Low-energy hydrothermal fabrication of α-Ni(OH)2 nanosheet arrays as efficient electrodes for sustainable supercapacitors

This paper reports a low-energy pressure-free hydrothermal fabrication of α-Ni(OH)2 nanosheet arrays (NSAs) as effective electrodes for binder-free aqueous supercapacitors. The hydrothermal temperature was critical for the microstructure and electrochemical properties. At the low temperature of 95 °C, a highly interlaced α-Ni(OH)2 NSA was achieved. The successful preparation of uniform α-Ni(OH)2 NSAs was confirmed by several characterization techniques. For electrode applications in sustainable supercapacitors,the present α-Ni(OH)2 NSAs revealed a great capacitance of 1759 F/g, great rate capability of 50% at 20 A/g, and great cycle stability of 90.3% after 5000 cycles. Furthermore, aqueous two-electrode supercapacitors made of Ni(OH)2 NSAs possessed a large energy density of 44.5 Wh/kg at 400 W/kg. Therefore, this reduced energy hydrothermal preparation of α-Ni(OH)2 NSAs has great potential for efficient sustainable energy device applications.