Abstract:Nickel oxide (NiO) hollow microspheres with hierarchical structure were fabricated through a process consisting of a self-assembling, hydrothermal reaction and calcination. The prepared NiO hollow microspheres composed of many nanoflakes, are about 2-3 μm in diameter. The length of the NiO flakes, having clear edges, is about 500-700 nm, while the thickness is only about 40-50 nm. This indicates that the NiO microspheres possess a hierarchical structure that can provide porous channels to facilitate the transmission of both electrons and electrolyte ions. NiO microspheres exhibit a high specific capacitance of about 1340 F/g at a current density of 1 A/g and high capacitance retention about 96.5% after 1000 cycles. What’s more, the conductive mechanism of nickel oxide for electrochemical capacitor electrodes was also studied.

Key words: nickel oxide hollow microsphere; hierarchical structure; controllable preparation; self-assembling; pseudo-capacitance