Dual Hybrid Effect Endowing Nickel–Cobalt Sulfides with Enhanced Cycling Stability for Asymmetrical Supercapacitors

Abstract

The construction and optimization of electrode materials with a stable structure have received great attention to realize high-performance supercapacitors. Herein, we present the fabrication of nickel–cobalt sulfide (NiCo)9S8 nanoparticles protected by NiCo-based oxyhydroxides coupled with nitrogen and sulfur codoped graphene substrates (N, S-doped G) via an ethylenediamine (EDA)-mediated assembly and electrochemical oxidation strategy, named O-(NiCo)9S8/N, S-doped G. It was found that the (NiCo)9S8 nanoparticles coated by the metal oxyhydroxide shell are tightly encapsulated into N, S-doped G frameworks, yielding a unique dual hybrid effect to achieve ample heterojunctions/interfaces and robust architecture, which is conducive to enhance electroactivity and cycling stability. As a proof-of-concept application, the as-fabricated O-(NiCo)9S8/N, S-doped G as the electrode for the supercapacitor achieves a high specific capacity of 1247 F g–1, that is, 166 mA h g–1 at 0.5 A g–1 and a superior rate capability of 89% at 20 A g–1. Further, the asymmetric supercapacitor made of the O-(NiCo)9S8/N, S-doped G//activated carbon along with a high mass loading of about 6 mg cm–2 exhibits an ultralong cycling stability of 70% after 20,000 cycles and a high charge storage capability of 50.8 W h kg–1 at 400 W kg–1, which is much better than those of the other comparative electrode materials.

CuCo2S4–MoS2 nanocomposite: a novel electrode for high-performance supercapacitors

“…[1][2][3][4] Recently, the supercapacitor has emerged as a fascinating electrochemical energy storage device for automobile and electronic applications owing to its high-power density, fast chargedischarge rate, large capacity, long lifespan, wide range of operating temperatures, high-safety performance and low cost. [5][6][7][8][9][10] However, the widespread application of supercapacitors has not been possible yet because of their low-energy density 4,[11][12][13] since a high energy density is essential for longduration applications such as in batteries. Several recent investigations 12,[14][15][16] reported that designing and tailoring the type, morphology and architecture of the electrode material can be beneficial for improving the energy storage capacity of supercapacitors.…”

One‐Dimensional Co‐Carbonate Hydroxide@Ni‐MOFs Composite with Super Uniform Core–Shell Heterostructure for Ultrahigh Rate Performance Supercapacitor Electrode

“…[ 28 ] For instance, Yang et al. [ 29 ] taken synergistic effect advantage of (NiCo) 9 S 8 nanoparticles and metal oxyhydroxide to fabricate heterostructure supercapacitor electrode, showing a high capacity and superior rate capability. Wan et al.…”

“…[27] Spontaneously, extra active sites are also created due to the crystal distortion at the interface, which can boost the electrochemical performance. [28] For instance, Yang et al [29] taken synergistic effect advantage of (NiCo) 9 S 8 nanoparticles and metal oxyhydroxide to fabricate heterostructure supercapacitor electrode, showing a high capacity and superior rate capability. Wan et al [30] applied a Co@Co(OH) 2 heterostructure for supercapacitor, of which the created interface active sites can significantly enhance the electrochemical performance.…”

Facile hydrothermal synthesis of cobaltosic sulfide nanorods for high performance supercapacitors

“…The intrinsically high redox activity of cobalt sulde, relative to its metal oxide analogs, and the higher electrical conductivity due to the lower optical band gap energy, are of particular interest. [26][27][28] Hence, a series of cobalt sulde nanomaterials with various morphologies have been designed as electrode materials for supercapacitors, and good electrochemical properties have been obtained. For instance, Peng et al synthesized CoS 2 hollow spheres with high surface area by hydrothermal method.…”