A Ni(OH)₂ nanopetals network for high-performance supercapacitors synthesized by immersing Ni nanofoam in water

Abstract

Developing a facile and environmentally friendly approach to the synthesis of nanostructured Ni(OH)2 electrodes for high-performance supercapacitor applications is a great challenge. In this work, we report an extremely simple route to prepare a Ni(OH)2 nanopetals network by immersing Ni nanofoam in water. A binder-free composite electrode, consisting of Ni(OH)2 nanopetals network, Ni nanofoam interlayer and Ni-based metallic glass matrix (Ni(OH)2/Ni-NF/MG) with sandwich structure and good flexibility, was designed and finally achieved. Microstructure and morphology of the Ni(OH)2 nanopetals were characterized. It is found that the Ni(OH)2 nanopetals interweave with each other and grow vertically on the surface of Ni nanofoam to form an “ion reservoir”, which facilitates the ion diffusion in the electrode reaction. Electrochemical measurements show that the Ni(OH)2/Ni-NF/MG electrode, after immersion in water for seven days, reveals a high volumetric capacitance of 966.4 F/cm3 at a current density of 0.5 A/cm3. The electrode immersed for five days exhibits an excellent cycling stability (83.7% of the initial capacity after 3000 cycles at a current density of 1 A/cm3). Furthermore, symmetric supercapacitor (SC) devices were assembled using ribbons immersed for seven days and showed a maximum volumetric energy density of ca. 32.7 mWh/cm3 at a power density of 0.8 W/cm3, and of 13.7 mWh/cm3 when the power density was increased to 2 W/cm3. The fully charged SC devices could light up a red LED. The work provides a new idea for the synthesis of nanostructured Ni(OH)2 by a simple approach and ultra-low cost, which largely extends the prospect of commercial application in flexible or wearable devices.

The Effect of an External Magnetic Field on the Electrochemical Capacitance of Nanoporous Nickel for Energy Storage

“…As shown in Figure 2c, the average specific capacitances of the np-Ni 0 electrode were calculated as 96, 63, 59, and 40 F g −1 , while the average specific capacitances of the np-Ni 500 electrode were calculated as 180, 139, 99, and 57 F g −1 , at the scan rates of 5, 10, 20, and 50 mV s −1 , respectively. The specific capacitance decreased gradually with the increasing of the scan rate, which agrees with the literature [32,33]. According to the mathematical relation between specific capacitance (F g −1 ) and specific charge capacity (mAh g −1 ), 1 F g −1 = 1 mAh g −1 × 3.6 C (mAh g −1 ) −1 /Δ V , where Δ V is the potential range for discharge, and the specific charge capacities of the np-Ni 0 electrode were calculated as 15, 10, 9, and 6 mAh g −1 at the scan rates of 5, 10, 20, and 50 mV s −1 , respectively.…”

Electrodeposition of NiSn-rGO Composite Coatings from Deep Eutectic Solvents and Their Physicochemical Characterization

“…The presence of a thin film is observed on top of both samples, evidencing a nano-petal like morphology, which may be ascribed to the formation of a nickel oxy-hydroxide layer. A similar morphology was reported in [54] for Ni(OH) 2 nanostructures formed as corrosion products on Ni nanofoams. After 336 h of immersion in 0.5 M NaCl, the morphology of the sample was analyzed by SEM, as illustrated in Figure 17.…”

In Situ Formation of Nano Ni–Co Oxyhydroxide Enables Water Oxidation Electrocatalysts Durable at High Current Densities

“…Diffraction rings at 2.5, 2.1, 1.5Å were clearly observed, corresponding to the (111), (100), and (110) crystal planes of CoO/Co(OH) 2 , carbon, and Ni(OH) 2 , respectively. [ 24,25 ]…”