A thin film of Ni nanocone arrays loaded with MnO2 nanostructures is prepared by an electro-deposition process and peeled off from the carrier substrate. This electrode shows superior performance for micro-supercapacitors.

To meet the rapidly growing demand, it is necessary to develop novel flexible energy storage devices with a high energy density in a limited area, a fast charging ability, a low cost for mass production and a miniaturized device size. To address the above issues, here we introduce the co-electro-deposition strategy, which is able to prepare an electrode material with a high areal capacitance (1670 mF cm À2 at 0.5 mA cm À2 ), a high areal mass (8.5 mg cm À2 ), an excellent mechanical robustness, a high through-put and great convenience even on a piece of a ubiquitous stainless steel mesh current collector. Based on this advancement, we are able to obtain an ultrathin (less than 200 mm) aqueous asymmetric supercapacitor device with a high energy density (1.8 Â 10 À3 W h cm À3 ), a high power density (0.38 W cm À3 at 3.62 Â 10 À4 W h cm À3 ) and an excellent rate capability. This energy storage device is integrated into a prototype smart card to drive a light emitting diode (LED) indicator, which is charged for 5 seconds and can light up the indicator for more than 2 hours, demonstrating great promise in miniaturized novel flexible energy storage devices.

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To determine the effect of F − on the electrochemical formation of Zr, the reduction mechanism, kinetic properties, and nucleation mechanism of Zr(IV) were compared in the LiCl−KCl−K 2 ZrF 6 system before and after the addition of F − at different concentration ratios of F − /Zr(IV). As indicated by the results, when the ratio of F − /Zr(IV) ranged from 7 to 10, the intermediate state Zr(III) was detected, and the reduction mechanism of Zr(IV) was converted into Zr(IV) → Zr(III) → Zr. The diffusion coefficients of Zr(IV), Zr(III), and Zr(II) decreased with an increase in the value of F − /Zr(IV). The exchange current density (j 0 ) of Zr(II)/Zr exceeded that of Zr(III)/Zr, and the j 0 and α values of Zr(III)/Zr decreased with the increase of F − /Zr(IV). The nucleation mechanism at different ratios of F − / Zr(IV) was investigated through chronoamperometry. The result suggested that the nucleation mechanism of Zr varied with the overpotential at F − /Zr(IV) = 6. The addition amount of F − led to the variation of the nucleation mechanism of Zr, i.e., progressive nucleation when F − /Zr(IV) = 7 and instantaneous nucleation when F − /Zr(IV) = 10. Zr was prepared through constant current electrolysis at different concentrations of F − and then analyzed through X-ray diffraction (XRD) and scanning electron microscopy (SEM), suggesting that the concentration of F − can exert a certain effect on the surface morphology of products.

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Electrically conductive composites have been intensively studied as the interconnects and the printed lines in the next generation of electrical devices. Silver fillers have been widely accepted as the key conductive filler material due to their excellent electrical conductivity, malleability, chemical and mechanical stability. Here we for the first time introduce a scalable synthesis of the mono-dispersed silver dendrites with 3-D micro-and nano-structures, and their uses as the conductive filler for the electrically conductive adhesives (ECAs) with ultralow silver content. These silver dendrites have a unique 3-D fractal structure, which are able to provide excellent low-temperature sintering ability due to the abundant nanostructures at the edge of the dendrite leaves. This feature renders them form excellent electrical percolation network with ultralow concentration (percolation threshold down to 20 wt%) in conventional engineering resins, which is currently the one with the lowest percolation threshold for the micro-metal-filler based ECAs. Thermal analysis (TGA/DSC) and scanning electron microscopy (SEM) suggest that the silver dendrite powders go through a sintering process at the temperature below 150 ºC, thus the adjacent dendrites are able to form effective ohmic conductance. Considering the low materials preparation cost and negligible environmental risk, this method suggests an effective way to develop environmentally benign materials for the flexible printed electronics devices.

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