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[Display omitted] Nickel-iron bimetallic phosphide (Ni-Fe-P) is the ideal battery-type materials for supercapacitor in virtue of high theoretical specific capacitance. Nevertheless, its actual adhibition is astricted on account of inferior rate capability and cyclic stability. Herein, we constructed hierarchical core–shell nanocomposites with hollow mesoporous carbon nanospheres (HMCS) packaged via prussian blue analogs derived Ni-Fe-P nanocubes (Ni-Fe-P@HMCS), as a positive electrode for hybrid supercapacitor (HSC). Profiting from the cooperative effects of Ni-Fe-P nanocubes with small size and good dispersibility, and HMCS with continuously conductive network, the Ni-Fe-P@HMCS composite electrode with abundantly porous architectures presents an ultrahigh gravimetric specific capacity for 739.8 C g−1 under 1 A g−1. Specially, the Ni-Fe-P@HMCS electrode presents outstanding rate capability of 78.4% (1 A g−1 to 20 A g−1) and cyclic constancy for 105% after 5000 cycles. Density functional theory implies that the composite electrode possesses higher electrical conductivity than bare Ni-Fe-P electrode by reason of the incremental charge density, and the electrons transferring from NiFe 3 P 4 to HMCS layers. Additionally, the assembled Ni-Fe-P@HMCS//HMCS HSC facility delivers the high energy density for 64.1 Wh kg−1, remarkable flexibility and mechanical stability. Thus, this work proffers a viable and efficacious measure to construct ultra-stability electrode for high-performance portable electronic facilities. [ABSTRACT FROM AUTHOR]

Abstract We report a wire-shaped three-dimensional (3D)-hybrid supercapacitor with high volumetric capacitance and high energy density due to an interconnected 3D-configuration of the electrode allowing for large number of electrochemical active sites, easy access of electrolyte ions, and facile charge transport for flexible wearable applications. The interconnected and compact electrode delivers a high volumetric capacitance (gravimetric capacitance) of 73 F cm−3 (2446 F g−1), excellent rate capability, and cycle stability. The 3D-nickel cobalt-layered double hydroxide onto 3D-nickel wire (NiCo LDH/3D-Ni)//the 3D-manganese oxide onto 3D-nickel wire (Mn3O4/3D-Ni) hybrid supercapacitor exhibits energy density of 153.3 Wh kg−1 and power density of 8810 W kg−1. The red light-emitting diode powered by the as-prepared hybrid supercapacitor can operate for 80 min after being charged for tens of seconds and exhibit excellent electrochemical stability under various deformation conditions. The results verify that such wire-shaped 3D-hybrid supercapacitors are promising alternatives for batteries with long charge–discharge times, for smart wearable and implantable devices.

Highlights: The flexible 3D porous structure with a large surface area provides pathways for rapid ion/electron transport and ion diffusion as well as numerous electroactive sites. The wire-shaped supercapacitor exhibits a high energy density of 153.3 Wh kg−1 and a power density of 8810 W kg−1. The hybrid device demonstrates excellent durability under various mechanical deformations. We report a wire-shaped three-dimensional (3D)-hybrid supercapacitor with high volumetric capacitance and high energy density due to an interconnected 3D-configuration of the electrode allowing for large number of electrochemical active sites, easy access of electrolyte ions, and facile charge transport for flexible wearable applications. The interconnected and compact electrode delivers a high volumetric capacitance (gravimetric capacitance) of 73 F cm−3 (2446 F g−1), excellent rate capability, and cycle stability. The 3D-nickel cobalt-layered double hydroxide onto 3D-nickel wire (NiCo LDH/3D-Ni)//the 3D-manganese oxide onto 3D-nickel wire (Mn3O4/3D-Ni) hybrid supercapacitor exhibits energy density of 153.3 Wh kg−1 and power density of 8810 W kg−1. The red light-emitting diode powered by the as-prepared hybrid supercapacitor can operate for 80 min after being charged for tens of seconds and exhibit excellent electrochemical stability under various deformation conditions. The results verify that such wire-shaped 3D-hybrid supercapacitors are promising alternatives for batteries with long charge–discharge times, for smart wearable and implantable devices. [ABSTRACT FROM AUTHOR]

Hybrid supercapacitors have drawn much attention since they possess both high energy density and power density. Carbon felt (CF) is chosen as the substrate in this work due to its 3D porous structure, good conductivity, and excellent flexibility. FeCo 2 S 4 nanoneedles are uniformly deposited on CF via hydrothermal, annealing and sulfidation processes, forming the binder-free FeCo 2 S 4 @CF electrode. The morphology of FeCo 2 S 4 deposited on the CF can be designed and regulated by controlling the hydrothermal reaction time. The electrode with unique features is beneficial to the exposure of electroactive sites and the rapid transport of electrons/ions, showing a high specific capacitance of 847.8 mF cm−2 and outstanding rate performance. The hybrid supercapacitor assembled by FeCo 2 S 4 @CF electrode and activated carbon felt exhibits the maximum specific capacitance of 309.7 mF cm−2, energy density of 110.1 μWh cm−2 and power density of 562.4 μW cm−2. Besides, the capacitance retention of the device reaches 98.5% after 10,000 charge-discharge cycles and 87.2% after 3000 bending cycles respectively, revealing its great cycling stability and flexibility. Therefore, this work provides an effective and feasible strategy for the morphology regulation of binary transition metal sulfides with superior electrochemical performance for supercapacitors. [Display omitted] • Green foxtail-like FeCo 2 S 4 nanoneedles are designed to deposit on carbon felt. • The 3D porous electrodes with FeCo 2 S 4 exhibit excellent electrochemical performance. • The device shows an energy density of 110.1 μWh cm− 2 and good stability/flexibility. [ABSTRACT FROM AUTHOR]

Due to the large requirement of portable consumer electronics in the present era, much efforts were devoted for the development of light weight, flexible and even wearable technologies. Here, CoFe 2 O 4 /reduced graphene oxide (rGO)/polyaniline (PANI) (CCGP) composite is synthesised and efficiently utilized as negative electrode. Similarly, the prepared rod shape β-Co(OH) 2 is served as positive electrode. Fourier transform infrared and Raman spectroscopy results revealed the existence of covalent bond between rGO and PANI. This covalent bond enhances the fast charge carrier transfer that leads to improve the performance of CCGP. As well as the pores containg rod shape β-Co(OH) 2 supports to access large amount electrolyte ions. Potential dependant charge storage mechanism is revealed from Power’s law for the charge storage of CCGP. Trasatti plot corroborates that CCGP provides more inner surface charge storage contribution than CoFe 2 O 4 (CC) and CoFe 2 O 4 /rGO (CCG) electrodes. The fabricated hybrid fiber supercapacitor delivers a high length capacitance (1.41 F m −1 ), energy density (270 × 10 −8 Wh cm −1 ) and excellent cycling stability. Connecting two devices in series successfully powered the light emitting diode to glow, which reveals the good reliability of the device for energy storage applications. [ABSTRACT FROM AUTHOR]

The rational design of hierarchical nanostructure consisting of multiple components with remarkable electrochemical performance is regarded as a significant technique for fabricating high-performance energy storage devices. Herein, self-supported tree-like (Ni,Co)Se 2 /Ni(OH) 2 heterogeneous nanoarrays on carbon cloth (CC) used as electrode materials of supercapacitors (SCs) are designed and synthesized by a multi-step approach. The (Ni,Co)Se 2 core can boost electron transport due to excellent conductivity, and the shell layer of Ni(OH) 2 nanoflakes improves the surface area. Profiting from the cooperative effects of two active materials and core-shell architecture, the tree-like (Ni,Co)Se 2 /Ni(OH) 2 composite delivers a superior capacity, outstanding rate capability and still retain 151.3 mAh g−1 after 3000 charge/discharge cycles. Meanwhile, the flexible hybrid supercapacitor (HSC) fabricated by the (Ni,Co)Se 2 /Ni(OH) 2 and activated carbon (AC) also manifests a satisfied energy density of 0.79 mWh cm−2 under 1.35 mW cm−2. Therefore, it can be considered that the as-prepared hierarchical (Ni,Co)Se 2 /Ni(OH) 2 nanoarrays are promising candidate for HSC devices in energy storage and conversion. • The tree-like (Ni,Co)Se 2 /Ni(OH) 2 core-shell nanoarrays were successfully designed. • The (Ni,Co)Se 2 /Ni(OH) 2 electrode exhibits superior electrochemical performance. • Due to construct heterogeneous core-shell structure, the hierarchical nanoarrays possess rich active sites. • The assembled HSC device achieves outstanding energy density. [ABSTRACT FROM AUTHOR]

The rational design of hybrid structures which consist of multiple components with distinctive characteristics is an effective strategy for developing materials when energy storage applications. In this paper, a novel hierarchical CoS 2 @Ni(OH) 2 core-shell nanotube array covered carbon cloth is successfully designed and synthesized for use in supercapacitors (SCs). The CoS 2 nanotube (NT) arrays are synthesized using the metal organic framework template method, and serve as the scaffold for the growth of ultrathin Ni(OH) 2 nanosheets via the electrodeposition process. The optimized CoS 2 @Ni(OH) 2 hybrid electrode exhibits high specific capacity of 743 C g−1 at current density of 1 A g−1, which is nearly 5.9 times higher than that of a single CoS 2 electrode. In addition, a solid state hybrid supercapacitor device is fabricated with CoS 2 @Ni(OH) 2 hybrid electrode as positive and activated carbon as negative. The as-prepared devices deliver high energy density (29.22 W h kg−1 at 899.2 W kg−1) and high power density (8.99 kW kg−1 at 11.74 W h kg−1), as well as good cycling stability (85.5% retention of specific capacitance after 3000 cycles). The devices also display excellent flexible properties under different bending conditions. The present work shows that electrode materials with hybrid structure have considerable application prospect for flexible energy storage and conversion. [ABSTRACT FROM AUTHOR]

The rapid development of portable and wearable electronic devices requires novel energy storage devices. Flexible, high-performance electrode materials are critical for meeting the demands yet remain challenging. Here, a rationally designed flexible NiCo 2 S 4 @rGO/rGO film constructed with NiCo 2 S 4 @rGO frameworks is successfully prepared through a step-wise process (hydrothermal, freeze-drying, vacuum filtration, and then sulfurization/reduction). The NiCo 2 S 4 @rGO/rGO film as flexible electrode shows typical battery-type faradaic redox features and exhibits a high specific capacitance of 1100.0 F g−1 at 1 A g−1, a good rate performance of 89.1% capacity retention at 10 A g−1 coupled with long cycling stability of 90.2% after 5000 cycles. The good electrochemical performance is mainly attributed to the loose layered structure and strong interaction between NiCo 2 S 4 and rGO nanosheets, which enhance the diffusion of electrolyte ions/electrons and decreases intrinsic resistance and contact resistance. A flexible hybrid supercapacitor assembled using the NiCo 2 S 4 @rGO/rGO film as cathode and the rGO film as anode shows a high energy density of 30.0 Wh kg−1 at a power density of 857.6 W kg−1 at an extended operating voltage of 1.8 V. The method can also be readily adapted for loading other bimetallic sulfides on rGO films, indicative of its feasibility and flexibility to prepare rGO-based hybrid film for high-performance flexible electrochemical energy storage. • A flexible NiCo 2 S 4 @rGO/rGO film with a unique loosely-layered structure was constructed with NiCo 2 S 4 @rGO frameworks. • The NiCo 2 S 4 @rGO/rGO film exhibits excellent electrochemical performances. • A flexible hybrid supercapacitor delivers high energy and power density. • This work provides an ideal and feasible route of constructing flexible rGO-based hybrid film electrodes. [ABSTRACT FROM AUTHOR]