A nickel hydroxide-coated 3D porous graphene hollow sphere framework as a high performance electrode material for supercapacitors

Abstract

A three-dimensional (3D) porous graphene hollow sphere (PGHS) framework has been fabricated via a hard template method and used to anchor α-Ni(OH)₂ nanoparticles with the size of about 4 nm through electrochemical deposition. It is found that a 3D PGHS framework can improve the capacitive performance of Ni(OH)₂ effectively. In hybrid materials, α-Ni(OH)₂ achieves the high specific capacitance of 2815 F g⁻¹ at a scan rate of 5 mV s⁻¹ and 1950 F g⁻¹ even at 200 mV s⁻¹ with a capacitance retention of about 70%, indicating that the α-Ni(OH)₂-coated 3D PGHS framework exhibits high rate capability. The excellent performance of such hybrid material is believed to be due to the smaller size of Ni(OH)₂ nanoparticles and the PGHS framework with large specific surface area promoting efficient electron transport and facilitating the electrolyte ions migration. These impressive results suggest that the composite is a promising electrode material for an efficient supercapacitor.