Ni(OH)2/NiO/Ni composite nanotube arrays for high-performance supercapacitors

Abstract

Transition metal oxide nanostructures are one of current investigation focuses for energy storage applications. We herein report a novel template-free electrochemical approach to fabricate Ni(OH)2/NiO/Ni composite nanotube array films on the nickel substrate. The inner diameter of the composite nanotubes can be effectively tuned by tailoring the concentration of Cu2+ in the precursor solutions. The as-constructed composite nanotube array film electrode, which is fabricated by the electrochemical approach using the 0.1 M Cu2+ containing precursor solution, delivers the specific capacitance of 1070 F g−1 at the current density of 15 A g−1 after 10,000 charge–discharge cycles. The specific capacitance of the cycled electrode at 150 A g−1 is as much as 79.3% of that at 15 A g−1, demonstrating its excellent rate capability. The cycled electrode presents a high specific energy density of 31.4 Wh kg−1 at a larger power density of 11.1 kW kg−1. The excellent pseudocapacitive performance of the Ni(OH)2/NiO/Ni composite nanotube array electrodes can be attributed to their unique structure characteristics.