Shape-controlled synthesis of NiCo₂S₄and their charge storage characteristics in supercapacitors

Abstract

In this work, a facile hydrothermal approach for the shape-controlled synthesis of NiCo2S4 architectures is reported. Four different morphologies, urchin-, tube-, flower-, and cubic-like NiCo2S4 microstructures, have been successfully synthesized by employing various solvents. The obtained precursors and products have been characterized by X-ray diffraction, field-emission scanning electron microscopy and transmission electron microscopy. It is revealed that the supersaturation of nucleation and crystal growth is determined by the solvent polarity and solubility, which can precisely control the morphology of NiCo2S4 microstructures. The detailed electrochemical performances of the various NiCo2S4 microstructures are investigated by cyclic voltammetry and galvanostatic charge-discharge measurements. The results indicate that the tube-like NiCo2S4 exhibits promising capacitive properties with high capacitance and excellent retention. Its specific capacitance can reach 1048 F g(-1) at the current density of 3.0 A g(-1) and 75.9% of its initial capacitance is maintained at the current density of 10.0 A g(-1) after 5000 charge-discharge cycles.

Is NiCo2S4 Really a Semiconductor?

“…These hollow nanotubes likely result from the well-kown Kirkendall effect of the sacrificial precursor template during the anion ion exchange process. 18 Energy dispersive spectra (EDS) were collected to provide further insight into the elemental composition and distribution of the asprepared NiCo 2 S 4 . An even distribution of the elements Ni, Co, and S (Figure 2c) on the surface is clearly visible, further demonstrating the successful preparation of high quality thiospinel NiCo 2 S 4 .…”

Self-templating Scheme for the Synthesis of Nanostructured Transition-Metal Chalcogenide Electrodes for Capacitive Energy Storage

“…Our performance is superior to that of all reported ternary nickel cobalt sulfides based materials (literature reports were summarized in Supplementary Table S1). 24,34,38,40,[46][47][48][49][50] This phenomenon may be attributed to the unique double shell structure which offers many desirable features. First of all, the highly porous double shells surfaces are covered with self-assembled nanosheets which are full of mesopores (with size distribution centered around 3-5 nm, Supplemental Figure S7B).…”

In situ grown cockscomb flower-like nanostructure of NiCo2S4 as high performance supercapacitors

“…Moreover, ternary metal sulfides such as NiCo 2 S 4 and CoNi 2 S 4 have emerged as promising class of active materials for SCs. Ternary metals possess multiple oxidation states to achieve richer redox activities compared to metal sulfides [14][15][16][17][18]. However, the use of NiCo 2 S 4 for electrodes still faces challenges such as attaining high capacity, long cycle stability, and high-rated performance.…”