Rational
designing advanced materials with multicomponents and
multiscale nanostructures is an important pathway to promote the rapid
development and practical application of high-performance supercapacitors.
Herein, FeCo2S4@Ni@graphene nanocomposites are
prepared through electroless depositionhydrothermal two-step
method. In this hybrid structure, the metal nickel as a conductive
bridge significantly enhances the charge transport and the structural
stability between FeCo2S4 and graphene by encouraging
the heterogeneous nucleation of FeCo2S4 on the
active Ni@graphene. More importantly, the rich defects are induced
into FeCo2S4@Ni@graphene by the interface engineering
due to the lattice mismatch at the interface between Ni and FeCo2S4 and partial substitution of Ni for Co or Fe.
These defects can provide additional faradic redox reactions and abundant
active sites. Benefiting from the synergies of above advantages, the
optimized FeCo2S4@Ni@graphene shows a specific
capacity of 390.0 mAh g–1 at 1 A g–1. Additionally, the asymmetric supercapacitor based on FeCo2S4@Ni@graphene delivers a high energy density of 65.8
Wh kg–1 at 849 W kg–1, as well
as capacitance retention of 89.2% after 6000 cycles at 20 A g–1. This work proposes an effective strategy, which
is to regulate the defects in transition-metal compounds through heterointerface
engineering to prepare advanced energy-storage materials.
In this work, the hierarchical porous Ni1.5Co1.5S4/g-C3N4 composite was prepared by growing Ni1.5Co1.5S4 nanoparticles on graphitic carbon nitride (g-C3N4) nanosheets via a hydrothermal route. Due to the self-assembly of larger size g-C3N4 nanosheets as a skeleton, the prepared nanocomposite possesses a unique hierarchical porous structure that can provide short ions diffusion and fast electron transport. As a result, the Ni1.5Co1.5S4/g-C3N4 composite exhibits a high specific capacitance of 1827 F g−1 at a current density of 1 A g−1, which is 1.53 times that of pure Ni1.5Co1.5S4 (1191 F g−1). In particular, the Ni1.5Co1.5S4/g-C3N4//activated carbon (AC) asymmetric supercapacitor delivers a high energy density of 49.0 Wh kg−1 at a power density of 799.0 W kg−1. Moreover, the assembled device shows outstanding cycle stability with 95.5% capacitance retention after 8000 cycles at a high current density of 10 A g−1. The attractive performance indicates that the easily synthesized and low-cost Ni1.5Co1.5S4/g-C3N4 composite would be a promising electrode material for supercapacitor application.
In this study, monodispersed NiSe@Ni particles were successfully anchored on graphene sheets by electroless nickel plating combined with a chemical-vapor-reaction process, in which the nickel particles were first deposited onto graphene sheets and subsequently transformed in situ into NiSe@Ni at an elevated temperature. The obtained product showed a unique multi-dimensional coupling structure, namely, monodispersed NiSe@Ni particles (0 D) anchored on graphene sheets (2 D), which enabled maximum synergy on the specific surface area, conductivity, and the electrochemical activity of NiSe, Ni, and graphene multi-phases. The NiSe@Ni/graphene composite showed a specific capacity of 302 mAh g−1 at a current density of 1 A g−1 in a potassium-hydroxide-electrolyte solution. Meanwhile, the hybrid supercapacitor of NiSe@Ni/graphene//AC exhibited a high energy density of 68.0 Wh kg−1 at 803.0 W kg−1 and maintained 72.53% of the initial capacity after 10,000 cycles at a current density of 10 A g−1.
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