electrodeposited nitrogen-doped graphene quantum dots (NGQDs) directly constructed on NCS nanoarrays (NiCo 2 S 4 /NGQDs) by electrodeposition techniques and reported the electrochemical properties of 1803 mC cm −2 at 3 mA cm −2 . Moreover, the use of composite NiCo 2 S 4 with carbon material as the collector prevents direct exposure of NiCo 2 S 4 to the electrolyte, and this will still cause the dissolution of NiCo 2 S 4 during long-term cycling.…”