LAUSR

Abstract Cotton-like NiO is formed on the surface of bare Ni foam after hydrothermal process and calcination process, while ultrathin NiO nanoflakes occur on Ni foam coated with graphene. The high specific capacitance of 1782 F g− 1 at 1 A g− 1 and 90.2% capacity retention at 1 A g− 1 after 5000 cycles charge-discharge test are found. The graphene induces the high electrical conductivity and excellent interfacial contact, in addition, the graphene facilitates the forming of ultrathin NiO nanoflakes which result in huge pseudocapacitance due to large surface area and abundant mesoporous. The unique microstructure characteristic promotes interfacial electron transport in the electrode material and improves ion diffusion during the electrochemical reaction process.