Polyvinylpyrrolidone and freeze drying-assisted growth of an α-Ni(OH)2/reduced graphene oxide hybrid structure as a superior electrode material for supercapacitors

Herein, alpha-Ni(OH)(2) ultrathin sheets on reduced graphene oxide layers were synthesized via a simple single-step precipitation process. The structure, morphology, and chemical composition of the as-synthesized alpha-Ni(OH)(2)/rGO hybrid structure are well characterized using X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy. A 30 wt% alpha-Ni(OH)(2)/rGO denoted as NG2 achieved a superb supercapacitor performance, displaying specific capacitance (capacity) of 1050 F g(-1) (580 C g(-1)) at 1 A g(-1) current density. The assembled supercapacitor delivered specific energy of 60 W h kg(-1) at a specific power of 1.1 kW kg(-1). Still, it retained a high specific power of 3.9 kW kg(-1) at 43 W h kg(-1), demonstrating a retention percentage of 88% after 4000 repetitive charge/discharge cycles.

Automated summary

Alpha-Ni(OH)(2) ultrathin sheets were successfully synthesized on reduced graphene oxide layers via a simple single-step precipitation process. The synthesized alpha-Ni(OH)(2)/rGO hybrid structure exhibited excellent supercapacitor performance, showing high specific capacitance and specific energy.