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Trimetallic sulfide microspheres with flower morphology prepared based on novel bimetallic MOF via sequential ion exchange processes exhibit promising energy storage properties. Rational design of electrical active materials with high performance for energy storage and conversion is of great significance. Herein, Cu(NiCo) 2 S 4 /Ni 3 S 4 , a three-dimensional (3D) hierarchical hollow heterostructured electrode material, is designed by etching the well-defined bimetal organic framework (MOF) via sequential in-situ ion-exchange processes. This trimetallic sulfides with unique structure provide large surface area, hierarchical pore distribution and enhanced electrical conductivity, can enrich the active sites for redox reactions, facilitate electrolyte penetration and rapid charge transfer kinetics. As a result, the Cu(NiCo) 2 S 4 /Ni 3 S 4 electrode exhibits a high specific capacitance of 1320 F/g at 1 A/g and excellent rate performance (only 15% of capacitance is attenuated when the current density is increased by 20 times). Furthermore, a fabricated hybrid supercapacitor of Cu(NiCo) 2 S 4 /Ni 3 S 4 /AC can deliver a maximum energy density of 40.8 Wh/kg, remarkable power density of 7859.2 W/kg and superior cycling stability (85% retention of capacitance after 5000 cycles), demonstrating great potential for practical applications in energy storage and conversion devices. [ABSTRACT FROM AUTHOR]

Compressible and flexible supercapacitors have aroused enormous interest of many scientific researchers for potential applications in wearable electronic products. However, the design and construction of the electrode with superior mechanical as well as electrical properties still face a lot of challenges. In present work, melamine foam/polypyrrole (MF/PPy) electrode with high deformation-tolerance and excellent electrochemical performance is prepared by in-situ interfacial polymerization of polypyrrole on commercial melamine foam, where PPy nanoparticles with size of 700 nm are uniformly anchored on the MF skeletons. The electrochemical characterizations show that the electrode exhibits excellent specific area capacitance of 2.685 F cm−2 at 2 mA cm−2 and good cyclic stability with more than 80% of capacitance remained after 3000 cycles. Furthermore, a symmetrical aqueous supercapacitor is assembled and exhibits an excellent energy density up to 75.95 μWh cm−2 at the power density of 5.82 mW cm−2 and excellent cycling stability as the current density increases by 10 times. Even under a high strain of 70%, about 95.76% of the initial capacitance is retained after 500 consecutive compressions. These outstanding performances enable the MF/PPy composite a promising candidate for potential applications in compressible and flexible electrochemical energy storage devices. [ABSTRACT FROM AUTHOR]

The hollow and spinous NiCo 2 S 4 nanotubes were designed and prepared through hydrothermal sulfurization reaction using the degummed natural cocoon silk as a template. Recently, ternary cobalt nickel sulfide, performing as the promising electrode material for supercapacitors has obtained great interests. Herein, the hollow and spinous NiCo 2 S 4 nanotubes are designed and prepared through a simple hydrothermal reaction using the natural silk as the template. The spinous Ni-Co precursors are grown on the natural silk through a facile hydrothermal strategy and the hollow structure is obtained by decomposing the silk via hydrothermal sulfurization. After the calcination treatment, the hollow and spinous NiCo 2 S 4 nanotubes are applied as the electrode material and exhibit better electrochemical performance than the solely vulcanized samples. In addition, owing to the unique hollow and spinous structure of NiCo 2 S 4 nanotubes, the supercapacitor electrode material shows good specific capacitance (630 F g−1 at 1 A g−1), low internal resistance R s (0.68 Ω) and high capacitance retention (91% after 3000 cycles) at 10 A g−1. Furthermore, an all-solid-state asymmetric supercapacitor is self-assembled with the SC400 composite and exhibits an energy density of 52.34 Wh kg−1 at the power density of 2206.37 W kg−1. Additionally, a blue LED indicator can be powered by connecting two ASCs in series. The prepared hollow and spinous NiCo 2 S 4 nanotubes with excellent electrochemical properties can envision promising applications in energy storage devices and nanotechnology. [ABSTRACT FROM AUTHOR]