One-pot hydrothermal synthesis of flower-like β-Ni(OH)2 encapsulated by reduced graphene oxide for high-performance supercapacitors

Flower-like β-Ni(OH)2 encapsulated by flexible reduced graphene oxide (rGO) nanosheets have been synthesized by one-pot hydrothermal process and were used as Faradaic electrodes for supercapacitors. β-Ni(OH)2 microflowers whose particle sizes ranging from 1.7 to 2.5 μm were effectively encapsulated by flexible rGO nanosheets. Due to the efficient charge transfer and unimpeded ion transports, such β-Ni(OH)2/rGO composites can deliver ultrahigh specific capacity of 618 C g−1 at a current density of 3 A g−1 and maintain 276 C g−1 at 30 A g−1 in 6 M KOH electrolyte. Besides, the β-Ni(OH)2/rGO composite electrode exhibits outstanding cyclic stability. When tested at a current density of 10 A g−1, high capacity retention ratio up to 90% can be achieved for the composite electrode after 2000 cycles. The outstanding cycling stability can be mainly attributed to rGO-encapsulating structure that effectively prevent the descent of electrical conductivity for the entirety of the electrode during the cycle processes. The ultrahigh specific capacity together with superb cycle performance make such composite a prospective candidate in capacitive energy storage field.