Controllable synthesis of hierarchical nanoporous carbon@Ni(OH)2 rambutan-like composite microspheres for high-performance hybrid supercapacitor

Design of electrode materials with excellent electrochemical properties for advanced energy storage device are important to the sustainable development of energy resources. In this manuscript, a novel hierarchical nanoporous [email protected] hydroxide ([email protected](OH)2) composites were prepared through simple in-situ chemical deposition of Ni(OH)2 nanocrystals on HNCMs. By tailoring the deposition amount, core–shell structured rambutan-like [email protected](OH)2 microspheres with hairy nickel hydroxide nanocrystal covered on HNCMs were obtained. Ascribed to the high specific capacitance of nickel hydroxide and the interconnected hierarchical porous structure of HNCMs, the resultant rambutan-like [email protected](OH)2 microspheres as electrode materials display outstanding electrochemical properties including high specific capacity of 248.9 mAh/g at 1 A/g and good capacitance retention of 62.9% at 20 A/g. Furthermore, a hybrid supercapacitor with rambutan-like [email protected](OH)2 microspheres as cathode and HNCMs as anode were assembled and showed a comparable energy density of 41.3 Wh/kg at the power density of 173.3 W/kg and high capacity retention of 85.2% after 20,000 cycles at 5 A/g. As a proof of concept example, the fabricated hybrid supercapacitor can be utilized as energy source to instantaneous light up a red LED indicator. We envisioned that the as-prepared rambutan-like [email protected](OH)2 microspheres have great potential in constructing of advanced energy storage devices.