Search

Currently, substantial attention has been concentrated on the preparation and practical application of complex hierarchical nanostructure composite, which exhibits excellent electrochemical properties compared to the single-structured materials. Hence, a novel electrode of NiMoO4@Co3O4–5H composite nanoarrays supported on reduced graphene oxide/Ni Foam (rGO/NF) was synthesized through the facile hydrothermal method. The composite combines the advantages of the large specific capacitance of NiMoO4 and the great rate capability of Co3O4, exhibiting the distinguished specific capacitance and rate performance. The prepared NiMoO4@Co3O4–5H composite shows an enhanced pseudocapacitive performance of about 1722.3 F g−1 at a current density of 1 A g−1, and eminent rate capability of 80.8% at 10 A g−1. Moreover, the composite delivers good long-term cycling stability with capacitance retention of 91% after 6000 cycles. An asymmetric supercapacitor (ASC) was fabricated using NiMoO4@Co3O4–5H and AC as the positive electrode and negative electrode, achieving the high energy density of 37.1 Wh kg−1 at a power density of 798.0 W kg−1, and exceptional cycling stability (100% retention after 4000 cycles). These consequences suggest that NiMoO4@Co3O4–5H could be considered as a potential electrode material for energy storage devices. [ABSTRACT FROM AUTHOR]

Summary: Textile‐based flexible supercapacitors have various desirable advantages in practical applications due to their excellent flexibility, ease of large‐scale production, and low cost. In this study, a flexible supercapacitor was designed and fabricated using a two‐step polymerization method based on fiberglass cloth and unique morphology of polypyrrole (PPy). In this extraordinary nanostructure, not only do PPy tentacles provide high‐speed channels for the transfer of electron and ion, but they also create a larger specific surface area, thus enhancing the energy storage. The fabricated PPy/CFC supercapacitor possesses an excellent area‐specific capacitance of 549.6 mF cm−2 and a remarkable energy density of 48.85 μWh cm−2. Besides, it achieves the high capacitance retention of 92.4% after 10 000 charge and discharge cycles and 96.08% after 1000 bending cycles. Furthermore, it is demonstrated that the PPy/CFC supercapacitor is capable of ensuring a stable power supply for practical applications by driving an LCD electronic watch. The fiberglass cloth‐based supercapacitors with PPy tentacles provide a new approach to the practical applications of wearable power supplies. [ABSTRACT FROM AUTHOR]

• Hierarchical Ni 3 S 2 @NMV-L/rGO heterostructure was prepared by heteroatom doping and electrodeposition methods. • The influences of V doping content on the electrochemical performances of NMV-L/rGO composites were investigated. • The Ni 3 S 2 @NMV-L/rGO electrode exhibits excellent specific capacity of 1412.0 C g−1 at 1 A g−1. • The assembled battery-supercapacitor hybrid (BSH) device exhibits desirable energy density of 60.0 W h kg−1 at 849.1 W kg−1. [Display omitted] Transition metal dopant engineering and rational architecture design have been proven to be effective strategies to improve the electrochemical energy storage properties of electrodes. Herein, V-doped NiMn-layered double hydroxide composites were supported on reduced graphene oxide-coated Ni foam (NMV-L/rGO) by a hydrothermal method. The influences of V content on the electrochemical performances of NMV-L/rGO composites were investigated in detail. At an optimal content of V doping (15%), the NMV-L/rGO-15 reveals enhanced electrochemical properties, and it is subsequently applied as the substrate for the electrodeposition of Ni 3 S 2 layer. Benefiting from the collaborative effect of NMV-L/rGO-15, Ni 3 S 2 , and rGO materials, as well as the unique hierarchical architecture, excellent electrochemical performance is obtained in the as-prepared Ni 3 S 2 @NMV-L/rGO-15 composite, which exhibits a high specific capacity of 1412.0 C g−1 at 1 A g−1 as well as desirable long-term stability of 89% over 5000 cycles. Furthermore, the as-fabricated battery-supercapacitor hybrid device (BSH) based on Ni 3 S 2 @NMV-L/rGO-15 and activated carbon (AC) electrodes displays a remarkable energy density of 60.0 W h kg−1 at the power density of 849.1 W kg−1 and superior capacity retention of 96% through 7000 cycles. Such excellent results indicate that the Ni 3 S 2 @NMV-L/rGO-15 composite holds great potential as electrode material for high-performance BSHs. [ABSTRACT FROM AUTHOR]

• Ni 3 S 2 /CoAl-LDH/rGO heterostructures were prepared via hydrothermal and electrodeposition methods. • The influences of different mass loading of Ni 3 S 2 on morphology and electrochemical performances are investigated. • The optimized electrode delivers excellent specific capacitance of 2457.5 F g−1. • The assembled asymmetric supercapacitor exhibits an outstanding energy density and a high cycling stability. [Display omitted] Three-dimensional hierarchical hybrid composites incorporating both CoAl-layered double hydroxide and Ni 3 S 2 grown onto the framework of reduced graphene oxide (rGO) on Ni foam were successfully fabricated by hydrothermal procedure combined with electrodeposition method (Ni 3 S 2 /CoAl-LDH/rGO). The Ni 3 S 2 nanoplates was anchored on the surface of the CoAl-LDH/rGO nanosheets, forming a cross linked core-shell structure. Electrochemical measurements demonstrate that the outer Ni 3 S 2 layer can significantly influence the morphology and electrochemical properties of the hybrid electrodes. Benefiting from its attractive structural feature and strong synergy of multiple components, excellent results were obtained in the composite with the optimal mass loading of Ni 3 S 2 layer, which exhibited an excellent specific capacitance of 2457.5 F g−1 at 1 A g−1 and a desirable cycling behavior of 90.0% retention over 5000 cycles. The assembled asymmetric supercapacitor using Ni 3 S 2 /CoAl-LDH/rGO as positive electrode and active carbon as negative electrode delivers a high energy density of 59.8 W h kg−1 at a power density of 402.8 W kg−1 and a good cycling property (91% capacitance retention after 8000 cycles). These encouraging results demonstrate that such hybrid nanostructure provides great potential as electrode material for the energy storage devices. [ABSTRACT FROM AUTHOR]

Mixed transition metal sulfides with high electrochemical activity and theoretical capacitance have been investigated as promising electroactive materials for energy-related applications. Herein, a series of Ni 3 S 2 /MnS (NMS) composites with different sulfurization times were directly grown on reduced graphene oxide (rGO)-coated Ni foam (NF) via a facile and cost-effective hydrothermal method (NMS/rGO). The time-dependent experiments show that the sulfurization time exhibits a pronounced influence on the morphologies and electrochemical properties of NMS/rGO composites. Remarkably, the optimum electrochemical performance was obtained in the composite when the sulfurization time is 3 h (NMS/rGO-3h). The NMS/rGO-3h electrode exhibits a high specific capacitance of 3374.6 F g−1 at a current density of 1 A g−1 along with an outstanding cycling stability of 90.7% at 10 A g−1 through 8000 successive cycles. Furthermore, an asymmetric supercapacitor composed of NMS/rGO-3h electrode as a positive electrode and nitrogen-rich rGO as a negative electrode was assembled, which provided a maximum energy density of 58.9 W h kg−1 at 852.3 W kg−1 and a suitable cycling performance of 99% over 8000 cycles. The superior electrochemical behavior of NMS/rGO composites indicates their potential utilization as electrodes for energy conversion and storage devices. Image 1 • Ni 3 S 2 /MnS/rGO composites were prepared by an ion-exchange method. • Sulfurization time has a pronounced influence on electrochemical performance. • The optimized electrode delivers excellent specific capacitance of 3374.6 F g−1. • The assembled asymmetric supercapacitor exhibits outstanding energy density. [ABSTRACT FROM AUTHOR]

• Ni 3 S 2 /NiV-LDH/rGO/NF composites were prepared by two-step hydrothermal method. • The influence of sulfurization time on electrochemical performance is investigated. • Ni 3 S 2 /NiV-LDH/rGO/NF composite exhibits a high specific capacitance of 3004 F g−1. • ASC delivers a high energy density and an excellent cycling stability. Composite electrodes that possess both appropriate integration and reasonable structures are needed to provide eminent electrochemical performance in energy storage devices. At this work, an innovative electrode material with a composite structure of Ni 3 S 2 /NiV-LDH nanosheets fixed on the reduced graphene oxide/Ni Foam (rGO/NF) was fabricated by a convenient two-step hydrothermal process. The intriguing compositional/componental advantages significantly facilitate the efficient penetration of the electrolytes and increase active sites of redox reactions in energy storage application. The Ni 3 S 2 /NiV-LDH/rGO/NF electrode reaches a standout specific capacitance of 3004.3 F g−1 at a current density of 1 A g−1 and a superb cycle stability with 92.2% capacitance retention after 5000 cycles. Furthermore, an asymmetric supercapacitor (Ni 3 S 2 /NiV-LDH/rGO/NF//AC) was also assembled, achieving a high energy density of 59.4 Wh kg−1 at 852.3 W kg−1 and favourable cycle life, where 98.3% of the capacitance was retained after 8000 cycles. These consequences show that Ni 3 S 2 /NiV-LDH/rGO/NF composite is a potential electrode material in the future. [ABSTRACT FROM AUTHOR]

• Asymmetric supercapacitor based on all-conducting-polymer hydrogel electrodes. • Integrated design of electrode and electrolyte with the same substrate materials. • Strong mechanical flexibility and durability along with high energy density. • Positive and negative electrodes can be used interchangeably. • Available in series without distinguishing between positive and negative. [Display omitted] Flexible supercapacitors are promising flexible energy storage devices. However, manufacturing devices with high energy density, stable energy supply under harsh deformation, and more efficient modular application is still a challenge. Here, an all-gel-state integrated asymmetric flexible supercapacitor based on poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) and polypyrrole (PPy) composite hydrogel electrodes with an interchangeable positive and negative electrode was fabricated. The device has robust flexibility and mechanical durability, with an elongation at break of 286% at a tensile strength of 22.3 MPa and a capacitance retention rate of 98% after 1000 bending cycles, as well as fascinating electrochemical properties, with an energy density of 397.99 μWh cm−3 and a capacitance retention rate of 88.1% for 10,000 charges/discharge cycles. Moreover, the positive and negative electrodes of this asymmetric device can be used interchangeably, and it can power the light-emitting diodes (LEDs) without distinguishing between positive and negative. This design concept will perhaps open a new trend in the design of high-energy-density flexible energy storage devices. [ABSTRACT FROM AUTHOR]

• 3D flower-like NiVSe-6h composite was prepared by simple hydrothermal and the subsequent distinctive selenization method. • The influence of selenization time on electrochemical performance is investigated systematically. • NiVSe-6h composite exhibits a high specific capacity of 1197.6 C g−1. • HSC delivers a high energy density and an excellent cycling stability. Binary metal selenide-based electrodes with absorbing structures are gaining wide attention in energy storage technology, ascribing to the excellent electrical conductivity, outstanding charge storage performance and a low band gap of these electrodes. Herein, a novel three dimensional (3D) flower-like Ni-V-Se composite was established by the hydrothermal method and vertically grew on reduced graphene oxide/Ni foam (rGO/NF) with tunable composition and morphologies. With the increase of selenization time, the morphology of composites is gradually incorporated from the nanosheets into nano-flowers and finally aggregates into large nanoparticles. The prepared optimal sample (NiVSe-6h) shows a palmary specific capacity of 1197.6 C g−1 at a current density of 1 A g−1, and stable long-term cycling performance (89.4% retention after 8000 successive charge-discharge cycles at 10 A g−1). The established NiVSe-6h//AC device uses NiVSe-6h and AC as the positive electrode and negative electrode, which obtains a large specific capacity of 225.1 C g−1 at 1 A g−1 and the high energy density of 53.1 Wh kg−1 at power density of 878.5 W kg−1. Meanwhile, the device exhibits notable cycle stability (94.4%) after 6000 charge discharge cycles. These superior electrochemical behaviors of NiVSe-6h composite indicate their possible utilization as electrodes for storage devices and energy conversion. [Display omitted] [ABSTRACT FROM AUTHOR]

The development of bifunctional electrochemical active heterostructures for both hydrogen evolution reaction (HER) and supercapacitors provides the possibility to integrate energy conversion and storage into one single system. In this article, we have designed and investigated three-dimensional (3D) hybrid CoNiO 2 /CoO composites through simple hydrothermal and annealing processes, in which CoNiO 2 nanowires layered on CoO nanowires arrays with distinctive hierarchically nanowires structure were supported on nickel foam. Specifically, the CoNiO 2 /CoO-140-400 composite (optimum experimental conditions: hydrothermal temperature 140 °C, annealing temperature 400 °C) can efficiently catalyse the HER in an alkaline electrolyte with a small overpotential of 70 mV at 10 mA cm−2 current density, and exhibit a beneficial kinetics and excellent long-term stability of 15 h without obvious fluctuations. Moreover, the material shows an areal capacitance of 5.37 F cm−2 at a current density of 1 mA cm−2, remarkable rate capability (83.9% capacity retention at 20 mA cm−2) and cycle stability (82.9% retention after 5000 cycles) for supercapacitor. This work reveals that the synergistic effects between CoNiO 2 and CoO in CoNiO 2 /CoO-140-400 heterostructures are powerful for electrochemical property and provide a strategy to explore low cost and highly efficient electrocatalysts for the energy conversion and storage applications. Image 1 • Double-layered CoNiO 2 /CoO nanowire arrays are formed by CoNiO 2 nanowires layered on CoO nanowires. • CoNiO 2 /CoO proved to be successful bifunctional electrodes for hydrogen electrocatalysis and supercapacitors. • Enhanced catalytic activity is ascribed to the synergistic effect. [ABSTRACT FROM AUTHOR]