A Ten-Minute Synthesis of α-Ni(OH)2 Nanoflakes Assisted by Microwave on Flexible Stainless-Steel for Energy Storage Devices

Abstract

Although numerous methods have been widely used to prepare nickel hydroxide materials, there is still a demand for lowering the required heating time, temperature, and cost with maintaining a high-quality nanomaterial for electrochemical energy storage. In this research, we study the relationship between microwave-assisted heating parameters and material properties of nickel hydroxide nanoflakes and evaluate their effect on electrochemical performance. X-ray diffraction spectra show that the samples prepared at the highest temperature of 220 °C have crystallized in the beta phase of nickel hydroxide crystal. While the sample synthesized at 150 °C in 30 min contains both beta and alpha phases. Interestingly, we obtained the pure alpha phase at 150 °C in just 10 min. A scanning electron microscope shows that increasing the temperature and heating time leads to enlarging the diameter of the macro-porous flower-like clusters of interconnected nanoflakes. Electrochemical measurements in potassium hydroxide electrolytes demonstrate that the alpha phase’s electrodes have much higher capacities than samples containing only the beta phase. The maximum areal capacity of 17.7 µAh/cm2 and gravimetric capacity of 35.4 mAh/g are achieved, respectively, at 0.2 mA/cm2 and 0.4 A/g, with a small equivalent series resistance value of 0.887 ohms on flexible stainless-steel mesh as a current collector. These improved nickel hydroxide electrodes can be ascribed to utilizing the diffusion-controlled redox reactions that are detected up to the high scan of 100 mV/s. Such fast charge-discharge processes expand the range of potential applications. Our nickel hydroxide electrode, with its rapid preparation at medium temperature, can be a cost-effective candidate for flexible supercapacitors and batteries.

Nickel Hydroxides: Requirements, Targeted Construction and Choice of Characteristics and Industrially Applicable Synthesis for Targeted Use in Electrochemical Devices

“…Nickel hydroxides, both in the form of an individual substance [6–8] and in the composite form [9,10] are used as the active substance of the Faraday electrodes of hybrid supercapacitors. When manufacturing electrodes for thin‐layered supercapacitors, a Ni(OH) 2 film is formed on a conductive base [11–13] …”

“…When manufacturing electrodes for thin-layered supercapacitors, a Ni(OH) 2 film is formed on a conductive base. [11][12][13] Nickel hydroxides have electrocatalytic properties and can be used for the electrochemical oxidation of methanol [14,15] or oxygen evolution. [16] Nickel hydroxides can also be used as an active substance for sensors.…”

Non-enzymatic Glucose Sensor Based on Ni(OH)2/NF Materials Using Different Pulse Voltammetry Technique

“…In response to this challenge, numerous transition metal oxides or metal hydroxides, such as NiO, CuO, Co3O4 [6,7], and Ni(OH)2, [8,9] have emerged as promising materials. Among these cost-effective candidates, nanostructures of Ni(OH)2, a significant transition metal hydroxide, hold great promise as active electrode materials in non-enzymatic glucose electrochemical sensors [10].…”

“…Among these cost-effective candidates, nanostructures of Ni(OH)2, a significant transition metal hydroxide, hold great promise as active electrode materials in non-enzymatic glucose electrochemical sensors [10]. Ni(OH)2 materials can be fabricated via solgel synthesis [9], hydrothermal, and solvothermal methods [8] and then deposited on the electrode surface using a binder. Using a binder may increase electrode mass, modify electrode surface, or decrease charge transfer.…”

Investigation of the mechanism of nickel hydroxide formation from nickel nitrate

“…Ni(OH) 2 is used both individually [5] (in the form of nanoparticles [6] or ultrafine particles [7]) and as composite materials with nanocarbon structures (graphene oxide [8], carbon nanotubes [9]). For thin-layer supercapacitors, a Ni(OH) 2 film is formed during the manufacture of electrodes on a conductive basis [10,11].…”