Development of high-utilization honeycomb-like α-Ni(OH)2 for asymmetric supercapacitors with excellent capacitance

Abstract

The low utilization rate of active materials has been a critical obstacle for the industrialization of ultracapacitors. In this study, a thin layer of cross-structured ultrathin α-Ni(OH)2 nanosheets was successfully grown in situ on the surface of a nickel foam as a high-conductivity framework by a vibratory water bath route under a low temperature (80 °C) and mild conditions. Combining the ultrathin α-Ni(OH)2 nanosheets and ultrashort electron transport, the strategy of a perfect intercalation structure of α-Ni(OH)2 and a thin layer of active material on a continuous conductive framework resulted in a high utilization rate of active material, which further achieved high specific capacitance of 213.55 F g−1 at 1 A g−1 in a two-electrode system and high capacitance retention from three to two electrode system (753.79 F g−1 at 1 A g−1 in the three-electrode system). Meanwhile, the device also achieved high energy density of 74.94 W h kg−1 at power density of 197.4 W kg−1 and still retained 24.87 W h kg−1 at power density of 3642 W kg−1.