Morphology-dependent electrochemical performances of nickel hydroxide nanostructures

Abstract

Electrochemical capacitors form part of the developing technologies in the field of alternative energy sources. In the present work, nickel hydroxide (Ni(OH) 2) nanosheets and microflowers are hydrothermally prepared employing different chemical precursors. Structure, morphology and chemical analysis are conducted using powder X-ray diffraction, field emission scanning electron microscopy and energy-dispersive X-ray spectroscopy measurements. Electrochemical performances as supercapacitor electrodes of the synthesized nanostructures are evaluated through cyclic voltammetry and galvanostatic charge-discharge measurements with three-electrode configurations. The results indicated the specific capacitance of 180 and 417 F g −1 at a scan rate of 5 mV s −1 for Ni(OH) 2 nanosheets and microflowers, respectively. The higher specific capacitances for Ni(OH) 2 microflowers could be attributed to the higher specific surface area, morphology, electronic conductivity and porosity. Both Ni(OH) 2 nanostructures exhibited good capacitance retention for 1500 cycles.

The effect of template residual content on supercapacitive characteristics of Ni(OH)2, obtained by template homogeneous precipitation

“…Difficulties with template removal lead to the whole template-free direction for the preparation of ultrafine systems, such as calcium titanate [47] and zeolite ZSM-5 [48]. The paper [49,50] describes the method for template-free synthesis of nanosized Ni(OH) 2 . For supercapacitor applications, the presence of the template in the active material can lead to partial blocking of the material surface, template oxidation, and other side-effects.…”

Synthesis of Ni(OH)2, suitable for supercapacitor application, by the cold template homogeneous precipitation method

“…The complexity of template removal led to the emergence of a whole "template-free" direction, i.e., template-free synthesis of ultradispersed systems, for example, the preparation of calcium titanate [47] and zeolite ZSM-5 [48]. Template-free synthesis is used to obtain nanosized Ni(OH) 2 [49,50]. When used in a supercapacitor, the presence of a template in the composition of the active substance can lead to partial blocking of the particle surface and other side effects.…”