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

•Ni(OH)2/NiO/Ni composite nanotube arrays are fabricated by an electrochemical method.•The inner diameter of the composite nanotube arrays can be conveniently tuned.•The composite nanotube arrays show high electrochemical cycling stability.•The composite nanotube arrays exhibit large capacitances at high current rates.

ABSTRACTTransition 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.

Graphical abstractA novel template-free electrochemical approach is developed to fabricate Ni(OH)2/NiO/Ni composite nanotube arrays. The as-fabricated Ni(OH)2/NiO/Ni composite nanotube array electrodes show prominent pseudocapacitance properties, especially at high current rates.Figure optionsDownload full-size imageDownload as PowerPoint slide