Ionic liquid-assisted grown of beta-nickel hydroxide nanowires on reduced graphene oxide for high-performance supercapacitors

Beta-nickel hydroxide nanowires/reduced graphene oxide (RGO) composites are fabricated by a one-step reactable ionic liquid-assisted hydrothermal method, using the versatile 1-butyl-3-methylimidazolium trifluoroacetate as templates, co-solvents and reactants. The results show that β-Ni(OH)2 nanowires are well dispersed on the surface of reduced graphene oxide sheets, and the as-prepared β-Ni(OH)2 nanowires/RGO composite exhibits a huge BET surface area of 216.99 m2 g−1 with a pore volume of 0.34 m3 g−1. Furthermore, β-Ni(OH)2 nanowires/RGO composite as an electrode material for supercapacitors displays high specific capacitance, good cycling stability and coulombic efficiency. An extremely high specific capacitance of ∼1875 F g−1 can be obtained at 1 A g−1 in 6 M KOH aqueous solution, and retains 98.3% of its original capacity after 1000 charge-discharge cycles at 8 A g−1. The resulting composite is a promising candidate as an electrode material for extensive applications in energy storage systems.