3D flower-like β-Ni(OH)2/GO/CNTs composite was prepared via a facile phase transformation method with a high specific capacitance of ∼1815 F g−1 (nearly 96% of its theoretical pseudocapacitance) at 2 A g−1 and a good cycling performance of ∼97% capacitance retention after 2000 cycles at 10 A g−1. The morphology of β-Ni(OH)2 undergoes successive changes that could be controlled by adjusting the reaction time.
